| To solve the problem of soil environment deterioration because of soil continuous cropping obstacles in greenhouse, the straw are buried in to the soil with deeply buried straw technology. This technology could not only improve soil physico-chemical properties and structure,but also improve soil envirment and water storage capacity of soil. This study contains the soil columnn experiment in lab, dirp irrigation experiment as wel as infiltrating irrigation. The impact of deeply buried straw size on the distuibution of the soil moisture in one dimensional vertical water movement and two dimensional water movment is analyzed through these experiment. The experiments are comprised of rod-shaped straw (RS), segment-shaped straw (SS), filament-shaped straw (FS), mixed segment-shaped straw and soil (MS) to control treatment (CK). The effect of different size straw on saturated hydraulic conductivity, saturated water content, cumulative evaparation of soil and straw, etc, are analyzed. The water movement in soil with different size of straw are simulated by Hydrus. The saturated hydraulic conductivity, soil water retension curve are obtained. The size of straw has significant impact on these hydrology parameters. The study provides scientific basis for deeply buried straw soil technology and irrigation management in the different soil region of Northeastern. The results indicated as follow:1. The effect of deeply buried straw on the soil water movement in greenhouse(1) The effect of deeply buried straw on the one-dimensional vertical soil water movement in greenhouseIn the process of soil water infiltration, soil water infiltration rate is increased by burying RS under sandy loam condition, the cumulative infiltration of SRS is 434 mm; But it is decreased by burying SS, the cumulative infiltration of SSS is 281 mm. Compared with the saturated hydraulic conductivity of sandy loam, the saturated hydraulic conductivity with RS and FS is higher, they are 4.01 mm·min-1 and 1.33 mm·min-1 respectively, but the saturated hydraulic conductivity with SS is lower, it is 0.03 mm·min-1; The treatment of different size straw improved the soil water infiltration and increased saturated hydraulic conductivity under clay loam condition. In the process of soil water evaparation, the soil water content of deep soil layer is increased by deeply buried straw. The more crushed the corn straw is, the higher the saturated moisture content. The evaporation in MS treatment is decreased by decreasing of the saturated soil water content.(2) The effect of deeply buried straw on the two-dimensional soil water movement with drip irrigation in greenhouseIn the process of soil water infiltration, the soil water infiltration is decreased by deeply buried different size straw, but it is increased in MS treatment. There is no significant difference among water infiltration rate of different size straw. In the process of soil water evaporation, compared with CK, the soil water content of soil layer above the straw layer is lower in treatments of different deeply buried straw, but the soil water content of deep soil layer in all the treatment is same. The effect of soil disturbance result from deeply buried straw on soil water retention curves and saturated hydraulic conductivity of soil is obvious.(3) The effect of SS on the two-dimensional soil water movement with infiltrating irrigation in greenhouseUnder the condition of infiltrating irrigation, the main soil water content is higher at the straw and adjacent soil than water content in other regions. The change of soil water content is lower with the horizontal distance between the irrigation point and soil. The change of soil water content is low in the region of furrow. In infiltrating irrigation experiement, distance of horizontal water movement is more and speed of horizontal water movement is faster in upper and lower soil layer of straw layer in SS treatment. Meanwhile, compared with upper soil layer, the distance and speed of horizontal water movement in the lower soil layer are higher.2 The simulation and verification of soil water movement with deeply buried straw in greenhouse base on Hydrus 、One-dimensional soil water movement in different treatments is simulated by Hydrus 1D, Two-dimensional soil water movement in different treatments is simulated by Hydrus 2D. All simulations base on the model of van Genuchten and Mualem. Saturated hydraulic conductivity of different size straw is obtained by inverse solution. The saturated hydraulic conductivity of different size straw from high to low is:RS (58.80 cm·h-1), FS (1.22 cm·h-1), SS (0.08 cm·h-1), respectively. The saturated straw water content of different size straw from high to low is:FS (0.35 cm3·cm-3), SS (0.27 cm3·cm-3), RS (0.27 cm3·cm-3), respectively. Compared with the soil water retention curves in treatment:SS and RS, water content in SS is higher than water content in RS treatment.2) Under drip irrigation treatment, the available water in different treatment from high to low are:FS (34 to 46 m3·ha-1), SS (about 32 m3·ha-1), RS (9 to 20 m3·ha-1). In the infiltrating irrigation, the largest available water in SS is (63 to 76 m3·ha-1).In conclusion, segment-shaped straw is the best size for deeply buried straw technology. Our result can provide scientific basis for deeply buried straw technology and water management. |
