Field Water Budget and Tile-Drainage Effluent Loads as Affected by Lignocellulosic-Feedstock Production Systems.

Lignocellulosic-feedstock production systems have been proposed as a way to enhance United States energy security. Excessive harvesting of above-ground plant biomass may degrade desirable soil qualities that influence nutrient cycling and water dynamics.  However, research of the impacts such practices have on quantity and quality of tile-drain effluent and the field water budget has been limited.  The objective of this study is to determine the effects of six lignocellulosic-feedstock production systems consisting of mixed prairie (nitrogen fertilized and unfertilized), continuous maize with 50 % stover removal (with and without cover crop), and maize-soybean rotation (each crop type grown each year) on tile-drainage effluent loads and the field water budget.  The research site is located near Ames, Iowa and consists of twenty-four (27 x 61 m) individually tile-drained plots on Webster silty clay loam (fine-loamy, mixed, superactive, mesic Typic Ednoaquoll) and Nicollet loam (fine-loamy, mixed, superactive, mesic, Aquic Hapludoll) soils.  Production systems were replicated four times in a randomized complete block design.  The prairie treatments had smaller drainage volumes than the annual crop treatments.  Less nitrogen and phosphorus appeared in the prairie drainage than in the annual crop drainage.  Full results from 2009 and 2010 will be presented.