Date Full Report Received


Date Abstract Report Received



Primary Investigator:
Co-Investigators: Gyles Randall

Manure is a valuable source of nutrients and organic material for the soil. The observations that have been conducted across several studies have been completed in research plots. A study using actual producer data was conducted by collecting soil and manure test for nutrients across the Midwest. The aggregate data set from these surveys was over 50,000 acres of cropland in four states. There is a large amount of soil variability in the samples collected that often prevented a direct statement about the impact of manure in a particular field. However, across the complete set of observations manure increased the soil organic matter by 0.05% per year after five years of manure application at agronomic rates. During this same time period, there was no increase in the soil P levels or soil chemicals or pH. Increases in crop yield due to manure application have been reported on farms but were not found in this study because of the lack of a consistent yield data base. Producers can manage manure on their fields and enhance the soil without potential environmental problems. This study has promoted the development of three manure studies on producer fields in Iowa to be implemented in the fall of 2003 to directly compare manure versus commercial fertilizer and the changes in soil properties.