A five-year successive rice straw-derived biochar (BC) amendment pot trial was conducted to investigate the BC effects on crop growth responses, soil properties and ammonia volatilization in a calcareous alkaline soil from 2010-2015 under the greenhouse condition. We adopted 0 (the control; BC0), 2.25 t·hm-2(BC2.25) and 22.5 t·hm-2(BC22.5) for each wheat/millet crop season with an identical dose of NPK fertilizers. The results showed that BC treatments (BC2.25 and BC22.5) improved soil fertility and crop growth compared to the no BC control. During the five rice/millet rotations, BC22.5 treatment increased the total yields of grain and straw by 24.1% and 74.1%, while the cumulative aboveground uptake amounts of N, P and K were significantly increased by 93.5%, 71.2% and 46.3%, respectively. After the rotations, soil available P, K, and CEC under the BC22.5 treatment were enhanced by 262%, 274% and 58.3%, compared to the control. By contrast, soil bulk density was decreased by 46.6%, while no difference was found in soil pH between the BC treatments and the control. Soil TOC and soil C/N ratio increased by 843% and up to 25 in response to the BC22.5 treatment, respectively. The annual apparent BC loss was 3.5%-5.7% in the BC2.25 and BC22.5 treatments. High level of BC application simulated ammonia volatilization, which increased by 102% in BC22.5 treatment over the course of the crop rotations compared to the control.
通过5年10季的小麦/谷子轮作盆栽试验,持续观测了每季0、2.25和22.5 t·hm-2黑炭施用下作物生长和土壤性质变化及氨挥发数量.结果表明: 相同NPK肥施用下,与不施黑炭处理相比,黑炭处理能促进作物生长,提高土壤养分供应.22.5 t·hm-2黑炭处理下5年作物累积籽粒和秸秆产量分别增加24.1%和74.1%;相应地上部N、P和K累计吸收量分别增加93.5%、71.2%和46.3%;轮作结束后土壤有效P、K含量及阳离子交换量分别提高262%、274%和58.3%,有机碳提高843%,C/N增至25,容重降低46.6%, 土壤pH值则无明显变化.2.25和22.5 t·hm-2黑炭处理的黑炭表观分解率为每年3.5%～5.7%.高量黑炭施用可导致氨挥发数量增加,22.5 t·hm-2黑炭处理下10季氨挥发总量增加102%.
Keywords: ammonia volatilization; biochar-C loss; crop growth; straw-derived biochar; successive incorporation.