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Agricultural imagery is the best value in precision agriculture. As you gain experience, you will find many uses. Some of the most useful are managing Irrigation, Weeds, Soil Fertility, Nitrogen, Early crop growth, Drainage, and Estimating yield. When you place an order, you will be asked for the purpose of the photo. The reason for this is so we can acquire the image at the right time and under the right conditions to accomplish your need.
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To check on uniformity of irrigation, order an image from late July on, after several passes of the sprinkler system, or after completing one cycle of gravity irrigation. The more times you’ve irrigated the more sensitive the image will be.
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If a photo is taken near planting time, and the soil is covered with 30% or less residue, the color variations may have a strong correlation to organic matter levels in the surface soil. This effect is enhanced a day or two after a rain, since high organic matter soils retain more water. Often the patterns in the image can be used to set up a smart sampling scheme that performs even better than grid sampling in defining the variability of soil nutrients. Organic matter content has a strong correlation to phosphorous, potassium, and zinc levels. Images taken at this time (they are called “Bare soil images”) are a great value, since they can be used for several years.
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Nitrogen deficient corn is visibly yellow. Of course corn varieties vary in their greenness, so the best strategy is to include a reference strip somewhere in the middle of each variety in the field. This strip should have 40-60 lbs extra N applied. If the strip is visible in the photo, the surrounding corn is probably N deficient. Of ten this occurs in only parts of the field. Research is currently being conducted at the University of Nebraska and elsewhere to develop quantitative methods based on remote sensing. The best time to acquire this imagery would be after corn is over waist high, and prior to tassel, since this is the period of greatest nitrogen uptake by corn, but often the effects can be seen through August.
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Crops will begin to be visible in aerial images when the canopy is about half developed. This would be waist high corn, or late flowering in beans. Before this time, there is too much reflection from the soil for the crop to be visible. A photo taken at this early time will show areas of the field that are slow to develop.
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A bare soil image after a heavy rain will show ponding, tile drainage, and surface drains. Timing is essential here, as the contrast will disappear after 3 or 4 days.
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The best time to acquire an image for this purpose is in September, when the crop has started to turn color. A normalized vegetation index, which is a ratio of bands in an infrared image, can be used to estimate relative yield in an area where planting date is the same, and only one variety is planted. It is then a simple matter to estimate actual yield at a few locations in the field, and use this to convert the index to actual yield. Inquire about receiving an index if you are interested in this purpose.
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Maximum coverage is ½ mile on a side, or 160 acres.
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Log in and you will see a page with a “New request” button. When you come to the photo request form, fill in the legal description, and put a helpful name (like “Dad’s west pivot”) in the comment section. Within a day or so you will receive an email telling you that a verification image is posted. This image is a black and white bare soil image very similar to what you see on your FSA maps. The purpose is to verify that we have the correct location. Look at that, and use the form provided to make any needed adjustments to the photo coverage. When the infrared and true color photos are posted, you will see thumbnail images on the order details page. Click on a thumbnail, and the actual photo will display in a new browser window. You can then download the photo (select “File>Save as” in your browser menu and indicate where you wish to store the photo), or just leave it on the site, and let those concerned view as needed.
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