咸水滴灌下塔里木沙漠公路防护林土壤生化作用强度及微生物生态特征

Biochemical intensity and microbial eco-characterization of soils irrigated with saline water from the Tarim Desert Highway shelter-belt

土壤生化作用强度是表征土壤生物学活性的重要指标。选择传统研究方法,从氨化作用、硝化作用、固氮作用、纤维素分解、呼吸作用以及酶活性6个方面,揭示了咸水滴灌下塔里木沙漠公路防护林地土壤生化作用强度的分异规律。结果表明,(1)随防护林定植年限的增大,土壤氨化作用、固氮作用、纤维素分解和呼吸作用的强度均明显增强,其中氨化作用和呼吸作用变化尤为明显;而硝化作用强度有所减弱。(2)0—50 cm土体内,随土壤深度增大,生化作用强度提高,氨化作用、硝化作用、固氮作用、纤维素分解和呼吸作用强度的垂直差异均达极显著水平(F>F0.01)。(3)随防护林定植年限的增大,不同土壤酶活性的变化各异,其中,过氧化氢酶活性显著增大(F>F0.01),纤维素酶和蔗糖酶的活性明显提高(F>F0.05),而蛋白酶、磷酸酶和脲酶的活性变化不大(F<F0.05)。(4)回归分析表明,不同生化强度因子与土壤环境因子的最优回归方程不同,但决定系数均大于0.95;全盐、全氮和速效氮进入了所有回归方程,是决定塔里木沙漠公路防护林地土壤生化强度的关键土壤环境因子。因此,咸水滴灌条件下,塔克拉玛干沙漠腹地防护林土壤生化作用强度不断提高的趋势,这对于防护林工程的科学管理有重要指示意义。

Biochemical intensity of soil is an important index for characterizing biological activity. In this study, traditional research methods were employed to determine the soil biochemical characteristics of the Tarim Desert Highway shelter-belt from six aspects, including ammonification, nitrification, azotification, cellulose decomposition, respiration, and enzymatic activity. The main experimental results were as follows： （1） With increasing years since planting, ammonification and respiration showed the greatest improvements; azotification and cellulose decomposition also showed significant improvements, but nitrification was weakened. （2） Vertical differences in ammonification, nitrification, azotification, cellulose decomposition, and respiration in the 0--50 cm soil layer reached highly significant levels （F 〉 F0.01 ） , and biochemical activity of the soil increased with depth. （3） As years since planting increased, catalase activity showed the greatest increase （F 〉 F0.01 ）, cellulose and invertase activity also significantly increased （F 〉 F0.05）, and protease, phosphatase, and urease activity only minimally increased （F 〈 F0.05 ）. （4） The optimal regression equations between different biochemical intensity factors and soil environmental factors differed, but the regression determination coefficients were 〉0.95. Total salt, total nitrogen, and available nitrogen were included in all of the regression equations and were key factors in the determination of biochemical intensity of the soil in the Tarim Desert Highway shelter-belt. Therefore, in the hinterland of the Taklamakan Desert, biochemical intensity of soils from the shelter-belt lands that were drip-irrigated with saline water exhibited an increasing trend. This knowledge will aid in the scientific management of the shelter-beh project.