膜下滴灌不同灌水控制下限对设施土壤团聚体分布特征的影响

发布时间：2018-03-16 09:54

本文选题：设施土壤　切入点：膜下滴灌　出处：《中国农业科学》2017年18期 　论文类型：期刊论文

【摘要】：【目的】灌溉是设施土壤水分的主要来源,也是影响土壤结构稳定性的重要因子。探究不同灌水控制下限对设施土壤团聚体分布特征和稳定性的影响,为设施农业合理水分调控、促进设施土壤结构改善提供理论依据。【方法】选用6年膜下滴灌试验地为对象,供试作物为番茄(Lycopersicon esculentum Mill.),种植模式为沟垄覆膜。设置了3个灌水控制下限,其土壤水吸力值分别为20、30及40 k Pa(分别记为D20、D30、D40),灌水控制上限均为6 k Pa。各小区以埋设深度30 cm的张力计指示土壤水分变化,确定灌水时间和灌水量。通过干筛法和湿筛法测定了土壤团聚体的组成,0.25 mm团聚体含量(R0.25)、平均重量直径(MWD)、几何平均直径(GMD)、分形维数(D)、以及土壤结构破坏率(RDS)和不稳定团粒指数(El T)。【结果】在0—30 cm土层,D40处理的土壤电导率(EC)、阳离子交换量(CEC)和容重都显著低于D20和D30处理(D40D30D20);D20处理的p H显著低于D30和D40处理(D40D30D20)(P0.05)。通过干筛法和湿筛法对团聚体数量和大小的测定发现,在0—30 cm土层,土壤机械稳定性团聚体主要集中在2和1—0.25 mm粒级(23.01%—39.98%),而水稳性团聚体主要集中在1—0.25和0.25—0.053 mm粒级(31.08—47.27%)。在0—20 cm土层,D30处理的R0.25、平均重量直径(MWD)和几何平均直径(GMD)均高于D20和D40处理;但在20—30 cm土层,D20处理的水稳性团聚体的含量高于D30和D40处理。不同灌水控制下限下的土壤结构破坏率(RDS)和不稳定团粒指数(El T)随土壤深度增加而增加,且RDS与El T的变化规律相似。在0—20 cm土层,D30处理的土壤结构破坏率(RDS)和不稳定团粒指数(El T)显著低于D20和D40处理(P0.05)。但在20—30 cm土层,D20处理的土壤结构破坏率(RDS)比D30和D40处理分别低了12.2%和16.8%。干筛下在10—20 cm土层内,D20、D30、D40处理的分形维数最小,分别是2.13、2.08、2.19;湿筛下在10—20 cm土层内,D40、D30、D40处理的分形维数最小,分别是2.31、1.99、2.12。结果表现出,与D20和D40处理相比,D30处理显著降低了团聚体中的分形维数(D)。【结论】在保证设施番茄产量和节约用水的条件下,将土壤水吸力30 k Pa作为膜下滴灌灌水控制下限,有利于土壤结构的形成和稳定。
[Abstract]:[objective] Irrigation is not only the main source of soil moisture, but also an important factor affecting the stability of soil structure. To provide the theoretical basis for rational water control in protected agriculture and to promote the improvement of soil structure. [methods] A six-year drip irrigation field under mulch was selected as the object. The tested crop was Lycopersicon esculentum Mill. esculentum. The planting pattern was furrow and ridge mulching, and three irrigation control limits were set. The soil water suction values were 20 KPA and 40 KPA (D20 D30 D40, respectively), and the upper limit of irrigation control was 6 KPA. The soil moisture change was indicated by a tensor with a depth of 30 cm in each plot. The composition of soil aggregate was determined by dry sieve method and wet sieve method. The composition of soil aggregate was determined by means of dry sieve method and wet sieve method. The composition of soil aggregates was determined as follows: R0.25mm aggregate content, mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (DN), soil structure failure rate (RDSs) and soil structure failure rate (RDSs) were determined by means of dry sieve method and wet sieve method. [results] the soil electrical conductivity, cation exchange capacity (CEC) and bulk density of soil treated with D40 in 0-30 cm soil layer were significantly lower than those in D20 and D30 treatments. The pH of D40D30D20 and D20 D20 treatments was significantly lower than that of D40D30D20D20 treatment and D40 treatment D40D30D20P0.05. Determination of the number and size of aggregates by HPLC, In the 0-30 cm soil layer, The soil mechanical stability aggregates were mainly concentrated in 2 and 1-0.25 mm grain grade (23.01-39.98), while the water-stable aggregates were mainly concentrated in 1-0.25 and 0.25-0.053 mm grain size 31.08-47.270.In 0-20 cm soil layer, R0.25, mean weight diameter MWD) and geometric mean diameter (GMDs) were higher than those in D20 and D40 treatments. However, the content of water stable aggregates in 20 ~ 30 cm soil layer treated with D20 was higher than that in D30 and D40 treatments. The soil structure damage rate (RDS) and unstable particle index (UPI) increased with the increase of soil depth under different irrigation control limits. The changes of RDS and El T were similar. In 0-20 cm soil layer, the soil structure damage rate and unstable aggregate index were significantly lower than that of D20 and D40 treatments, but the soil structure damage rate of D20 and D40 treatments was higher than that of D30 soil layer. Under the dry sieve, the fractal dimension of D20D30 / D40 treatment was the smallest in 10-20 cm soil layer, and D40 treatment was 12.2% and 16.8cm lower than that of D40 treatment, respectively. The fractal dimension of D40D30D40 treatment under the wet sieve was the smallest (2.31 ~ 1.99 ~ 2.12) in the soil layer of 10-20 cm, respectively. The results showed that the fractal dimension of the treatment was 2.31 ~ 1.99 ~ (9) ~ 2.12, respectively, in the soil layer of 10 ~ (-20) cm. Compared with D20 and D40 treatments, D30 treatment significantly reduced the fractal dimension of aggregates. [conclusion] under the condition of guaranteeing tomato yield and saving water, the soil water suction of 30 KPA was taken as the control limit of drip irrigation under film. It is beneficial to the formation and stability of soil structure.
【作者单位】：沈阳农业大学土地与环境学院/农业部东北耕地保育重点实验室/土肥资源高效利用国家工程实验室;
【基金】：国家科技支撑计划(2015BAD23B0203) 辽宁省高等学校优秀人才计划辽宁省农业领域青年科技创新人才培养计划(2015051)
【分类号】：S152.4;S275.6

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