Iowa Expands Free Nitrogen Soil Testing Across 26 Counties Ahead of Fall Sampling Season
The Iowa Department of Agriculture and Land Stewardship (IDALS) has expanded its free Nitrogen Soil Sampling Project to 26 counties in the Greater Des Moines and Middle Cedar watersheds. The initiative, conducted with the Iowa Nutrient Research & Education Council (INREC), aims to help farmers adjust fertilizer rates and maintain crop yields while limiting excess nutrients moving from fields into waterways.
The project now covers all 22 counties in the Greater Des Moines Watershed and four counties in the Middle Cedar Watershed. The goal is to collect samples from 250 farm fields, with participating farmers providing information over three years on nitrogen management, crop rotations, manure applications, cover crop history, and post-harvest conditions.
Iowa Agriculture Secretary Mike Naig said that combining soil sampling with the Iowa Nitrogen Initiative's N-FACT tool can help farmers minimize fertilizer costs while maintaining yields and improving water quality. The N-FACT tool supports decisions on nitrogen application rates, and the multi-year approach can reveal patterns that a single soil sample cannot capture.
The economic calculation is significant for corn producers because nitrogen remains a major variable input. Applying too little can limit yields, while excessive applications increase costs without guaranteeing additional production. The project could provide another layer of field-level information for determining where nitrogen investments are most likely to deliver an agronomic return.