Precision Nutrient Management

By Mick Johnston

Precision agriculture has evolved into a vibrant and important sector of the agricultural industry. From the initial foundation of grid sampling and Variable Rate Technology (VRT) applications, we now have sub-inch equipment management, electric and hydraulic control of planter row units, cloud-based data management, and many companies providing decision-support tools. With all the technology advancements pressing against the professional producer, the base question still rings true: where is my return on investment, and how does it impact future decisions on my farm?

Many producers have invested in precision management of nutrients on the farm. This has provided better stewardship of the soil and increased the net profit per unit of product produced. The majority of producers use grid sampling to lead better applications of dry fertilizer and lime on the soil. Few producers and companies have looked at management of liquid products to increase efficiency of plant and soil-available nutrients.

In 2015 Larson Farms, in Western Iowa, decided to reevaluate the way they manage all nutrient applications to achieve optimum efficiencies. For many years Clayton and David Larson had managed dry fertilizer and lime applications by using Zone Sampling to lead VRT applications. The rest of the nutrients were applied at a flat rate, based on the overall average need for the field. They didn’t feel this was a responsible way to manage the needs of the soil and crop produced.

Nitrogen is a major input cost, and Clayton and David figured they would receive a return on their investment if they purchased tools to help them better manage the application rates and timing of applications of nitrogen. They began planter-applying liquid nitrogen. They also invested in a 360 Yield Soil Scan, which enabled them to have real-time, zone specific soil nitrate analysis while in the field. This information, along with Geo-Advantage imagery of their fields, allowed the Larsons the flexibility to make multiple applications of nitrogen for extended plant availability. They also have implemented the use of CDS Piston Pumps with rate controllers, which enable them to apply multiple products at different rates with each pump.

Larson Farms utilizes manure applications in their nutrient management plan; while they have moved to a mostly-liquid fertilizer program, they use dry fertilizer when manure and liquid applications either won’t support the crop or the soil. Clayton and David have achieved better results by applying lower rates, more often with No-Till farming. To ensure they are achieving optimum soil nutrition, they soil test every two years with a 6” and a 2” stratification sample for better understanding of lime and nutrient levels across the soil profile.

Larsons oversee their manure management very closely. They use the soil test to provide VRT application layer for cattle and poultry manure. Application rates vary from four to seven ton per acre They use a Tebbe Spreader with John Deere Dry Fertilizer controller, which enables them to increase the acres spread while being better stewards of the soil and water, as well as manage soil needs with manure. With limited manure availability, Larson’s were able to increase acres covered by over 30% by utilizing the available technology.

Another major input cost for any farm is seed. In the past , Larson Farms variety management has been straight rate. With better understanding of management zones and nutrient timing, the Larsons began a VRT seed program in 2015

As more professional producers look at the 4R’s of nutrient management: Right Source, Right Rate, Right Time, and Right Place, the opportunity to manage the crops’ needs with liquid nutrients is now. The drive to change the management of nutrition for Larson Farms wasn’t to save money, but to be better stewards of the soil and resources needed to grow a profitable crop. With growing concerns around water quality and nutrient applications, innovators like Clayton and David Larson and Larson Farms are finding ways to be better stewards of the soil while producing top yields.

Management of soil and plant needs with liquid nutrition is not difficult; it’s just different. Technology continues to provide opportunities for producers to be more efficient in management of equipment and products applied. Innovators like David and Clayton Larson see Responsible Nutrient Management as an opportunity – not a requirement.


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