The malpractice of flood irrigation often changes the way and the benefit increases.

China is not only a country with poor water resources, but also a large agricultural country with large water consumption, agricultural water consumption accounts for about 60% of the total water consumption, and the effective utilization rate of irrigation water is less than 50%, especially for vegetables that are watered frequently.

It has been thousands of years from the waterwheel irrigation to the flood irrigation, which is a great improvement in the watering speed. However, things always have its two sides, the disadvantages brought by large water output and high speed are more water loss and low utilization rate, among which the greater harm is that soluble fertilizer moves down into the ground to pollute the underground water source. In view of this situation, at present, advanced agricultural countries are using drip irrigation and sprinkler irrigation to irrigate land in a large area.

In order to explore the vertical and horizontal direction of water in the soil layer under different watering rates, the author has measured it. The results show that when the water flows through the border, the water will quickly reach saturation in the vegetable root concentration layer, that is, the 30 cm soil layer. the excess water will carry fertilizer down to the underground layer with few roots and no roots and enter the underground shallow water layer. Especially the sandy soil, the lower part of the lack of "holding water" clay layer, the loss of water and fertilizer is faster. The greater the amount of water, the greater the amount of loss. Because the infiltration and loss of water and fertilizer occurs in a "hidden" environment that is invisible to people's eyes. Therefore, people do not feel the harm of flood irrigation. This is the main reason why vegetable farmers are still reluctant to give up flood irrigation so far.

So how to carry out water-saving irrigation? Now put forward several specific measures, farmers can choose according to their specific conditions.

Advocating drip irrigation is a relatively advanced fertilizer-saving and water-saving irrigation technology which can control water and realize the integration of fertilizer and water. Because it has been promoted for many years, the problem of eyedropper blockage has been solved, and the current price is relatively cheap, with an investment of only 400 to 500 yuan per mu. In the concentrated area of the protected area, as long as there is a water tower or no tower water supply pressure equipment, through the underground buried pipe directly into the shed, the water meter can be used to show the water consumption. The advantage of drip irrigation is that because the valve switch is installed at the main water inlet and the water meter is measured, the scientific water supply can be achieved according to different growth periods and seasons of vegetables, which can not only reduce the loss of water and fertilizer, but also optimize the root growth environment in the soil layer.

At present, improving flood irrigation is still one of the main irrigation methods in vegetable fields. In order to achieve the purpose of saving water and fertilizer, the following improvement suggestions are put forward: first, long beds are changed to short ones. At present, the border length of vegetable fields is about 50 meters, and some of them can be as long as 80 meters. In this way, if the water flows from the head of the border to the end of the border and stays in the border for too long, there will be more infiltration and loss. For this reason, it is suggested that the long beds be cut into short beds of no more than 10 meters each. Second, when watering, the water will be changed at the head of the border, so that the ditch is full and the border is overflowing. Third, each watering width line and narrow line alternately, this time watering narrow line, the next watering wide line, so that the amount of watering can be controlled. Fourth, in addition to reasonable water supply according to different growth stages of vegetables, plastic film mulching should be carried out in the whole field to reduce the number of watering.

Peasant friends often say that watering the land should be "thoroughly", but how much water per mu is "thoroughly" and how thick the soil layer is "thoroughly", I am afraid few people can tell. With the help of meteorological knowledge, it can be explained that if the precipitation is 20 mm in 24 hours, the amount of water obtained on one mu of land is 13340 kg, or 13.34 cubic meters, which is "permeable rain" according to the experience of ordinary farmers. That is, the water held by the root concentration layer can fully meet the needs of vegetables. If the amount of water for each watering is determined according to this standard, 10 cubic meters of water per mu can meet the requirements. After the "quantity" is determined, the interval time of each watering can be determined according to the water requirement of different vegetables, the water demand of different growth stages of vegetables, the degree of water retention of different seasons and different soil quality. Master the principle of frequent watering of small water and change the habit of flooding.