青藏高原东部高寒草甸牦牛粪便的分解过程和科学管理

Decomposition process and scientific management of yak dung on alpine meadow in the eastern Qinghai-Tibetan Plateau

放牧家畜粪尿养分回归是影响草地系统的重要方式之一,特别是对于养分分解缓慢的高寒生态系统。本研究对青藏高原东部高寒草甸牦牛粪便自身养分特征以及夏、秋季节养分释放的动态变化进行了初步研究,并通过计算植物生长的养分需求和粪便养分输入量,探讨了高寒草甸牦牛粪便的科学管理问题。研究表明,研究地区典型高寒草甸每公顷每年通过牦牛粪便输入的氮量为79.4kg,磷为11.8kg。牛粪在夏季经过85d的分解后,主要养分降为初始状态的0.48%～6.98%,基本完全分解;秋季养分的分解趋势与夏季相似,但是分解速率缓慢得多,主要养分只降为初始状态的13.44%～40.06%。据估计,研究地区平均每户牧民的牦牛每年可产4.08×105kg鲜牛粪,其中需有3.08×105 kg牛粪用于维持草地肥力,8.93×104 kg鲜牛粪用于煮饭、烧茶、取暖等的燃料。这样,除了维持草地肥力和生活自用之外,仅剩余2.5%的牛粪。因此,不建议将牛粪用于培养食用菌等商业用途。

Ruminant dung fertilization is one of important ways to impact grassland ecosystems, especially for high-altitude ecosystem nutrient cycling. In this study, characteristics and decomposition dynamics of nutrients of yak dung were determined and scientific management strategy of yak dung was explored through calculating nutrient demands of plant growth and input amounts of yak dung on the alpine meadow of the eastern Qinghai-Tibetan Plateau. The results indicated that released nitrogen and phosphorus from yak dung on a typical alpine meadow were 79.4 and 11.8 kg ·ha-1 . a-1 , respectively. After 85 d decom- position in summer, most of the major nutrients were degraded （approximately 0.48%--6.98% of the ini- tial state）, while in autumn the decomposition rate was much lower （approximately 13.44%- 40.06% of the initial state）. It was estimated that the input amount of fresh yak dung on the study area was approxi- mately 4.08×10^5 kg per household. If 3.08× 10^5 kg and 8.93 ×104 kg of fresh dung were used for mainte nance of soil fertilization and daily life per household respectively, there was only 2.5% of total fresh yak dung remaining per year. Based on these calculations, yak dung for commercial use was not recommended on the alpine meadow.