Study On The Characteristics Of Horse Dung Decomposition In Desert Steppe

In this paper, the decomposing rate,the features of nutrient release and the main factors that influence the decomposition process of horse dung were studied in Xilamuren desert steppe, Inner Mongolia. The main results as follow:1. Under the condition of the desert steppe, the weight lossing of fresh horse dung was about 24% during decomposing period from spring to autumn. The average weight lossing was about 0.34% per day. The rate of weight lossing of horse dung in summer was quicker than that of in autumn. The rates of weight lossing were 14% and 6% separately. The average weight lossing per day were 0.47% and 0.31% separately.2. During the process of horse dung decomposition, the features of different nutrients release were obviously difference. In fresh horse dung, the contents of organic C,N,P,K were 458.9g·kg^-1,10.41g·kg^-1,3.77g·kg^-1 and 6.26g·kg^-1 separately. Through a decomposition period that from spring to autumn, the contents of organic C,N,P,K were decreased to 347.9g·kg^-1, 5.59g·kg^-1, 2.47g·kg^-1 and 1.05g·kg^-1 separately. The percent of them contents lossing were 24%,46%,35% and 83% separately.3. From May to October 2007, a total of 13400 specimens of coprophagous scarabs belonging to 26 species, 4 genera and 3 families were collected in fresh horse dung. For the community of coprophagous scarabs in horse dung, the dominant species was Aphodius comma. It accounted for 80.90% of the total individuals. The number of common species and rare species were 7 and 18. After excreted, there were more number of individuals and species of coprophagous scarabs entered into the horse dung immediately. As the time of horse dung excreted prolong, the changes of number of individuals and species of coprophagous scarabs were slowly in 1-4 days, and then the number and species of coprophagous scarabs were quickly decreased. After excreted 6 days, all the coprophagous scarabs disappeared in horse dung. The number of coprophagous scarabs species was the most abundant in August in horse dung. It was 13. And the individual number of coprophagous scarab was highest in July.4. The seasonal variation of urease activity in horse dung appeared to be a"W"shape. The urease activity was lower in June and August. And it was higher in May, July and September. And it was highest in May. The activity of proteinease in horse dung maintained about 50.0 mg·tyrosine 48h^-1·g^-1 from May to August and reduced to 13.61 mg·tyrosine 48h^-1·g^-1from August to September.The seasonal variation of cellulase activity appeared to have a tendency of decline in horse duang. The activity of celluase was highest in May. It was 9.93 mg glucose 72h^-1·5g^-1. And it was lowest in September. It was 0.90 mg glucose 72h^-1·5g^-1.In horse dung, the number of bacteria was highest in May. As the time going, the number of bacteria was decreas, and was lowest in July, and increased slightly from July and September. The number of fungi was 21×10² cfu·g^-1 dry dung in May which was the highest, then reduced quickly and reached lowest in June, but increased in July. The quantity of actinomycetes was 180×10⁴ cfu·g^-1 dry dung in May which was the highest, then reduced quickly and reached 10×10⁴cfu·g^-1 dry dung in September which was the lowest.5.The results that from the experiments in laboratory showed that keeping humidity and using dung scarabs to active in horse dung can significantly increase the horse dung decomposition process and the release rates of nutrients.