tag:blogger.com,1999:blog-83274735692145717732024-02-19T07:10:54.504-08:00Dummies Guide To Precision Farmingintansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.comBlogger90125tag:blogger.com,1999:blog-8327473569214571773.post-87376726339147100032008-10-28T14:51:00.000-07:002008-10-28T14:58:29.162-07:00Training and Pruning (1)In general greenhouse crops (tomatoes, peppers and cucumbers) are indeterminant (vining) types to take advantage of the vertical volume of the greenhouse. The plant vines are supported on vine twine by vine clips. The twine is wrapped around some sort of device from which it can be unwound (tomahook, bobbin, etc.).<br />Plants are trained up the twine to the wires forming a “V” shape. As the plants grow up to the overhead support wire, the twine is unwound, the plants lowered and shifted one space – “LEANED AND LOWERED”.<br />Tomato vines should not be lowered more than 2 feet at a time OR another good way to tell, DO NOT lower the vine such that an 80 or higher degree bend is created in the vine near the floor. High angles promote stem cracking. Plants are trained to 1-3 stems by removing (pruning) side shoots or “suckers”.<br /><span style="font-weight: bold; color: rgb(204, 0, 0);">Tomatoes</span> are trained to 1 stem (or 2 stems to replace a topped or broken neighbor<br />or during a season of high light, i.e., Spring or early Summer).<br /><span style="font-weight: bold; color: rgb(255, 153, 0);">Peppers</span> are usually trained to 2 or 3 stems. Their stems are much more brittle<br />than tomatoes and tend to snap if they are leaned and lowered.<br /><span style="font-weight: bold; color: rgb(0, 102, 0);">Cucumbers</span> have traditionally been trained using such methods as the “V-cordon”<br />or “umbrella”. However, they can also be trained to 1 stem like tomatoes.<br />*Side shoots or suckers are so named because they suck nutrients from the main plant.<br />The process of removing suckers = “sucker pruning” or “suckering”.intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-87374925856356433442008-08-28T19:36:00.000-07:002008-08-28T19:37:21.704-07:00General Cultural Practices - Plant Spacing & Crop Layout<div style="text-align: justify;"><span style="font-weight: bold; color: rgb(153, 51, 0);"></span><span style="font-weight: bold;"><br />Plant spacing is determined by two main factors:</span><br />1) <span style="color: rgb(153, 0, 0); font-weight: bold;">The availability of light to the canopy</span> - Plants must be far enough apart so that a maximum amount of light reaches the leaves for optimum photosynthesis.<br />2) <span style="font-weight: bold; color: rgb(153, 0, 0);">The availability of water and nutrients to the roots</span> - Plants must be far enough apart so that all plants have an optimum supply of these items.<br />*Plant spacing in “vining” greenhouse crops, including tomatoes, is much closer than for field crops.<br />Example: Field (bush) tomatoes = 4000 – 5000 plants/acre.<br />Hydroponic greenhouse tomatoes = 10,000 – 11,000 plants/acre.<br />*Why? A vine has a much smaller diameter than a bush, so they can be closer together and the leaves will still obtain optimum light for photosynthesis. <span style="color: rgb(0, 0, 0);">The roots of a plant growing in hydroponics receives all the water and nutrients</span><span style="color: rgb(0, 0, 0);"> </span><span style="color: rgb(0, 0, 0);">it requires</span><span style="color: rgb(0, 0, 0);">. </span>They are “spoon-fed” and do not have to grow large systems. The roots of a field grown plant will be more spread out as they search for water and nutrients in the soil matrix. Therefore, field grown plants must be positioned far enough apart to avoid competition of neighboring plants for water or nutrients. NOTE: Drip irrigation allows for closer spacing.<br />*Typical hydroponic plant spacing:<br /></div><ul style="text-align: justify;"><li>Tomatoes = 2.5 – 3 plants per square meter</li><li>Peppers = 2.5 – 4 plants per square meter</li><li>Cucumbers = 1.25 – 3 plants per square meter</li><li>Melon = 2.5 - 3 plants per square meter<br /></li></ul><div style="text-align: justify;">*The typical layout of the greenhouse for vining vegetable crops is in rows tending approximately north and south. This is important because during the day the sun moves from east to west and if the rows were also set up east to west the southern most rows (in the<br />northern hemisphere) would shade the rows behind them. Typically, tomatoes are also grown in “double rows”. These double rows are usually 5-6 feet apart. With 3 plants per Rockwool slab (1 meter long each) or perlite bag (about 36”), sets of 2 slabs/bags are placed side by side. With 6 plants per slab/bag a single row of slabs/bags is used. Overhead support wires are set at least 2 feet apart.<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFyRqPgg9YDW7EkO5S8G74sni-fPSIXgvLNCReNn-qV8PXXOHbZaJjwrvszFFe51daIzqkauevcEFP8OeW005BYZFsYZNSwwrdh7jIC97oiXrN7SV3FgpGMbjQjn4jdyOeJFb41QhoXP4u/s1600-h/Jarak+Pokok.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFyRqPgg9YDW7EkO5S8G74sni-fPSIXgvLNCReNn-qV8PXXOHbZaJjwrvszFFe51daIzqkauevcEFP8OeW005BYZFsYZNSwwrdh7jIC97oiXrN7SV3FgpGMbjQjn4jdyOeJFb41QhoXP4u/s400/Jarak+Pokok.png" alt="" id="BLOGGER_PHOTO_ID_5236394066261653522" border="0" /></a></div>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-80088340165366440232008-08-28T19:34:00.000-07:002008-08-28T19:35:11.217-07:00GENERAL CULTURAL PRACTICES : Enviromental Conditions Required - 2<div style="text-align: justify;"><span style="color: rgb(153, 51, 0);"></span><br />2) <span style="font-weight: bold; color: rgb(0, 0, 153);">TEMPERATURE</span>: The optimum growing temperatures (day and night) vary for different<br />plant species and different varieties within a species. Eg. for most Tomatoes, germination and post-emergence temperatures = 23-25 C (74-77 F). Production optimum temperatures = 22 C (72 F) day/20C (68 F) night.<br /><br />3) <span style="font-weight: bold; color: rgb(0, 0, 153);">RELATIVE HUMIDITY (RH)</span>: The amount of water in the air compared to the total amount of water that the air can hold at a given temperature. %RH = Amount of water in the air X 100 Amount of water possible at a given temp. As the temperature increases the amount of water that the air can hold increases. When the air is saturated water molecules condense. This causes clouds when at altitude or fog when near the ground. How does this relate to tomato plants growing in a greenhouse? As the RH increases around the leaf (concentration of water molecules outside increases) it makes it more difficult for the water molecules inside the leaf to move out (transpiration) via diffusion (the passive movement of a substance from high to low concentration . Therefore, as the RH increases, transpiration decreases, water and therefore<br />nutrient movement decrease, and nutrient deficiencies can result. ALSO, as RH increases and transpiration decreases, leaf temperatures often increase, since transpiration is the plant’s way of cooling itself.<br />Optimum RH range for tomatoes (and most plants) = 55% - 95%. During hot, dry weather, fan and pad cooling adds moisture to the air. On hot, humid days, fan and pad cooling adds moisture but does not cool as well. During cool, damp weather, RH inside the greenhouse can approach 95%.<br /><br />4) <span style="font-weight: bold; color: rgb(0, 0, 153);">CARBON DIOXIDE</span>: As mentioned earlier, carbon dioxide is critical for photosynthesis and enrichment is most important during the Winter on cold mornings. Outside ambient levels are around 330 ppm, part per million, (higher in cities due to industrial exhaust products). Enrichment = 800 to 1000 ppm.<br /><br />5) <span style="font-weight: bold; color: rgb(0, 0, 153);">AIR CIRCULATIONS</span>: This avoids pockets of high or low temperature, humidity or carbon dioxide. This also reduces the BOUNDARY LAYER (the physical “still air” layer around<br />the leaf) so that proper gas exchange and transpiration can occur. When cooling fans are off use HAF (horizontal air flow) fans in the upper part of the greenhouse.<br /><br />6) <span style="font-weight: bold; color: rgb(0, 0, 153);">OXYGEN</span>: All parts of the plant require oxygen for respiration. There is usually no problem supplying the top part of the plant with enough. But waterlogging and high temps. will inhibit oxygen movement to the roots.