Production agriculture has entered a new era, in which growers can maximize profit not just on every acre, but on every fraction of an acre—even tiny fractions. But only a few farmers are benefitting from it.
The tool that can maximize profit, as well as resource use, is variable-rate technology. In addition to allowing growers to adjust the rate of seed, fertilizer and pesticide, this technology also lets them switch plant varieties, row by row and even foot by foot, across their fields.
This kind of farming deserves a brand-new name: variable-input technology, or VIT for short.
Does VIT pay? A four-year farm-scale study conducted by Farm Journal Field Agronomist Ken Ferrie and his team says it does.
The study found a farmer who varied inputs to match soil conditions, we’ll call him Mr. V.R. Tea, netted more profit than Mr. Homer Unswinger, who shoots for the same high yield regardless of soil type, and Mr. I.M. Cawshus. Cawshus, like Unswinger, uses the same practices on every acre, but he takes a more conservative, or defensive, approach.
“Cawshus, Unswinger and V.R. Tea are putting forth the same effort, but V.R. Tea is netting from $63 to $100 per acre more profit than the other two growers,” Ferrie says. “The reason for the difference is V.R. Tea understands his soils and uses variable-input technology to apply the right inputs, at the optimum rate, on every acre.”
Admittedly, these profit calculations don’t include a charge for technology. “But you can buy a lot of technology for $100 per acre,” Ferrie says.
Today’s technology allows you to prescription-treat areas under an acre. Got 200'x300' pockets of alkaline soil scattered in a field of high-producing black ground? Plant a soybean variety with a higher iron chlorosis score or increase plant population in those areas. With corn, switch those areas to a hybrid that tolerates high pH and adjust your starter rate to compensate for reduced phosphorus and sulfur availability. Plant the better soil with your standard practices.
If you have zones of light, sandy, droughty soil, plant a bushier soybean variety to close the canopy faster, or a corn hybrid and population suited to the soil. Adjust your nitrogen fertilizer rate based on the soil’s nitrogen-supplying power and crop need.
The slow adoption rate of multi-hybrid planters suggests many farmers haven’t yet realized the potential of farming by the foot. “A large percentage of my clients and the growers I meet across the country would identify with I.M. Cawshus,” Ferrie says.
The smallest, though increasing, group of farmers pattern their management after Mr. (or Ms.) V.R. Tea. “For them, no zone is too small to manage,” he adds.
Facilitating this revolutionary management change is data. “Never before have we had the ability to collect so much data on our fields,” Ferrie says. “Our capacity for data accumulation increases every season, and most is fairly inexpensive or almost free.”
Ferrie identifies the following sources of data:
- Calibrated yield monitors provide the foundation for putting all the pieces together.
- Yield maps can be overlayed with geo-referenced soil maps downloaded free from the internet.
- Most counties have access to LIDAR (Light Detection and Ranging) maps, made by remote sensing.
- Images of your fields available on Google Earth, if taken at the right time, can provide valuable detail.
- Thermal and NDVI (Normalized Difference Vegetation Index) maps are economical to obtain.
- Higher-resolution images are available from drones and planes.
- Real-time data, including cation exchange capacity and organic matter content, can be collected using sensors pulled through the soil, such as smart firmers on your planter and soil mapping machines made by Veris Technologies.
- Planter and tractor monitors that record how planters adjusted downforce and managed depth, and when tractors changed speed to maintain rpm in tough-pulling soils, resulting from soil type changes, can produce as-applied maps that match up well to maps showing soil type and structure.
“In just a few years, we can collect more information about our soils than earlier farmers could collect in a lifetime,” Ferrie says.
Using VIT requires organizing and interpreting all the data. “Don’t stack all your layers of data—yield maps, soil maps, remotely sensed images, etc.—together and look at a summary,” Ferrie advises. “Separate the layers and interpret them. Crops react differently in dry and wet seasons. If you stack years of yield maps together, you get an average, which may cause you to overlook zones in your field, and fail to understand when and how yield losses happened.”
Search for correlations between layers, such as between soil type and yield. “When studying layers of data, look for contrast and areas that stand out,” Ferrie says. “When you find one, narrow down when it occurs—in wet years versus dry years or in soybeans rather than corn. Start to put patterns together.
“In the short term, look for annual or seasonal issues to direct your scouts to problem areas,” Ferrie advises. Perhaps most rewarding is when you identify zones with perennial, or recurring, problems. Go to the field and determine the cause. When you discover a field’s weakness, you can farm around the weakness and take advantage of the field’s strengths.”
