The Impact of Feedlot Manure Application on Hydrology, Soil Carbon, and Nutrient Loss

Feedlot manure is a potentially valuable resource to provide plant nutrients and improve soil. A field experiment was undertaken with the objective of determining the effect of feedlot manure applications on hydrology, and nutrient loss. The five treatments imposed over a three-year period were no manure or inorganic fertiliser (NM), a moderate annual manure application + N (MAN), a high initial application + N in year 1 (HIN) and an inorganic fertilizer treatment (I) applied in each year. Relay crops of sorghum (Sorghum vulgare) and triticale (Triticosecale spp. cv. Madonna) were grown throughout the 3 years. EnviroCSAN multisensor capacitance probes were used for soil water measurement. Unsaturated hydraulic conductivity was measured in-situ using an automatic recording disc permeameter. Steadystate infiltration was determined at two tensions (40 and 10 mm). Soil moisture was consistently higher on the HIN treatment despite higher crop production. Surface runoff was highest in the NM treatment. At the end of 3 years, infiltration rate was highest in the I and M treatments. Highest losses of N occurred in the I and highest K loss in in M. Runoff P concentration exceeded an acceptable concentration in more than 86% of runoff events. Incorporation of feedlot manure into soil with minimum disturbance, coupled with relay cropping can have substantial benefits for both nutrient cycling and hydrology.