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81.
在夏玉米生育期间设75%、65%、55%田间持水量3个灌水控制下限,研究地膜覆盖和不同秸秆覆盖量对喷灌夏玉米生长发育、产量、耗水量及水分利用效率的影响。结果表明,地膜覆盖能明显促进植株的生长,地膜覆盖和秸秆覆盖量大于7 500 kg/hm2处理的增产效果相当,覆盖增产效果均随着土壤水分的降低而增加。地膜覆盖处理耗水量最小,无覆盖的最大;秸秆覆盖处理的耗水量随着覆盖量的增加呈减少趋势,土壤水分越高的处理,覆盖节水量越多。地膜覆盖处理的水分利用效率(WUE)最高,比不覆盖处理提高50%以上;秸秆覆盖处理的WUE随着覆盖量的增加而增加,当覆盖量达到7 500 kg/hm2时,WUE的增加幅度变小。 相似文献
82.
The effects of pressure, nozzle diameter and meteorological conditions on the performance of agricultural impact sprinklers 总被引:1,自引:0,他引:1
This study evaluates agricultural impact sprinklers under different combinations of pressure (p), nozzle diameter (D) and meteorological conditions. The radial curve (Rad) of an isolated sprinkler, i.e., the water distribution along the wetted radius, was evaluated through 25 tests. Christiansen's uniformity coefficient (CUC) and the wind drift and evaporation losses (WDEL) were evaluated for a solid-set system using 52 tests.The Rad constitutes the footprint of a sprinkler. The CUC is intimately connected to the Rad. The Rad must be characterized under calm conditions. Very low winds, especially prevailing winds, significantly distort the water distribution. The vector average of the wind velocity (V’) is recommended as a better explanatory variable than the more popular arithmetic average (V). We recommend characterizing the Rad under indoor conditions or under conditions that meet V’ < 0.6 m s−1 in open-air conditions.The Rad was mostly affected by the sprinkler model. V’ was the main explanatory variable for the CUC; p was significant as well. V was the main variable explaining the WDEL; the air temperature (T) was significant, too.Sprinkler irrigation simulators simplify the selection of a solid-set system for farmers, designers and advisors. However, the quality of the simulations greatly depends on the characterization of the Rad. This work provides useful recommendations in this area. 相似文献
83.
We compare the net present costs of two approaches for managing irrigation-induced deep percolation under border-check irrigated pasture: (1) conversion from border-check irrigation to sprinkler irrigation to minimise deep percolation and (2) installation of a subsurface drainage system to extract excess deep percolation under the existing border-check system. Results for a dairy farm in northern Victoria, Australia, show that conversion to sprinkler irrigation is the more cost-effective approach. The net present cost of the second approach varies across an irrigation landscape, depending on the most suitable subsurface drainage and disposal system that can be used for a particular location. Where an aquifer is high yielding and of low salinity and thus drainage water is suitable for reuse on farm, tubewell drainage and farm reuse of drainage water provides a viable alternative to conversion from border-check irrigation to sprinkler irrigation. Where tubewell drainage or farm reuse is not feasible, sprinkler irrigation is more cost-effective than border-check irrigation with subsurface drainage. 相似文献
84.
In Mediterranean environments, flood irrigation of rice (Oryza sativa L.) crops is in danger of disappearance due to its unsustainable nature. The aim of the present study was to determine the short- and long-term effects of aerobic rice production, combined with conventional and no-tillage practices, on soils' physical, physicochemical, and biological properties, as well as on the rice yield components and productivity in the semi-arid Mediterranean conditions of SW Spain. A field experiment was conducted for three consecutive years (2011, 2012, and 2013), with four treatments: anaerobic with conventional tillage and flooding (CTF), aerobic with conventional tillage and sprinkler irrigation (CTS), aerobic with no-tillage and sprinkler irrigation (NTS), and long-term aerobic with no-tillage and sprinkler irrigation (NTS7). Significant soil properties improvements were achieved after the long-term implementation of no-tillage and sprinkler irrigation (NTS7). The short-term no-tillage and sprinkler irrigated treatment (NTS) gave lower yields than CTF in 2011 and 2012, but reached similar yields in the third year (NTS 8229 kg ha−1; CTF 8926 kg ha−1), with average savings of 75% of the total amount of water applied in CTF. The NTS7 data showed that high yields (reaching 9805 kg ha−1 in 2012) and water savings are sustainable in the long term. The highest water productivity was with NTS7 in 2011 (0.66 g L−1) and 2012 (1.46 g L−1), and with NTS in 2013 (1.05 g L−1). Thus, mid- and long-term implementation of sprinkler irrigation combined with no-tillage may be considered as a potentially productive and sustainable rice cropping system under Mediterranean conditions. 相似文献
85.
喷灌以其节水、节能、高效等优点,越来越被广泛的应用于园林绿化建设中。一套完美的喷灌系统不但能满足植物对水分的需求,而且在灌水同时还可以形成水动景观效果。喷灌系统应用过程中常见问题分别进行分析,并从中总结出一些实际经验。 相似文献
86.
87.
方形喷洒域摇臂式喷头喷洒机理分析 总被引:2,自引:3,他引:2
对方形喷洒域摇臂式喷头的喷洒机理进行了深入分析。应用有关射程公式得出了方形喷洒域摇臂式喷头的理论和修正压力-转角关系曲线,将该关系曲线应用于ZY-1型方形喷洒域摇臂式喷头的设计中,进行了实际场地喷洒试验。结果表明,该方形喷洒域摇臂式喷头的实际压力-转角关系曲线与修正压力-转角关系曲线吻合得较好。 相似文献
88.
89.
自压喷灌管网系统优化设计 总被引:1,自引:0,他引:1
着重研究了杈形自压喷灌管网系统的优化问题。根据各级管道的特点及相互关系,采用了线性规划与动态规划相结合的方法,用线性规划对各级管道进行优化;用动态规划寻求整个管网系统的优化方案。两种方法交替进行,最终求得管网系统投资最小的设计方案。这一方法便于计算机求解,具有占用内存少、运算速度快的特点。 相似文献
90.
多孔管允许最大长度的计算 总被引:1,自引:0,他引:1
导出了不同地面坡度的多孔管允许最大长度公式,这一成果可用于喷灌及微灌工程的规划设计。 相似文献