</div>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-16544384963902731542008-07-06T17:14:00.000-07:002008-07-06T19:07:20.008-07:00GENERAL CULTURAL PRACTICES : Enviromental Conditions Required - 1<div style="text-align: justify;"><span style="font-size:130%;">These factors includes 1) </span><span style="color: rgb(153, 0, 0); font-weight: bold;font-size:130%;" >Light</span><span style="font-size:130%;"> 2) </span><span style="color: rgb(153, 0, 0); font-weight: bold;font-size:130%;" >Temperature</span><span style="font-size:130%;"> 3) </span><span style="color: rgb(153, 0, 0); font-weight: bold;font-size:130%;" >Relative Humidity (RH)</span><span style="font-size:130%;"> 4) </span><span style="font-weight: bold; color: rgb(153, 0, 0);font-size:130%;" >Carbon Dioxide </span><span style="font-size:130%;">5) </span><span style="font-weight: bold; color: rgb(153, 0, 0);font-size:130%;" >Air Circulation</span><span style="font-size:130%;"> and 6) </span><span style="font-weight: bold; color: rgb(153, 0, 0);font-size:130%;" >Oxygen</span><span style="font-size:130%;">. First we will cover - </span><span style="font-weight: bold; color: rgb(0, 0, 153);font-size:130%;" >Light</span><span style="font-size:130%;">: Two factors are important and can be affected by greenhouse structures and coverings . NOTE: Both of these vary with plant species.<br /></span></div><ul style="text-align: justify;"><li><span style="font-weight: bold;font-size:130%;" >Quality</span><span style="font-size:130%;">: Refers to wavelengths of light. (Remember in physics: light spectrum) Visible light = 390-760 nm: blue at the low end, red at the high end. PAR (</span><span style="font-style: italic;font-size:130%;" >photosynthetically active radiation</span><span style="font-size:130%;">) = between 400 and 700 nm (blue, yellow, orange and red… but not green)NOTE: This varies slightly for each plant species.</span></li><li><span style="font-weight: bold;font-size:130%;" >Quantity</span><span style="font-size:130%;">: Is affected by both day length and sun angle (changes with season): Day Length & Sun Angle.<br /></span></li></ul><div style="text-align: justify;"><span style="font-size:130%;">**The quantity (amount) of light reaching the Earth’s surface is therefore higher in Summer than it is in Winter.<br />**For tomatoes in the desert southwest or other high light areas:<br /></span></div><ol style="text-align: justify;"><li><span style="font-size:130%;">During the Winter or times of low light the quantity of light available is enough to support 3 – 4 fruit/cluster.</span></li><li><span style="font-size:130%;">During Spring/Summer/Fall the quantity of light may be too high and shading may be needed. 4 – 5 fruit/cluster is typical.</span></li></ol>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-21093919144889956512008-07-06T17:12:00.001-07:002008-07-06T17:17:29.320-07:00GENERAL CULTURAL PRACTICES : Enviromental Conditions Required - 2<span style="font-size:130%;">2) </span><span style="font-weight: bold; color: rgb(0, 0, 153);font-size:130%;" >TEMPERATURE</span><span style="font-size:130%;">: The optimum growing temperatures (day and night) vary for different<br />plant species and different varieties within a species. Eg. for most Tomatoes, germination and post-emergence temperatures = 23-25 C (74-77 F). Production optimum temperatures = 22 C (72 F) day/20C (68 F) night.<br /><br />3) </span><span style="font-weight: bold; color: rgb(0, 0, 153);font-size:130%;" >RELATIVE HUMIDITY (RH)</span><span style="font-size:130%;">: The amount of water in the air compared to the total amount<br />of water that the air can hold at a given temperature. %RH = Amount of water in the air X 100<br />Amount of water possible at a given temp. As the temperature increases the amount of water that the air can hold increases. When the air is saturated water molecules condense. This causes clouds when at altitude or fog when near the ground. How does this relate to tomato plants growing in a greenhouse? As the RH increases around the leaf (concentration of water molecules outside increases) it makes it more difficult for the water molecules inside the leaf to move out (transpiration) via diffusion (the passive movement of a substance from high to low concentration . Therefore, as the RH increases, transpiration decreases, water and therefore<br />nutrient movement decrease, and nutrient deficiencies can result. ALSO, as RH increases and transpiration decreases, leaf temperatures often increase, since transpiration is the plant’s way of cooling itself.<br />Optimum RH range for tomatoes (and most plants) = 55% - 95%. During hot, dry weather, fan and pad cooling adds moisture to the air. On hot, humid days, fan and pad cooling adds moisture but does not cool as well. During cool, damp weather, RH inside the greenhouse can approach 95%.<br /><br />4) </span><span style="font-weight: bold; color: rgb(0, 0, 153);font-size:130%;" >CARBON DIOXIDE</span><span style="font-size:130%;">: As mentioned earlier, carbon dioxide is critical for photosynthesis and enrichment is most important during the Winter on cold mornings. Outside ambient levels are around 330 ppm, part per million, (higher in cities due to industrial exhaust products). Enrichment = 800 to 1000 ppm.<br /><br />5) </span><span style="font-weight: bold; color: rgb(0, 0, 153);font-size:130%;" >AIR CIRCULATIONS</span><span style="font-size:130%;">: This avoids pockets of high or low temperature, humidity or carbon dioxide. This also reduces the BOUNDARY LAYER (the physical “still air” layer around<br />the leaf) so that proper gas exchange and transpiration can occur. When cooling fans are off use HAF (horizontal air flow) fans in the upper part of the greenhouse.<br /><br />6) </span><span style="font-weight: bold; color: rgb(0, 0, 153);font-size:130%;" >OXYGEN</span><span style="font-size:130%;">: All parts of the plant require oxygen for respiration. There is usually no problem supplying the top part of the plant with enough. But waterlogging and high temps. will inhibit oxygen movement to the roots.</span>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-71661406074963681102008-05-23T16:44:00.000-07:002008-12-11T23:42:34.659-08:00Guide To Propagate Chilly seedlings<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFQLZJIClBoKTsHXrACntXAf1VC4WoLteDPNFn3K6zF5KPlHNj6_l9PsGSDCqICAUrnI0qV-lItZA8yRptkeDu4jskGnwWNbkmsEMhOuJhyHF4jyYBw_oXf9LC9RhoaLAtnI9TLwWyuYw2/s1600-h/2081133082_367efa73db_m.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFQLZJIClBoKTsHXrACntXAf1VC4WoLteDPNFn3K6zF5KPlHNj6_l9PsGSDCqICAUrnI0qV-lItZA8yRptkeDu4jskGnwWNbkmsEMhOuJhyHF4jyYBw_oXf9LC9RhoaLAtnI9TLwWyuYw2/s400/2081133082_367efa73db_m.jpg" alt="" id="BLOGGER_PHOTO_ID_5187070043316836642" border="0" /></a><br /><span style="font-size:130%;">Propagating seedlings means simply germinating seeds and growing the seedlings until they are big enough to be planted into a bigger pot, or directly into the ground. </span><p style="text-align: justify;"><span style="font-size:130%;">The first thing you'll need to propagate seedlings is some really good quality seed compost. There's no hope for your seeds if you just go outside and scoop up some earth from your garden as its physical structure just won't be up to scratch and it will also be host to lots of pathogens which will cause problems later on for your new seedlings.<br />But you don't want potting compost either as it has too many nutrients and put seedlings at risk of fertilizer damage, plus it provides a lovely environment for liverworts and moss, which will then compete with your seedlings for water, space and light.<br />A good soil-based seed compost is the answer for seedlings that are going to take a few weeks to germinate. For plants that grow rapidly, you can just use a soil-free organic mixture. But in my video above (in Malay language), I insists on Peat Moss which is the best media for seedling.<br /></span></p><span style="font-size:130%;"> Then you'll need the all important seeds. You should not try propagating seedlings from old seeds; buying fresh ones every year isn't very expensive and will ensure that you grow the best quality seedlings possible. Also, some plants need to be germinated from fresh seedlings and old seeds will simply not grow. So make sure you do your research to get the best results. Chilly seeds can't resist stress (of heat and too high in humid & nutrient). So, an extra care is needed when doing the seedling for chilly.<br />Finally what you need is a place to grow your seedlings in. This means some seed trays, and somewhere warm and humid. This could be a greenhouse, a conservatory or even just a propagator (a seed tray with lid a bit like a fish tank), but your seedlings need to stay protected from the cold at all costs otherwise they will not make it.<br />When everything ready, start with filling the tray with enough (but not too much) peat moss. Spray a misty water onto it using a sprayer and then place the seed on each hole. Then carefully sprinkle a small amount of peat over the seed with your only 2 finger to make sure the seed does not expose directly to the air. Put the tray in black & thin plastic bag (or trash bag) and leave it under shelter for 2 days. After 2 days, take out the plastic cover but still need to be put under shelter (or under 50% sunlight). The bud will start to appear on the 5th - 7 day.