HIGHER INPUT PRICES RESULT IN GREATER ECONOMIC INCENTIVES HIGHER INPUT PRICES RESULT IN GREATER ECONOMIC INCENTIVES FOR PRECISON AGRICULTURE.FOR PRECISON AGRICULTURE.

F. John Barker III, Extension Educator, OSU Extension – Knox County, Mt. Vernon OH 43050

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MethodsMethodsNine years of accurate and calibrated yield data was available for a local field utilizing a GPS based yield monitor. This field was in a strict corn-soybean rotation. Fertilizer recommendations were developed utilizing the four following scenarios.

Scenario 1: Fertilizer recommendations were made according to the farmers’ normal production practices. Variable rate technology was not utilized in this scenario. All applications were made through the planter.

Farmers often question the economic value GPS-based technology. Does precision agriculture pay? In most precision agriculture circles, this is the most often asked question, and at times a most difficult question to answer. Today’s technology allows farmers to vary the application rates of crop inputs throughout a field. GIS software allows field specific data to be analyzed and incorporated into the decision making process. Theoretically, combining field based data with the ability to vary input usage at specific locations within a field should increase input efficiency. Increased efficiency should improve profit margin and result in the adoption of more environmentally sound practices. The objective of this study was to evaluate phosphorus and potassium fertilizer application rates utilizing four different fertility scenarios on a Central Ohio farm with nine years of GPS based yield data. These scenarios were; 1) The farmers normal production practices, 2) Soil testing and fertilizer recommendations based upon 2.5 acre grid samples, 3) Soil testing and fertilizer recommendations based upon management zones developed by soil type and 4) Fertilizer recommendations based upon management zones developed by GPS based crop removal. Does precision agriculture pay? The results of this analysis show economic advantages for each GPS based scenario. When compared to the farmers’ normal production plans, the grid sampling scenario resulted in savings of $36.36 per acre. The soil type management zones and the crop removal management zones resulted in savings of $84.91 and $88.04 respectively.

AbstractAbstract

ObjectiveObjectiveThe objective of this study was to evaluate fertilizer use and application rates utilizing four different fertility recommendation scenarios. Only phosphorus and potassium applications were analyzed in this study. Economic implications will also be analyzed.

ResultsResultsTable 1 contains the fertilizer use data from this analysis. Fertilizer recommendations were made for each of the four scenarios using the Tri-State Fertilizer Recommendations as a guide (OSU Extension Bulletin E-2567). Overall fertilizer use was the highest using the farmers’ normal production practices (scenario 1). Utilizing grid soil sampling and variable rate applications (scenario 2) fertilizer use was reduced by 3,420 pounds. Soil sampling using management zones based upon soil type and utilizing variable rate fertilizer applications (scenario 3) reduced overall fertilizer use by more than 3.5 tons. Scenario 4 which utilized G.I.S. software to divide the field into management zones based upon crop removal and utilizing variable rate fertilizer applications produced the most efficient fertilizer use. This scenario, which is based on the actual field production, shows phosphorus recommendations were reduced by almost 1.5 tons and the potash recommendations were cut in half.

Economic ImplicationsEconomic Implications

Table 2: Economic ResultsTable 2: Economic Results

Table 1: Fertilizer ComparisonTable 1: Fertilizer Comparison

The economic implications of this study are displayed in Table 2. Fertilizer prices of $650/ton for Potash and $850/ton for D.A.P. were used for this analysis. Soil testing charges and variable rate fertilizer application charges were included where appropriate. Scenario 4, fertilizer recommendations based upon crop removal produced the greatest savings. This scenario which had the lowest fertilizer use and no soil testing charges resulted in a savings of $88.04 per acre when compared to the farmers normal production plans. Soil sampling by soil type (scenario 3) and 2.5 acre grid sampling (scenario 2) resulted in savings of $84.91 per acre and $36.36 per acre respectively, when compared to the normal production practices for this farm.

But does it pay? In this analysis Yes! Each scenario involving variable rate fertilizer applications resulted in lower fertilizer use and a greater net return. With today’s soaring fertilizer prices, savings of $36 to more than $88 per acre can have a significant impact on most Central Ohio farms.

Figure 2: Harvest Dreams.

$88.04$84.91$36.36$0.00Saving vs. Normal Plan ($/A)$134.81$137.94$186.49$222.85Total Cost ($/A)

$6.00$6.00$6.00$0.00Variable Rate Fert. Application$128.81$131.94$180.49$222.85Fertilizer Cost + Soil Test ($/A)

0.00$0.70$0.70$0.00Soil Test Cost($/A/Year)$128.81$131.24$179.79$222.85Total Fertilizer Cost ($/A)

$55.00$49.50$79.75$110.00K Cost ($/A)$73.81$81.74$100.04$112.85P Cost ($/A)

9,94510,08013,90517,325Total Fertilizer Use (Lbs./Field)10090145200K Recommendation (LBS. K2O/A)121134164185P Recommendation (LBS. P2O5/A)

Crop Removal

Soil Type

2.5 Acre Grid

Normal  

Scenario 2: The field was divided into 2.5 acre grids. Soil samples were pulled and sent to a lab for analysis. The fertilizer application data was developed for this field utilizing a variable rate technology based upon the results from the soil test data.

Scenario 3: The field was divided into management zones based upon soil type. Soil samples were then pulled from each soil type. Each sample size was approximately 2.5 acres or less. The fertilizer application data was developed for this field utilizing variable rate technology based upon the results from the soil test data.

Scenario 4: GIS software was used to divide the field into management zones. These zones were based upon actual, historic crop removal data from this field. Fertilizer recommendations were based upon the actual crop removal in each of these management zones. Fertilizer applications were made utilizing variable rate technology (Fig. 1.).

Figure 1: Management Zones based on Crop Removal.

(-4500)(-4950)(-2475)--K Difference(LBS. K2O /Field)

4500405065259000K Recommendation(LBS. K2O /Field)

(-2880)(-2295)(-945)--P Difference(LBS. P2O5 /Field)

5445603073808325P Recommendation(LBS. P2O5 /Field)

CropRemoval

SoilType

2.5 A GridsNormal