Comparison Of Water Balance And Crop Response Between Plain And Terrace In The Hill-Gully Region Of Loess Plateau

This paper mainly addressed the issue of maize and millet fields' water balance and corps' response between plain and terrace in the hill-gully region of Loess Plateau. The experiments were conducted at the An'sai Soil and Water Conservation Research Station, Chinese Academy of Science, in 2002. The main results showed:1. There was obvious difference between plain and terrace's water surface evaporation (E0). From April to October the total EO was 700.3 mm in the plain and 823.0 mm at the terrace. Both in the plain and at the terrace the E0 of July was the biggest in the whole year. But the month of the lowest EO was different between plain and terrace. October and September was the lowest month in the crops growing season in the plain and at the terrace respectively.2. The crops' response to the land condition were different. Terrace millet's LAI was smaller than that of plain millet at the beginning stage, but it was reverse in the later. In the whole growing period, plain millet's height was higher than terrace millet's. There was no evident difference in millet's yield and kernel weight between plain and terrace. But the plain millet's WUE was a little higher than that of terrace millet. The terrace maize's height and LAI were clearly got behind of plain maize in the whole growing period. The plain maize's yield, aerial biomass and WUE were 1.34, 1.54 and 1.17 times than those of terrace maize.3. The crops' water consumption was quite different between plain and terrace. The total water consumption of millet was 544.1mm in the plain and 461.8mm at the terrace. As to maize, it was 564.9mm in the plain and 491.7mm at the terrace. In the whole growing period, the ET/E0 (Evapotranspiration/water surface evaporation) of millet was 0.97 in the plain and 0.69 at the terrace, which was 0.99 of plain maize and 0.77 of terrace maize.4. There was no evident difference in crops' yield, kernel weight and aerial biomass between sufficient water supplying condition and rainfed condition in the experiment year. Millet and maize's crop coefficient (Kc) value were 1.10 and 1.05.5. The soil moisture's dynamic variation of bare lands during crop's growing period could be separate to two stages. April to July is the soil water's accumulation period, and August to October is whose decreasing period. The result showed that in October the soil storage water of plain's bare land was decreased 10.9mm if compared with that of April, but to terrace whrch was increased 66.8mm. Compared with plain, every layer's soil moisture of terrace fluctuated more violently. The cv (coefficient of variation) of soil moisture's variation was 9.3%-6.7% in the plain and 8.7%-21.4% at the terrace.