Effects of amendment of biochar-manure compost in conjunction with pyroligneous solution on soil quality and wheat yield of a salt-stressed cropland from Central China Great Plain

Salt stress has been one of the extreme conditions threatening world crop production which may become more serious under climate change. This study is to address the potential of using biochar as an organic matter-rich material to ameliorate salt stressed soil in order to enhance crop production in dry croplands. A two year field experiment with soil amendment of biochar poultry manure compost (BPC) and pyroligneous solution (PS) was conducted in a moderately salt stressed Entisol from Central China. The soil was amended with BPC at 12 t ha−1 following treatment with diluted PS solution at 0.15 t ha−1 1 week before winter wheat sowing. Samples of topsoil and plant were collected while the yield was measured when harvested. The changes in soil salinity, fertility properties as well as crop yield were examined with comparison between the plots treated for one year and for two years. In the first cropping year of 2010–2011, a significant decreases under BPC-PS amendment was observed in soil salinity by 3.6 g kg−1, soil pH by 0.3 and in soil bulk density by 0.1 g cm−3 while increase was seen in SOC and available phosphorous by 2.6 g kg−1 and by 27 mg kg−1 respectively. The yield was increased over the control by several folds and by 38% under BPC-PS treatment respectively for 1 year and for 2 years. Furthermore, the decrease in soil salinity, soil pH, and bulk density was even greater in the plots treated for 2 years than for one year though the yield under the treatment was not significantly different between the consecutive two years with a spring drought in 2012. These results demonstrated a strong effect of BPC-PS treatment on salinity reduction and crop productivity enhancement in the salt stressed soil, which could sustain for at least two years. Therefore, biochar amendment of biochar compost in conjunction with pyroligneous solution from wheat straw could be an effective option to alleviate the salt stress and improving crop productivity in salt affected croplands.

► A 2-year field experiment with amendment of biochar poultry manure compost and pyroligneous solution in a salt soil. ► Wheat yield was significantly increased consistently in the 2 years on the mended soil compared to the control. ► The amendment significantly decreased soil salinity and soil pH, more greatly in the 2nd year than in the 1st year. ► The amendment could have multiple benefits for crop through salt leaching, improvement of soil structure and nutrient and moisture supply.