The effects of straw return on potassium fertilization rate and time in the rice-wheat rotation
Zhao, X. ((Chinese Academy of Sciences, Nanjing (PR China). Institute of Soil Science, State Key Laboratory of Soil and Sustainable Agriculture), (University of Chinese Academy of Sciences, Beijing (PR China))) | Wang, H. | Lu, D. | Chen, X. | Zhou, J.
In order to investigate the effects of straw return on potassium (K) fertilizer application rate and time in the rice-wheat rotation, field experiments were conducted at three sites. The results showed that when the K rate was decreased to 70% of the recommended K dosage, crop yields showed no significant decrease. With K fertilization only at rice phase, crop yields showed no marked difference compared with that provided K fertilizer both at wheat and rice seasons. Though the NH4OAc-extracted K and HNO3-extracted K differed slightly among the treatments, the soil apparent K balance was negative without K fertilization. With crop straw fully incorporated, the recommended K dosage could be at least reduced by 30% at the experimental sites and the K fertilizer could be applied only at rice phase. A further hypothesis can be made that the best K rate was the amount of K took away by crop grain. In the long run, straw return combined with K fertilization would be an effective method to maintain soil K fertility and productivity.
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