Studies on the Soil Water Transport Characters in Soil-Plant-Atmosphere Continuum System under Different Conservation Tillage in Dryland of Loess Plateau
|School||Gansu Agricultural University|
|Keywords||Loess Plateau No-tillage Straw mulch Water use efficiency Water characteristic curve Leaf water potential|
By setting different conservation tillage trials in the western arid area in the Loess Plateau, does not cover conventional tillage, no-tillage does not cover, NTS, conventional tillage mulching of straw, conventional tillage, no-tillage mulching soil physical properties of water, crop water characteristics, soil water balance and water in the SPAC system different interface relationship between research, basic informed of spring wheat - pea rotation agroecosystem soil moisture characteristic curve, soil saturated hydraulic conductivity, soil organic matter content, soil temperature, the crops leaf water potential, the crop leaf relative water content and saturation deficit, soil moisture balance, atmospheric water potential and other indicators of response to different treatment, the following main conclusions: 1) the two rotation sequence, different conservation tillage tilth 0 -30cm soil moisture characteristic curve in the high suction phase, i.e. 5bar and 15bar almost coincide, only to 3bar, 1bar and 0.5bar relatively large differentiation, especially at 1bar and 0.5bar, two rotation order each processing the moisture content by mass in the same water suction difference showed significant differences. 2) two rotation sequence, the NTS and traditional farming straw processing 0-5cm soil bulk density was significantly lower than conventional tillage and conventional tillage mulching treatment is not covered, while increasing the surface and subsurface soil total porosity. 3) different rotation order 0-5,5-10,10-30 cm soil mechanical stability of aggregates and water stable aggregates, reunion the body stability coefficient of determination, mechanical stability is obtained by dry sieving aggregates mainly expressed in large aggregates; variety of conservation tillage compared with conventional tillage to improve the content of water-stable aggregates, especially grain size larger water stable aggregate content and soil aggregate stability rate in the three soil levels are higher than traditional farming does not cover the treatment. 4) soil saturated hydraulic conductivity of each treatment under the order of two rotations behave differently. But in general, the NTS dealing with traditional farming does not cover the, conventional tillage straw mulching of traditional farming, the difference between the no-tillage mulching treatment are reached 5% level of significance, and no-tillage mulching treatment significantly lower than traditional farming does not cover, no-till is not covered conventional tillage straw treatment. 5) at all levels of soil organic carbon content trends showed NTS, conventional tillage straw compared with the traditional farming not cover treatment at three levels were increased, this trend is particularly evident in the surface layer. 6) NTS processing can reduce the observation layer soil temperature has a significant cooling effect, and no-tillage does not cover conventional tillage straw processing more than 15cm at all levels of the ground temperature, the warming effect \7) crop growth period leaf water potential diurnal variation showed a decreased since the early morning, about 12:00 to 14:00, to a minimum, and then a gradual recovery trend, and with the promotion of the growth period, the mean diurnal variation of leaf water potential decreased . Different growth stages of the crop leaf water potential, leaf relative water content in the NTS, conventional tillage with high does not cover the treatment of straw and no-tillage compared with conventional tillage treatment, leaf water saturation deficit was the opposite trend the same time, the processing of the spring wheat leaf relative water content showed a heading gt; jointing stage GT; flowering period gt; trend of the grain-filling stage, pea processing leaf water potential reaches its maximum in the budding stage, branching and flowering of the second, pod lowest seed filling stage. 8) in terms of crop yields, evapotranspiration, water use efficiency, NTS, the conventional tillage mulching, no-tillage mulching treatment compared with other treatments. April 2008 - August under different rotation order evapotranspiration findings show that: different conservation tillage soil evaporation (E) P → W → P sequence (spring wheat field) for conventional tillage straw field (139.72mm) gt; conventional tillage does not cover (134.01mm) gt; NTS (105.33mm) gt; no-till is not covered (100.21mm) W → P → W sequence (pea fields) for the traditional farming does not cover (109.60mm) gt; conventional tillage straw (96.91mm) gt; no-till is not covered (85.45mm) gt; the NTS (85.35mm). But two rotation sequence of each treatment the total evapotranspiration volume performance for the no-tillage straw covered GT; conventional tillage does not cover the GT; no-tillage does not cover the GT; conventional tillage straw; the two rotation sequence processing evapotranspiration With the advancement of crop growth period, experienced a small to large, to the process. 9) among the treatments 0-200cm soil water storage at different times of the same, but in general different conservation tillage 0-200cm soil profile in water storage in the same determination phase difference, and in inter-change, and the test area the moisture content of the soil profile during the trial never reached the maximum soil drainage (DUL), the upper limit of crop moisture. According to the inter-annual trend of soil water storage, can be roughly a year 0-200cm soil water storage volume is divided into three periods, namely from mid-May to mid-July, the spring and summer crops thrive soil moisture loss period, from mid-July to 10 month in late summer and the rainy season increased moisture of November to early May, the winter and spring soil moisture stable period. 10) Path analysis showed that the main meteorological factors affecting plant leaf water potential diurnal variation due to different crops and different. Among them, the most direct impact on spring wheat leaf water potential diurnal variation meteorological factors atmospheric water potential, followed by the relative humidity of the atmosphere, soil water suction and atmospheric temperature; affect the pea leaf water potential date change factors most important is the relative atmospheric humidity, followed by atmospheric water potential soil water suction, air temperature and solar radiation.