Pasture type and fertilization effects on soil chemical properties and nutrient redistribution

Soil samples were collected from beef pastures varying in species composition and fertilizer inputs after being grazed by cow-calf pairs for 4 yr (1995-1998) near Brandon, Manitoba. The objective of this experiment is to examine the impact of 4 yr of continuous rotational grazing on soil chemical properties and nutrient redistribution in mixed alfalfa-grass and pure-grass pastures with or without fertilization. Pastures were established on an Orthic Black Chernozemic, fine sandy-loam soil. Compared with N-fertilized pure-grass pastures, alfalfa-grass pastures had greater seasonal soil mineral-N supply, and tended to have higher total soil C, N and organic C. In grazed systems in this environment, the use of alfalfa as the primary N source may be more profitable and sustainable than using fertilizer N. However, considering the seasonal changes in soil nitrification rate observed in alfalfa-grass pastures, caution needs to be taken when stands with high legume content are used to maximize animal performance...