黄土台塬土壤—水分—植物生态系统与旱地小麦生产

Soil--Water--Plant Ecosystem and Rainfed Land Wheat Production on the Loess Tableland Area

对黄土台源土壤—水分—植物生态系统连续7年(1986～1992)的定位观测研究表明:降水量少、分配不均,蒸发量大,是台源致旱的根本原因。台原土壤优良持水特性是黄土旱源优势的生态条件。土壤水分周年变化有明显的阶段性,有利于小麦生长,旱塬小麦耗水系数高,水分利用效率低。因此夏休闲利用土壤水库,饱蓄自然降水,提高水分生产率,最大发挥蓄水的生产效益,减少水分非生产消耗等是创造旱塬小麦高产稳产墒情条件的根本途径和有效措施。

The 7 years' (1986～1992) fixed position observation of soil — water —plant ecosystem successively indicated that less rainfall but uneven distribution andgreat evaporation are the basic causes resulting in dryness or drought on the tablelandarea. The behavior of good soil field holding capacity on the tableland area is the superi-or advantage of ecological conditions for this region. The yearly variation of soil and wa-ter is obviously characterized by stages, which is favourable for wheat growth. Waterconsumption coefficient by wheat on the rainfed highland is high but water use efficiencyis low. Accordingly,soil reservoir in summer fallow period can be used to store naturalrainfall water,to improve water use efficiency,to bring about maximum productive effi-ciency and to reduce the non—productive losses of soil moisture,which is the basic wayand effective measure to create the conditions of high—stable yields of wheat in the caseof good moisture conditions on rainfed highland.