红三叶人工草地营养元素的生物循环

 本文研究了我国北亚热带高海拔地区红三叶人工草地11种营养元素的生物循环特征。结果表明:1.营养元素的存留量、归还量和吸收量均可分为5个水平；(1)高量级：氮、钾、钙；(2)中量级：磷、镁；(3)低量级：铁；(4)少量级：锰、锌、铜、硼；(5)微量级：钼。2．红三叶群落地上部的净生产量、自然归还量和元素的存留量均显著高于地下部。3．红三叶人工草地的元素输出量以氮、钾、钙较大。此外，对草用和种用红三叶群落营养元素生物循环特征的差异进行了比较。为维持本区红三叶人工草地营养元素的平衡，目前必须施用磷肥，施用量不能小于250kg·hm-2过磷酸钙。

THE BIOCYCLING OF NUTRIENT ELEMENTS IN ARTIFICIAL TRIFOLIUM PRATENSE GRASSLAND

This paper deals with the biocycling characteristics of 11 nutrient elements of artificial Trifolium pratense grassland in high mountain region of northern subtropical zone of China. The chief results obtained are as follows:1. The retaining, returning and uptake amount of nutrient elements could be classified into five levels: 1 ) high-amount: N, K, Ca; 2 ) middle-amount: P, Mg; 3) low-amount: Fe; 4) a small-amount; Mn, Zn, Cu, B; 5) micro-amount :Mo. 2. The net production, natural returning and retaining amount of elements in aboveground portion were a markedly higher than that of underground in T. pratense community. 3. The outputs of N, K, Ca were higher than other elements. 4. The difference of nutrient element biocycling characteristic between T. pratense community for forage and for seed are as follows: l) the retaining amounts of nutrient element of aboveground portion in the community for forage were all higher than that of in the community for seed. The retaining amounts of underground portion were contrary to aforementioned results. 2) The returning amounts and returning ratio in the community for seed were a markedly higher than that of in the community for forage generally. 3) The uptake amounts of P,K and Fe in the community for seed were higher than that for forage, the uptake amounts of Ca, Mg and B in the community for forage were higher than that for seed. In order that the balance of nutrient matter of artificial. T. pratense grassland in this region was maintained, P fertilizer must be applied. The application amount should not be less than 250kg·hm-2 calcium superphosphate at present.