<br />Please refer to the posts <a href="http://precision-farming-for-dummies.blogspot.com/search/label/Seed%20and%20Seedlings">How To Make Proper Seedlings</a> & <a href="http://pertanianmoden-precisionfarming.blogspot.com/2008/04/3-basic-need-for-fertigation-selected.html">Basic Need For Fertigation-Selected Seed & Seedlings</a></span><br /><object height="355" width="425"><param name="movie" value="http://www.youtube.com/v/oseK8CVQwyY&hl=en"><param name="wmode" value="transparent"><embed src="http://www.youtube.com/v/oseK8CVQwyY&hl=en" type="application/x-shockwave-flash" wmode="transparent" height="420" width="450"></embed></object>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com1tag:blogger.com,1999:blog-8327473569214571773.post-20601715012112596912008-05-23T16:43:00.000-07:002008-05-25T04:13:50.316-07:00GENERAL CULTURAL PRACTICES (Enviromental Conditions Required) – TEMPERATURE<div style="text-align: justify;"><span style="font-size:130%;">Temperature: The optimum growing temperatures (day and night) vary for different plant species and different varieties within a species. For example, if you decided to grow tomatoes:<br /></span></div><ul style="text-align: justify;"><li><span style="font-size:130%;">Germination and post-emergence temperatures = 23-25 C (74-77 F)</span></li><li><span style="font-size:130%;">Production optimum temperatures = 22 C (72 F) day/20C (68 F) night.</span></li></ul><div style="text-align: justify;"><span style="font-size:130%;">One of the major reasons for a greenhouse is to control temperature. Air at 70° F will hold twice as much moisture as air at 50°F. In the range of temperatures encountered in a greenhouse, for every 20° F rise in dry bulb temperature, the water-holding capacity of the air doubles, and the relative humidity is reduced by one-half. This relationship is important in managing humidity in the greenhouse.</span><span style="font-size:130%;"> Most of the crops grown in a greenhouse are of tropical or subtropical origin or are grown at inclement times of the year. The greenhouse is used to maintain an optimum night temperature (above freezing). This is usually accomplished with some kind of heating system. During the day, however, the greenhouse structure can actually interfere with temperature control by trapping heat. Therefore, various cooling methods must then be used.</span><span style="font-size:130%;"><span> </span>Temperature is a measure of heat energy. The energy balance or movement of energy into, within, and out off a greenhouse occurs by three different methods:</span> </div><ol style="text-align: justify;"><li><span style="font-size:130%;"><span style="font-weight: bold;">Conduction</span>: diffusion of thermal energy through a continuous medium, the rate of which depends on the properties of the medium. Heat energy movement is always from a region of high temperature to lower temperature.</span></li><li><span style="font-size:130%;"><span style="font-weight: bold;">Convection</span>: diffusion of thermal energy between two dissimilar materials, usually between a gas and liquid, gas and solid, or liquid and solid.<span style="font-family:'Times New Roman',serif;"> Heat energy movement is always from a region of high temperature to lower temperature.</span></span></li><li><span style="font-size:130%;"><span style="font-family:'Times New Roman',serif;"></span></span><span style="font-size:130%;"><span style="font-family:'Times New Roman',serif;"><span style="font-weight: bold;">Radiation</span></span>: radiation heat transfer occurs when electromagnetic energy leaves one object and is intercepted and absorbed by another. This differs markedly from conduction and convection. All objects emit radiation, warmer objects more so than cooler objects. The wavelengths usually considered to be involved in radiation heat transfer are in the infrared band.</span></li></ol><div style="text-align: justify;"><span style="font-size:130%;"></span><span style="font-size:130%;"><span style="font-weight: bold;">Radiation Cooling</span>: On clear, cold nights, plants and other objects within a greenhouse will lose heat to the outside by radiation cooling. Because objects within the greenhouse are much warmer than those outside, they lose heat by emitting infrared radiation through the glazing and into the clear sky. Under such conditions, the foliage temperature may be 5°F cooler than the surrounding air. Radiation cooling occurs very little when skies are cloudy.</span> </div><p style="line-height: 0.291251in; text-align: justify;"><span style="font-size:130%;"><span style="font-weight: bold;">Condensation</span>: When the foliage of plants in the greenhouse are cooler than the surrounding air, moisture in the air may condense on the leaf surfaces. This is most common in the spring and fall when days are bright and warm and nights are cool and clear. The moisture that collects on the leaves serves as an ideal medium for the germination of several disease-causing spores, mainly powdery mildew. Condensation also occurs on the inside pf poly-covered greenhouse when the inside air is warm and humid and the outside air is cold. Under these conditions, condensation can rain-down on the foliage creating an environment for diseases.</span></p><div> </div><p style="line-height: 0.291251in; text-align: justify;"><span style="font-size:130%;"><span> </span>Greenhouses heat up during the day for two reasons: 1) the greenhouse effect, 2) because the greenhouse is an enclosed space. How much a greenhouse heat up during the day depends on how much solar radiant energy is coming in through the glazing, what happens to that energy, and how much is retained.</span></p> <p style="line-height: 0.291251in;"> </p>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-48398333221608818302008-05-22T09:17:00.000-07:002008-05-23T04:07:37.800-07:00GENERAL CULTURAL PRACTICES (Enviromental Conditions Required) - Relative Humidity<span style="FONT-WEIGHT: bold; COLOR: rgb(186,0,173); LINE-HEIGHT: 100%; FONT-STYLE: italicfont-family:Verdana;font-size:16;" ><span style="font-size:130%;">Different Types & Brands of Digital RH Meter</span> </span><br /><img alt="The image “http://www.thermastor.com/HA-DEH3000/images/HA.jpg” cannot be displayed, because it contains errors." src="http://www.thermastor.com/HA-DEH3000/images/HA.jpg" /><span style="FONT-WEIGHT: bold; COLOR: rgb(204,0,0)">_</span><img alt="The image “http://www.geodetic.com.au/images/tramcrh1kit.jpg” cannot be displayed, because it contains errors." src="http://www.geodetic.com.au/images/tramcrh1kit.jpg" /><img style="WIDTH: 236px; HEIGHT: 181px" alt="http://www.edgetech.com/images/Model_635_both_options1.jpg" src="http://www.edgetech.com/images/Model_635_both_options1.jpg" /><span style="Z-INDEX: 679; LEFT: 531px; WIDTH: 17px; POSITION: absolute; TOP: 1045px; HEIGHT: 24px"></span><span style="FONT-WEIGHT: bold; COLOR: rgb(204,0,0)">____</span><span style="FONT-WEIGHT: bold; COLOR: rgb(204,0,0)">___</span><br /><br /><br /><div style="TEXT-ALIGN: justify"><span style="font-size:130%;"><span style="FONT-WEIGHT: bold; COLOR: rgb(204,0,0)">Relative humidity (RH)</span>: The amount of water in the air compared to the total amount<br />of water that the air can hold at a given temperature. (<span style="FONT-WEIGHT: bold">%RH = Amount of water in the air X 100 </span><span style="FONT-WEIGHT: bold">Amount of water possible at a given temp</span>). As the temperature increases the amount of water that the air can hold increases. When the air is saturated water molecules condense. This causes clouds when at altitude or fog when near the ground. How does this relate to plants growing in a greenhouse?<br />*As the RH increases around the leaf (concentration of water molecules outside increases) it makes it more difficult for the water molecules inside the leaf to move out (transpiration) via diffusion.<br />*Therefore, as the RH increases, transpiration decreases, water and therefore nutrient movement decrease, and nutrient deficiencies can result.<br />*ALSO, as RH increases and transpiration decreases, leaf temperatures often increase, since transpiration is the plant’s way of cooling itself.<br />Optimum RH range for tomatoes (and most plants) = 55% - 95%<br />In USA & other other advenced Western countries during hot, dry weather, fan and pad cooling adds moisture to the air.<br />On hot, humid days, fan and pad cooling adds moisture but does not cool as well.<br />During cool, damp weather, RH inside the greenhouse can approach 95%.</span></div>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-88728777377494765552008-05-22T09:16:00.000-07:002008-05-23T04:08:02.098-07:00GENERAL CULTURAL PRACTICES (Enviromental Conditions Required) – TEMPERATURE<div style="TEXT-ALIGN: justify"><span style="font-size:130%;">Temperature: The optimum growing temperatures (day and night) vary for different plant species and different varieties within a species. For example, if you decided to grow tomatoes:<br /></span></div><ul style="TEXT-ALIGN: justify"><li><span style="font-size:130%;">Germination and post-emergence temperatures = 23-25 C (74-77 F)</span></li><li><span style="font-size:130%;">Production optimum temperatures = 22 C (72 F) day/20C (68 F) night.