By Blake Jackson
Soil testing is an important part of effective crop production, and grid soil sampling offers a more detailed way to understand field nutrient levels. Cornell University’s Nutrient Management Spear Program (NMSP) recently studied how grid sampling can help decision makers manage nutrient deficits and surpluses with greater accuracy.
Traditional soil testing uses 15 to 20 soil cores mixed into one sample for an entire field. While helpful, this method can hide differences within the field. According to data analyst Manuel Marcaida III, soil types, slopes, and management histories can vary widely. “Within-field differences are common in regions with diverse soil types, slopes, and management histories,” he said.
To better understand these variations, advisors began using grid sampling, dividing fields into smaller sections and sampling each one separately. Although grid sampling requires more time and cost, NMSP researched whether these added efforts are worthwhile. “Our goal was to answer that question with data,” said Marcaida.
Working with Certified Crop Advisors across New York, NMSP evaluated different grid sizes—0.5, 1.0, and 2.5 acres. Smaller 0.5-acre grids captured nutrient differences more accurately in variable fields, while more uniform fields did not require fine-scale sampling. Their recommendation is to begin with 0.5-acre grids to understand field patterns, then group similar grids into management zones for future sampling. This allows for more efficient lime and fertilizer applications.
“The results of the study showed how detailed soil information can help farmers make better lime and fertilizer decisions, avoid unnecessary costs and get the most out of every acre,” Marcaida added.
Grid sampling also helps highlight areas that need more or fewer inputs. Some parts of a field may require less fertilizer, reducing expenses, while others may need additional lime or nutrients to support yield goals. Even when more input is required, improved productivity usually justifies the cost.
Overall, grid sampling reduces guesswork. Decision makers can see where money should be spent or saved, based on real data. As Marcaida explained, “The immediate benefit is getting to know the fertility variations of the nooks and crannies of the field.”
Researchers are continuing their work by studying how grid sampling can help assess phosphorus loss risk using the New York P-index.
Photo Credit: gettyimages-shotbydave
Categories: New York, Crops, Education, Equipment & Machinery