For example, when a weakness shows up only in wet years that suggests an area of poor drainage. “Now you know how big the problem is and can estimate the cost to fix it,” Ferrie says. “If an area tends to be waterlogged, you can make a plan to drain it and estimate the cost and return on investment. You might decide to change your nutrient management practices to minimize nutrient loss. Or, you might look for genetics that tolerate wet feet, or add a seed treatment to control water molds.”
If you find areas with perennial pests, such as wireworms or nematodes, VIT technology lets you apply insecticide treatments, plant resistant varieties or plant treated seed only in those areas.
Some management zones, or contrasting areas on your maps, might need more than drainage. “We now can use variable inputs to fix almost every weakness we find on maps,” Ferrie says.
Which Type of Farmer Are You When it Comes to Management Style?
Mr. V.R. Tea
- Uses variable-input technology.
- Studies layers of data to create management zones based on topography, soil type and soil tests.
- Identifies strengths and weaknesses of every management zone; uses variable-input technology to maximize strengths and minimize weaknesses.
- Sets yield goals based on the water supply in each management zone.
- Bases plant population on yield goal and hybrid.
- Bases N rate on soil’s supplying power, population and yield goal; identifies risk areas for N loss, tests for soil nitrates and adjusts application rates.
- Scouts and reacts to pest problems as necessary.
Mr. Homer Unswinger
- Sets high yield goals (250 bu. to 270 bu.) on every acre, regardless of soil type.
- Applies 250 lb. of N per acre on corn following soybeans; adds more if he thinks he lost some, basing loss estimates on coffee shop conversation rather than soil tests.
- Plants all hybrids at 38,000 plants per acre, regardless of soil type.
- Focuses primarily on top yields when studying plot data, leading him to select mostly racehorse hybrids, rather than choosing defensive types for situations such as alkaline or droughty soils.
- Doesn’t scout much; sprays every field if he finds diseases or insects.
Mr. I.M. Cawshus
- Sets conservative yield goals, viewing high yield as high input cost.
- Wishes he could grow 250 bu. per acre corn, but does nothing to achieve it.
- Sets yield goal of 200 bu. per acre across all acres.
- Applies a flat rate of 180 lb. per acre of N on corn following soybeans.
- Does not vary fertilizer rate or take nitrate tests to estimate soil’s N-supplying power.
- Plants all hybrids at the same population.
- Uses his farm’s past yield history to select hybrids, which results in mainly defensive varieties.
- Is not big on scouting; applies fungicides and insecticides only when everyone else is doing it.
Farm Journal Study Shows Benefits of Variable-Input Technology
The yield and profit numbers below were generated by a multiyear farm-scale study involving multiple farms. It was conducted in a corn/soybean rotation using no-till or vertical tillage. Yields were calculated by calibrated yield monitors backed up by scale weights on every pass.
Farm Journal Field Agronomist Ken Ferrie and his crew planted two offensive hybrids and two defensive hybrids at three populations, and applied three nitrogen rates. Corn was planted with a 60' planter set for eight 30" rows and eight twin rows on 30" centers. In each management zone, yields were recorded by hybrid, nitrogen rate, population and row spacing.
To simulate farming styles, Ferrie assigned the yield resulting from defensive hybrids and the medium nitrogen rate and plant population to I.M. Cawshus. He assigned the yield from offensive hybrids with high population and nitrogen rates to Homer Unswinger. Mr. V.R. Tea was assigned the yield resulting from planting defensive hybrids on lighter soil and offensive (racehorse) hybrids on heavier, more-productive soil; plant populations based on hybrid and ear type; and an optimum rate of nitrogen based on population, yield goal and the nitrogen-supplying power of the soil (determined by the Illinois Soil Nitrogen Test).
Partners in the study included AgriGold, Great Plains Ag, Blu-Jet (Thurston Manufacturing Company), Ag Leader, Unverferth Manufacturing Company, Aeroptic LLC, AirScout, Bob Kuntz, Mike Craig and Crop-Tech Consulting.
Varying Inputs Returns $100 More Per Acre
After four years (one dry, one wet and two normal) Mr. V.R. Tea had a higher average yield on every soil type. The results were even more impressive after gross profit was calculated by subtracting the cost of seed and nitrogen from the value of the crop.
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