</span></li></ul><div style="TEXT-ALIGN: justify"><span style="font-size:130%;">One of the major reasons for a greenhouse is to control temperature. Air at 70° F will hold twice as much moisture as air at 50°F. In the range of temperatures encountered in a greenhouse, for every 20° F rise in dry bulb temperature, the water-holding capacity of the air doubles, and the relative humidity is reduced by one-half. This relationship is important in managing humidity in the greenhouse. Most of the crops grown in a greenhouse are of tropical or subtropical origin or are grown at inclement times of the year. The greenhouse is used to maintain an optimum night temperature (above freezing). This is usually accomplished with some kind of heating system. During the day, however, the greenhouse structure can actually interfere with temperature control by trapping heat. Therefore, various cooling methods must then be used. Temperature is a measure of heat energy. The energy balance or movement of energy into, within, and out off a greenhouse occurs by three different methods: </span></div><ol style="TEXT-ALIGN: justify"><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Conduction</span>: diffusion of thermal energy through a continuous medium, the rate of which depends on the properties of the medium. Heat energy movement is always from a region of high temperature to lower temperature.</span></li><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Convection</span>: diffusion of thermal energy between two dissimilar materials, usually between a gas and liquid, gas and solid, or liquid and solid.<span style="font-family:'Times New Roman',serif;"> Heat energy movement is always from a region of high temperature to lower temperature.</span></span></li><li><span style="font-family:'Times New Roman',serif;"></span><span style="font-size:130%;"><span style="font-family:'Times New Roman',serif;"><span style="FONT-WEIGHT: bold">Radiation</span></span>: radiation heat transfer occurs when electromagnetic energy leaves one object and is intercepted and absorbed by another. This differs markedly from conduction and convection. All objects emit radiation, warmer objects more so than cooler objects. The wavelengths usually considered to be involved in radiation heat transfer are in the infrared band.</span></li></ol><div style="TEXT-ALIGN: justify"><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Radiation Cooling</span>: On clear, cold nights, plants and other objects within a greenhouse will lose heat to the outside by radiation cooling. Because objects within the greenhouse are much warmer than those outside, they lose heat by emitting infrared radiation through the glazing and into the clear sky. Under such conditions, the foliage temperature may be 5°F cooler than the surrounding air. Radiation cooling occurs very little when skies are cloudy. </span></div><p style="LINE-HEIGHT: 0.291in; TEXT-ALIGN: justify"><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Condensation</span>: When the foliage of plants in the greenhouse are cooler than the surrounding air, moisture in the air may condense on the leaf surfaces. This is most common in the spring and fall when days are bright and warm and nights are cool and clear. The moisture that collects on the leaves serves as an ideal medium for the germination of several disease-causing spores, mainly powdery mildew. Condensation also occurs on the inside pf poly-covered greenhouse when the inside air is warm and humid and the outside air is cold. Under these conditions, condensation can rain-down on the foliage creating an environment for diseases.</span></p><div style="TEXT-ALIGN: justify"><span style="font-size:130%;"></span></div><p style="LINE-HEIGHT: 0.291in; TEXT-ALIGN: justify"><span style="font-size:130%;">Greenhouses heat up during the day for two reasons: 1) the greenhouse effect, 2) because the greenhouse is an enclosed space. How much a greenhouse heat up during the day depends on how much solar radiant energy is coming in through the glazing, what happens to that energy, and how much is retained.</span></p><p style="LINE-HEIGHT: 0.291in"></p>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-3172543611511465722008-05-22T09:15:00.000-07:002008-05-23T04:08:44.670-07:00GENERAL CULTURAL PRACTICES (Enviromental Conditions Required) – LIGHT<div style="TEXT-ALIGN: justify"><span style="font-size:130%;">ENVIRONMENTAL CONDITIONS REQUIRED are included 1)<span style="FONT-WEIGHT: bold">Light</span> 2)<span style="FONT-WEIGHT: bold">Temperature</span> 3) <span style="FONT-WEIGHT: bold">Relative Humidity (RH)</span> 4)<span style="FONT-WEIGHT: bold">Carbon Dioxide</span> 5)<span style="FONT-WEIGHT: bold">Air Circulation</span> and of course 6)<span style="FONT-WEIGHT: bold">Oxygen</span>. I will cover one by one and we starts with light.<br />*<span style="COLOR: rgb(102,0,0)"><span style="FONT-WEIGHT: bold">Light</span></span>: Two factors are important and can be affected by greenhouse structures and coverings (see also posts </span><a href="http://guide-to-precision-farming.blogspot.com/2008/02/greenhouse-control-systems-light.html"><span style="font-size:130%;">Greenhouse Control system-Light</span></a><span style="font-size:130%;"> and </span><a href="http://guide-to-precision-farming.blogspot.com/2008/02/greenhouse-structures-greenhouse.html"><span style="font-size:130%;">Greenhouse Glazing material</span></a><span style="font-size:130%;">). NOTE: Both of these vary with plant species.<br /></span></div><ul style="TEXT-ALIGN: justify"><li><span style="font-size:130%;">Quality: Refers to wavelengths of light. (Remember in physics: light spectrum) Visible light = 390-760 nm: blue at the low end, red at the high end. PAR (photosynthetically active radiation) = between 400 and 700 nm (blue, yellow, orange and red… but not green)NOTE: This varies slightly for each plant species.</span></li><li><span style="font-size:130%;">Quantity: The quantity of light monitoring is very crucial especially in countries which have four season. The quantity of light is affected by both day length and sun angle (changes with season): 1)<span style="FONT-WEIGHT: bold">Day Length</span>: eg. In North-West area in USA, day length on June 21 is 14 hours 15 min. On December 21 day length, however, is only about 10 hours. 2)<span style="FONT-WEIGHT: bold">Sun Angle</span>: In June the angle is high = 81o from the horizon (almost overhead). In December the angle is low = 34o from the horizon. **The quantity (amount) of light reaching the Earth’s surface is therefore higher in Summer than it is in Winter. **For tomatoes in the desert southwest or other high light areas: During the Winter or times of low light the quantity of light available is enough to support 3 – 4 fruit/cluster.During Spring/Summer/Fall the quantity of light may be too high and shading may be needed. 4 – 5 fruit/cluster is typical. For Tropical countries like Malaysia & Thailand , the amount of light is almost consistent. But sometimes when droughts happens or at locations where sunlight are so intense, shading may also be needed to cut down some damaging effects from high intensity light of the Sun. This is crucial especially for Chillies and Melons grower.<br /></span></li></ul>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-57731324807096753402008-05-21T09:14:00.000-07:002008-05-23T04:09:02.828-07:00GENERAL CULTURAL PRACTICES - Greenhouse Preparation<span style="font-size:130%;">Factors To Consider For The Greenhouse Preparation:<br /><br />*Select a site for the greenhouse that is appropriate for the operation (see posts </span><a href="http://guide-to-precision-farming.blogspot.com/search/label/Greenhouse%20site/location"><span style="font-size:130%;">12 Things To Consider When Selecting A Greenhouse Site</span></a><span style="font-size:130%;">).<br />*Select a greenhouse structure that is appropriate for the operation (see posts on </span><a href="http://guide-to-precision-farming.blogspot.com/search/label/Greenhouse%20Structure"><span style="font-size:130%;">Greenhouse Structure</span></a><span style="font-size:130%;">).<br />*Make sure all equipment is cleaned, serviced and working at optimum efficiency.<br />*For any crop, incl. tomatoes, the following items must be considered prior to planting:<br /></span><ul><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Good light transmission</span>: Choose the proper greenhouse covering and structure. If year-around production is planned, shading must be used in Summer.</span></li><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Adequate cooling</span>: Either passive (vents), active (fan and pad), or both. Heating is necessary in Winter: NATURAL GAS is the most economical way. (Other, more expensive, methods of heating: propane, oil, electric, solar.)</span></li><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Carbon dioxide generation</span>: This is especially important for Winter mornings. The sun rises, but it’s cold. So if fans come on, it’s only for a short time. Plants begin to photosynthesize, using up the ambient carbon dioxide to the point where photosynthesis is effected and even reduced.. If photosynthesis is reduced, fruit set is reduced – and that’s $$!