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OBJECTIVES: 1. Define remote sensing as it relates to climate. 2. Explain why farmers can use images to detect plant health .3. Explain how using remote sensing can benefit both farmers and the environment. |
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INTRODUCTION: Remote Sensing can be used in agriculture to determine damage caused by weeds, pests, or nutrient deficiency. For this tutorial we will study how remote sensing can help in those three areas. In response to the prospect of disaster, many farmers carry insurance. Insurance coverage varies. However, in the advent of serious crop loss due to weed, pest, or nutrient deficiency, insurance can be a lifesaver. The producer will recover some economic loss even though the crop may be destroyed. |
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USE OF IMAGERY An image collected by the IKONOS satellite was obtained on July 17th, 2002 for a farm in southeast South Dakota. An image was prepared using IKONOS bands 4 (near infrared), 2 (red) and 1(blue). An image using these bands in this combination is called a false color image.Observation of the image showed many problem areas in this soybean field (Figure 4). Figure 1.(on right) Areas with problems marked in yellow. |
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PEST DAMAGE In this IKONOS image several abnormalities were observed. Farmers will look at the image. Then using the image, they will visit areas where they think problems might occur in the field. This is called 'ground truthing". Each of the individually marked area shows problems in the field. This image is again used with "ground truthing" to identify the problem accurately. The patch of pest damage in the upper right shows up in the image. Simply driving down the road north of the field will identify the problem. The map can then be used to measure the extent of the problem and treatment options. In one soybean field, bean leaf beetles and grasshopper damage could be detected from space (Figure 1) as well as on the ground (Figure 2). If the infestation is small enough they can be sprayed manually before the problem has a chance to spread. If the infestation covers a large area then the entire field can be treated for the proper problem. Figure 2.(below left) bean leaf beetles and grasshopper damage |
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| Figure 2.(above) bean leaf beetles and grasshopper damage | Figure 3.(above) waterhemp infestation in soybean field |
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WEED DAMAGE In a second soybean field, an area of suspected waterhemp weed was noted (Figure 1). Ground truthing confirmed waterhemp weed present in this area (Figure 3 above right). Once the extent and locations of the problems are known, corrective action can be taken. Similar to the pests, the satellite image can show the extent of the weed problem. The main advantage to the map image is being able to treat only the small infected area rather then the entire field. |
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NUTRIENT DEFICIENCY Potassium deficiencies may be observed in coarse textured soils and where erosion has removed the topsoil. Potassium (K) deficiencies may reduce yields and profitability. Potassium is a mobile nutrient within a plant. When K deficiency appears in plants, symptoms usually occur on older leaves first because K is translocated from the older leaves to the younger leaves. When K is deficient, the tips and edges of the older leaves start to turn yellow(Figure 4 on below left). Eventually the leaf margins will die and turn brown. IKONOS imagery was
obtained on July 3rd, 2002 for a farm in east central South Dakota. A
false color image was prepared using IKONOS bands 4 (near infrared), 2
(red) and 1(blue). In a false color image, healthy plant vegetation appears
darker or brighter red. Upon investigation of the imagery by the farmer,
areas in cornfields did not appear as healthy as other areas (Fig. 5)
and plants in this area have symptoms similar to these shown in Fig. 4.
This farmer suspected that these areas might be low in soil K. The remote sensed image brought home the extensiveness of the problem and that K management needs to be investigated more closely. Economic benefits from the imagery include solving the K deficiency problem in this and other fields resulting in higher yields. The farmer plans to use this information to improve potassium management in his fields. |
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Figure 4. Yellow leaves show Potassium deficiency. |
Figure 5. Suspected areas require further checking. |
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HOW CAN USING REMOTE SENSTING POTENTIALLY HELP FARMERS AND THE ENVIRONMENT? Numerous insect and weed problems were observed in this field. The image assisted the land manager in finding these problem areas in the field in a timely manner. Several advantages that are both environmental and economic exists from using remote sensing in agriculture. Environmental benefits include using imagery to scout for insect problems, identifying only the problem, area and variable rate applying chemicals to control the pests in these specific areas. This way only the plants that are affected are treated rather then an entire field. Figure 6. (below left) Economic advantage to the land manager includes a reduced cost of pesticides, herbicides or insecticides. Also, the farmer may save scouting time by using remote sensing imagery. The image on the right(Figure 7.) shows an area of nitrogen deficiency in a corn field. Crop scouting found that the corn inside the 25 acre strip marked in black was 3 ft tall. Corn in the rest of the field was 5 ft tall as show figure 8 |
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Figure 6. Machinery has several options and uses for GPS technology.
