作 者 ：刘禹池,曾祥忠,冯文强,秦鱼生,王昌全,涂仕华,陈道全
期 刊 ：植物营养与肥料学报 2014年 20卷 6期 页码：1450-1459
Keywords:straw mulch, long-term experiment, rice-rapeseed rotation, yield, physical and chemical properties,
摘 要 ：【目的】研究长期秸秆还田与施肥对作物产量和土壤肥力的影响,为该种植模式下作物最佳养分管理提供技术支撑。【方法】自2005年起在成都平原的广汉市开展了水稻-油菜轮作下连续秸秆覆盖还田+免耕与不同施肥的长期定位试验。试验为随机区组设计,共有8个处理,3次重复。这8个处理包括对照(只施化肥、 无秸秆覆盖)和秸秆覆盖还田下4个氮肥用量、 2个磷肥用量和3个钾肥用量的7个组合处理。自2005年起每季收获时采集植株样本,分析不同处理下水稻和油菜的农艺形状与产量变化情况,2010年水稻收获后采取耕层(0—5 cm、 5—15 cm和15—30 cm)土样,分析不同处理的土壤肥力演化趋势。【结果】在稻-油轮作下,同一处理水稻和油菜产量受气候变化影响存在显著的年度间差异。秸秆还田对水稻产量的影响始于覆盖后的第三年,即秸秆覆盖处理的水稻产量显著高于相同施氮量的无覆盖对照处理,油菜秸秆覆盖条件下的减磷和减钾处理的水稻产量相当或高于对照处理。按此计算,秸秆还田在水稻季每公顷可节约大约N 60 kg和K2O 90 kg。在油菜季,稻草覆盖似乎不能明显减少氮肥投入,减磷处理的油菜产量始终最低。因此,施用充足的磷肥成为油菜高产的关键,该结果为稻-油轮作制度中磷肥的合理分配提供了科学依据,即磷肥应重点施在油菜上,水稻上可少施或不施磷肥。在油菜季,秸秆还田每公顷能节约大约N 30 kg和K2O 90 kg。连续秸秆覆盖+免耕使土壤有机质和氮、 磷、 钾养分在0—5 cm土层聚集,但对下层土壤影响不大; 减磷、 减钾处理使土壤磷、 钾耗竭,但无覆盖对照处理的土壤钾耗竭大于减钾处理;在磷钾施肥量不变的情况下,增加氮肥施用量降低了土壤速效钾与有效磷含量。长期秸秆覆盖还田+免耕能显著改善0—5 cm土层的土壤物理性状,即降低土壤容重,增加孔隙度、 非水稳性和水稳性团聚体的数量,但增加了下层土壤的容重和降低了土壤孔隙度。【结论】长期秸秆覆盖还田+免耕能显著提高水稻-油菜轮作下的作物产量,减少肥料投入和提高表层土壤肥力水平,但油菜季必须注意施用足够的磷肥以保证油菜籽高产的需要。
Abstract:【Objectives】The study of the effects of long-term returning of crop residues and fertilization oncrop yields and soil fertility can offer the scientific base for the best nutrient management in cropping system. 【Methods】 A long-term field experiment with rice-rapessed rotation has been conducted in Guanghan City, Chengdu Plain since 2005. The experiment consisted of eight treatments: chemical fertilizers without straw mulch (CK), four rates of nitrogen, two rates of phosphorus and three rates of potassium under straw mulch, respectively. Since 2005, plant samples of each plot were collected and crop seed/grain yields were recorded at harvest, soil samples were collected at 0-5, 5-15 and 15-30 cm depths of each plot after rice harvested in 2010. 【Results】 Under rice-rapeseed rotation, crop yields vary considerably from year to year due to the weather changes. Rice yields were significantly affected by the surface mulched rapeseed residue since the third year of the experiment. The rice yield of the treatments with the straw mulch was significantly higher than those treatments receiving equal amount of N fertilizer without mulch, and equivalent or even higher rice yields were obtained in treatments of -P and -K with mulch than the CK. Thus, about 60 kg of N and 90 kg of K2O per hectare could be cut off from the fertilizer input through rapeseed residue mulch in the rice season. In the rapeseed season, however, rice straw mulch was not able to reduce nitrogen input, the -P treatment produced the lowest rapeseed yield, indicating that P fertilizers should be applied in the rapeseed season, but less or not in the rice season. In the rapeseed season, about 30 kg of N and 90 kg of K2O per hectare can be saved by rice straw mulch. Continued straw mulch and no-tillage mainly benefit the accumulation of soil organic matter, N, P and K at 0-5 cm soil layer, much less in the soil layers below. The -P and -K treatments obviously depleted the soil P and K reserves and the CK treatment mainly depleted soil K reserves. Under the same P and K rates, contents of soil available K and P were decreased with the increase of N input rates. Long-term straw mulch and no-tillage dramatically decreased soil bulk density, increased soil porosity, non water-stable aggregates and water-stable aggregates, improved the physical properties of the 0-5 cm soil layer.【Conclusions】Long-term straw mulch plus no-tillage in the rice-rapeseed rotation system could significantly increase crop yields, reduce fertilizer inputs (particularly in rice season) and improve top layer soil fertility. Adequate P fertilizer should be applied in rapeseed, less or not in rice for high yield and high profit production.
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