Nitrate, Phosphate, and Ammonium Loads at Subsurface Drains: Agroecosystems and Nitrogen Management
- Guillermo Hernandez-Ramirez *a,
- Sylvie M. Brouderb,
- Matthew D. Ruarkc and
- Ronald F. Turcob
- a New Zealand Institute for Plant and Food Research, Canterbury Agriculture and Science Centre, Private Bag 4704, Christchurch, New Zealand
b Agronomy Dep., Purdue Univ., West Lafayette, IN 47907-2054
c Dep. of Soil Science, Univ. of Wisconsin, Madison, WI 53706-1299. Assigned to Associate Editor Elizabeth Stockdale
Artificial subsurface drainage in cropland creates pathways for nutrient movement into surface water; quantification of the relative impacts of common and theoretically improved management systems on these nutrient losses remains incomplete. This study was conducted to assess diverse management effects on long-term patterns (1998–2006) of NO3−, NH4+, and PO43− loads (L). We monitored water flow and nutrient concentrations at subsurface drains in lysimeter plots planted to continuous corn (Zea mays L.) (CC), both phases of corn–soybean [Glycine max (L.) Merr.] rotations (corn, CS; soybean, SC), and restored prairie grass (PG). Corn plots were fertilized with preplant or sidedress urea–NH4NO3 (UAN) or liquid swine manure injected in the fall (FM) or spring (SM). Restored PG reduced LNO3− eightfold compared with fields receiving UAN (2.5 vs. 19.9 kg N ha−1 yr−1; P < 0.001), yet varying UAN application rates and timings did not affect LNO3− across all CCUANs and CSUANs. The LNO3− from CCFM (33.3 kg N ha−1 yr−1) were substantially higher than for all other cropped fields including CCSM (average 19.8 kg N ha−1 yr−1, P < 0.001). With respect to NH4+ and PO43−, only manured soils recorded high but episodic losses in certain years. Compared with the average of all other treatments, CCSM increased LNH4+ in the spring of 1999 (217 vs. 680 g N ha−1 yr−1), while CCFM raised LPO43− in the winter of 2005 (23 vs. 441 g P ha−1 yr−1). Our results demonstrate that fall manuring increased nutrient losses in subsurface-drained cropland, and hence this practice should be redesigned for improvement or discouraged.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2011. . Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.