西辽河流域玉米秸秆夹层改碱机理研究

In view of the characteristics of saline-alkali soil in the West Liaohe River Basin, which is high degree alkalinity, high content of calcium carbonate，utilizing the richer maize straw resources, a maize straw interlayer was made for improvement the soil, through flat stripping topsoil, tiling crushed straw (including rotten agent) and covering soil layers. The maize straw interlayer could damage the continuous of soil capillary action and cut off the diving evaporation channel. Maize straw decomposition could produce organic acid to activation of calcium ions and released potassium ions. It substituted and leached the sodium ions on the alkali soil colloid. It also reduced ESP and pH of plough layer. So the maize straw interlayer repair technology of saline alkali land was put forward.VIa the field experiment we analyzed the dynamic changes of physicochemical properties of saline alkali soil which was derived from different depth and different periods. we examined microorganism quantity, enzyme activity and plant biomass of the saline alkali soil; And we also determined the alterations in soil moisture, soil permeability coefficient, agglomerates, compactness, bulk density, porosity, organic matter and soil enzyme activity, microbial population and diversity, microbial biomass carbon and nitrogen, plant growth etc.According to the modified mechanism of soil fertility we examined the alterations in composition, calcium, magnesium, potassium, Na, ESP, pH, calcium carbonate, salt exchange of soil. And we explore the effect of sodium and alkali modification for assessing the evaluate the effect of each treated group. In here, we explored the method for the restoration of saline alkali soil with corn straw inter-layer for the restoration of soda saline alkali soil in the West Liaohe River basin.

针对西辽河流域盐碱地碱化度、碳酸钙含量高的特点，利用丰富的玉米秸秆资源，通过平整剥离表土平铺粉碎秸秆（含腐熟剂）覆土形成夹层，切断土壤毛细管、腐解产生有机酸活化钙离子和释放的钾离子，代换和淋洗碱土胶体上的钠离子，降低耕作层ESP、pH，据此提出玉米秸秆夹层修复盐碱地技术。采取田间定位试验的方法，测试分析各试验处理不同深度、不同时期盐碱地土壤理化性状、微生物种类数量及酶活性、植物生物产量动态变化；分析土壤水分、渗透系数、土壤团聚体、紧实度、容重、孔隙度、有机质及土壤酶活性、微生物数量及多样性、微生物量碳氮、植物长势等的变化，研究增肥改土效应；分析土壤腐殖质组成、交换性钙、交换性镁、交换性钾、交换性Na、碳酸钙、ESP、pH、含盐量等的变化，探讨脱钠改碱机理；对各试验处理修复盐碱地效益进行评价，确定玉米秸秆夹层修复盐碱地最佳模式，为修复西辽河流域苏打盐碱土提供理论依据和技术支撑。

背景：.通辽市盐碱土面积广，玉米秸秆贮量大，可利用秸秆改良碱土。同时减轻秸秆焚烧对环境以及交通等的危害。.内容：.针对该地区盐碱地碱化度高、碳酸钙含量高的特点，采用玉米秸秆夹层技术，研究玉米秸秆夹层改碱机理、玉米秸秆夹层培肥改土效应、盐碱地最佳修复模式等内容。.结果、数据及科学意义：.1)项目试验设计方案.选择秸秆用量A、秸秆掩埋深度B、灌排次数C三因素各具三个水平的田间试验。.2)重要结果、关键数据及其科学意义.①盐碱土物理性状明显改善.多数处理的容重减至1.4 g/cm3以下，大团聚体增至2.4%-2.6%之间，通透性能明显改善。.②培肥改土效应良好.改良后的碱化土壤养分明显提高，碱解氮最高达36.86g/mg、有机质增至8.99g/kg，速效磷高达20.12g/mg，速效钾高达426.69g/mg，胡敏酸高达0.87g/kg、富里酸为0.29g/kg，CEC含量增至12-14coml.kg-1之间。.改良后的盐碱土全盐量降低11%-30%，pH降低2%-5%，碱化度降低7%-37%；有的处理碳酸盐、交换性Na+的含量分别下降了40%、28.66%，交换性钾离子提高了373.33%。.③土壤生物数量增多，酶活性增强.碱土改良后数量和种类明显增多，细菌、真菌、放线菌、反硝化细菌、磷细菌、纤维素分解菌数量较高分别为3.4864×106cfu·g-1、0.44×105cfu·g-1、0.014×106cfu·g-1、0.88×105cfu·g-1、1.18×105cfu·g-1、8.96×103cfu·g-1。.碱土改良后酶活性明显增强，纤维素酶、蔗糖酶、脲酶、过氧化氢酶、多酚氧化酶、蛋白酶的活性最高分别达0.14mg•g-1•72h-1、6.32 mg•g-1•24h-1、33.15 mg•g-1•24h-1、221 mg•g-1•20min-1、20.33 ml•g-1、0.17 mg•g-1•24h-1。.④改良模式：.根据试验研究与实践，得出西辽河流域盐碱地改良模式：除“碱障”+种植适宜作物改碱模式.碱障是碱地碱化层的层位及厚度对作物的影响程度；除碱障的措施：耕作、物料、灌排、生物。.适宜作物指能在不同类型盐碱地上生长的草本及木本植物。