不同隔离垫层对宁夏盐碱地盐碱动态和土壤养分及垂柳生长的影响

Effects of isolation cushion type on the soil nutrient dynamics and growth of Salix babylonica on saline-alkali land in Ningxia, China

宁夏地区盐碱地面积大,利用率低,限制了当地的土地资源利用,因此改良利用盐碱地显得尤为重要.在宁夏吴忠市进行田间试验,选取玉米秸秆（JG）、黄沙（HS）、粉煤灰（FM）作为隔离垫层（铺设于树坑底部60 cm处,各垫层厚度均为15 cm）,测量并分析7、8、10月份土壤0-80 cm土层中pH、电导率（EC）的动态变化,10月份土壤全氮、全磷、全钾含量及9月份垂柳胸径（DBH）、树高、新梢长、冠幅的生长量.结果显示,从7月到10月,玉米秸秆显著降低了40-80 cm土层的pH（10月比7月减少了5.85%）,黄沙、粉煤灰均降低了土壤pH,但是效果不显著.玉米秸秆、黄沙、粉煤灰这3种处理均显著降低了0-20 cm土层EC（10月比7月减少了65%、68.7%、60%）,其中玉米秸秆、黄沙还分别降低了60-80 cm、40-80 cm土层的EC.土壤中全氮和全磷含量最多的处理分别是玉米秸秆和粉煤灰,分别比CK增加了8%、19.48%,其中玉米秸秆显著增加了60-80 cm土层中的全氮含量,粉煤灰显著增加了40-60 cm土层中的全磷含量,黄沙对土壤养分含量没有影响.对垂柳生长指标的主成分分析显示玉米秸秆得分最高,改良效果最好.因此选择玉米秸秆作为宁夏地区盐碱地改良的最佳方案.

Large areas of saline-alkali land occur in Ningxia, China. However, since the rate of utilization of such land by humans is low, the use of local land resources is also restricted in these areas. Therefore, it is important to improve the management of saline-alkali land. This study was done at a site located in Wuzhong, Ningxia province. Corn stalk （JG）, yellow sand （HS）, and fly ash （FM） were applied to form isolation cushions, which were applied at thicknesses of 15 cm and laid at the bottom of tree pits. Changes in soil pH and electrical conductivity （EC） were measured in July, August, and October in 2016, and their dynamics were then analyzed. Soil total nitrogen, phosphorus, and potassium content, as well as tree height, diameter at breast height （DBH）, length of new branches, and crown growth volume, were measured in October and September, respectively. The results showed that JG significantly reduced the pH of the soil by 5.85% in the 40-80 cm layer from July to October, while such a significant reduction in soil PH did not occur in the areas treated with HS and FM. Moreover, the EC value of the soil significantly decreased in all treatments in the 0-20 cm layer （by 65% with JG, 68.7% with HS, and 60% with FM from July to October）. Furthermore, JG also reduced the EC value in the 60-80 cm layer, while HS reduced the EC value in the 40-80 cm layer. In addition, the highest soil total nitrogen and phosphorus content occurred in the JG and FM treatments, respectively, which were 8% and 19.48% higher than those in the control group. The JG treatment significantly increased the total nitrogen content in the 60-80 cm layer, while the FM treatment significantly increased the total phosphorus content in the 40-60 cm layer; however, the HS treatment did not significantly increase the content of any nutrient in the soil. Based on a principal component analysis of growth factors （DBH, tree height, length of new branches, and crown width） of Salix babylonica, the JG treatment was found to have performed better at improving the soil than the other two treatments. Insummary, the treatment with a JG isolation cushion is likely the best solution that should be used to improve the saline-alkali land in Ningxia.