Short-Term Legacy Effects of Feedlot Manure Amendments on Irrigated Barley Yield and Soil Macronutrient Supply

Limited research exists on short-term legacy effects of land application of different feedlot manures on barley (Hordeum vulgare L.) yield and soil macronutrient (NO3-N, PO4-P, K, and SO4-S) supply. In a study conducted in southern Alberta, feedlot manures with straw (ST) or wood-chip (WD) bedding were either stockpiled or composted and applied annually to a clay loam soil at 13, 39, and 77 Mg ha(-1) dry wt. for 17 yr. Control treatments without any amendments or with inorganic fertilizer were included. In the second and third year (2016-2017) after discontinuing manure applications in 2014, barley silage yield and soil nutrient supply measured in situ with plant root simulator (PRS (R)) probes were determined. No significant (P > 0.05) treatment effects occurred on barley yield. Significant treatment effects occurred on soil nutrient supply, but these depended on date and interaction with other treatment factors. Manure rate generally increased soil nutrient supply. Soil NO3-N and PO4-P supply were 40%-59% lower for composted manure with ST than the other three manure type-bedding treatments, and they were 26%-53% greater for stockpiled than composted manure. This indicated variable manure type effects at different dates. At the two highest rates, soil K supply was 60%-106% greater for ST than WD bedding, and the reverse trend occurred where SO4-S supply was 40%-174% greater for WD than ST bedding. Overall, short-term legacy effects of feedlot manure type and bedding were more persistent on soil macronutrient supply than barley silage yield.