| The soil secondary salinization had become the common obstacle in the production of facility agriculture, which not only influenced the production of vegetable, but also brought the environmental risk on reginal soil and groundwater environment. An important production task of soil science and technology work to be solved is how to solve the above situation, to ensure the facility agriculture sustainable development quality and efficiently. One of solutions to reduce greenhouse soil secondary salinization was searching suitable irrigation frequency, because of the obviously effect on the soil salt. Therefore, By simulated experiments of soil box in the laboratory, temporal and spatial variation characteristics of greenhouse soil moisture and salt was studied under different irrigation frequencies during the pepper growth period, in order to provide theoretical basis for effective prevention of greenhouse soil, HYDRUS-1D model was applied to simulate the dynamic of moisture and salt under different irrigation. The main results were as following:(1) In seedling stage of pepper, the variation of soil moisture mainly concentrated in the layer of 0-30 cm soil layer after irrigation, the soil moisture of 20-30 cm soil layer under 5-day treatment,10-day treatment and 15-day treatment increased by 0.95%,2.26% and 5.05% after irrigation. In squaring stage of pepper, soil moisture under 5-day treatment in 10-20 cm and 30-40 cm soil layers were high before irrigation, and the total soil moisture showed the order of 15-day> 10-day> 5-day treatment after irrigation. In maturation stage of pepper, the water content in 30-40 cm soil layers was the highest under 5-day treatment before irrigation, and the increase amplitude of 0-20 cm soil layer was increased with the decreasing irrigation frequency, the water content in 10-20 cm and 30-40 cm soil layers were the highest under 5-day treatment and 10-day treatment after irrigation. Water reserve and increase amplitude of 0-20 cm soil layer was decreased with the growth of pepper, and water reserve of 0-20 cm was increased with the decreasing irrigation frequency. The appearance time of preferential flow was 5-day>10-day> 15-day treatment.(2) The electrical conductivity (EC) of soil profile decreased rapidly in 20 days under different irrigation frequencies, slowed the decreasing in 21-40 days, and tended to be stabilize in 41-62 days, and the variation coefficient of EC showed an order of 10 d>5 d>15 d. After firse irrigation in seeding stage of pepper, The soil salt accumulation contents of 0-20 cm under 5-day,10-day and 15-day treatments were decreased 47.57%, 49.85% and 52.41%, and the soil salt accumulation contents of 10-day treatment was 19.07% and 13.50% higher than those of 5-day treatment and 15-day treatment respectively in 20-50 cm soil layer. After irrigation in squaring period of pepper, the decreasing amplitude of soil salt content in 0-20 cm soil layer under each irrigation frequency were smaller than the decreasing amplitude of soil salt content after firse irrigation in seeding stage of pepper, and the biggest decreasing amplitude under 5-day treatment was in 30-40 cm soil layer after irrigation. After irrigation in maturation stage of pepper, the decreasing amplitude of soil saltcontent contents in 0-20 cm soil layer showed an order of 5-day> 15-day> 10-day treatment, the soil salt accumulation contents under 5-day treatment was 18.86% and 15.29% higher than those of 10-day treatment and 15-day treatment respectively in 20-50 cm soil layer. The effect of salt leaching was better than those treatments in 10-day treatment, and the 10-day treatment had a continuous effect of salt leaching in late growth stage of pepper, there was no obvious distingiuish to the phenomenon of soil salt or other salt ions gathered surface soil layer, The effected of irrigation on soil salt ions leaching showed an order of NO3->Ca2+>K+>SO42-, the NO3- was lost easily with the soil water, and were harmful to the groungwater enviroument, there was an obvious distingiuish to the phenomenon of the Ca2+ gathered surface soil layer under 15-day treatment in the growth stage of pepper. (3)The soil moisture simulated by HYDRUS-1D modelwere in good agreement with the measured value, and the REMS of soil water content in each irrigation frequency was about 0.03 cm3·cm-3, showed an order of 15-day> 10-day>5-day treatment. There was a big difference between simulated and observed soil water content in the 0-20 cm soil layer under 5-day treatment, and the difference was increased with the stage of prpper prolong between simulated and observed soil water content, the differences between simulated and observed soil water content in the 20-40 cm soil layer was big under 10-day and 15-day treatments. The REMS between the simulated by HYDRUS-1D modelwere and the observed value of EC in each irrigation frequency were about 0.2 S·m-1,and showed an order of 10-day>5-day>15-day treatment, the difference was big between simulated and observed of EC in 30-50 cm soil layer. The result of precision by HYDRUS-1D modelwere in water content is better than EC, the simulated water content could describe the distribution of soil water under different irrigation frequencies, but the simulated EC ccould not describe the phenomenon of the salt ions accumulated in the below soil layers. |
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