Using "High Tech Gadgets" In Test Plots

Many of us are involved in plot work that provides useful information. One caution we make is that any management decision should not be based on a single test plot, in a single year. Look around and use all the information that is available from your neighbors and other sources over a minimum of two years.

Since plot work is time consuming and detail oriented, it is beneficial to investigate ways that we can speed up the process and still get accurate results. Technology exists to help us with this task and it’s even getting reasonable in price. Using light bars, GPS guidance systems, automated flow controllers and yield monitors, we can do some things that previously would have taken a lot of time and effort.

Cost Estimates

The figures quoted give us a "ball park" for determining costs. The capital outlay for the equipment is about $20,000 to 22,500.

Light bar and receiver	$7000
Flow Controller and Monitor	$4000
Magnet sensor for ground speed	$1000
Yield monitor	$8000
Software and other	$2000
Total Capital Investment	$22,000

If your crop is custom combined, you save the cost of the yield monitor and if the operator has a yield monitor, try and get the data from them.

Light Bars

Light bars are a technology that helps us to drive straight. Although most of us pride ourselves at the ability to drive straight and accurately, studies have shown that in cultivation, planting, spraying and other operations, there is considerable overlap or misses. Lightbars can increase efficiency in tillage and input operations, such as fertilizer and chemical applications.

Flow Valves and Rate Controllers

Flow valves and rate controllers allow accurate application of fertilizers and herbicide inputs regardless of ground speed. This can reduce over use, costs and give you accurate and variable application rate possibilities.

Yield Monitors

Yield monitors map yields across fields. They show the field variability that can then be analyzed to determine what factors are influencing yield. In test plot harvesting, when properly calibrated, the yield monitor can give us a very good estimation of the crop yield between treatments.

Calculating Payback Period

When calculating the payback from this capital investment, there are many factors that should be included:

• savings in input costs
• greater working efficiency in time per acre (ac) or per hour
• hours that equipment can be used (working better in the dark)
• ease of operation for hired labor etc.

Let us consider some assumptions that we can use to make and example calculation;

• Corn acres - 500
• Soybean acres - 500
• Herbicide costs of corn - $30 / ac
• Herbicide costs soybeans - $20 / ac
• Application costs - $7.50 / ac
• Nitrogen reduction - 30 lbs/ac
• Nitrogen cost - 0.35 / lb
• Field efficiency (misses/overlaps) improves 5% with light bar
• Speed of operations increases 13% (as we can go faster and don’t have to look back as often, if at all)

Cost Savings detailed

Herbicides
Corn 500*(30.00+7.50)*.05 = $937.50
Soybeans 500*(20.00+7.50+7.50)*.05 = $875.00
Total savings = $1,812.50

Fertilizer
Corn 500*30*0.35 = $5,250.00

Tillage Efficiency
(less field time with reduced overlaps (6" vs 20") and slightly faster 6 vs 7 miles/hour))
Assuming $200.00/hr to have man and equipment in the field and improve efficiency by 10% reduces cost to $180.00/hr.
We have 500 acres of corn to be worked twice
$8/ac*0.1(10% increase in efficiency)*2(passes)*500(acres) = $800.00

Total Savings from these inputs = $7,862.50 / yr.

Using these numbers alone, it would take about 3 years to pay for the technology. There are also more costs involved, like training and setup. You also have to consider whether the saving of 30 lbs N /ac per year would be achieved every year.

However, there are likely more savings than have been detailed here, such as extending the workday into the night (reducing the overall fixed costs of equipment). The information made available by using the technology should help to identify additional savings. On-farm testing would help identify which cultivars we should choose, where we should be liming or other management decisions.

N Test Plots

Let’s look at how we would use this technology in a nitrogen (N) rate test plot, using side dress nitrogen with a flow meter and rate controller. Program into the unit a medium and high application rate of N. Then apply N at 3 rates:

1. Starter + zero side dress
2. Starter + medium rate
3. Starter + high rate.

Put 2 or more replicates of these rates in the field.

Rates can be changed with a flip of a switch and you can have confidence that the rates are accurate.

Make a map and keep it some place safe. Alternatively, use the GPS system to create your map and save it in memory. Using the yield monitor equipped combine, harvest the plots and summarize the data to look for a response. From this information you can determine what the rate of N should have been. Over a number of years you can fine tune the nitrogen rates. Remember that the rates change depending on the weather, previous crop, manure use, and other factors.

Next time more information on how the lightbar can be brought into the process to help with test plots.