</span></li><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Ground cover:</span> Usually white plastic or a white woven material is put down first. Reflects light back up into the crop increasing photosynthesis. Provides a barrier between the plants and pathogens in the soil. Helps to control weeds.</span></li><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Allows for ease of cleaning</span>: CLEANLINESS IS PARAMOUNT! Trash, leaf litter, etc. is a perfect habitat for bugs/disease.</span></li></ul><ul><li><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">Irrigation system</span>: (see posts on </span><a href="http://guide-to-precision-farming.blogspot.com/search/label/Irrigation%20System"><span style="font-size:130%;">Irrigation System</span></a><span style="font-size:130%;"> for details and diagram) This inlcudes: 1)<span style="FONT-WEIGHT: bold">Timer/controller</span> to regulate the “fertigation” (water + fertilizer) schedule. This will be hard-wired to solenoid valves that open for watering. <span style="FONT-WEIGHT: bold">2) Reservoirs</span> to contain the nutrient solution (full strength or concentrate). <span style="FONT-WEIGHT: bold">3) Injectors</span> (if concentrates are used) to dilute the nutrient solution. <span style="FONT-WEIGHT: bold">4) Distribution tubing/emitters/drainage</span> and/or recycling system. <span style="FONT-WEIGHT: bold">5)Possibly integrated pH (acid/base) and EC (electrical conductivity)</span> probes.<span style="FONT-WEIGHT: bold"> 6) Overhead support wires</span>: These need to be strong enough to support the crop and high enough (8-14 feet) to make use of the vertical space provided.</span></li></ul><br /><span style="font-size:130%;"><embed src="http://www.youtube.com/v/2tchCvKTEMk&hl=" width="460" height="420" type="application/x-shockwave-flash" wmode="transparent"></embed></span>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-45585494004009205962008-05-21T09:13:00.000-07:002008-05-25T04:15:37.256-07:00GENERAL CULTURAL PRACTICES: CROP SCHEDULING<p align="justify"><span style="font-size:130%;">Plan ahead… When do you want to market your product for the best monetary return? For hydroponic tomato growers in seasonal countries, get a better price in Winter – no field competition and little from greenhouses in northern latitudes. Alternative: grow year around to maintain stable, consistent market/shelf space. Tomatoes: 2 examples of crop scheduling </span></p><ul><li><div align="justify"><span style="font-size:130%;"><strong>Example 1</strong>: Passively cooled greenhouses (vents): No Summer harvesting. Seed first crop in early July in 1" (or 1.5") Rockwool cubes. Transplant in mid-July into 3" (or 4" with 2 holes) Rockwool blocks. Plant 1-month-old seedlings onto Rockwool slabs in August. Harvest from October until March – Top the plants in February, remove when second crop begins producing in March. Seed a second crop in early December as above. Transplant in mid-December as above. Interplant new 1 month old seedlings onto Rockwool slabs in January. Harvest from this new crop from March until July. Remove plants. Clean. </span></div></li><li><div align="justify"><span style="font-size:130%;"><strong>Example 2</strong>: Actively cooled greenhouses (fan and pad): Year around harvesting. Seed, transplant and plant first and second crops as above, removing first crop as above in March. Continue second crop, harvesting from March until the next October. Seed, transplant and plant the third crop, as the first, in July/August. When third crop is ready to harvest in October, remove second crop. Continue the process for up to 5 years.</span> </div></li></ul><p><span style="font-size:85%;"><span style="font-size:130%;">Note: Concentrate on the production end (growing the plants, harvesting, marketing, etc.)<br />and purchase 1 month old seedlings from a TRANSPLANT GROWER.<br />NOTE: Why 2 crops/year? Fruit size and quality go down over time.</span><br /></span></p>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-77613717507843285072008-05-21T09:12:00.000-07:002008-05-23T04:11:58.957-07:00GENERAL CULTURAL PRACTICES: CROP AND CULTIVAR SELECTION – Experience<span style="font-size:130%;">EXPERIENCE: If a grower has experience with a particular crop… stick with it. Example: A family with experience in growing long cucumbers in British Columbia, Canada, moved south of Willcox, AZ and is growing cucumbers… not tomatoes. If a grower does not have experience with a particular crop… Work for someone who is successful with that crop to gain experience.<br />Hire someone who is experienced… an expert!</span>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-58271873972572056062008-05-20T09:12:00.001-07:002008-05-25T04:15:55.975-07:00GENERAL CULTURAL PRACTICES (Crop & Cultivar Selection) – LOCATION<span style="font-weight: bold;font-size:130%;" >LOCATION: </span><span style="font-size:130%;">The selection of a crop will dictate the best location for the operation…<br />and visa versa.<br />Example: If a grower chooses tomatoes in Cameron Highlands, Malaysia, the optimum elevation is between 3,000 and 4,000 feet. Any lower and it is usually too hot to grow. Any higher and it is too cold to grow (especially during rainy days)…UNLESS SIGNIFICANT EXPENSE ($$) IS PUT TOWARD COOLING OR HEATING!<br />Example: If a grower has land at about 2500 feet in elevation in Cameron Highland, a crop<br />that can tolerate warmer temperatures than tomatoes, such as cucumbers could be selected. The selection of a “cultivar” or “variety” is also important when choosing a location. Seed companies are always coming out with new cultivars (or varieties) to suit different climates and tastes. With the move of many growing operations to higher light regions of the world<br />… remember photosynthesis… (Most of Asian & Middle East countries, Northern Africa, Northern Australia, Southwest USA, Mexico, Spain) AND the demand for good quality, good tasting tomatoes year around, many seed companies are introducing more HEAT TOLERANT varieties. Example (from one of the greenhouse cultivator company in Southwest USA) TRUST Tomato veriety were selected: a Dutch variety (DeRuiter Seed); optimum day temperature = 72 F. The first 10 acres (and next 30) of greenhouses were passively cooled (no fan and pad/evaporative cooling). They were not able to grow in the Summer and therefore started with transplants (1 month old seedlings started in Canada) in August and removed the crop the following July.</span>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-87470221524184767952008-05-20T09:11:00.000-07:002008-05-23T04:10:10.431-07:00GENERAL CULTURAL PRACTICES - (Crop & Cultivar Selection) – MARKET<div style="TEXT-ALIGN: justify"><span style="font-size:130%;">INTRODUCTION<br />General cultural practices include all information, techniques and skills required to successfully produce a crop and optimize yields – the main goal of any grower! We will concentrate on tomatoes with reference to other crops to illustrate the variability in cultural practices between crops.<br /><span style="FONT-WEIGHT: bold">CROP AND CULTIVAR SELECTION</span><br />This is one of the most important decisions a grower will make and depends on:<br />MARKET… LOCATION… EXPERIENCE<br /><br /><span style="FONT-WEIGHT: bold">1)MARKET</span>:<br /></span></div><ul style="TEXT-ALIGN: justify"><li><span style="font-size:130%;">Research the region. Know if there are other growers in the area = <span style="FONT-WEIGHT: bold">competition</span>. If there are too many tomato growers… try cucumbers, peppers, basil, melon, chillies/capsicum etc.</span></li><li><span style="font-size:130%;">Know the market. Brokerage houses, grocery vs specialty stores, farmer’s markets, restaurants, etc.</span></li><li><span style="font-size:130%;">Hydroponics/greenhouse culture is expensive. Therefore, a high cash-value crop must be chosen. These include: <span style="FONT-WEIGHT: bold">1)Tomatoes</span>: Indeterminant (vining) varieties to take advantage of the vertical space in the greenhouse that has been paid for! Beefsteak: large fruit, harvested individually. Cluster, truss or TOV (tomato on the vine): medium to large fruit, harvested as an entire truss. Cherry: small fruit, harvested individually or as an entire truss. <span style="FONT-WEIGHT: bold">2)Peppers/Capsicums</span>: Colored bells only, primarily yellows – require sun protection. <span style="FONT-WEIGHT: bold">3)Cucumbers</span>: Long (European, seedless, parthenocarpic, burpless). They are thin-skinned and must be wrapped in plastic after harvest. <span style="FONT-WEIGHT: bold">4)Lettuce:</span> Head, leaf or cos; specialty or bred for hydroponics/CEA (<span style="font-family:Verdana,Arial,Helvetica,sans-serif;"> Controlled Environment Agriculture)</span>. Summer Bibb or “Limestone” lettuce. <span style="FONT-WEIGHT: bold">5)Melons</span>: Many types of Melons (Musks, Signal, Cupid, Rock, Sweet etc) <span style="FONT-WEIGHT: bold">6)Specialty Greens, Herbs and Medicinals</span>: Several types and varieties.