A “MANAGE”ed Approach for 4R Nutrient Stewardship on Drained Land

As agriculture in the 21^st century is faced with increasing pressure to reduce negative environmental impacts while continuing to efficiently produce food, fiber and fuel, it becomes ever more important to reflect upon more than half a century of drainage water quality research to identify future paths towards increased sustainability. For this project, nearly 400 drainage water quality studies (all based on actual rainfall and no rainfall simulation) were reviewed to create a publically available database that compiles site, climate, cropping, and agronomic management information across more than 50 years of drainage research. This new “Drain Load” table in the “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database was then used to compare drainage water quality and crop yield based on this pooled dataset. Although nutrient application timing and placement are generally known to affect agronomic performance and water quality, these two components of 4R nutrient management showed no significant impact on dissolved N or total/dissolved P loads in our meta analyses. This finding may have been complicated by a general lack of P drainage studies under natural rainfall.

Many gaps in drainage nutrient research were identified through this project: including the need for longer-term studies focused on newly drained areas, on ditch-drained areas, and on factors affecting P in drainage water; especially with coordinated controls across sites and years. Future work should include studies outside North America and the creation of a “Drain Concentration” table to complement the new “Drain Load” table in MANAGE. In fact, this project was recently leveraged to secure funding to create a MANAGE "Drain Concentration" table (Illinois Nutrient Research and Education Council).

In 2015, this project has generated two peer-reviewed publications and two more publications are currently under review. The MANAGE database may be downloaded via the following link: http://www.ars.usda.gov/sp2UserFiles/Place/30980500/manage2.zip.