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Figure 7. Remote sensing data shows area poor plant growth. The 25 acre area boxed off is used in the example below to demonstrate the use of this map. |
| Figure 8. on the left shows the crop scouting from figure 7. The shorter corn on the left shows the difference between the areas of the field. | |
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EXAMPLE Spending $160 is definately worth $1175 in return. Also, if the problem occured over a larger area then the difference in income would change dramatically. |
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VARIABLE RATE TECHNOLOGY In the example above, fertilizer application cost $25 per acre resulting in a total cost of $625. Although the increased profit made it worth the application, new technology can still decrease that cost yet with Variable Rate Technology (VRT). VRT is categorized by what it applies. VRT can be broken into three specific areas. 1. Seeds These different areas of application can be used for a variety of things on a farm. |
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PLANTING(Gregg Carlson, Tom Doerge, David Clay) Many times when plants are unevenly spaced, one plant does not produce grain and can actually act like a weed, drawing nutrients and moisture from the other plant. Under these conditions, yields can be reduced. The accuracy of planting can vary from perfect to very poor. Many agronomists believe that importance of a uniform field increases with row width. A split planter study by Pioneer Hi-bred showed an average yield improvement of 4.2 bushels per acre due to planter calibration. At some locations, the advantage for calibration exceeded 20 bushels per acre. In a research study conducted by Purdue Universty, yield losses from 7 to 15 bushels per acre were observed in uneven standards. Clearly, fine-tuning planters to achieve the best possible yields should be the goal of every producer. Of all production variables that affect farming, planter condition is one of the most controllable. A two-inch spacing is the best spacing uniformity a farmer can expect to obtain under normal production planting conditions. Variable rate technology can be very useful in planting. It can be used to determine, record, and make adjustments for: 1. How many seeds
are planted |
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Figure 9. The two corn plants in the middle will act as weeds using up important water and nutrients from the soil and resulting in lower yields. |
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SPRAYING Spraying operations variable rate technology has many advantage. Its biggest advantages are parallel tracking and autosteer. This assisted steering system is extremely accurate (within 4-inches pass to pass accuracy) and guides the tractor in a straight line down the row. You will still turn your tractor at the end of each pass, and steer around obstacles such as trees, ditches, and waterways (Deere & Company). It is a big help to farmers that are spraying. The automatic steering insures that the same area of a field is not sprayed twice or that an area of a field is not missed. This allows you to travel at a higher speed, save chemical, and be overall more efficient in your operation. The computer software can record and make adjustments for: 1. Mixing the fertilizer The VRT technology also allows you to spray small areas of a field that are infected while not using chemical spray on the rest of the field. Reducing the amount of spray is helpful not only to the farmer but also to the environment. |
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Figure 10. Variable Rate Technology is useful in spraying such as shown in the picture above. |
Figure 11. Autosteer provides a big advantage during tillage |
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TILLAGE A tillage operation uses VRT in a similar way to spraying and planting. The biggest VRT advantage in tillage is autosteer and parallel tracking to eliminate overpass. The concept of a tractor steering itself and eliminating human error is a fast and exciting development in agriculture. Remote sensing information can also be useful in tillage management decisions. Choices of what type of tillage to use from plowing to disking to no-till can be made using remote sensing data collected from soil testing or yield testing the year before.
