2, water-saving water

  Are used in China for thousands of years of irrigation water from the soil drainage water delivered to farms. Such a large number of water delivered to farms not yet been wasted. China's current water utilization coefficient of irrigation canals is very low, generally 0.3 a o.5. Therefore, in the process of saving water in water potential is great. Commonly used methods are two kinds of anti-seepage and water pipes.

(A) anti-seepage canal seepage control materials used in many types of commonly used building blocks are dry stone, block stone paste (or pebbles), precast concrete blocks, in-situ concrete surface protection, plastic film, geomembrane, etc. , the recent more general promotion of the domestic "light on three sides," channels in the case of this category. When using concrete surface cover, such as the U-channels, little concrete pipes can also be used, so that could also improve the water flow, reducing the cross section.

(B) In addition to water drainage pipe and channel bed seepage, there are drainage water surface evaporation and weed transpiration bed. The piped water supply can be essential to avoid these water losses. For sprinkler irrigation, drip irrigation and micro-irrigation demands high-pressure water (300 ~ 1200kPa), while for low-pressure pipes can be used for surface irrigation (less than 200kPa).

1. High-pressure water pipe required to withstand high pressure pipeline, and thus require a higher strength pipe, commonly used are steel, cast iron pipes, aluminum tubes, plastic pipe, prestressed reinforced concrete pipe and asbestos cement pipes and so on, to Note that learn from past use of glass, plain concrete pipes, stone pipes and a number of high-pressure pipeline contractors can not be learned. High-pressure pipes under pressure due to high requirements, cost will inevitably be higher, such as for low-pressure water is not be enough. Therefore, in the short term does not explicitly have to be converted into low-pressure spray of micro-irrigation pipe distribution system can afford not to use high-pressure pipeline in order to avoid the backlog of capital.

2. Low-pressure water pipelines due to the low pressure requirements, you can use a special low-pressure pipe, the unit cost can be greatly reduced. This is mainly used for surface water irrigation systems, primary and secondary channels in the United States is now basically have been replaced by low-pressure pipelines. In China a few years ago from the "Little White Dragon" (ie, thin-film plastic tube), the subsequent gradual improvement as a special technical measures - "tube feeding", that is ground water with low-pressure pipe irrigation. According to the 1993 statistics, nationally, there are more than 3.33 million hectares of low pressure pipe irrigation water for irrigation, soil drainage than 40% of water-saving and less an area of 1.5-3.5%, and acres of lower investment, and therefore unable to sprinkler and micro-irrigation areas, using pipe irrigation is a direction, in the irrigation areas, should be gradually replaced with low-pressure pipes to all the small and medium sized channels. Can also be achieved very significant water-saving effect. In the Drainage Irrigation District, if the channel system equipped with a complete water seepage control measure is still used is appropriate, if the topography of a certain slope, and the channel system matching is incomplete, you should consider supporting the direct use of water pipes. However, in a very flat gravity irrigation to the use of piped water should be weighed carefully. In some places, pipe irrigation only sent to the edge of the water pipe is not directly into the irrigation ditch, field layout of the input had to ditch, in order to further water conservation, it should produce the gate-hole pipe, making up from the water into the irrigation ditch (or the plot of ), water flow in pipes.

3, water-saving irrigation system

(A) is not sufficient for irrigation according to the guiding ideology of the early irrigation, as long as there is sufficient water supply, it is necessary to crop the water supply to the fullest in order to reach as high as possible yield per unit area, which is fully irrigated. This irrigation methods can get the highest yields, but the unit of water would not necessarily receive the highest return. Therefore, insufficient irrigation, Ding proposed in recent years, that is not the purpose of irrigation to achieve maximum yield per unit area, but to a higher unit water consumption of crop yields. This is Today, an increasing scarcity of water resources, becomes particularly important. Because of limited water resources is less per acre irrigated, if some of it is possible to irrigate more area, and thus a higher total output. We had to sit people in the past have used water species, the key water irrigation irrigation systems fall into this prototype. But now will have to a complete irrigation system is not adequate. We have to do a lot of experimental work, and this irrigation system for the different areas of different crops is not the same.

(B) irrigation of rice drying thin wetting a traditional rice irrigation is generally maintained long-term deep-water layer. In some areas, using string irrigation, flooding, severe loss of water and fertilizer. Recent studies using a thin, shallow, wet. Drying irrigation system, and achieved very good water-saving effect. The basic approach is to thin water-planting, shallow water turn green, wet fields early tillering management, Shaitian late tillering, jointing heading to maintain a thin water, milky to keep the fields wet and Huang Shu wet down dry. This method is widely in Guangxi, promotion, promotion of an area totaled 178.2hm:, in practice proved to be more than 7.72% increase, due to shallow water layer, leakage and plant trees between the amount of evaporation is greatly reduced, thereby reducing the field water consumption, the average annual to reduce water consumption 1069m3/hm2 (as early as late rice total). But also to obtain the effect of increasing yield per unit area, per mu for the promotion of such technology for as little as 0.3 ~ 0.4 yuan, can be said to invest in small, yields great results. However, this method subject to geographical and conditions for large, all localities should explore the most suitable for the local irrigation system. Is worth in the South vigorously promote water-saving irrigation technologies.

4, water-saving measures to support field

 A variety of root crops, irrigation methods are wet active layer of the soil, so absorbed by crops. This should be moist most of the surface, there is an inevitable part of the crop is not absorbed directly into the air from the soil surface evaporation, and this part of the water is basically wasted. Therefore, to water in many parts of the various support measures have been taken to reduce soil surface evaporation. Commonly used methods of cultivating, preserving soil moisture, straw geographical coverage. Row crop is moisture-conserving irrigation after each harrow the soil surface, so that you can cut off the capillary, so that below the surface soil moisture in the capillary under the action will not be sent to the surface of evaporated. Straw cover, is the straw (or other plant stem and leaves) chopped at the soil surface after the shop, so you can effectively reduce soil surface evaporation. To sum up, we can see water-saving irrigation technology is diverse, each technology has certain conditions for the application, every place, every kind of conditions can choose a suitable water-saving irrigation technology. We have carried out water-saving irrigation work, it must be adapted to local conditions choose to use one or several methods simultaneously. Our aim is to save water, as long as an effective water-saving irrigation techniques, we will actively adopt according to local conditions. First, choose investment