Influence of long-term application of stockpiled feedlot manure with straw or wood-chip bedding on net nitrogen mineralization and nitrification in a clay loam soil
Miller, J.J., Beasley, B.W., Drury, C.F., Larney, F.J., Hao, X., Chanasyk, D.S. (2018). Influence of long-term application of stockpiled feedlot manure with straw or wood-chip bedding on net nitrogen mineralization and nitrification in a clay loam soil, 98(2), 200-211. http://dx.doi.org/10.1139/cjss-2017-0082
Plain language summary
A shift by feedlot producers from straw to wood-chip bedding may decrease crop nitrogen supply by lower mineralization of organic nitrogen to inorganic N, and by lower nitrification of ammonium-N to nitrate-N.
Little research has been conducted on the influence of land application of stockpiled feedlot manure (SM) containing either wood-chip (WD) or straw (ST) bedding on soil net N mineralization (Nm) and nitrification (Nn) rates during the barley (Hordeum vulgare L.) silage growing season. The stockpiled manure containing ST or WD bedding at 77 Mg (dry weight) ha yr was annually applied for 13–16 yr to a clay loam soil in a field experiment in southern Alberta. The net Nm and Nn rates were measured using the “in situ-soil core” method over 30–33 d (Nm1, Nn1) and 46–50 d (Nm2, Nn2) in each of 4 yr (2011–2014). Net Nm1 rates were generally significantly (P ≤ 0.05) greater for ST (1.0–1.9 mg N kg d ) than WD (0.1–0.9 mg N kg d ). Net Nn1 rates were also generally significantly greater for ST (0.9–2.0 mg N kg d ) than WD (0.03–0.9 mg N kg d ). Similar trends were found for Nm2 and Nn2. The Nn rates, however, were limited by NH supply during the incubations as Nm:Nn ratios were typically <1 with relatively low initial ammonium levels. Hence, the nitrification rates reflected the Nm rates and they would have been considerably lower than potential nitrification rates. A shift from ST to WD bedding by feedlot producers may decrease crop N supply 2- to 10-fold by lowering Nm (2- to 10-fold) and Nn (2- to 30-fold), and supplemental inorganic N fertilizer may be required when WD bedding is used. −1 −1 −1 −1 −1 −1 −1 −1 −1 −1 4