Optimized cropping systems based on ensure index of precipitation in Sichuan Province | 基于降水保证指数的四川省种植制度优化研究

Chinese. 研究自然降水对四川省农业生态区作物需水的满足程度及其保证指数，为各区域充分合理利用降水资源，选择防旱避灾种植制度提供理论依据。依据气温、海拔、干燥度、地形地势、地理位置等特点，将四川农业生态区划分为8个不同类型区，采用联合国粮农组织（FAO）推荐的分段单值平均作物系数法，订正各区域主要作物及其主要生育阶段的作物系数（初始生长期作物系数（Kcini）、生育中期作物系数（Kcmid）和成熟期作物系数（Kcend）），计算并比较各区域代表性站点的常见种植模式、主要作物、作物主要生育阶段自然降水对作物需水的满足度及其保证指数，选出各区域防旱避灾最优种植模式。各种作物的Kcmid、Kcend值均小于或等于FAO的推荐值；盆地内部各区域作物系数较FAO推荐值偏低更多，攀西地区与FAO推荐值接近；小麦、油菜等夏收作物Kcend值均与FAO推荐值相同，而玉米、水稻等秋收作物Kcend值均低于FAO推荐值。四川省各种植模式多年平均降水满足度地区之间差异较大。攀枝花、西昌、平武、成都、遂宁、巴中、宜宾、雅安降水满足度依次递增，分别为0.48，0.56，0.63，0.64，0.70，0.72，0.74，0.85。四川省各种植模式降水保证指数变化范围较大，最低值仅为0.35，而最高值达到0.89。攀枝花各种植模式的降水保证指数普遍偏低，且多数低于0.4；雅安各种植模式的降水保证指数普遍较高，均在0.85以上。攀枝花等川西南山地干热河谷区、西昌等川西高原安宁河平原半湿润区和平武等川北半湿润山地丘陵过渡区最优种植制度为小麦-玉米-红薯（大豆）旱三熟；雅安等盆西高原盆地过渡湿润气候区和宜宾等川南中低山丘陵湿润气候区最优种植制度为油菜（马铃薯）-水稻水旱轮作两熟制；成都平原湿润气候区最优种植制度为马铃薯-水稻和油菜-玉米-红薯；遂宁等川中丘陵夏伏旱频发区最优种植制度为油菜（小麦）-玉米-红薯旱三熟；巴中等川东北盆周湿润山区防旱避灾最优种植制度为马铃薯（小麦）-玉米-红薯旱三熟。

English. This study was aiming at assessing the role of natural precipitation played in water requirement by crop and its guarantee rate in the ago-ecological areas of Sichuan. It will help increase precipitation utilization in each region of Sichuan province and provide theoretical support for choosing the proper cropping systems to resist drought and avoid disasters. The ago-ecological areas in Sichuan were divided into eight ago-ecological zones according to temperature, altitude, dryness, topography and geogrophic characteristics. The crop coefficient during the whole growing season and main growth stage period in each type area was amended using single-value crop coefficient method made by Food and Agriculture Organization (FAO), and then precipitation satisfaction between rainfall and crop water requirement and its ensure index for main crop were calculated at the represented stations in each location.Besides, cropping pattern or cropping system for avoiding drought was established.Ａll values of Kcmid and Kcend calculated were not more than the values recommended by FAO for all the crops. Kcmid and Kcend values were much lower in the basin compared with other regions, and they were much closer to the values recommended by FAO in the west of Panzhihua. Kcend values for summer crops, such as wheat and rape were similar to the values recommended by FAO, and the values for autumn crops, such as maize and rice, were smaller than the recommended values. Precipitation satisfaction differed significantly in different regions.Level of annual average precipiation satisfaction was lower in Panzhihua (0.48), followed by Xichang (0.56), Pingwu (0.63), Chengdu (0.64), Suining (0.70), Bazhong (0.72), Yibin (0.74), and Yaan (0.85). Ensure index of precipitation varied widely, from 0.89 to 0.35, among the cropping systems in Sichuan.The index was low for all the cropping systems in Panzhihua, and it was less than 0.4. The ensure index was high in Yaan for all the cropping systems, and it was more than 0.85. The optimized cropping system for avoiding drought was wheat-maize-sweet-potato (bean) in dry-hot valley areas of southwest Sichuan province (representative region of Panzhihua), sub-humid Plateau and Anning river plain of west Sichuan province (representative region of Xichang), and sub-humid hilly transitional zone of north Sichuan province (representative region of Pingwu). The optimized cropping system for avoiding drought was rape (sweet potato) rice in humid transition zone of Basin and Plateau of west Sichuan province (representative region of Yaan), and humid hilly areas of south Sichuan province (representative region of Yibing). The optimized cropping system for avoiding drought was potato-rice and rape-maize-sweet potato in humid Chengdu Plain area.The optimized cropping system for avoiding drought was rape (wheat)-maize-sweet potato in central hilly area of Sichuan province with frequently summer drought(representative region of Suining). The optimized cropping system for avoiding drought was potato (wheat)-maize-sweet potato in humid mountainous areas of northeastern Sichuan province (representative region of Bazhong).