Dairy Manure Nitrogen Availability in Eroded and Noneroded Soil for Sugarbeet Followed by Small Grains

Published in Agron. J. 103:628–643 (2011) Published online 02 Mar 2011 doi:10.2134/agronj2010.0409 Copyright © 2011 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. T U.S. dairy herd of 9 million animals produces an estimated 20 million Mg manure annually. In regional dairy centers (0.5 million cows) such as southern Idaho, 1.1 million Mg manure are generated each year. Manure and composted manure amendments improve soil physical properties, supply nutrients to crops, and can aid in rebuilding eroded soils, which are common in this historically furrow irrigated region (Robbins et al., 1997). To maximize their use of manure and minimize losses of N to the environment, growers need to understand how manure or composted manure additions infl uence soil N availability and how availability may vary with soil erosion status, that is, between whole (noneroded) soils and eroded soils. Research evaluating manures as a source of soil nutrients has been underway for decades (Heck, 1931; Herron and Erhart, 1965), yet questions remain especially with regard to the N derived from these organic residues (Cabrera et al., 2005). Much of the N in manure is in the organic form and is released to soil via the microbially mediated process of mineralization. Th is process is strongly infl uenced by the character of the manure applied, soil abiotic environmental factors such as soil temperature, water content, and soil characteristics, such as clay content (Eghball et al., 2002). Laboratory studies have evaluated N mineralization rates at optimal soil water content and temperature for diff erent soils or manures (Chae and Tabatabai, 1986; Qian and Schoenau, 2002; Van Kessel and Reeves, 2002; Griffi n et al., 2005; Honeycutt et al., 2005; Azeez and Van Averbeke, 2010) and quantifi ed the eff ects of varying soil temperature and water content on N mineralization (Honeycutt et al., 2005; Watts et al., 2007). Carpenter-Boggs et al. (2000) used variabletemperature incubations that mimicked fi eld temperature regimes to quantify eff ects of crop rotation and N fertilization on N mineralization. Comparison studies found that N-mineralization rates derived from laboratory incubations generally tended to overestimate rates measured in the fi eld (Adams and Attiwill, 1986; Honeycutt, 1999; Sistani et al., 2008). Nitrogen-mineralization rates of soils are measured in the fi eld (in situ) to obtain values that better refl ect the environmental factors and dynamic conditions and that are specifi c to an individual region or management conditions (Jansson and Persson, 1982; Stenger et al., 1996; Hanselman et al., 2004). Direct in situ measurements of net N mineralization are typically accomplished by isolating small soil volumes (<750 cm3) in the fi eld and monitoring inorganic N concentration in these volumes over time. Th e advantages and disadvantages of the methodologies devised to accomplish this task have been discussed by Motavalli et al. (1989), Honeycutt (1999), and Hanselman et al. (2004). Given its successful application in previous southern Idaho research (Westermann and Crothers, 1980; Westermann and Crothers, 1993; Meek et al., 1994), the buried bag approach was used in this study. Th e frailty of buried bags can be problematic, the plastic may be perforated by insects or roots, which may ultimately compromise the obtained N mineralization data (Eno, 1960; Westermann and Crothers, 1980; Monaco et al., 2010). ABSTRACT