Effect of long-term application of potash and straw return on wheat yield and soil K balance in Qinghai province

This fixed-site, irrigated spring wheat experiment is on a loamy, Chestnut soil site in northeastern Xining City of Qinghai Province since 1993. The study is evaluating the long-term agronomic effects of NP and NPK treatments used in combination with complete, 50%, and zero straw recycling.

In 2011, after 19 years of study, wheat yield of NP treatment was 5.9% lower than that of NPK treatment. Use of NP plus 50% or 100% straw recycling were as productive as the NPK treatment. Straw recycling with fertilizer K generated similar yield to straw recycling without fertilizer K. The K balance in the NP treatment was -139 kg/ha, while in the NPK treatment, it was -21 kg/ha. Partial and complete straw recycling without fertilizer K application generated a soil K deficit of -84 kg/ha and -14 kg/ha, respectively. Only the NPK plus straw return could maintain a positive soil K balance and soil K surplus. Testing of soil physical properties indicated that straw returning decreased soil bulk density and increased soil moisture content. Qinghai-2011