<br /></span></li></ul><div style="TEXT-ALIGN: justify"><span style="font-size:130%;">NOTE: Consult seed companies for suitable crops/varieties.</span></div>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-37597388179559662702008-05-20T09:10:00.000-07:002008-05-23T04:10:35.420-07:0012 Thing To Consider When Selecting Greenhouse Site - Expansion, Labour & Management Residence<div style="TEXT-ALIGN: justify"><span style="font-size:130%;"><span style="FONT-WEIGHT: bold">10. Capability of Expansion </span>– Purchase more land than you anticipate using in the beginning so that you have the ability to expand your operation. Locate the initial greenhouses such that future expansion will utilize the land area most efficiently.<br /><br /><span style="FONT-WEIGHT: bold">11. Availability of Labor</span> – The grower needs people who will want to work as laborers and who are “trainable” to become a retainable workforce.<br />*Such skills included pruning/training the plants and harvesting/packing the fruit.<br />*SPECIALTY LABOR will include people with additional training in such fields as plant production, plant nutrition, plant protection (insects and diseases) computers, labor management, marketing, etc. These may or may not be part of the regular workers, but could be call on as consultants as needed.<br /><br /><span style="FONT-WEIGHT: bold">12. Management residence </span>– The grower/manager residences should be close to the<br />greenhouse so that they can get to the greenhouse quickly in case of emergencies.</span></div>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-5545553887261351552008-05-16T06:47:00.000-07:002008-05-16T06:47:01.072-07:0012 Things To Consider When Selecting Greenhouse Site - Utilities, Roads & North-South Orientation<span style="font-weight: bold;font-size:130%;" >7. Utilities</span><span style="font-size:130%;"> – Availability of utilities should include telephone service, three-phase electricity and fuel for heating and carbon dioxide generation.*Note that, when compared to propane, electricity or fuel oil, natural gas is the most economical heating energy source.<br /><br /></span><span style="font-weight: bold;font-size:130%;" >8. Roads </span><span style="font-size:130%;">– Need access to good roads to transport the “product”. Good roads close to a large population center, or to a brokerage center aids wholesale and retail marketing.<br /><br /></span><span style="font-weight: bold;font-size:130%;" >9. North-South Orientation</span><span style="font-size:130%;"> – The greenhouse should be oriented north-south, AND the<br />plant rows within the greenhouse should be oriented north-south. *If oriented north-south, the greenhouse structure itself will not cast consistent shadows on any one area of the plants throughout the day. *If oriented north-south, the plant rows will receive equal light throughout the day. If oriented east-west the south most rows (in the northern hemisphere) will shade the rows to the north.</span>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-14531356595102992782008-05-16T06:46:00.001-07:002008-05-16T06:46:00.316-07:0012 Things To Consider When Selecting Greenhouse Site - Pest Pressure & Level and Stable Ground<div style="text-align: justify;"><span style="font-weight: bold;font-size:130%;" >5. Pest Pressure </span><span style="font-size:130%;">– Choose a site away from existing agriculture production areas which could harbor insect pests in the fields. Insect pests of concern include white flies, aphids, spider mites and thrips (see <a href="http://pertanian-moden-precision-farming.blogspot.com/2007/11/serangga-perosak-tanaman.html">here</a> for pests and control methods).<br /><br /></span><span style="font-weight: bold;font-size:130%;" >6. Level and Stable Ground</span><span style="font-size:130%;"> – The ground upon which the greenhouse will sit must be<br /></span></div><ul style="text-align: justify;"><li><span style="font-size:130%;">Graded for routing surface water to a drainage system or a holding pond. (Typical grade = ½ % or a 6 inch drop over a distance of 100 feet.)</span></li><li><span style="font-size:130%;">Compacted such that there will be no settling of the site after the greenhouse has been constructed.</span></li></ul>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-21400093964164547552008-05-16T06:46:00.000-07:002008-05-16T06:46:00.555-07:0012 Thing To Consider When Selecting Greenhouse Site - Elevation & Microclimate<div style="text-align: justify;"><span style="font-weight: bold;font-size:130%;" >3. Elevation </span><span style="font-size:130%;">– will effect the summer maximum and the winter minimum temperatures.<br />Choosing an appropriate elevation will minimize heating costs in the winter and cooling costs in the summer. Example: In Arizona tomato production is most economical between 4000 and<br />5000 feet (1220m-1520m). Below 4000 feet cooling costs in summer will be more whereas above 5000 feet heating costs in the winter will be more. Lower elevations might be suitable for peppers or cucumbers.<br /><br /></span><span style="font-weight: bold;font-size:130%;" >4.</span><span style="font-size:130%;"> </span><span style="font-weight: bold;font-size:130%;" >Microclimate</span><span style="font-size:130%;"> - Factors which falls in microclimate considerations:<br /></span></div><ul style="text-align: justify;"><li><span style="font-size:130%;">Latitude – Unless the global climate changes drastically, sea level at the poles will be colder than sea level in the tropics… latitude makes a difference!</span></li><li><span style="font-size:130%;">Large bodies of water – will tend to moderate the temperature (e.g., coastal areas tend to have smaller day/night temperature differences than inland areas)</span></li><li><span style="font-size:130%;">Trees, mountains or other obstructions – may cast shadows on the greenhouse, especially in the morning or afternoon hours. Mountains can also effect wind and/or storm patterns.</span></li><li><span style="font-size:130%;">Clouds and fog – Note that certain areas (e.g., on the lee side of certain mountain ranges, or near coastal regions) may develop clouds or fog during certain times of the day or year that will reduce potential sunlight.</span></li><li><span style="font-size:130%;">High Wind Areas – High winds can “suck” heat away from the greenhouse structure and therefore increase the heating energy demands.</span></li><li><span style="font-size:130%;">Blowing dust/sand – High winds can “kick up dust or sand”, especially in desert regions, which can damage some greenhouse glazings.</span></li><li><span style="font-size:130%;">Snow – The weight of heavy, wet snow on a greenhouse could crush it. However, high winds in snow areas can also blow snow up against the greenhouse structure (snow drifts) and cause damage to it. This danger can be reduced by using windbreaks (trees, snow fences, etc.).</span></li></ul>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-2934300064604043022008-05-15T06:45:00.000-07:002008-05-15T06:45:00.583-07:0012 THINGS TO CONSIDER WHEN SELECTING A GREENHOUSE SITE: Solar Radiation & Water Supply<span style="font-size:130%;">Selecting a “good” site for the location of a greenhouse is crucial. But what constitutes a “good” site? There are several things that should and must be considered in order to increase the<br />chances of a successful operation and business.<br /><strong>12 THINGS TO CONSIDER WHEN SELECTING A GREENHOUSE SITE:</strong><br /><strong>1) Solar Radiation</strong> – Plants require sunlight in order to perform photosynthesis. When plants experience cloudy days their photosynthetic rates, and therefore their ability to grow and yield a product, such as tomatoes, cucumbers, peppers, etc., will be reduced. Therefore, a region and location with high light intensity year-round is desired.<br /><br /><strong>2) Water</strong> – Water quantity and quality is crucial. Water will be needed for irrigation (maximum of 1 gal/plant/day for tomatoes). Water will be needed for the evaporative cooling system and can equal or exceed the irrigation water amounts (10,000 – 15,000 gal/acre/day). In the past, excess irrigation and bleed-off water from the evaporative cooling system was allowed to “run off” onto the ground adjacent to the greenhouse (with a rec. minimum percolation rate into the soil of 1”/hr.).<br /><strong>*</strong>HOWEVER, due to more strict regulations and a desire to avoid ground water contamination with high concentrations of salts, large greenhouses are now recirculating the nutrient solution.<br />*THEREFORE, excess nutrient solution should be recycled and/or mixed with the cooler bleed-off water and redirected onto designated areas, such as grass, shrubs, trees/windbreaks, etc.<br />*No matter what the source of the water, a water analysis should be done.<br />*Note: Sea water = 32,000 ppm (mg/l) VS Tucson water = 200-400 ppm.