不同水氮条件下生物炭对夏玉米水氮耦合效应的影响

【目的】提高水氮亏缺下夏玉米籽粒产量并促进水氮耦合效应,实现夏玉米节水增产。【方法】采用田间小区试验,设定4个生物炭施用水平(0、5、10、15t/hm²,分别记为C0、C1、C2、C3)、2种灌溉方式(正常灌溉I1、亏缺灌溉I2)和2个施氮水平(常规施氮N1、亏缺施氮N2),正常、亏缺灌溉灌水量分别为100%和50%作物需水量,常规、亏缺施氮量分别为200 kg/hm²和100 kg/hm²,探究了不同水氮条件下生物炭对砂壤土持水保肥效果以及夏玉米水氮耦合效应的影响。【结果】添加5 t/hm²和10 t/hm²生物炭处理明显提高了土壤总孔隙度和持水能力,并减少了土壤铵态氮和硝态氮的淋洗,10 t/hm²下效果最佳。同时,5 t/hm²和10 t/hm²生物炭可促进夏玉米根系生长,提高籽粒产量及水氮利用效率,在10 t/hm²下产量,水分利用效率和氮素偏生产力显著增加(P<0.05),较未施炭组分别增加了6.74%~13.12%、9.84%~19.48%和6.74%~13.12%。然而,生物炭添加至15t/hm²时增益效果有所下降。在10 t/hm²生物炭下,I1N2处理的产量和水分利用效率显著提高(P<0.05),相比C0,I1N1处理产量增加了13.12%,水分利用效率提高了16.93%,I2N2处理产量和氮素偏生产力与C0下I1N2处理间差异不显著,且I2N2处理产量显著提高(P<0.05),较C0处理增产12.84%,相比C0,I1N1处理仅减产5.60%。【结论】10 t/hm²生物炭能够在水氮亏缺下有效地提高水氮利用效率,进而达到保产增效目的,且10t/hm²生物炭与水分充足减氮50%处理的增产效果最好,可作为夏玉米生产中节水节肥的有效途径。

The Efficacy of Biochar in Improving Crop Yield is Impacted by Irrigation and Nitrogen Fertilization

【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/hm~2(C2) and 15 t/hm~2(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/hm~2 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/hm~2 improved soil porosity and its water holding capacity, while reducing ammonium and nitrate leaching, especially the 10 t/hm~2 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/hm~2 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/hm~2 would lead to a decrease in grain yield.【Conclusion】Amending the soil with biochar at 10 t/hm~2 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.