Greenhouse Evaluation of Simulated Injected Liquid Beef Manure

Abstract

AbstractIn response to observed crop production problems (uneven growth, stunting, and chlorosis) encountered when liquid manure was knife injected into soil, a greenhouse study was initiated to detemine corn (Zea mays L.) response to simulated knife (vertical) and sweep (horizontal) placement of liquid beef manure (equivalent field application rate of 37 400 L ha−1). Derinda silt loam soil (fine, mixed mesic Typic Hapludalf), 0‐ to 20‐cm depth, was collected from a field site where crop growth problems associated with knife‐injected manure had been documented by previous field research. This soil, with and without simulated manure injections, was placed into pots and incubated at 8.9, 15.6 and 22.2 °C for 3 wks. Corn was then planted and grown for 26 d in the greenhouse. At all preplant incubation temperatures, vertical placement of the manure severely reduced plant growth throughout the duration of the study. With horizontal placement, growth was reduced early after planting, but recovered as time progressed, especially at the 22.2 °C preplant incubation temperature. Reductions in plant growth were related to toxic conditions within the manure zone. Analysis of the manure zone indicated toxicity from NH3, inferred from the high pH and high concentrations of NH+4, lowered redox potential, followed by accumulation of NO−2‐ to toxic levels. Horizontal placement resulted in reduction or elimination of these toxicities, except NO−2, which had accumulated at the end of the incubation period. Because vertical placement created a more concentrated zone of manure at the point of injection than did horizontal placement, method of injection appears to dflerentially affect potential toxic conditions and resultant plant growth.