<br />Note: 640 ppm TDS (total dissolved solids) = 1 mmhos/cm or 1 mS/cm.<br /><br />*Desired salt levels in the source water:<br />SO4 < 240 ppm_____ Cl < 140 ppm___ Non-Fertilizer Salts<br />Ca < 120 ppm______ Fe < 5 ppm_____ Na <50 ppm<br />Mg < 24 ppm_______Zn < 5 ppm_____Al < 5 ppm<br />K < 10 ppm________Mn < 2 ppm_____F < 1 ppm<br />P < 5 ppm_________B < 0.8 ppm<br />NO3 < 5 ppm_______Cu < 0.2 ppm<br />Mo <>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-38242928988446000222008-05-15T06:44:00.000-07:002008-05-15T06:44:01.068-07:00Environment Control System In A Greenhouse<p><span style="font-size:130%;">Control systems can be very simple or very complex. Examples include: </span></p><p><span style="font-size:130%;">1) The "original" environmental control systems were manual: </span></p><ul><li><span style="font-size:130%;">Manually rolling up a side vent. </span></li><li><span style="font-size:130%;">Manually opening a roof vent or door. </span></li><li><span style="font-size:130%;">Manually turning on a heater or cooler. </span></li></ul><p><span style="font-size:130%;">2) Simple controllers operate from a thermostat in the greenhouse and: </span></p><ul><li><span style="font-size:130%;">Automatically set day and night temperature ranges. </span></li><li><span style="font-size:130%;">Automatically open and close vents (side, roof, etc.). </span></li><li><span style="font-size:130%;">Automatically turn on or off heaters and coolers. </span></li></ul><p><span style="font-size:130%;">3) Step controllers operate from a thermostat in the greenhouse and: </span></p><ul><li><span style="font-size:130%;">Automatically set day and night temperature ranges. </span></li><li><span style="font-size:130%;">Automatically control 1 or 2 heating stages (depends on # of heaters). </span></li><li><span style="font-size:130%;">Automatically control several cooling stages using cooling fans and<br />pump(s) to wet the pads. </span></li></ul><p><span style="font-size:130%;">4) Sophisticated computers operate from a temperature sensor in the greenhouse and: </span></p><ul><li><span style="font-size:130%;">Automatically set day and night temperature ranges. </span></li><li><span style="font-size:130%;">Automatically control heating equipment including boilers, root zone<br />heating, heat retention curtains, etc. </span></li><li><span style="font-size:130%;">Automatically control other equipment including HAF fans, exhaust<br />fans, vents, pad pumps, fogger systems, etc. </span></li><li><span style="font-size:130%;">Automatically control relative humidity. </span></li><li><span style="font-size:130%;">Automatically control shade curtains and artificial lighting depending on<br />light requirements. </span></li><li><span style="font-size:130%;">Sophisticated computers can also monitor an external weather station and use<br />data from that station to control internal conditions in the greenhouse. </span></li><li><span style="font-size:130%;">Data monitored includes: outside light, temperature, RH, rain and wind.<br />Sophisticated computers can also operate the fertigator system </span></li><li><span style="font-size:130%;">Automatically using light quantity (e.g., X ml of solution/Y amt. of light) </span></li><li><span style="font-size:130%;">Automatically controlling timing of watering, duration of watering,<br />nutrient solution pH and EC, misting, watering booms, etc.</span><br /></li></ul>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-91157487955946636072008-05-15T01:42:00.000-07:002008-12-11T23:42:34.897-08:00Greenhouse Control System - Air Circulation<div align="justify"><span style="font-size:130%;"><strong>Importance</strong>: One reason for having a greenhouse is to create a "controlled environment" for<br />all of the plants. And each plant within the greenhouse should receive the same conditions. However, especially during times when the heating and cooling systems are not in operation, pockets of high or low temperature, relative humidity or carbon dioxide may develop which can be less than optimal for plant growth or flower/fruit development.<br /><strong>Ways of improving air circulation</strong>:<br />The HAF (HAF) concept utilizes the principle that air that moves in a coherent horizontal pattern in a building like a greenhouse needs only enough energy to overcome turbulence and friction loss to keep it moving. Besides the obvious advantage of more uniform temperature within the greenhouse, HAF systems can reduce the incidence of foliar diseases. The moving air removes moisture from the plant canopy resulting in a drier microclimate. When leaf temperatures are allowed to cool much below the air temperature, the dew point is reached and condensation occurs harboring disease organisms. Radiant cooling on clear nights,, especially in non-infrared poly covered houses will cool plant leaves several degrees below air temperature. HAF will reduce this difference.<br />During daylight hours, photosynthesis depletes the carbon dioxide that is in the boundary layer of air next to the leaf. Moving air will replace this depleted air with fresh air having a higher carbon dioxide content. If carbon dioxide is being added, a lower level is usually adequate to get the same plant responses, for instance, 800 - 1000 ppm rather than 1200 - 1500 ppm. Horizontal air flow fans can be placed in the rafters of the greenhouse to circulate air above the crop. This helps to minimize pockets of warm or cold air and high or low humidity or carbon dioxide within the greenhouse. HAF fans can be used in conjunction with hot air heating systems to circulate warm air throughout the greenhouse. HAF fans can also be used at anytime to enhance air mixing in the greenho<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg90sXp1a1l5OlWwF8tLxZ2gg8_nCOq4VZucYxVxwsI98ACxDwS502ZtY6xxppR1omP2Gab-NZ9y8yEZOdivXHqotHy7KW03MTp85T3mHQclKkwoO0-alpD_CeJ4PfDonqFjEXLPOgShCE/s1600-h/2010514030_bdb8838791_m.jpg"><img id="BLOGGER_PHOTO_ID_5173617091544583682" style="margin: 0px 10px 10px 0px; float: left;" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg90sXp1a1l5OlWwF8tLxZ2gg8_nCOq4VZucYxVxwsI98ACxDwS502ZtY6xxppR1omP2Gab-NZ9y8yEZOdivXHqotHy7KW03MTp85T3mHQclKkwoO0-alpD_CeJ4PfDonqFjEXLPOgShCE/s320/2010514030_bdb8838791_m.jpg" border="0" /></a>use.</span> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLVbFhBBPtR_J21eLweK3ZUADrTDNfZv3IkxUHVaLYkxVp5vYAd2ljAB2wyRTB8lNeglOOdvQwUsnJaPaDigNOtN_Pkm1KHiDqBVaCHcH7bFSEVEQoFbsC7ZAtVVBMHwqlNxgHNb871RU/s1600-h/greenhousefans2.jpg"><img id="BLOGGER_PHOTO_ID_5173617293408046610" style="margin: 0px 0px 10px 10px; float: right;" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLVbFhBBPtR_J21eLweK3ZUADrTDNfZv3IkxUHVaLYkxVp5vYAd2ljAB2wyRTB8lNeglOOdvQwUsnJaPaDigNOtN_Pkm1KHiDqBVaCHcH7bFSEVEQoFbsC7ZAtVVBMHwqlNxgHNb871RU/s320/greenhousefans2.jpg" border="0" /></a></div>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-82650385905456209692008-05-14T01:41:00.000-07:002008-05-14T01:41:01.773-07:00GREENHOUSE CONTROL SYSTEMS - CO2 ENRICHMENT<div style="text-align: justify;"><span style="font-weight: bold;font-size:130%;" >Importance:</span><span style="font-size:130%;"> The rate of photosynthesis is dependent upon the availability of carbon dioxide.<br />Carbon dioxide enrichment is most important during the winter months in the morning. The sun has risen and photosynthesis has begun. The plants can reduce the levels of carbon dioxide from the ambient level of about 330 ppm (higher in cities due to industry and vehicles) to around 220 ppm. Lowered carbon dioxide levels will reduce growth and can cause flower and<br />fruit drop reducing overall yields.<br />*Ways of controlling carbon dioxide levels in the greenhouse:<br /></span></div><ol style="text-align: justify;"><li><span style="font-size:130%;">Ventilating (bringing air in from the outside) may provide sufficient carbon dioxide during the Spring, Summer and Fall months.</span></li><li><span style="font-size:130%;">Ventilating during the Winter months, or anytime in cold climates, will, however, result in cold outside air being brought into the greenhouse. Heating will then be needed to maintain the proper temperature which may become uneconomical. Therefore, carbon dioxide generation is a typical and effective way to increase levels in the greenhouse during the Winter or in cold climates.<br /></span></li><li><span style="font-size:130%;">Carbon dioxide generators can burn various types of fuel including natural gas (most economical)or propane. Carbon dioxide levels above 800 ppm, even as high as 1200 ppm, have been shown to be beneficial to plant growth.