Winter wheat is generally bounded by the Great Wall in China, with spring wheat in the north and winter wheat in the south. Winter wheat is the main crop in China.

wheat

Winter wheat is planted in a slightly warmer place. Generally, it is sown 10 from the middle and late September to the early June, and ripens from the end of May to the middle and late June of the following year. For example, North China and its south are all winter wheat. In China, it is generally bounded by the Great Wall, with spring wheat in the north and winter wheat in the south. China is dominated by winter wheat.

wheat

1. The northern winter wheat areas are mainly distributed in Qinling Mountains, north of Huaihe River and south of the Great Wall, where the winter wheat production accounts for about 56% of the total wheat production in China. Mainly distributed in Henan, Hebei, Shandong, Shaanxi, Shanxi and other provinces.

2. The southern winter wheat areas are mainly distributed in the south of Huaihe River in Qinling Mountains. This is the main rice producing area in China. Planting winter wheat is beneficial to improve multiple cropping index and increase grain yield. It is characterized by high commodity rate. The main producing areas are concentrated in Jiangsu, Sichuan, Anhui and Hubei provinces.

3. Spring wheat area, mainly distributed in the north of the Great Wall. The temperature in this area is generally low and the production season is short, so it is mainly harvested once a year. The main producing provinces are Heilongjiang, Xinjiang, Gansu and Inner Mongolia.

Law of water demand

1, sowing to jointing stage

During this period, due to the small plants, low temperature and low ground evaporation, the water consumption accounts for 35% ~ 40% of the total water consumption in the whole growth period, and the average daily water consumption is about 6.0 m3/hm2.

2, jointing to heading stage

During this period, wheat entered a vigorous growth period, and the water consumption increased significantly. During this 25-30 d period, the water consumption accounts for 20%-25% of the total water consumption of wheat, and the average daily water consumption is 33.0-51.0m3/hm2. This period is the key period of wheat water demand, and if it is short of water, it will seriously reduce production.

wheat

Step 3 mature

This period is about 35 ~ 40 d, and the water consumption accounts for 26% ~ 42% of the total water consumption, and the average daily water consumption is slightly higher than that in the previous period. Especially before and after heading, the stems and leaves grow rapidly, and the green area reaches the largest in a lifetime, with an average daily water consumption of about 60 m3/hm2.

It can be seen that wheat consumes less water in seedling stage and early jointing stage, and the most water is consumed from jointing stage to heading stage, while the flag-raising stage is the most sensitive to water response, which is called the "critical period" of water demand. Followed by flowering to grouting, some people call it "the second critical period"; The water consumption at maturity has decreased again. Therefore, it is very important to meet the water supply in the critical period of wheat water demand as much as possible for winning a bumper harvest of wheat.

In addition, the water consumption before jointing stage of wheat is small, but the water supply in this period is very important to realize the whole seedling, uniform seedling, Miao Zhuang, packaging, tillering and high-yield shelf. Farmers' proverb: "It rains on the eighth, tenth and third day of the lunar calendar" is an objective summary of farmers' experience in wheat production in the long-term production practice.

Suitable soil water content in different growth stages of wheat;

① From emergence to tillering stage, the soil moisture content is about 80%.

② During overwintering, the soil moisture content is 55% ~ 80%.

③ From greening to jointing stage, the soil moisture content is 70% ~ 80%.

④ From booting stage to flowering stage, the soil moisture content is about 80%.

⑤ During grouting, the soil moisture content is above 60%.

Irrigation technology

The correct irrigation technology is to ensure the rational use of water in the wheat field, send the water to the field in time, so that the irrigated field can receive water evenly, without causing ground loss and deep leakage, and without destroying the soil structure, so as to achieve the purpose of economic and rational use of water and increase yield. At present, there are four main ways of wheat field irrigation: surface irrigation, sprinkler irrigation, drip irrigation, pipeline water delivery and pipeline irrigation.

1, surface irrigation

Border irrigation in wheat field is an irrigation method created by working people in China. Border irrigation is to build a ridge in the field on the basis of leveling the land and divide it into several rectangular or square borders. Water is introduced into the border from the irrigation ditch, forming a thin water layer on the ground, flowing along the longitudinal slope of the ground, and gradually wetting the soil during the flow, thus achieving the purpose of improving the soil water content.

