| Over last two decades, micro-rainwater harvesting technology has been widely used in dryland agricultural practice, but the effects of this technique and the variability of regional rainfall on rainwater harvesting, and its storage, migration and utilization in soil were little reported. Field experiments were conducted using the spring oat (Avena sativa L.) variety, Dingyou 3 as trial material, at Dingxi Agricultural Meterological Experimental Station of Gansu Province, northwest China in two years from 2009 to 2010. Despite the total rainfall amount for the growing period of oat was similar in 2009 and 2010, there was a significant difference in the temporal distribution of rainfall over two growing seasons. The rainfall distribution pattern in 2009 was similar to the long-term trend over last three decades (consisting of 33.1% aand 66.9% of total rainfall in the first and the second half growth period respectively). Conversely, the year 2010 turned to be characterized by"more in the first half and less in the second half"(accounting for 46.4% and 53.6% of total rainfall of whole growth period, respectively). The coefficients of variation of rainfall distribution were 1.0 and 0.8 in 2009 to 2010, respectively. In this study, eight treatments of micro-rainwater harvesting were designed, including: (1) the flat bare plot without cultivation (CK group 1), (2) flat plot with cultivation (CK group 2), and (3) six combinations with ridge-furrow and plastic mulching treatments (3 ridge to furrow ratios in width (2:1, 1:1 and 2:3), and two mulching treatments (plastic mulch and no mulch). The data were systematically collected from all the treatments in both years, including the moisture indexes (water consumption and water storage in different period profile along with soil profile), growth index, seedling emergence, plant height, leaf area index, dry matter distribution, soil temperature, yield and its related components and water use efficiency index. The results were achieved as follows:1. The results showed that the treatment with film mulching on the ridge led to a significantly greater emergence rate, plant height and leaf area index than the treatments of non-mulching ridge and flat cultivation did, and no significant difference between the treatments of flat cultivation and non-mulching ridge cultivation over last two years. Among the different treatments of film mulching on the ridge, the above parameters in M20 treatment were the highest in 2009, and M40 was the best pattern in 2010. In comparison of year 2009, the parameters mentioned above were significantly higher in micro-harvesting treatment in 2010, suggesting that the"forward distribution"in rainfall is conducive to the seeding emergence and vegetative growth of oat crop.2. In terms of rainfall variability in two years, water consumption curve of crop displayed a "wave type" change at jointing stage (about 60 days after emergence) and reached up to the maximum water consumption in the whole growth period at the 70th day. The waer consumption was afterwards decreased at booting stage, and then turned to rise up to the second water peak of water consumption at grain filling stage (about 90 days after emergence). On the other hand, among all the combinations, there was a greater gap between the highest and the lowest water consumption amount in the treatment of film mulching on the ridge comparing with those treatments of non-mulching and flat cultivation. Further, the gap was greater in 2009 than that of 2010. This showed that forward transfer of rainfall distribution led to a lower variability in water consumption for crop. This was indirectly to optimize the water supply in growing season, which temporarily suffered the extent of drought stress.3. Two-year test results showed that the micro-catchment treatment significantly increased soil moisture in 0-30 cm soil layer, but the soil moisture content in above 30 cm varied from years and treatments. Soil ridge and flat cultivation treatments were observed to have a reduction in water storage; both years showed a reduction of water in the 30-90cm profile, but less in 2010 than 2009. To a large extent, the water deficit amount was 45.4 mm in flat cultivation treatment. For the micro-catchment model, the water consumption was significantly higher in the film mulching treatments than non-mulching treatments. In the 90-130cm profile, the average water deficit was 10.3 mm in 2009, but the average deficit was over 20.1 mm in 2010. The results showed that the conventional law of rainfall changes can significantly decrease water deficit, and the rainfall distribution of"forward transfer"significantly improved the surface and bottom water consumption, but enhanced the extent of water consumption in middle-level soil layer.4. In M40 treatment, whose yield reached the 989kg/hm~2 and 1833.5kg/hm~2, water use efficiency based on yield were 6.2kg/mm ? hm~2 and 9.3kg/mm ? hm~2, dry weight, respectively 11034.2kg/hm~2 and 15339.8g/hm~2, at the same time based on the amount of water use efficiency of dry matter were also reached 59.6kg/mm ? hm~2 and 77.5kg/mm ? hm~2, all indicators are the highest in two years shows that all treatments. showed rainfall change law, "after more than a little before the" year The micro-catchment model can significantly increase crop yield, dry matter and water use efficiency, while treatment with film mulching on the ridge, especially the M40 treatment showed even more evident.5. In 2010 one month after the film ridge sowing treatment significantly increased the soil 5cm ground temperature reached 17.7℃, compared with an increase of soil ridge 1℃, and the flat treatment for the maximum ground temperature 18.2℃; for changes of the whole growth period, the film ridge treatment was the level of ground temperature trends, the whole growth period is about steady at 17.7℃, The soil ridge and flat treatment with the overall performance of the single peak trend, maximum temperature reached to 19.6℃and 18.8℃; the soil temperature level significant impact on the soil water evaporation, treatment with film mulching on the ridge's low temperature of the whole growth period ensure rainwater invalid while inhibiting evaporation, effectively preventing the evaporation of soil moisture in the form of an invalid lost to the atmosphere and optimize the migration of water.In summary, the micro-ridge rainwater harvesting technology, especially film mulching treatment have shown a high efficient performance in harvesting rainfall and saving effect in the whole growth period of crops t. It can mitigate the inhibitive effect of water stress on crop growth, thereby promote the growth and development of crop throug growth period and ultimately increase the performance of the crop yield and water use efficiency. But the improvement in yield is accompanied by high consumption of soil moisture. The rainfall in late growth stages played a crucial role in regulating recovery of soil water. The rainfall distributive pattern of fewer in the latter half season than that of the former half one" received better overall performance in the capture and use of rainwater, and ultimately a substantial increase in productivity. |
PDF Full Text Request