Abstract:

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.