Abstract: 【Objective】 In subtropical China, agricultural production of the red soil sloping land is limited by water erosion and seasonal drought. The hydrological relationships between water erosion and seasonal drought are not well understood. The objective of this study was to explore how field commonly used conservation practices influence the hydrologic processes in rainy and dry seasons and the soil and crop water stress in the red soil sloping land, and to provide a theoretical basis for selecting more pertinent field management practices. 【Method】 From 2008 to 2010, a field experiment was conducted in Xianning, Hubei. The zonal soil was red soils (Ultisols), developed from the Quaternary red clay. The experiment field is a typical low hill with a slope of 8°. Four treatments were used in the experiment plots, including no-conservation practice or control treatment (CK), grass strip (GS), application of polyacrylamide on the soil surface (PAM), and mulching the soil surface with rice straw (SM). Peanuts (Arachis hypogaea L., Baisha 1018) and maize (Zea mays L., Denghai 3632) were planted in the first and the next two years, respectively. The surface runoff amounts, sediment yields, soil water storages, soil and crop drought, and crop yields among the four treatments were studied. 【Result】 When rainfall amounts were close, surface runoff amounts and sediment yields generally increased with the rising rainfall intensities. As a whole, surface runoff amounts and sediment yields were in the same declining order of CK＞PAM＞GS＞SM, indicating the four treatments reduced water erosion by different degrees. Compared with the CK, the three conversation practices reduced surface runoff amounts and sediment yields by about 36.6% and 52.7% on average, respectively, with more significant decreases in the sediment yields. Soil water storage dynamics in the 0-45 cm depth were obviously different between the rainy and dry seasons. In general, the water storages rose up in rainy seasons, while gradually reduced during dry seasons. In addition, the differences among the four treatments turned to be smaller and smaller in persistent rainfalls, however they became larger and larger during rain free periods. Both in rainy and dry seasons, the SM had the highest soil water storage and the least fluctuation, followed by the PAM. GS and CK had close water storages. Values of soil drought degree (D) in the 0-15 cm depth gradually increased during the continuous drought in dry seasons. Both in the two years, D values were in the declining order of CK＞GS＞PAM＞SM, suggesting that soil drought degrees in the four treatments declined in turn. Under the influences of climate, crop growing periods and conversation practices, the increases in stress degree day (SDD) and the variability in differences among treatments appeared obvious periodicity. In the whole dry season, values of SDD were all in the reducing order of CK＞GS＞SM and PAM, showing that crop water stresses in the four treatments reduced in sequence. SM and PAM had larger crop yields than GS and CK. Compared to the CK, the GS, PAM and SM separately increased peanut yields by 19.3%, 33.0%, and 27.3% in 2008. While in 2009, the GS reduced maize yield by 0.5% and the PAM and SM separately increased maize yields by 17.1% and 36.3%. Different conversation practices had different kinds of impacts on the drought. For example, the GS didn’t greatly relieve soil and crop drought for its water consumption. The PAM reduced soil and crop drought mainly by reducing the loss of evaporation. The SM markedly increased soil water storage in rainy seasons, and greatly reduced soil moisture loss in dry seasons, and therefore significantly alleviated soil and crop drought. 【Conclusion】When applied in the red soil sloping farmland, all the three conservation practices of GS, PAM, and SM could reduce water erosion and alleviated seasonal drought in different ways, with different characteristics and degrees. In rainy seasons, the three conservation practices reduced surface runoff amount and increased soil water storage only by limited volumes. The function in increasing the soil water storage in the rainy season was smaller than that in alleviating the soil and crop water stress in the dry season.

Key words: field conservation practices, soil and crop drought, hydrologic process, red soil