亚热带丘岗区雨养水稻初探

亚热带丘岗区降水丰沛 ,全年降水总量大于蒸发量。以试区为例 ,平均年降水量是蒸发量的1.32倍 ,每年 4～ 7月下旬降水在时间上的分布较为均匀 ,降水频数大 ,8～ 10月底 ,则会出现水分亏缺 ,降水频数少 ,时间上分布不匀。对于第一季水稻的生产 ,耕灌雨养 (天灌 )与传统的灌溉方式在产量形成方面没有多大的差异 ,最大减产率仅为传统灌溉方式总产量的 6.68% ,晚稻则会造成大量减产 ,减产率达 2 0 .98%。因此 ,考虑到在广大的亚热带丘岗区水分调蓄的特殊性 ,可针对区域内具体的水分条件适时插秧 ,充分利用天然降水完成第一季水稻的生产 ,第二季则可种植旱地作物以避开季节性干旱 ,这样既可以缓解水资源紧缺的矛盾 ,又可以节约因水稻灌溉带来的大量人力、物力和财力。

PRELIMINARY STUDY ON RAIN-WATERED PADDY FIELDIN SUBTROPICAL HILLY-LAND

The rainfall in subtropical hilly land is sufficient,and on average is 1.32 times of the annual water evaporation.The rainfall is almost even throughout the period from April to late July,with a relatively high frequence.However,the yield of rice is not significantly affected by the rain irrigation.A maximum of 6.68% reduction of the grain product may be expected.Although the rainfalls from August to October are quite sporadical,the reduction of the grain production due to the rainfalls in this season can be serious,and may reach 20.98%.When considering the unique adjusting ability of the hilly-land in the subtropical region,paddy should be planted at a proper time to take the advantage of the rainfalls.Subsequently,dry-land crops may be planted during the drought season.Thus,the contradiction of the water shortage can be overcome,and the labour and money due to irrigation be saved.