OBJECTIVETo study Astragalus membranaceus absorption characteristic of nitrogen, phosphorus and potassium at different growth stages.

METHODThrough the field experiment and the sampling analysis, the absorbing capacity of nitrogen, phosphorus and potassium as well as the growth of plant at different growth stages in A. membranaceus were analyzed.

RESULTThe dry matter accumulation reached 88.22% of the total accumulation in 100-163 days after seedling emergence, The content of N, P, K in the stem was higher than that in the root system. Nitrogen, phosphorus and potassium absorbing capacity in the stem, the leaf and the root systems was N > K > P. In the whole growth period, nitrogen accumulation reached the highest, and followed with the accumulation of potassium, and the accumulation of phosphorus was the lowest. In the last phase of the exuberant growth period, the accumulation intensity of nitrogen, phosphorus and potassium reduced. During the harvesting time, the accumulation intensity of nitrogen and potassium increased, and the accumulation intensity of phosphorus remained stable.

CONCLUSIONThe dry matter accumulation reached the maximum in 100-163 days after seedling emergence. The absorption strength of nitrogen, phosphorus and potassium in aerial part reached the maximum in 100-132 days after seeding emergence, the maximum absorption comes earlier than that of phosphorus and potassium, at that time the needs of nutrients reach the highest. For producing of 100 kg A. membranaceus 2.32 kg N, 0.323 kg P2O5, 1.62 kg K2O are needed to be absorbed from soil and fertilizer.