LONG-TERM EFFECTS OF BEEF FEEDLOT MANURE APPLICATION ON SOIL PROPERTIES AND ACCUMULATION AND TRANSPORT OF NUTRIENTS

Authors: FERGUSON, R - UNIV NEBRASKA; Nienaber, John; Eigenberg, Roger; Woodbury, Bryan

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 8/15/2003
Publication Date: 10/12/2003
Citation: FERGUSON, R.B., NIENABER, J.A., EIGENBERG, R.A., WOODBURY, B.L. LONG-TERM EFFECTS OF BEEF FEEDLOT MANURE APPLICATION ON SOIL PROPERTIES AND ACCUMULATION AND TRANSPORT OF NUTRIENTS. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS MEETINGS PAPERS. pg 1-9. 2003

Interpretive Summary: A study initiated in 1992 was designed to evaluate the long-term effects of using manure or compost to fertilize corn. The focus was on nutrient needs of the plants, and changes in the soil over an extended period. Two rates of application of manure or compost were used. Material was applied to satisfy the nitrogen needs of the crop, but this provided more phosphorus than the plants could use. The second rate was to apply just enough phosphorus to meet crop use, but this meant additional commercial fertilizer was needed to supply the nitrogen. Each of these application rates was compared to commercial fertilizer without any manure or compost. The corn was harvested for silage. Over the 10-yr period, the high rate of manure resulted in the highest yield, but there also was some nitrogen that moved beyond the roots of the plants. There also was an unacceptable build-up of phosphorus in the surface layer of soil. Use of the lower rate of manure application gave the next highest silage yield. Both phosphorus and nitrogen levels in the soil were within acceptable ranges. This study demonstrated that livestock manure, composted or uncomposted, can be successfully used to supply crop nutrients and may increase yields above commercial fertilizer. However, application of manure to satisfy the nitrogen needs of the crop cannot be sustained without causing a phosphorus accumulation risk.

Technical Abstract: A field study was initiated in 1992 to investigate the long-term impacts of application of beef feedlot manure (composted and uncomposted) on soil nutrient accumulation and movement. Of particular interest were comparisons of two strategies for application -- to provide annual crop nitrogen requirements (N basis) or to meet crop phosphorus removal (P basis), as well as an inorganic fertilizer treatment. Additionally, effects of a winter cover crop were evaluated. Irrigated corn (Zea mays L.) was produced annually from 1993 through 2002. Average silage yields and crop nutrient removal were highest at the high manure application rates (N basis), intermediate at the low manure application rates (P basis), and least with inorganic N fertilizer. The winter cover crop substantially depleted soil moisture in the spring in some years, resulting in silage yield reductions in 4 of 10 years in the presence of a winter cover treatment. However, the cover crop did significantly reduce nitrate-nitrogen accumulation at the bottom of the root zone in latter years of the study, most likely due to immobilization of manure N near the soil surface. Soil apparent electrical conductivity (EC) measured throughout the growing season in 2002 showed significant correlation with surface nitrate-nitrogen concentration. Higher EC values during most of the growing season for the no-cover treatments suggest that substantial amounts of manure-mineralized N were being immobilized early in the growing season in the winter cover treatments. The composted manure N-basis treatment (CN) resulted in significantly greater soil profile nitrate-nitrogen concentrations and higher soil P concentrations at the soil surface. While repeated annual application of beef feedlot manure to supply the total crop N requirement may be acceptable for this soil for several years, sustained application over many years carries the risk of unacceptable accumulation of soil P.