Abstract: From June 2008 to September 2009, a field experiment was conducted to study the decomposition characteristics of horse dung in Inner Mongolia typical steppe. The dung pats were deposited on the ground surface and buried into soil at a depth of 10 cm. In a paddock with an area of about 47 hm² and 100 pursang horses free-grazing, the inputs of horse dung were 48.8 kg·hm^-2 per month and 277.1 kg·hm^-2 per year. The horse dung decomposition mainly occurred in the initial period of the experiment (0-60 days), with a mass loss rate of 45.0%. After  this period, there was a slight variation of the mass loss. The total organic matter content in fresh horse dung was 77.0%, and decreased to 48.7% and 28.3% at the 60th and 330th days of the experiment, respectively. The nitrogen in fresh horse dung was mainly in organic form, and its mineralization rate and release rate were lower. In contract, the phosphorus in fresh horse dung was mainly in inorganic form, and its release rate was higher. Burying horse dung pats into soil eliminated the fragmentation of the pats by wind erosion and livestock’s trampling and mitigated the impact of water erosion on the nutrient concentrations in the pads, but had little effects on their organic matter decomposition rate.

Key words: Wuyishan scenery district, Landscape type, Patch size, Probability distribution