Carbon Gaps, Nitrogen Bulges, and Phosphorus Imbalances: In Search of Sustainable Soil Organic Matter Management

View the project final report

Commodities

Practices

• Animal Production: manure management
• Crop Production: catch crops, conservation tillage, cover crops, cropping systems, crop rotation, double cropping, fertilizers, no-till, nutrient cycling, nutrient management
• Education and Training: extension, on-farm/ranch research, workshop
• Natural Resources/Environment: carbon sequestration
• Production Systems: agroecosystems
• Soil Management: organic matter, soil analysis

Problem and justification

Agricultural soils in the Chesapeake Bay watershed are losing an average of 2 lbs/ac/yr phosphorus (P) in runoff water and 23 lbs/ac/yr N in nitrate leaching, contributing to severe water pollution. Simultaneously, soil carbon (C) levels are declining by 95 lbs/ac/yr, negatively impacting soil health and contributing to global climate change. Elemental C-N-P cycles are inextricably linked through the process of growing crops, feeding livestock, and applying manure to agricultural lands, but optimizing the management of these cycles to achieve high soil C levels while minimizing N and P losses is fraught with tradeoffs in heavily concentrated areas of livestock production. A survey that we conducted was answered by 44 farmers managing 10,984 acres of farmland and revealed that 68% of respondents only had a moderate or lower knowledge level about interrelationships between C-N-P cycles and 91% had a very high or extremely high interest in learning about management practices to achieve high soil C levels, reduce nitrate leaching, and reduce the risk for P runoff. These survey results, paired with the current environmental situation, demonstrate a need and highlight an opportunity to improve integrated C-N-P management on agronomic farms in the Chesapeake Bay watershed.

Solution and approach

This project will engage agronomic crop farmers in Pennsylvania, New York, and Maryland to learn about, evaluate, and improve C-N-P management on their farms. We will conduct research at 20 farms and a long-term research station experiment to identify combinations of management practices, such as planting cover crops, harvesting cover crops for forage, and strategic use of tillage and manure injection, that optimize C-N-P dynamics to achieve high soil C levels while minimizing N and P losses. These optimal combinations will emerge through unique approaches to data-mining on-the-ground farm management. Pairing the results from research sites with a cropping system computer model, we will also identify region- and soil-specific benchmark soil organic matter levels that can be achieved under optimal C-N-P management. To supplement our education program of workshops, field days, and webinars, we will develop an online simulation tool for farmers to compare C-N-P dynamics under different management scenarios. 84% of our survey respondents indicated that benchmark soil organic matter levels would be very or extremely useful in evaluating and adjusting their farm management practices and 75% said they would be very or extremely interested in using an interactive online modeling app to evaluate how farm management scenarios affect C-N-P relationships. Performance target Fifty agronomic crop farmers implement a cropping system management change to optimize soil C-N-P dynamics on 5,000 acres, increasing soil C by 5 tons/acre in the long-term while reducing nitrate-N leaching by 12 lbs/acre/yr and P runoff by 1 lbs/acre/yr (a 50% reduction of both).

Fifty agronomic crop farmers implement a cropping system management change to optimize soil C-N-P dynamics on 5,000 acres, increasing soil C by 5 tons/acre in the long-term while reducing nitrate-N leaching by 12 lbs/acre/yr and P runoff by 1 lbs/acre/yr (a 50% reduction of both).