关于提高作物水分生产率与建立作物生态需水区划问题的探讨

作物光合作用对土壤水分有明显的阈值反应。通过土壤水分预报,控制土壤水分较长期处在略多于阈值的范围,有利于提高作物水分生产率。大定额的蓄水灌溉有利于创造下湿上干的土壤水分剖面,可减少土壤蒸发,提高水分有效利用率。 根据作物需水与年内得到降雨的补偿程度进行作物种值区划,称之为作物生态需水区划。根据这一区划进行作物布局,有利于灌溉节水。 根据作物生态需水区划,华北地区可分为四个地带:①双季作物需水补偿带;②双季作物需水基本补偿带;③一季作物需水补偿带;④一季作物需水基本补偿带。

A Study on Issues of Improving Crop Water Productivity and Zoning of Crop Ecological Water Requirement

There is an obvious threshold response of plant photosynthesis to soil water content. A long-term control of soil water content to a state slightly higher than the range of threshold value,by the means of soil water forecast,is found to be helpful to the improvement of the crop water productivity. The practice of water-saving irrigation with a relatively large irrigation norm favours the formation of a soil profile whose lowre parts appear wetter and the upper parts dvier. Thereupon, water evaporation can be reduced and water use efficiency raised. The zoning of crop ecological water requirement refers to the zoing of plantation conducted in accordance with crop water requirement and the yearly rainfall. Cropping systems that are planned on the bais of this zoning are water -saving,when irrigation takes place. According to the principles of the zoning of crop ecological water requirement, North China can be divided into the following four belts- (i). the belt with a two -crop system where rainfall call fully meet crop water requirement; (ii). the belt with a two -crop system where rainfall can partially meet crop water requirement; (iii). the belt with a one -crop system where rainfall can fully meet crop water requirement;and (iv). the belt with a one-crop system where rainfall can partially meet crop water requirement.