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在陕西关中平原的冬小麦-夏玉米轮作区,采用尼龙网袋田间填埋与~(15)N同位素标记玉米秸秆相结合的方法,设置不施氮和施氮200 kg·hm~(-2)两个处理,研究施氮对小麦生长期内还田玉米秸秆腐解的影响以及腐解过程中秸秆碳、氮、磷、钾的养分释放.结果表明:从小麦播种到越冬期,施用氮肥对秸秆碳和干物质分解无显著影响,但可促进秸秆中磷的释放,抑制氮和钾的释放.灌浆到成熟期,氮肥对秸秆腐解及其N、P、K养分的释放无显著影响,但秸秆碳的释放显著增加.不同生育期,玉米秸秆碳的释放与干物质分解变化趋势一致,C/N逐渐下降.种植一季小麦后,秸秆干物质累计腐解率不足50%;秸秆碳释放率为47.9%~51.1%,不施氮和施氮处理的秸秆C/N分别由32.2降低到20.2和17.9.小麦收获时,秸秆氮、磷、钾均为净释放,氮释放量为7.2~9.4 kg·hm~(-2),占秸秆氮的12.7%~16.6%;磷释放量为1.29~1.44kg·hm~(-2),占29.0%~32.4%;钾的释放量大、释放快,越冬前超过80%,成熟时释放量为51.8~52.5 kg·hm~(-2),占90.5%~91.7%.在秸秆还田条件下,应考虑秸秆归还的钾,减少小麦钾肥用量,适量补充氮、磷.
In the winter wheat-summer maize rotation area in the Guanzhong plain of Shaanxi Province, the combination of nylon net bag landfill and ~ (15) N isotope labeled corn stover was used to set the nitrogen and nitrogen rates of 200 kg · hm -2, Two treatments were conducted to study the effects of nitrogen application on the decomposition of corn stalks during field growth and the nutrient release of carbon, nitrogen, phosphorus and potassium in the decomposing stages of wheat during the growth period.The results showed that when nitrogen was applied Straw carbon and dry matter decomposition had no significant effect, but could promote the release of phosphorus in straw, inhibit the release of nitrogen and potassium.Filling to maturity, nitrogen fertilizer on straw decomposition and N, P, K release of nutrients had no significant effect, But the release of straw carbon significantly increased.The release of carbon in corn stalks was consistent with the trend of dry matter decomposition and the C / N decreased gradually at different growth stages.After a quarter of wheat cultivation, the accumulated decomposition rate of dry matter of straw was less than 50% The results showed that when the wheat was harvested, the nitrogen, phosphorus and potassium of the straw were all net release, and the nitrogen release rate was 7.2 ~ 9.4 kg · hm -2, accounting for 12.7% -16.6% of the total nitrogen in the stalks, and the amount of phosphorus released was 1.29-1.44 kg · h m -2, accounting for 29.0% -32.4%. The release amount of potassium is large, the release is quick, over 80% before winter, and the release amount is 51.8-52.5 kg · hm -2 at maturity, accounting for 90.5% 91.7% .In the condition of straw returning, the potassium returned by straw should be considered to reduce the amount of potassium fertilizer in wheat, and the appropriate amount of nitrogen and phosphorus should be added.