半干旱地区膜垄和土垄的集雨效率和不同集雨时期土壤水分比较

于 2 0 0 2年 4月～ 8月在兰州大学干旱农业生态榆中试验站进行研究 ,在平地上形成沟垄相间的微地形 ,采用 3种沟垄比和两种下垫面材料 ,垄作为径流区 ,沟作为集水区 (沟内不种任何作物 )。采用平均产流率法分析了不同垄型集水面的集水效率 ,结果表明 ,膜垄的平均集水效率为 90 % ,土垄的平均集水效率为 16 .8% ;通过对不同垄型集水面垄中、沟边、沟中的土壤水分进行比较发现 ,对于膜垄在集雨的各个时期沟中的土壤含水量高于垄中 ,沟边的土壤含水量介于沟中和垄中土壤含水量两者之间。如 7月 14日测定 ,沟中、沟边和垄中 0～ 2 0 0 cm土层土壤平均含水量分别为 10 .39%、10 .2 4 %和 9.4 2 % ;对于土垄 ,在集雨前期和集雨中期 ,沟中和沟边的土壤含水量相差不大 ,沟中和沟边的土壤含水量均低于垄中的土壤含水量 ,表现出和膜垄完全不一样的特性 ,如 7月 14日测定 ,沟中、沟边和垄中 0～ 12 0 cm土层土壤平均含水量分别为 8.98%、8.6 8%和 10 .0 3% ,在集雨后期 ,沟边和沟中的土壤含水量大于垄中土壤含水量 ,如 8月 13日测定 ,沟中、沟边和垄中 0～ 12 0 cm土层土壤平均含水量分别为 9.76 % A、9.38% B和 7.94 % C,该试验表明土垄在集雨后期 ,在集雨和土壤水分分配方面表现出和膜垄的相似的特性

Runoff efficiency and soil water comparison of plastic-covered ridge and ridge with compacted soil at different rainfall harvesting stages in semiarid area

A micro-water harvesting (MWH) system was designed to increase water availability to crops for improving and stabilizing agricultural production in the semiarid Loess of northwest China.The system was built by shaping the soil surface with alternative ridges and furrows along contour. The study was conducted at Yuzhong division of Lanzhou University during April and August 2002. There were three ridge:furrow ratios (60:60 cm, 45:60 cm and 30:60 cm) and two ridge cover treatments (ridge covered with plastic film and ridge compacted with soil). Ridges served as runoff zones and furrows served as rainfall-harvesting zones. The objective of the research was to find difference in runoff and in distribution of soil water between two ridge treatments. Results showed that the average runoff efficiency (expressed as a ratio of runoff to rainfall) was 90% for the ridge covered with plastic film, and only 16.8% for the ridge with compacted soil. The ridge treatment changed the distribution of soil water content over the season. The soil water content at the bottom of furrow was higher than that at the top of ridge, whereas the soil water content at the side of furrow was intermediate for the ridge covered by plastic film in all growth stages. For example, the soil water contents measured on 14 of July were 10.39%, 10.24%, 9.42% at the bottom of furrow, the side of furrow and the top of ridge, respectively. As for ridge with compacted soil, there was no significant difference in soil water content at the bottom of furrow and at the side of furrow, but the soil moisture at those sites were higher than that at the top of ridge in early and middle growth stages. The soil water content in the early growth stage (measured on 14 of July) was 8.98.% at the bottom of furrow, 8.68% at the side furrow and 10.03% at the top of ridge. However, the soil water content in the late growth stage (measured on 13 of August) were changed to 9.76%, 9.38% and 7.94% for the bottom of furrow, side of furrow and top of the ridge respectively. This suggested that the distribution of soil water was similar between the ridge with compacted soil and ridge covered with plastic film in late growth stage due to soil crust.