Innovative drainage water management strategies to reduce nutrient loading

Algal blooms have increased in severity over the past two decades in the Great Lakes. An innovative drainage water management study was developed for mitigating nutrient loss and protecting the environment and ensuring food safety and quality. Studies were conducted on clay loam soils using large field plots equipped with automatic flow volume measurement and sampling systems over three separate 4-year periods (1995-1999; 2001-2005; 2008-2012) at three different sites to evaluate total nitrate and phosphorus losses under two drainage water management systems (regular free drainage, RFD, vs. drainage control/sub-irrigation, DCS) with a corn-soybean rotation. The results showed that averaged all three separate period DCS system reduced combined surface and sub-surface total nitrate loss by 41 % and total P loss by 12 % relative RFD system. For RFD system, of the total nitrate and phosphorus losses, about 9 % and 32 % were accounted for surface runoff water, while 91 % and 68 % were accounted for sub-surface tile drainage water, respectively. For DCS system, about 43 % and 73 % of the total nitrate and phosphorus losses were in surface runoff water, while 57% and 27 % were in sub-surface tile drainage water, respectively. DCS system can be considered a beneficial management practices to reduce total nitrate and soil P losses.