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| Figure 12. (Left) Yield monitors and other data collected during harvesting shows the end result of the work done throughout the year. |
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HARVESTING Another application of variable rate technology is in harvesting. Yield monitors, which are discussed in tutorial 7, are used to constantly record yields for different part of the fields. While this data is not immediately useful, once analyzed and mapped it becomes very helpful to a farmer. Someone using remote sensing can rely on a yield monitor to draw conclusions from data collected throughout the year. The yield monitor data collected while harvesting will tell how useful the GPS and remote sensing data have been. Did the area that was sprayed for weeds have higher yields? If it did then you can say the remote sensing saved money. Did the area that was sprayed with extra fertilizer grow better, saving you money as in figure 7 where $1175 was saved, or was too much fertilizer applied resulting in lower yields? Yield data is basically the final exam to how well a farmer used their remote sensing data throughout the growing season. Those spots that were identified as problems, given special attention, and did not have better yields must be looked at again to see if another problem exists to fix the next year. Tutorial 7 will go more in depth on the benefits of yield data. |
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QUESTIONS Download and print questions here 1. In figure 1, what are the three problems identified by the IKONOS image? 2. What advantage is the advantage of remote sensing in detecting small areas of insect damage? 3. What is the main advantage of a remote sensing image when it comes to weed identification? 4. How was remote sensing useful in figures 4 and 5? 5. Identify an environmental and economic benefit of remote sensing. 6. In figure 7, what color represents the healthiest vegetation? 7. In figure 7, what color shows where a possible problem is located? 8. In the example, assuming the information remained the same (yields 40 bushels per acre less, at $2/bu for corn, fertilizer and applications costs $25 per acre, the image cost $160 for the field). How much would the farmer return in income if the area of nutrient deficiency was 10 acres? 50 acres? 100 acres? 9. What three areas can variable rate technology be separated into? 10. Why is planter calibration important? 11. How many inches is the best average spacing for planting corn? 12. What adjustments and information can VRT provide while planting? 13. How accurate is an autosteer system? 14. What adjustments and information can VRT provide while spraying? 15. What does yield monitor data tell us? 16. A farmer treated a small 5 acre section of his 100 acre field for insect infestation. However, yield data showed the area was still very low in yields. Further examination of the data showed that the corn in that area had an extremely high moisture content. What secondary problem may exist that can be fixed for the next growing season? 17. A farmer found a section of his field showed signs of nitrogen deficiency. To fix the problem, the farmer doubled the amount of nitrogen applied to the area. However, yield data showed that the area was still low in yields. Soil tests were conducted in the area and the soil was found to be very high in nitrogen. What mistake might the farmer have made? 18. An area of a field was found to have low yields. Ground truthing found that a large canada thistle infestation was present. The 15 infected acres averaged 40 bushels per acre. The rest of the field averaged 120 bushels per acre. If corn is selling for $2.00 per bushel, herbicide costs $21 per acre, and a remote sensing map would have cost $200, how much money could the farmer have saved by purchasing a remote sensing image. 19. A farmer has a 100 acre field with a small grasshopper infestation. He estimates the loss to be about 8 bushels per acre. If the insecticide to treat the field would cost $15 per acre and the remote sensing image costs $150, should the field be treated? 20. A farmer finds a section of his field with very low yields. Ground Truthing shows that some of the corn plants over the area are spaced less then one-inch apart. What might the farmer consider investing in for the next growing season?
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MAP SECTION 1. Go to the map section by right clicking on the link below and opening the map in a new window. Map page 2. This map section has three different fields in the upper right corner. They are referred to by sw, mid, and e. 3. The roads layer may remain inactive for this tutorial 4. Do not forget to
use the
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QUESTIONS 1. What crop is present in field e? 2. What crop is present in fields sw and mid? 3. Which field is extremely low in Phosphorus or P 4. How does soil depth differ throughout the fields? 5. How does the elevation change as you move across the fields? 6. What section of the mid field has little to no nitrogen present? 7. In all three fields, what color represents high yield, what are the three different number ranges that this color can represent? 8. How many pounds per acre is considered to be a high phosphorus level? 9. How many pounds per acre is considered to be a high nitrogen level? 10. What 5 factors that affect yields are measured in this map? |
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EMAIL QUESTIONS (Message board not available) 1. Have you ever suffered losses from nutrient, pest, or weed problems? 2. Have you ever prevented a major problem that could have been caused by nutrient, pest, or a weed problem? If so, how did remote sensing and GPS technology help you? 3. Make up a third question as a small group or class. |
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to move through the tutorial and answer the questions.