Guan'gai paishui xuebao (Jan 2022)
The Efficacy of Biochar in Improving Crop Yield is Impacted by Irrigation and Nitrogen Fertilization
Abstract
【Background and objective】 Amending soil with biochar has seen a steady increase over the last few decades as an agent either to remediate soil contamination or to improve soil quality and nutrient availability. As the impact of biochar on crop growth is via changes in physical and biogeochemical properties of soil, its efficacy is likely to depend on inputs of other nutrients to soils. Taking maize as an example, this paper investigated how irrigation and nitrogen (N) fertilization combine to affect the effect of biochar amendment at different ratios on soil properties. 【Method】 The field experiment was conducted in plots, and compared four biochar application rates: 0 (C0), 5 (C1), 10 t/hm2 (C2) and 15 t/hm2 (C3). For each amendment, there were two irrigation treatments: normal irrigation by supplying 100% of water demand by the crop (I1) and deficit irrigation by halving that amount (I2), and two N treatments by fertilizing 200 kg/hm2 of N (N1) and halving that amount (N2). Change in soil properties and different N forms, as well as their impact on the ultimate grain yield were measured in each treatment. 【Result】 Biochar amendment at rates of 5 and 10 t/hm2 improved soil porosity and its water holding capacity, while reducing ammonium and nitrate leaching, especially the 10 t/hm2 treatment, all at significant level. They also promoted root growth and improved grain yield and water and nitrogen use efficiency as a result. Amending the soil with biochar at 10 t/hm2 increased yield, water use efficiency and partial productivity of N by 6.74% to 13.12%, 9.84% to 19.48% and 6.74% to 13.12%, respectively, compared with the control without biochar amendment. C0+I1+N2 increased grain yield and water use efficiency by 13.12% and 16.93%, respectively, compared to C0+I1+N1; the yield and nitrogen partial productivity of C2+I2+N2 and C0+I1+N2 were comparable, though the yield of the former was 12.84% higher than that of the latter (P<0.05) and 5.60% less than that in C0+I1+N1. However, increasing biochar application more than 10 t/hm2 would lead to a decrease in grain yield. 【Conclusion】 Amending the soil with biochar at 10 t/hm2 was most effective to improve water and N utilization efficiency to give a high yield when water and N were both deficit. It can then be used as an improved cultivation method for maize production in regions similar to what we studied.
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