Corn Growth Responses to Composted and Fresh Solid Swine Manures Terrance D. Loecke, Matt Liebman,* Cynthia A. Cambardella, and Tom L. Richard ABSTRACT Dewes, 1992; Rao Bhamidimarri and Pandey, 1996; Egh- ball et al., 1997; Tiquia et al., 2002). Swine (Sus scrofa L.) production in deep-bedded hoop structures Field trials comparing composted with fresh dairy is a relatively new swine finishing system in which manure can be applied to fields fresh or after composting. We conducted field-plot manures have shown similar corn yield (Brinton, 1985; trials near Boone, IA, during two growing seasons to determine the Ma et al., 1999) despite faster seedling growth rates in effects of fresh and composted swine hoop manures on corn (Zea response to fresh manure (Brinton, 1985). Composted mays L.) growth and yield. Both fresh and composted manures were and noncomposted beef feedlot manure applications re- applied at a total N rate of 336 kg ha -1 in the spring before planting sulted in similar corn growth rates and grain yields, al- corn, and a functional growth analysis approach with frequent plant though lower N-use efficiencies were reported with use harvests was used to assess total aerial dry matter (DM) production of composted manure (Eghball and Power, 1999). Field and leaf area development of the crop. Phytotoxicity bioassays utiliz- applications of composted poultry litter resulted in 25% ing annual ryegrass (Lolium multiflorum Lam.) and cress (Lepidium less corn biomass and grain yield than applications of sativum L.) seedlings as test species produced inconsistent responses raw poultry litter when these amendments were applied to manures. During the two seasons in which this experiment was conducted, corn in the composted manure treatment produced 10% at the same total N rate (Cooperband et al., 2002). The more grain than did corn in the fresh manure treatment. Corn treated lower N-use efficiency of compost is typically attributed with composted manure produced 12% greater aboveground DM in to increased humification of the compost relative to its 2000 and 15% greater DM in 2001 than did corn treated with fresh feedstock, fresh manure. Comparing sunflower (Helian- manure. In 2000, DM differences were evident early in the season, thus annuus L.) seedling growth response to composts at whereas in 2001, DM differences became evident near flowering. The increasing stages of humification, Baca et al. (1995) found time of treatment separation in both years coincided with the driest phytotoxic inhibition from immature composts and Fe, soil conditions of the season. As compared with the fresh manure Zn, and N deficiencies with more mature composts. Con- treatment, composted manure increased corn crop growth rate (CGR), versely, a substantial number of studies have demon- leaf N concentration, leaf area index (LAI), and, in one of two years, strated that animal manures, composts, and compost ex- net assimilation rate (NAR). Harvest index and leaf area ratio (LAR) were unaffected by manure treatments. Composting swine hoop ma- tracts can increase plant growth beyond levels explainable nure before field application appears to be an effective alternative to by increases in nutrient supply (reviewed by Chen and fresh-manure application for corn production. Aviad, 1990). Because of these potentially contradic- tory effects, the impacts of fresh and composted manures on crop performance cannot yet be predicted with con- A pplication of animal manures to agricultural fields fidence. is a widely used method of increasing soil organic Swine production in hoop structures is a relatively new matter and fertility (Khaleel et al., 1981). Most solid husbandry system in which deep-bedded manure can be livestock manures can be applied directly to crop fields either spread directly or composted before use (Hon- or piled for composting. Composting manure can reduce eyman et al., 2001). A comparison of composted and fresh field application costs by increasing bulk density and swine hoop manures on crop performance is relevant to reducing volume. Composting can also increase applica- the development of best management practices for uti- tion uniformity due to a reduction in particle size, and lizing manure. Quantitative growth analysis can be used decrease amounts of viable weed seeds (Wiese et al., to make such comparisons and may provide important 1998) and phytotoxic substances (Tiquia and Tam, 1998) insights into the dynamics of crop  climate  soil inter- contained in manure or manure and bedding mixtures. actions that will ultimately affect yield (Evans, 1972; However, with composting, there are potentially greater Hunt, 1982). The objective of this study was to use a production and environmental costs associated with ex- quantitative growth analysis approach to examine corn tra handling and possible losses of nutrients. Nitrogen responses to spring-applied composted and fresh hoop losses during composting of animal manures have manures under field conditions. ranged from 200 to 700 g kg -1 of total N (Martins and MATERIALS AND METHODS T.D. Loecke, Dep. of Crop and Soil Sci., Michigan State Univ., 562 Plant and Soil Sciences Bldg., East Lansing, MI 48824-1325; M. Lieb- Site, Experimental Design, and Management man, Dep. of Agronomy, 3405 Agronomy Hall, Iowa State Univ., The experiment was conducted on adjacent fields during 2000 Ames, IA 50011-1010; C.A. Cambardella, USDA-Agricultural Re- and 2001 at Iowa State University’s Agronomy and Agricultural search Service, 310 National Soil Tilth Lab., Ames, IA 50011-3120; T.L. Richard, Dep. of Agricultural and Biosystems Engineering, 3222 Engineering Research Farm near Boone, IA (42°01' N, 93°45' National Swine Research and Information Center, Iowa State Univ., W). Both field sites were in a soybean [Glycine max (L.) Ames, IA 50011-3080. Received 30 Dec. 2002. *Corresponding author Merr.]–corn–oat (Avena sativa L.) rotation with no animal (mliebman@iastate.edu). Abbreviations: CGR, crop growth rate; DAP, days after planting; Published in Crop Sci. 44:177–184 (2004).  Crop Science Society of America DM, dry matter; GDD, growing degree days; LAI, leaf area index; LAR, leaf area ratio; NAR, net assimilation rate. 677 S. Segoe Rd., Madison, WI 53711 USA 177