Technical measures to replenish the water needed for crops. In order to ensure the normal growth of crops and obtain high yield and stability, it is necessary to supply sufficient water to the crops. Under natural conditions, it is often impossible to meet the water requirements of crops due to insufficient precipitation or uneven distribution. Therefore, irrigation must be done artificially to compensate for the lack of natural rainfall.
Irrigation, that is, watering the land. The principle of irrigation is that the amount of irrigation, the number of irrigations and the time should be determined according to the water demand characteristics of the medicinal plants, the growth stage, the climate, and the soil conditions. It should be timely, appropriate, and properly irrigated. The types mainly include irrigation before planting, seedling irrigation, growth and irrigation, and winter irrigation.
Diffuse irrigation should be used to dig trenches, previously used artificially, and later with livestock, tractors, and later advanced machinery using laser ranging, depending on economic and geographical conditions, such as the size of the area to be irrigated, what technology is available, labor costs Wait. Plants line up in the rafts and gullies or grow on the seedbed, and water enters the field along the channel, flowing along the edge of the sulcus or seedbed. It is also possible to use a hard plastic tube or an aluminum tube to divert water in the field, open the hole at a distance from the tube, and connect the channel with a siphon.
The application of pipelines can control the flow of water. Due to differences in temperature, wind speed, soil, and permeability, flooding can easily cause water in some places. In some places, water is insufficient, and pipelines can move, so it is possible to control the phenomenon of not producing such unevenness. . Especially if automatic valves are used, the efficiency can be increased.
However, because flood irrigation is a waste of water resources, it requires more labor, and it is easy to cause the groundwater level to rise. Therefore, the soil is alkalized and has been gradually eliminated in developed countries. However, it is still widely used in most developing countries because it requires only a small amount of capital and technology.
Sprinkler irrigation is carried out by pipes to send water to the nozzles located in the field. It has the distinction between high pressure and low pressure. It can also be divided into fixed and mobile. The fixed nozzles are installed in fixed places, and some nozzles are installed on the ground surface height. They are mainly used in places where aesthetics are needed, such as golf courses, racecourse grass irrigation, parks, cemeteries, etc.
The pressure of the nozzle should not exceed 200 bar. If it is too high, it will produce water mist, which will affect the irrigation benefit. The nozzle can be rotated. The rotation can be 360 degree rotation or a certain angle. There are also spray guns. It can work at a pressure of 275-900 bar, with a long jet and a flow rate of 3-76 liters/second. The spray gun can also be used for industrial dust protection.
If the nozzle and the water source are connected by a pipe, the nozzle can be moved. For the mobile sprinkler, the plastic pipe is wound onto a reel, and the nozzle can be moved out as the nozzle moves, and the nozzle can be manually moved.
The disadvantage of sprinkler irrigation is that it also loses a lot of water due to evaporation, especially in windy weather, and it is not easy to evenly irrigate the entire irrigated area. Water remaining on the leaf surface is likely to cause mold to multiply. If there is fertilizer in the irrigation water, Hot and sunny weather can cause leaf burns.
（3）Micro sprinkler irrigation：
Micro-sprinkler irrigation is a form of irrigation that uses a refraction, rotation, or radiant micro-sprinkler to spray water evenly onto crop leaves and other areas, and belongs to the micro-irrigation category. The micro-sprinkler irrigation has low working pressure and small flow rate, which can increase the soil moisture regularly and quantitatively, improve the air humidity, and adjust the local microclimate. It is widely used in vegetables, flowers, orchards, medicinal plants, and cutting seedlings, breeding places, etc. Humidification and cooling.
Drip irrigation is an irrigation form in which water is dropped into the soil near the roots of plants in a uniform and slow manner. The dripping flow is small and the water drops slowly into the soil, which can minimize the evaporation loss. If the film is covered, it can be further reduced. Evaporation, under drip irrigation conditions, except that the soil moisture immediately below the dripper is saturated, the soil moisture in other parts is in an unsaturated state, and the soil moisture mainly infiltrates and diffuses by capillary tension.
However, if the drip irrigation time is too long, the phenomenon of soaking may occur under the root system. Therefore, drip irrigation is generally performed by a high-tech computer and manually operated. Drip irrigation water pressure is low, water saving, can be used to grow different plants, each plant is irrigated separately, but the slope needs to be pressure compensated, the computer can be controlled by adjusting the valves in different sections, the key is to control the regulation pressure and Remove particulate matter from the water to prevent clogging of the drip holes. The water is usually transported in a plastic tube, which should be black or covered under the mulch to prevent algae from growing and to prevent the tube from aging due to ultraviolet radiation. Drip irrigation can also be done with porous ceramic tubes buried in the ground, but at a higher cost, only for turf and golf courses.
Irrigation technology has been used for many years in places with high groundwater levels. It is a method of artificially raising the groundwater level and supplying water directly from the bottom of the plant.
Irrigation is often used in commercial greenhouse products, such as irrigation of potted plants, fertilization, soaking pots from the bottom with an aqueous solution containing fertilizer for 10 to 20 minutes, and then water can be recycled. This operation requires high-tech automatic operation and expensive equipment. But saves manpower, water and fertilizer, while maintenance and operating costs are low, the principle is the same as underground drip.
（6）Regulated deficit irrigation：
Reduced irrigation (deficiency) in the non-critical period of crops during regulated deficit irrigation, under drought stress, reducing transpiration and water consumption, and delaying vegetative growth, while providing limited water supply to the critical period of water demand for crops to meet reproductive organ formation And growth requirements. This technology can significantly improve water use efficiency without reducing or even increasing yield.
（7）Controlled roots alternate irrigation:
When the technique was originally proposed, on the one hand, part of the root system was in a dry soil area (dry area), the crop was subjected to water stress, a large amount of abscisic acid was formed in the roots, and the leaves were transported to the leaves, and the pore opening degree was reduced to reduce the transpiration water consumption; In terms of partial root system in the irrigation area (wet area), the crop absorbs water from the soil and meets the needs of normal physiological activities. The drying zone and the wet zone are alternately irrigated. After alternating stress, the number of secondary roots increased, the water absorption capacity of roots increased, and the water use efficiency increased significantly.
In practice, the technology is changed to an alternate irrigation system, an alternate irrigation system, and the like.