July 3, 2003

 

Research Shows Site-specific Farming Is Profitable

Research near Mandan shows that site-specific farming can be profitable in western North Dakota while providing environmental benefits, according to Vern Hofman, North Dakota State University Extension Service agriculture engineer.

"Producers are farming larger acreages using larger machinery to apply seed, fertilizer and pesticides uniformly over the entire field, Hofman says. "Now, farmers can apply fertilizer and some herbicides to an individual soil type based on its production capacity. More can be applied in some areas and less in other areas so inputs to large fields can be easily adjusted based on soil type and field topography."

The research was conducted over several years as a demonstration/research project involving the USDA-Agricultural Research Service, the Area IV Soil Conservation District and the NDSU Extension Service.

The Mandan study shows that variable-rate application on sunflower can improve returns by up to $11.50 per acre compared to uniform application. Spring and winter wheat returns were variable with some economic losses that were compounded by hail damage and dry weather.

"From an environmental standpoint, site-specific farming can reduce potential surface and groundwater problems," Hofman says. "That’s because researchers were able to apply fertilizer based upon the soil production capability. The crop is able to use all the fertilizer for producing the crop, leaving very little residual fertilizer in the soil. Any remaining fertilizer is a potential water pollutant. If a dry growing season occurs, all the fertilizer may not be used. But, researchers found that residual fertilizer can be used for the next season’s crop, reducing the fertilizer bill."

Researchers found that topography-based soil sampling provides as good or better soil nutrient information as compared to dense grid soil sampling. "For example, 51 soil samples taken on a one and a half acre grid were needed to equal the accuracy of only 14 samples taken on a topography zone based soil sampling scheme," Hofman says. "Much less sampling time is needed and we have a cheaper analysis cost."

Nutrients impacting yield must be variable across a field to justify variable rate application. If variability of a nutrient such as nitrogen is less than 30 pounds per acre (actual N) in the upper 24 inches of the soil profile, it is unlikely that variable rate fertilizer application will be profitable. Areas with nitrogen variability need to be sufficiently large, as a small isolated spot will not justify variable application.

Researchers also found that if yields are low due to environmental conditions such as hail or dry weather, it is unlikely that variable rate fertilizer application will be cost effective. Variable rate application will be most effective when high variability of a nutrient is present, the nutrient is variable within the zone where adjustment impacts crop yield and environmental conditions allow good yields to be achieved.

"Yield monitoring is another important aspect of site-specific farming and this study has shown that considerable variation in crop yield occurs across a field," Hofman says. "A record of that variability can be helpful so comparisons can be made between yield, fertilizer rates and pesticide applications so an analysis can be made for optimum use of crop inputs. A yield record can also be helpful in directing soil sampling and to help plan for next year’s crop."

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Source: Vern Hofman, (701) 231-7240, vernon.hofman@ndsu.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu