Influence Of Long-term Potash Application And Straw Return To Soil On Crops Yield And Soil Potassium Balance On Cinnamon Soil Under The Rotation Of Winter Wheat And Summer Maize

Potassium is one of the essential elements for plant, and has been becoming an important limiting factor for sustainable agriculture development. Long-term experiment for potassium application is an important method to monitor the change of soil K fertility and fertilizer effect. Based on long-term experiment established by Shanxi Academy of Agricultural Sciences in 1992, this study was conducted to monitor crop yield, biomass, nutrient uptake and soil potassium content in the soil layer of 0-100cm within the rotation of winter wheat and summer maize in 2012-2013. The effects of potash application and crop straw return to soil were analyzed, and soil potassium balance from different treatments were calculated. The purpose of this study was to provide scientific theoretical basis for the sustainable management of soil potassium. Main results and new progress were obtained as following:1. Climate factors had a significant impact on crop yield, biomass, nutrients uptake and soil potassium balance on cinnamon soil under the rotation of winter wheat and summer maize. The results indicated that crop yield, biomass and nutrient uptake in 2012 were higher than those in 2013. At the same time, there were also significant differences among the treatments. The order of different treatment from high to low was as following: NPKSt> NPSt> NPK> NP. As far as increasing percent of wheat and maize was concerned, winter wheat was higher than that of summer maize within the rotation system.2. NP treatment (farmer practice) had produced the lowest yield, biomass and nutrient uptake due to no K fertilizer application and without crop residue return to soil. And NPK treatment or NPSt treatment had higher yield, biomass and nutrient uptake compared with the NP treatment. These indicated that adding K to some extent was very useful for the increase of yield, biomass and nutrient uptake. NPKSt treatment had produced the highest yield, biomass and nutrient uptake due to the combination of potash application and crop residue return to soil. Comparing with NP treatment, differences of yield, biomass and nutrients uptake in other treatment were all significant in 2012 and 2013.3. As far as soil K balance was concerned, there was significant difference among the treatments. Soil K was deficit in NP treatment duo to no K input. Although there was K input to some extent in NPK or NPSt treatment, soil K still was deficit and K balance efficiency was only from 0.4 to 0.8 within the rotation of winter wheat and summer maize. However, soil K of NPKSt treatment was surplus and the balance efficiency was from 1.2 to 1.4. Therefore combined potash application with crop residue return to soil was helpful to improvement of soil K fertility.4. As far as soil K content was concerned, there was a decrease tendency from top to bottom in the profile (0-100 cm). From 2011 to 2013, soil available potassium content (0-20 cm) declined significantly by 15 mg/kg and soil slowly available potassium content (0-40 cm) decreased by 35 mg/kg in NP treatment. Compared with the NP treatment, under NPKSt treatment soil available potassium and soil slowly available potassium both had an increase tendency in the 0-40cm of soil profile, but there was not significant change below the 40cm in the soil profile.