磷对紫花苜蓿和奶山羊生态系统生产力的影响

Effect of Phosphorus on Productivity of Ecological System Composed of Alfalfa and Dairy Goat

在陕西省陇县跃先村生态农业试验区进行了土壤—紫花苜蓿—奶山羊生产系统磷素调控的试验。分别测定１—８年生紫花苜蓿人工草地在不同条件下土壤、草、根的磷含量，以及根、草产量；测定了用不同施磷量处理的紫花苜蓿饲喂奶山羊后的产奶量以及奶、粪和尿中的磷含量。分析表明，系统磷素最大允许输入量为８７．５ｋｇ／亩。最佳输入量为６２．５ｋｇ／亩。使系统保持稳定的磷肥输入量为６２．５—７５ｋｇ／亩。在最佳施肥条件下，苜蓿生产效益可增加１４０％，水土保持效益可增加４９．７％，系统综合经济效益共增加６２０元／亩·羊。此外，奶山羊生产效益增加范围为６．５—１１．５％。

A study on the state of phosphorus flow in the production system com-posed of soil,alfalfa and dairy goat was done in Yuexian village eco agro experimen-tal zone,Longxian County,Shaanxi Province.The content of phosphorus in soil,grass(stem and leaf)and root of alfalfa,and the yields of grass and root were determined seperately under different conditions.Also the milk yield and content of the phosphorus in milk,manure and urine were determined respectively after dairy goat had been fed with alfalfa grown in different fields which treated with differrent amount of phosphate fertilizer respectively.Based on this, a system dynamic model was estabilshed.The phosphorus flow state in the system was simulated with computer,the effect on eco e- conomic of inputting phosphate fertilizer was evaluated and analysed quantitatively re- spectively. The results show that the maximum input of phosphate fertilizer for this system is 87.5kg/mu,the optimum input is 62.5kg/mu and the minimum input for maintain the phosphorus balance in soil is 37.5kg.Under the optimum condition,the yield of alfalfa increased 140%,the return of conservation water and soil increased 49.7%,The multiple eco economic effects increase 620 Yuan in the field in which the age of alfalfa was 4 years,In addition,the economic effect of dairy goat increased 6.5 11.5%.