South Dakota Amber Waves

 

South Dakota was in 2014 one of the top four states in all wheat production with 131.26 million bushels. The state was also sixth in planted acres with 2.51 million, and fifth in acres harvested with 2.36 million. Production in bushels was up 53.7 million from 77.56 million in 2013 making for an unprecedented 69% growth between both years. With a yield of 56 bushels per acre and an average price of $5.6 per bushel, gross income per acre was roughly $314. From a wheat producer’s perspective the key is to be able to figure the cost of production. As with any other agricultural enterprise the total cost of production can be divided into operating and overhead costs. Operating costs are basically the yearly out-of-pocket expenses, whereas the overhead costs include all other costs such as the use of capital, taxes and insurance, opportunity cost of land, etc. Operating costs during 2014 were roughly $2.2 per bushel of wheat (Table 1). Once these costs were subtracted from the gross income the value of production per acre was roughly $191. The two single largest costs were fertilizer (by far), followed by chemicals, and then equipment maintenance. 

 

 

 

 

Furthermore, fertilizer and chemicals constitute half of the operating cost of production. These are two areas to focus to have significant impact on profitable wheat production. Here is where precision agriculture techniques come into play. Precision agriculture is more than just the purchase of high-tech expensive equipment. It is a toolbox of practices that combines information acquired from the field with the response of the crops to management practices. The process starts with a soil analysis for nutrient content early in the spring, right before planting wheat. Soil experts with SDSU Extension can help producers with guidelines to obtain an adequate, representative sample of the soil in which wheat is going to be planted. 

 

Using precision agriculture equipment seeds can be planted at variable rates across a field, and be also accompanied with different fertilizer rate recommendations (variable rate application: VRA). It was precisely based on the development of this VRA fertilizer that precision agriculture technology started to be developed nearly 30 years ago. Computer technology applied to agriculture was then emerging which, combined with radar-based GPS advances were made map-based VRA possible. At the time this technology was in the experimental stage and pretty much cost prohibitive. A variety of VRA technologies are nowadays available that can be used with or without a GPS. The two basic VRA technologies are map-based and sensor-based. The first one adjusts the application rate based on a map (fertilizer prescription map) created based on soil fertility differences within a field. With the field position from a GPS and the map of desired application rates, the concentration of fertilizer is changed as the VRA equipment moves through the field. The second one (sensor-based VRA) uses no map or GPS but has sensors on the VRA that measure soil properties or crop characteristics and it calculates the amount of fertilizer needed. It then transfers this information to a controller, which delivers the fertilizer. Some modern equipment have features of both types of VRA incorporated. 

 

In spite of the economic and environmental benefits associated with a reduction in fertilizer use VRA fertilizers are still not as widespread as one would like them to be. One reason is the use of financial caution when investing in new farm equipment. The other reason is associated with the differences in field and soil types. Fields with uniform soil types and fertility do not benefit that much from VRA fertilizer, whereas those with high and low spots benefit the most.