Soil aeration for dairy manure spreading on forage: Effects on ammonia volatilisation and yield

Experiments were conducted to evaluate the effects of performing soil aerat ion either before or after spreading liquid manure in forage production sys tems. The experiments included eight trials performed in 1996 using a non-i nterfering diffusion method to determine ammonia (NH3) flux emissions from both aerated and control plots. For all eight trials, the manure applicatio n rate was 75 355 L ha(-1). The average NH3 loss for the aerated treatment was 67.3 kg ha(-1) while the loss for the control plots was 63.0 kg ha(-1). Although differences in the NH3 loss between treatments were low, substant ial variations were observed between individual trials depending on the pre vailing meteorological conditions. To further evaluate the effects of soil aeration, 11 trials were carried ou t on Nova Scotia daily farms in 1996 and 1997 to identify yield effects. Ma nure application rates ranged from 18 000 to 64 000 L ha(-1). The average f orage yield on aerated treatments was 9.4% below control treatments (i.e., manure without aeration). Of the 11 trials, 9 resulted in significantly (P < 0.05) reduced yield with soil aeration.