Indiana Watershed Initiative

We are quantifying the benefits of watershed-scale agricultural conservation practices that may reduce nutrient runoff to downstream freshwaters as a part of the USDA Regional Conservation Partnership Program (RCPP) and the Indiana Watershed Initiative (IWI). We have monitored Shatto Ditch Watershed (SDW; Kosciusko Co, IN) since 2012 to assess the effects of watershed-scale planting of winter cover crops on 62-68% of croppable acres and the construction of 7 km of two-stage ditch. In Spring 2015, we added a second watershed, the Kirkpatrick Ditch Watershed (KDW; Jasper Co, IN), where we increased winter cover crop acreage to 13-32% of the croppable acres and monitored an existing 1 km of two-stage ditch. We collected water samples every 14 days from representative tile drains (n=6-25) and the base of the watershed at both SDW and KDW to quantify the effects of cover crops on nitrogen and phosphorus export. We collected soil samples from a subset of fields with and without cover crops in each watershed seasonally after cash crop harvest in the fall and before cover crop termination in the spring. Soil samples were analyzed for water extractable phosphorus, nitrate, ammonium, and soil organic matter.

本研究旨在量化流域尺度农业保护性措施所带来的益处，这些措施可能降低养分径流至下游淡水，作为美国农业部区域保护合作伙伴计划（USDA Regional Conservation Partnership Program，简称RCPP）和印第安纳流域倡议（Indiana Watershed Initiative，简称IWI）的一部分。自2012年起，我们对沙托沟流域（Shatto Ditch Watershed，简称SDW；位于印第安纳州的科斯丘索县）进行了监测，以评估在62-68%的耕作面积上实施冬季覆盖作物种植以及修建7公里双级排水沟对流域尺度的影响。2015年春季，我们增加了第二个流域，即柯克帕特里克沟流域（Kirkpatrick Ditch Watershed，简称KDW；位于印第安纳州的贾斯珀县），在该流域中，我们将冬季覆盖作物的面积增加到耕作面积的13-32%，并监测了已存在的1公里双级排水沟。我们每隔14天从代表性的排水沟（n=6-25）和两个流域的流域底部收集水样，以量化覆盖作物对氮和磷输出的影响。在每个流域的季节性监测中，即在秋季农作物收获后和春季覆盖作物终止前，我们从有和无覆盖作物的部分田地中收集土壤样本。土壤样本经分析，以测定水溶性磷、硝酸盐、铵以及土壤有机质。