Effect of N, P and K fertilizer combination and application rate on yield of Astragalus sinicus L.

The effect of nitrogen, phosphorus and potassium fertilization on the yield of Astragalus sinicus L. was investigated in 3414-design fertilization trial. The results show that comparing with no fertilizer treatment (CK), the thirteen fertilization treatments harvest average 21.1 t·hm^-2 higher yield, with a yield increase of 135%. Under the fixed combination rates of P₂₅-K₂O at 60-60 kg·hm^-2, N-K₂O at 75-60 kg·hm^-2 and N-P₂₅ at 75-60 kg·hm^-2, A. sinicus yield significant increase with respective increase in N (N 0~112.5 kg·hm^-2), P (P₂₅ 0~90 kg·hm^-2), K (K₂O 0~90 kg·hm^-2) application rates. And the highest yield increment rates caused by N, P, K fertilizers are 65.0%, 27.8% and 44.5% respectively. In view of nutrition efficiency, medium application rates of N (N 75.0 kg·hm^-2), P (P₂₅ 60 kg·hm^-2) and a low rate of K (K₂O 30 kg·hm^-2) are the best application rates. The results also show beneficial interactions among N, P and K. Medium application rates of N (N 75.0 kg·hm^-2), P (P₂₅ 60 kg·hm^-2) and K (K₂O 60 kg·hm^-2) have synergetic effects on nutrient and yield. The results therefore imply that fertilization significantly increases yield of A. sinicus and different combination and application rates of N, P and K are important factors that influence A.sinicus yield.