Effect of potassium application and straw returning on spring maize yield, nutrient absorption and soil potassium balance

【Objectives】 A field experiment was conducted for three years (2010-2012) to research the effect of straw returning and potassium application on the yield, nutrient absorption of spring maize and the soil potassium balance, aiming to provide scientific basis for the rational use of corn straw and fertilizer in northeast China.【Methods】The experiment was located at the main maize producing zone, Chaoyangpo Town, Gongzhuling City, Jilin Province. The four treatments of NP, NP+St, NPK, NPK+St were set up with the consistent cultivation technique and field management. Five representative maize plants were collected from each plot at maturity stage every year and divided into two parts of straw and grain, dry mater was weighed. Total nitrogen, phosphorus and potassium contents were determined. The middle four ridges of maize were harvested for calculating yield (the moisture content of maize used is 14%). Soil samples of 0-20 cm depth were taken before the experiment and after maize harvest for the soil available potassium determination. The related parameters of potassium utilization characteristics were calculated, and the effect of potassium application and straw returning on spring maize yield, nutrient absorption and soil potassium balance was analyzed.【Results】Compared with no K (NP) treatment, the treatment of NPK+St, NPK and NP+St increase the yield of maize by 13.8%, 9.6% and 3.8% respectively. Combined application of potassium fertilizer and straw returning could increase maize N, P, K absorption amounts in straw and grain. Compared with NP treatment, NPK, NP+St and NPK+St treatments increase the nitrogen, phosphorus, and potassium uptake by 9.4%- 24.7%, 12.2%-26.0% and 6.9%-26.4%, respectively. The treatment of NPK+St leads to the highest total nutrient uptake. Combined application of potassium fertilizer and straw returning could increase potassium harvest index, potassium utilization rare in chemical fertilizer and straw. Compared with NPK and NP+St, NPK+St increase potassium harvest index, potassium agronomic efficiency of chemical fertilizer, the recovery rate of chemical potassium and the straw potassium content. The potassium harvest index were increased by 5.5%-18.8%, the agronomic efficiency and recovery rate of chemical potassium were increased by 8.3% and 1.1% respectively, the agronomy efficiency and recovery rate of straw potassium were increased by 4.0% and 0.7% respectively. Straw returning with potassium fertilizer can improve the soil available potassium content, the increase range was 1.9%- 4.0% and increase order is NPK+StNP+StNPKNP. The surplus of potassium of NPK+St, NPK and NP+St were 15.0%, -51.1% and-18.1%, respectively. 【Conclusions】Maize straw returning combined with potash fertilizer application can not only increase maize yield and the total amount of nutrient uptake, but also sustain potassium balance and improve soil potassium storage, maintaining the stability of the soil potassium fertility. Therefore, the combined use of potassium fertilizer and maize straw returning should be extended widely in the tested agricultural production area.