玉米秸秆生物炭对稻油轮作农田磷流失风险的影响

以云南大理洱海流域典型稻油轮作模式为研究对象,通过2年田间定位试验,研究生物炭(玉米秸秆制备)、玉米秸秆与化肥配施对我国稻油轮作模式农田磷流失风险的影响。田间小区试验包括常规施用化肥(NPK)、生物炭与化肥配施(NPK+C)、生物炭与化肥减半配施(1/2NPK+C)、玉米秸秆与化肥配施(NPK+S)四个处理,通过比较不同处理间土壤有效磷含量、作物产量、吸磷量和水稻生长期间土壤有效磷、田面水总磷、可溶性总磷的动态变化特征,分析施用玉米秸秆生物炭和直接施用玉米秸秆对土壤、作物和磷流失风险的影响。结果表明,与NPK处理相比,增施生物炭和玉米秸秆,可显著提高水稻和油菜产量,但对水稻季田面水磷浓度无显著影响;施用生物炭条件下减施化肥,短期内未造成水稻和油菜减产,却降低了水稻整个生育期内田面水总磷(TP)和可溶性总磷(TDP)浓度;各处理水稻季田面水TP和TDP浓度在栽秧后第1 d内达到峰值,4~5 d内浓度迅速降低,7 d之后浓度趋于稳定。在此过程中,田面水TP下降64.2%~79.1%,TDP下降63.1%~82.4%。上述研究结果表明,为降低稻油轮作农田磷流失风险,可以考虑在水稻季施用生物炭的条件下减施化肥磷,并且在水稻栽秧后7 d内控制田面水外流。

Effects of maize stover biochar on phosphorus losses in rice-oilseed rape cropping system

A two-year (2013-2015) plot experiment was conducted to investigate the effect of biochar (made from maize stover) on phosphorus (P) losses in rice-oilseed rape cropping system in Dali Erhai Lake Basin in Dali, Yunnan Province, China. The experiment consisted of four treatments:conventional fertilizer (NPK), conventional fertilizer plus biochar (NPK+C), biochar in replacement of half of the conventional fertilizer (1/2NPK+C), and conventional fertilizer plus maize stover (NPK+S). Soil available P content, crop yields and P uptake as well as total P (TP) and dissolved P (TDP) in paddy field water were determined for all treatments throughout the study. Compared with the conventional fertilizer treatment, applications of biochar or maize stover significantly increased rice and rape yields, but did not significantly affect P concentrations in paddy field water. The treatment with biochar replacing half of the conventional fertilizer significantly decreased TP and TDP concentrations in paddy field water without reducing rice and rape yields. During the first week of transplanting rice, the con centrations of TP and TDP in paddy field water peaked on the first day, then decreased rapidly, and ultimately became stable. They de creased by 64.2% to 79.1% and 63.1% to 82.4% at the end of the first week. We conclude that replacing P fertilizer rate with biochar can reduce P loss risks via paddy field water without negatively affecting crop yields, and that the first week of transplanting rice is a critical period for controlling the risks of field water Plosses.