</span></li></ol>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-12871728528540063282008-05-14T01:40:00.000-07:002008-05-14T01:40:01.238-07:00GREENHOUSE CONTROL SYSTEMS – Cooling<a href="http://s87.photobucket.com/albums/k140/welllfleet/?action=view&current=CurrentGreenhouseLayout.jpg" target="_blank"></a><br /><span style="font-weight: bold;font-size:130%;" >Importance:</span><span style="font-size:130%;"> High temperatures can be detrimental to plant growth. High temperatures can cause such problems as<br /><br /></span><ul style="text-align: justify;"><li><span style="font-size:130%;">Thin, weak stems or, as in tomatoes, stick trusses (thin, weak truss stems)</span></li><li><span style="font-size:130%;">Reduced flower size or, as in tomatoes, flower fusion and boat formation</span></li><li><span style="font-size:130%;">Delayed flowering and/or poor pollination/fertilization and fruit set</span></li><li><span style="font-size:130%;">Flower and bud/fruit abortion<br /></span></li></ul><div style="text-align: justify;"><span style="font-weight: bold;font-size:130%;" >*Cooling requirements and calculations:</span><span style="font-size:130%;"> The National Greenhouse Manufacturer’s Association 1993 standards = 8 cubic feet per minute/square feet of greenhouse floor area OR…<br />1 full greenhouse volume exchanged per minute in warm climates. CFM = height x width x length (i.e., volume)<br />Example: Using the greenhouse dimensions in the heat calculation example:<br />CFM = volume lower section + volume triangular top<br />= (8 x 24 x 48) + (6/2 x 24 x 48)<br />= 9216 + 3456<br />= 12,672 cubic feet per minute => size fans/pads accordingly<br /><br /></span><span style="font-weight: bold;font-size:130%;" >*Passive ventilation systems:</span><span style="font-size:130%;"><br /></span></div><ol style="text-align: justify;"><li><span style="font-size:130%;">Shading: Shade cloth or shade paint/white wash, besides regulating the light intensity, can also help cool the greenhouse.</span></li><li><span style="font-size:130%;">Ridge Vents: Vents in the roof of a greenhouse that allow hot, interior air to escape. The area of the vents should be 25% of the floor area.</span></li><li><span style="font-size:130%;">Roll-up Side Walls: Can be used in flexible glazing (polyethelene film) single bay greenhouses where the side walls can be rolled up several feet allowing a natural horizontal flow of air over the plants. As with ridge vents, the area of the side wall vents should be 25% of the floor area.</span></li><li><span style="font-size:130%;">Cooling Towers: Water cooled pads at the top part of tall towers cool the surrounding air which then drops displacing warmer air below.</span></li><li><span style="font-size:130%;">Removable Roof: Recent greenhouse designs can include a roof that retracts completely for natural ventilation. This would allow for adaptation of greenhouse grown plants to outside conditions prior to movement outside.<br /></span></li></ol><div style="text-align: justify;"><span style="font-weight: bold;font-size:130%;" >*Active cooling systems:</span><span style="font-size:130%;"><br /></span></div><ol style="text-align: justify;"><li><span style="font-size:130%;">Fan and Pad: “Evaporative cooling” where air from the outside is pulled through porous, wet pads (usually cellulose paper). Heat from the incoming air evaporates water from the pads, thereby cooling the air. Evaporative cooling will also help to increase the relative humidity in the greenhouse.</span></li><li><span style="font-size:130%;">Fogging Systems: Uses evaporative cooling like the fan and pad but incorporates a dispersion of water droplets that evaporate and extract heat from the air. This system gives better uniformity since the fogging is distributed throughout the greenhouse and not just near one a pad end as with the fan and pad system. The smaller the droplet size, the faster each droplet evaporates and therefore the faster the cooling. Mist droplets = 1000 microns in diameter.</span></li><li><span style="font-size:130%;">Air Conditioning: Too expensive for most greenhouses</span></li></ol><span style="font-size:130%;"><a href="http://s89.photobucket.com/albums/k234/oldmudhouse/Harbor%20Freight%20Greenhouse/?action=view&current=exhaustfanin10-2.jpg" target="_blank"><img alt="exhaust fan in gh frame" src="http://i89.photobucket.com/albums/k234/oldmudhouse/Harbor%20Freight%20Greenhouse/exhaustfanin10-2.jpg" border="0" /></a></span><a href="http://s35.photobucket.com/albums/d153/Pablo93455/Greenhouse/?action=view&current=IMG_4558.jpg" target="_blank"><img alt="Automatic Vent Control" src="http://i35.photobucket.com/albums/d153/Pablo93455/Greenhouse/IMG_4558.jpg" border="0" /></a>intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com0tag:blogger.com,1999:blog-8327473569214571773.post-25263589728419254632008-05-14T01:39:00.000-07:002008-12-11T23:42:34.945-08:00GREENHOUSE CONTROL SYSTEMS – Heating<ul style="text-align: justify;"><li><div style="text-align: justify;"><span style="font-weight: bold;font-size:130%;" >Importance</span><span style="font-size:130%;">: Each plant species has an optimum temperature range. Heating devices<br />will maintain the temperature within that range during periods of cold weather.<br />*Types of heat loss from a greenhouse:</span></div></li><li><span style="font-weight: bold;font-size:130%;" >Conduction</span><span style="font-size:130%;"> = Heat transfer either through an object or between objects in contact. Conduction depends on area, path length, temperature differential and physical properties of the object(s). Example: Heat loss through the glazing material on the greenhouse.</span></li><li><span style="font-weight: bold;font-size:130%;" >Convection</span><span style="font-size:130%;"> = Heat transfer by the movement of warm gas or liquid to a colder location. Convection depends on temperature differential. Example: Movement of warm air near the plants upward toward the roof.</span></li><li><span style="font-weight: bold;font-size:130%;" >Radiation</span><span style="font-size:130%;"> = Heat transfer between separated objects. Radiation occurs from all objects and depends on the areas, temperatures and surface characteristics of the objects involved. Example: Heat transfer from all objects in the greenhouse.<br /></span></li></ul><div style="text-align: justify;"><span style="font-size:130%;">It is important to be able to estimate the heat loss from the greenhouse in order to choose the correct size of heater to replace that heat. Although radiation and convection transfer heat around the greenhouse, the main type of heat loss from a greenhouse is through conduction, i.e., the heat loss through the glazing material.<br /></span><span style="font-weight: bold;font-size:130%;" >*The basic system:</span><span style="font-size:130%;"> Consists of a fuel burner, heat exchanger, distribution system and controls. Heat delivery to the crop is by convection and radiation. The fuel = usually burn natural gas, but can also use oil, coal, wood, etc.<br /></span></div><ul style="text-align: justify;"><li><span style="font-weight: bold;font-size:130%;" >Heating by hot water or steam</span><span style="font-size:130%;">: Hot water or steam can be produced using boilers fired by natural gas, etc. The hot water or steam is then transported throughout the greenhouse in pipes. The pipes can end in a heat exchanger where a fan distributes heated air. The pipes can run along the floor and also be used as cart rails between aisles. Heat will then rise upward through the crop by convection. Heat pipes can also be positioned within the crop to steer plant growth . Heated tubes can create “bottom heat” for propagation or growing.</span></li><li><span style="font-weight: bold;font-size:130%;" >Heating by hot air</span><span style="font-size:130%;">: Fuel is burned to heat air that is then distributed by fans around the greenhouse. Horizontal air flow (HAF) fans circulate warm air above the crop. Fan jet systems, with unit heaters or heat exchangers and perforated polyethylene tubes, distribute warm air and improve air movement and ventilation throughout the greenhouse.</span></li><li><span style="font-weight: bold;font-size:130%;" >Moveable nighttime insulation</span><span style="font-size:130%;">: Insulating material (cloth or film curtains) can be positioned above the crop or near the roof to retain heat near the crop. The insulating material used during the night can be</span> the same material used for <span style="font-size:130%;">shading during the day.</span><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLWdcg8eM1PXXySrKR3WuNF-tYLk3lXE8JpUP6IyV1FH-FzYPfXY0V0AGROTNboyq62a43aqT77sCyatz-2aA-uERli8efgCRnXCb96ziZ25y_FXkrz2qRfblf8McLRBZqYBbCfR03M3w/s1600-h/heat.jpg"><img id="BLOGGER_PHOTO_ID_5168354549328819682" style="margin: 0px auto 10px; display: block; cursor: pointer; text-align: center;" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLWdcg8eM1PXXySrKR3WuNF-tYLk3lXE8JpUP6IyV1FH-FzYPfXY0V0AGROTNboyq62a43aqT77sCyatz-2aA-uERli8efgCRnXCb96ziZ25y_FXkrz2qRfblf8McLRBZqYBbCfR03M3w/s320/heat.jpg" border="0" /></a></li></ul><span style="font-size:100%;">Those are called dual fin heating tubes. The hot water from the boilers enters into these tubes, which radiate the heat out towards the plants</span><!-- ############## COMMENTS -->intansabreenahttp://www.blogger.com/profile/02520688165134669994noreply@blogger.com1