不同耕作方式对绿洲区夏玉米农田土壤呼吸及酶活性的影响

目的]研究民勤荒漠绿洲区免耕(Tn)、少耕(Tm)、深松(Ts)和秋翻(Tf)4种耕作方式下土壤呼吸速率的动态变化及其与土壤酶活性的关系,为制定科学有效的土壤碳调控管理措施提供依据。方法]在2a的田间定位试验基础上,利用LI-8100土壤碳通量测量系统测定不同生育时期(苗期、抽穗期和成熟期)玉米田土壤呼吸速率动态变化,同时取0—20cm土样测定土壤酶活性和理化性质。结果](1)民勤荒漠绿洲区土壤呼吸具有典型的日动态变化,4种耕作措施土壤呼吸速率日变化在玉米整个生育期呈单峰曲线变化,土壤呼吸速率依次为:TfTmTsTn,有机碳含量与土壤呼吸速率呈显著正相关(p0.05),说明在民勤荒漠绿洲区,传统耕作明显加快了玉米农田土壤碳的释放。(2)土壤脲酶、蔗糖酶、蛋白酶、过氧化氢酶和β-葡萄糖苷酶活性与土壤呼吸有较好相关性(p0.05),其中与过氧化氢酶、脲酶、蔗糖酶活性达到极显著水平(p0.01);pH值、速效钾、有机碳与脲酶、蔗糖酶、β-葡糖糖苷酶活性达到极显著水平(p0.01)。结论]耕作方式可以通过改变荒漠绿洲区土壤理化性质、激发酶活性从而使土壤呼吸速率发生不同程度的改变,影响玉米田CO2的释放。

Effects of Different Cultivation on Soil Respiration and Enzyme Activity of Summer Maize in Oasis Region

Objective] The dynamic changes of soil respiration rate and their relationships with soil enzyme activities under 4 different tillage methods of no tillage (T_n), medium tillage (T_m), subsoiling (T_s) and fall turnover (T_f) were studied in Minqin desert oasis, to provide basis for the establishment of feasible soil carbon management measures.Methods] Based on a 2-years field experiment, the soil respiration rate in different growth stages (seedling, heading and maturity stage) was measured by LI-8100 soil carbon flux measurement system. Soil enzyme activities and physicochemical properties were measured by collecting soil samples at 0-20 cm soil depths.Results] (1) Oasis soil respiration in Minqin desert showed a typical diurnal variation. The diurnal variation of soil respiration rate of the four tillage showed a single peak curve in the whole growth period of maize. The soil respiration rate were ranked as:T_f > T_m > T_s > T_n. There was a significant positive correlation between organic carbon content and soil respiration rate (P<0.05), indicating that traditional tillage significantly accelerated the release of soil carbon from maize fields in Minqin desert oasis area. (2) The activities of soil urease, invertase, protease, catalase and beta glucosidase were significantly correlated with soil respiration (p<0.05). The pH value, available potassium, organic carbon and the activity of urease, invertase glucose and beta glycosidase reached an extremely significant level (p<0.01).Conclusion] Different tillage can change soil respiration rate by changing the physical and chemical properties of soil and stimulate enzyme activity in the desert oasis area, thus, influence the release of CO₂ in summer maize field.