Organic Matter and Root Health

Sustainable farming means better management of soil organic matter and organic manures as the primary source of nitrogen for our crops. Our research helped us to better understand the linkages between the use of crop rotations and manure, and the health of roots and yields and nitrogen needs of corn. We developed an 'organic matter budgeter' program for helping farmers to plan how cropping and manuring practices will influence the organic matter content of their soils. Then we tested the budgeter with many farmers in Illinois, Iowa, and Wisconsin. That work involved on-farm trials, and field-based nitrogen budgets with corn for 3 years. Some of the results were as follows:

• The majority of the nitrogen that corn extracted from soils probably was derived from soil organic matter, even under conventional farming conditions. Corn seemed capable of extracting large quantities of nitrogen from organic matter when it was grown under both conventional and organic conditions.
• Conventionally farmed corn had about double as much root disease as did organic corn, and this disease seemed to cause greater (compensatory) root growth, and luxury consumption of nitrogen.
• Conventionally grown corn plants were inefficient as they took up much more nitrogen for every bushel of grain that they produced than did the organic corn.

Related links

• Organic Matter Budgeter [pdf 45kb]
• Final report: "Improving farm nutrient management by optimizing organic matter inputs and root health" [pdf 352kb]