Simon J. Neufeld1, Martin Entz1, and Yu Ying Shen2. (1) Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada, (2) College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
Dead and un-decomposed plant material on the soil surface, known as litter, plays an important role in native and tame pastures, affecting soil moisture and microclimate, and protecting site stability. The insulating effects of litter reduce soil temperature and evaporation at the soil surface. While the litter layer can benefit the water balance by reducing overland flow and increasing infiltration, it can also intercept rainfall thus trapping moisture above the soil surface and rendering it unavailable to plants. If the net effect of the litter layer is improved plant-available soil moisture, forage yields should be increased. The present research examines the effect of litter rate on soil moisture, and the subsequent forage yield. Five research sites in Southwestern Manitoba were established in the spring of 2006. Eight treatments were replicated four times at each site: seven litter rate treatments ranging from 0 to 3000 kg/ha were applied after existing litter was removed, and one in situ treatment was included where existing litter was not removed and no new litter was added. Soil moisture was measured throughout the 2006 and 2007 growing seasons. Soil moisture levels were only sometimes found to be affected by litter rate (P>0.05). Where a significant relationship was present, it was not consistent or linear – the highest and lowest rates of litter did not have the highest and lowest respective soil moistures. It is clear from this research that the relationship between litter rate and soil moisture is complex; the significance of litter in soil moisture dynamics depends on interactions with factors such as climate, landscape, soil characteristics, and plant community structure.
