Mark Carlton, Extension Field Agronomist and Sue Henderson, Clete Swackhamer, and Sandra McLain, County Extension Education Directors, Southeast Area
Retail cost of nitrogen, phosphorus, and potassium reached record levels during the summer and fall of 2008. At the same time the price of corn and soybean crashed from record highs. Growers were faced with the decision of whether to apply fertilizer to maintain high yields or forgo fertilizer applications and suffer perceived yield loss. Many lacked the knowledge and confidence to make a nutrient plan.
ISU Extension sponsored Nutrient Management Workshops in Monroe, Appanoose, Davis, and Van Buren Counties. Growers were lectured on soil testing techniques, interpreting soil test results, crop nutrient removal rates, ISU nutrient recommendations and research data, and using the Nitrogen Calculator. Growers were then given soil tests and asked to calculate nutrient application rates based on soil test values and yield history under several financial scenarios.
Medium to long-term change:
Seventy percent of the growers who attended the workshops said that after attending the workshop and working through the examples of soil tests, felt confident that they could interpret soil test values and make their own decision on how much fertilizer to apply to their fields rather than depend on agribusiness or a soil testing laboratory to make the recommendation.
Medium term result:
After looking over his soil test, one grower said that his soil tests were high enough that he could get not apply phosphorus and potassium for several years and not suffer yield loss. His saving in 2008 was more than $20,000.
An alfalfa grower went out and soil sampled her own field and found that the phosphorus levels were very low but the potassium levels were high. She made the decision to spend her fertilizer dollars on phosphorus rather than potassium.
Short-term results measure awareness and knowledge.
Medium-term results measure behavior change.
Long-term results measure condition (i.e., new standard).
100 Corn and Soybean Production and Protection
Page last updated:
April 29, 2009
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