Assessment of soil fertility in lucerne stands of different ages using grey correlative degree analysis

Soil fertility reflects the performance and growth potential of plant which is easily affected by the plant. In the perennial grasslandecosystem, the effect of forage age on the soil fertility has not been clearly elucidated yet. In the present study, the soil fertility in lucerne stands with six different ages were comprehensively analysed using grey correlative degree analysis to evaluate the effect of stand age on soil fertility. In different soil layers, the contents of organic carbon, total nitrogen, ammonium, nitrate, total phosphorus, available phosphorus and total potassium were different in different lucerne stands cultivated in different years, and they differently varied with stand age. Using grey correlative degree analysis, the best soil fertility was observed in 5year old stands in 0-10 and 10-20 cm soils, the best soil fertility was observed in 8year old stands and the better soil fertility was observed in 5year old stands in 20-30 cm soils. Conclusively, in the Loess Plateau, the optimal utilisation age of lucerne was 5year old considering soil fertility.