Winter and growing season nitrogen mineralization from fall-applied composted or stockpiled solid dairy manure

Authors: Lehrsch, Gary; BROWN, B - Retired Non ARS Employee; Lentz, Rodrick; JOHNSON-MAYNARD, J - University Of Idaho; Leytem, April

Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2015
Publication Date: 2/13/2016
Publication URL: http://handle.nal.usda.gov/10113/62936
Citation: Lehrsch, G.A., Brown, B., Lentz, R.D., Johnson-Maynard, J.L., Leytem, A.B. 2016. Winter and growing season nitrogen mineralization from fall-applied composted or stockpiled solid dairy manure. Nutrient Cycling in Agroecosystems. 104:125-142.

Interpretive Summary: Adequately characterizing the conversion of organic forms of nitrogen (N) to inorganic forms of N (termed N mineralization) with time from manure and other organic sources is needed to maximize manure N use efficiency, decrease producer costs, and protect groundwater quality. The objective of our two-year field study at Parma, ID, was to characterize in situ N mineralization with time as affected by a one-time fall application of solid dairy manure, either composted or stockpiled. The experiment included five treatments: a non-N fertilized control, two first-year rates of stockpiled dairy manure (21.9 and 43.8 Mg/ha, dry wt.) and two rates (53.1 and 106.1 Mg/ha, dry wt.) of composted dairy manure (hereafter termed compost). In our study we measured net N mineralization, which was the difference between N mineralization and N immobilization, defined as the incorporation of inorganic N into microbial biomass thereby rendering it unavailable for plant uptake. Net N mineralization (mineralization less immobilization) was determined to a depth of 0.3 m by repeatedly measuring soil inorganic N (ammonium-N + nitrate-N) concentrations in buried polyethylene bags. Overwinter mineralization was measured between amendment incorporation in fall and sugarbeet (Beta vulgaris L.) planting the following spring. In-season mineralization was measured in situ for seven consecutive incubation periods during the c. 220-d growing season for furrow-irrigated sugarbeet. Net N mineralization often varied among amendments and from year to year through mid-season, likely due to seasonal variation in temperature, annual differences in amendment properties, and other factors. In early spring 2003 after a warmer-than-normal winter, immobilization exceeded mineralization, regardless of treatment. In-season net N mineralization peaked between mid-August and early September each year, regardless of treatment. Annual (c. 11-mo) net N mineralization in 2003 averaged 52 kg N/ha, similar among treatments. In 2004, annual net N mineralization averaged 250 kg N/ha where manure treated, 150 kg N/ha where compost treated, and 106 kg N/ha where untreated. On average in 2004, 31% of compost’s annual net N mineralization occurred before the growing season and 69% during the season while essentially all of manure’s net mineralization occurred during the season. None of the amendments’ total N was, in net, mineralized in 2003 but in 2004 on average, 2% of compost’s and 16% of manure’s total N was mineralized, similar between rates within amendments. When estimating annual net N mineralization from fall-applied organic amendments, one must account for abnormal temperatures, including those overwinter.

Technical Abstract: Adequate characterization of nitrogen (N) mineralization with time from manure and other organic sources is needed to maximize manure N use efficiency, decrease producer costs, and protect groundwater quality. The objective of our two-year field study at Parma, ID, was to quantify in situ N mineralization with time as affected by a one-time fall application of solid dairy manure, either composted or stockpiled. The experiment included five treatments: a non-N fertilized control, two first-year rates of stockpiled solid dairy manure (21.9 and 43.8 Mg/ha, dry wt.) and two rates (53.1 and 106.1 Mg/ha, dry wt.) of composted dairy manure (hereafter termed compost). Net N mineralization (mineralization less immobilization) was determined to a depth of 0.3 m by repeatedly measuring soil inorganic N (ammonium-N + nitrate-N) concentrations in buried polyethylene bags. Overwinter mineralization was measured between amendment incorporation in fall and sugarbeet (Beta vulgaris L.) planting the following spring. In-season mineralization was measured in situ for seven consecutive incubation periods during the c. 220-d growing season for furrow-irrigated sugarbeet. Net N mineralization often varied among amendments and from year to year through mid-season, likely due to seasonal variation in temperature, annual differences in amendment properties, and other factors. In early spring 2003 after a warmer-than-normal winter, immobilization exceeded mineralization, regardless of treatment. In-season net N mineralization peaked between mid-August and early September (DOYs 230 to 251) each year, regardless of treatment. Annual (c. 11-mo) net N mineralization in 2003 averaged 52 kg N/ha, similar among treatments. In 2004, annual net N mineralization was similar between rates within amendments and averaged 250 kg N/ha where manure treated, 150 kg N/ha where compost treated, and 106 kg N/ha where untreated. On average in 2004, 31% of compost’s annual net N mineralization occurred before the growing season and 69% during the season while essentially all of manure’s net mineralization occurred during the season. None of the amendments’ total N was, in net, mineralized in 2003 but in 2004 on average, 2% of compost’s and 16% of manure’s total N was mineralized, similar between rates within amendments. When estimating annual net N mineralization from fall-applied organic amendments, one must account for abnormal temperatures, including those overwinter.