Performance of a liquid manure injector in a soil bin and on established forages

In this study, a liquid manure injector was tested both in a soil bin and in three established forage fields containing heavy clay and sandy soils. The injector featured sweep cutting tools behind Y-shaped coulters. In the soil bin, cutting forces and soil disturbance were measured fora single tool with coulter (WC) and without coulter (WOC) at three injection depths (50, 100, and 150 mm) and two tool forward speeds (0.56 and 1.40 m/s). In the forage fields, the injection unit with eight sweeps with coulters was tested at two depths (D1=80 to 90 and D2=110 to 150 mm) and three manure application rates (R1=28, R2=56, and R3=112 m³/ha). Soil disturbance, odour, and ammonia concentration in air above the ground following manure injection, and forage yields were measured. In the soil bin, the draft force and soil disturbance for both WC and WOC increased significantly with increased injection depth, and the speed effect was only significant for the WOC. Overall, more draft force and soil disturbance was observed for the WC than for the WOC arrangement. The effect of the Y-shaped coulter in front of the sweep was noticeable as the vertical force increased significantly below 100 mm. In the field study, soil disturbance increased significantly with injection depth in the sandy soils. No significant differences in odour concentrations were observed between treatments R3D1 and R2D2. However, manured plots had higher odour concentrations than the initial background levels. Ammonia emission was detected above the soil surface only for the treatment R3D1 in the clay soil. Forage yields were not significantly affected by injection depth or manure application rate. The combinations of the highest application rate and greatest injection depth increased the yield when compared to the control plot. Forage yield reduction was observed as the result of grass damage associated with the tillage operation of the injector.