Effects of liquid hog manure on soil available nitrogen status, nitrogen leaching losses and wheat yield on a sandy loam soil of western Canada

Manure can improve soil quality and enhance crop yields. However, excessive manure use may contribute to nitrate (NO3-) leaching, particularly on coarse-textured soils. The objective of this study was to evaluate the effects of liquid hog manure (LHM) on wheat yield, soil available N and NO3- leaching on a sandy soil in Manitoba. Manure treatments included three rates of LHM applied to supply 64 (low), 128 (medium) and 192 kg N ha(-1) (high) in 3 consecutive years (2002-2004). Unamended plots were used as a control. Available nitrogen was measured three times during each growing season at soil depths of 0-15, 15-30, 30-60, 60-90, and 90-120 cm. Undisturbed soil core lysimeters were used to measure NO3- leaching. Crop yields (grain and straw), N-uptake and N use efficiency were assessed at the end of each growing season. In 2002 and 2003, LHM had little effect on wheat yield, N nutrition and NO3- leaching due to below-normal rainfall in both years. In contrast, in 2004 when precipitation was above normal, LHM amendment increased grain yield and plant N-uptake. Relative to the control, grain yield was 20, 30 and 50% greater in the low, medium and high manure-N plots, respectively. Manure increased soil available N concentration 1.2-, 1.3- and 1.7-fold and induced additional NO3--N leaching of 4.7, 28.4 and 54.5 kg ha(-1) in the low, medium and high manure-N plots, respectively. Results suggest that LHM should be used with caution on sandy soils due to leaching potential in years of high precipitation and low crop yields in years of low precipitation.