|Nienaber, John - Jack|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 7/17/1998
Publication Date: N/A
Citation: Interpretive Summary: This report presents the results of a 5-year study on the use of manure on irrigated corn silage. Manure removed from a beef cattle feedlot was applied without treatment or following composting. Composting was done by weekly mixing rows of material to incorporate air and encourage biological activity. The compost or uncomposted manure was applied to treatment plots using two strategies. Material was analyzed to find the nitrogen and phosphorus contents and then applied to meet either the estimated nitrogen or the phosphorus requirements of the crop. Soil samples were taken each fall to monitor soil nutrient carryover. Availability of nutrients in manure was estimated and credit was given for carryover nutrients in the soil when calculating the annual application rates. After 5 years, excess phosphorus is evident in each treatment receiving manure or phosphorus. This suggests that the nutrient availability factor was too low for phosphorus. In the higher application rates, there was some nitrogen found near the bottom of the root zone. This was thought to be due to low crop yields in 2 years because of wind damage.
Technical Abstract: A long-term study was initiated in 1993 to investigate the impact of different strategies for the utilization of beef feedlot manure on soil accumulation and transport of nutrients. The two strategies compared were to provide the total crop N requirement annually, adjusted according to soil nitrate levels in the root zone, or to provide the crop removal of P annually. Forage N removal in the latter years of the study has been greatest with treatments supplying the total N requirement, with no difference between manure and composted manure. Forage P removal in all years has been increased with the application of organic materials. There is a trend over years for forage N recovery of the total N applied (organic + inorganic) to be greater with manure than for composted manure. In latter years of the study, nitrate has begun to accumulate throughout the root zone for treatments receiving the entire N requirement from organic sources. Soil P has also accumulated in the top 0.3 m of all treatments receiving organic resources, suggesting that the P mineralization credit allowed for treatments designed to supply crop removal of P annually is too low.