Late topdressing can sustain wheat grain yield under straw mulching in the Loess Plateau of China

Straw mulching has been widely used to conserve soil water and enhance soil fertility in dryland cropping systems. However, the lack of soil nutrient availability due to the immobilization with straw mulch decomposition would result in a decrease in crop yield and harvest index. Based on a 9-yr straw mulching field experiment, we evaluated the effect of late topdressing in 2 yr on crop yield under a winter wheat (Triticum aestivum L.) monoculture system in the Loess Plateau of China. Three treatments were included as straw mulching at rates of 9,000 (HSM) and 4,500 kg ha(-1) (LSM) during growing season and control without mulching (CK) from 2008 to 2019. Topdressing as urea was added to each plot at wheat tillering from 2017 to 2019. Across 2 yr, strawmulching significantly increased soilwater storage at most growing stages. Compared with CK, straw mulching promoted wheat growth (tiller density and plant density) but decreased grain yield and harvest index significantly. SoilmineralNcontents in later wheat-growing stages and net photosynthetic rate, transpiration rate of wheat flag leaf and leaf water use efficiency during filling stage decreased with HSM and LSM when compared with CK. However, late topdressing significantly increased wheat grain yield in both years. Generally, additional application of N fertilizer in the late growing stage could alleviate the yield decrease by straw mulching and should be considered for sustainable crop production in the Loess Plateau of China.

Automated summary

Straw mulching is widely used for soil water conservation and soil fertility enhancement, but it can lead to nutrient immobilization and decrease in crop yield. Late topdressing with urea can alleviate the yield decrease and should be considered for sustainable crop production in the Loess Plateau of China.