The suitable slope of border irrigation land is11000 ~ 3/1000. The slope of the ground is too large, and it is easy to wash away the topsoil during irrigation. Generally, the border is 30 ~ 50 m long and 2 ~ 3 m wide, and the flow rate per border width (average flow rate per meter width) is 3 ~ 6 L, which can be determined according to specific conditions. When the slope of the ground is small, the soil permeability is good and the land evenness is poor, the border length is easy to be short and the water inflow is easy to be large. The slope of the ground is large, the soil permeability is poor, and when the land is leveled, the border grows up and the water inflow is small.

Step 2: Sprinkle irrigation

Sprinkler irrigation is to spray pressurized water into the air with special equipment and disperse it into water droplets for irrigation. This technology, which started in 1970s, is an advanced irrigation technology, and its main feature is water saving. According to research, sprinkler irrigation technology generally saves 20% ~ 40% water than surface irrigation, and sprinkler irrigation does not destroy soil structure; Moreover, sprinkler irrigation has a wide application range, which is not only suitable for plain irrigation, but also especially suitable for mountainous areas, hills and uneven land.

There are three types of sprinkler irrigation: fixed, semi-fixed and mobile.

The parts of fixed sprinkler irrigation are basically fixed, the power and water pump form a fixed pumping station, the water pipeline is buried underground, and the sprinkler is installed on the fixed horizontal pipe in the field, but the sprinkler is put on fashion and removed after use.

The power of semi-fixed sprinkler irrigation, the main pipe of water pump and water pipe is fixed, while the branch pipe and nozzle are movable.

The power supply, water pump, water pipe and nozzle of mobile sprinkler irrigation are all movable, which can save a lot of water pipes.

3. Drip irrigation

Drip irrigation uses a set of equipment to filter water under pressure, and through various pipes and drip irrigation devices (drippers), water or fertilizer solution dissolved in water is evenly and slowly dripped into the soil near the roots of crops, so that the soil in the active layer of crop main roots always keeps the soil moisture suitable for crop growth.

The main advantages of drip irrigation are:

(1) saving water and energy; (2) It does not destroy or harden the soil, and the soil has good air permeability and rich nutrition, and is suitable for various terrains and soil conditions. Drip irrigation system consists of four parts: water source, head control hub, water pipelines at all levels and emitters. It can be divided into two types: unfixed irrigation and mobile irrigation, but this irrigation method has not been applied to wheat production in the field at present.

4, underground pipeline water and pipeline irrigation

The main advantages of underground pipeline water delivery and pipeline irrigation are:

① Water is delivered quickly. Compared with the earth canal, the pipeline transportation distance of 1 000m only needs 3 ~ 5 minutes, while the earth canal needs12 hours; ② Save water, land and labor. According to the research, because the pipeline water transmission reduces the evaporation and leakage of water, it can save water by 20% ~ 40% and reduce the cost by about 30%, which not only saves labor, but also occupies less land and saves land. This set of facilities includes main water tank, main water conveyance road, water diversion building, water conveyance branch road, water outlet building, exhaust hole, grit chamber, water conveyance channel, etc.

water-saving irrigation

Water-saving irrigation of wheat refers to obtaining higher yield and economic benefits with less irrigation in wheat field. It includes two aspects: ① to prevent flooding or blindly increase irrigation times, so as to obtain high yield with reasonable irrigation amount, thus avoiding waste of water resources and expanding irrigation area; (2) Limited irrigation, combined with appropriate agronomic measures, maximizes the use of limited water resources and ensures a considerable yield level. The main measures of water-saving irrigation for winter wheat are as follows.

1. Large-scale storage and irrigation before sowing.

The results show that the soil moisture in 50 ~ 200 cm soil layer can reach more than 80% of the field capacity by using large quota irrigation before wheat sowing, which is beneficial to the rooting of wheat roots and increasing the proportion of deep roots. In this way, wheat can not only use deep soil to store water during the growing period, but also reduce soil evaporation caused by a large number of frequent irrigation. According to the research, in the area with deep soil layer, the yield of wheat can reach 6000 kg/hm2 even if it is not watered during the whole growth period. Above.

2. Key water irrigation of wheat

According to the water demand characteristics of wheat and the water effect of wheat at different growth stages, irrigation of key water is an effective water-saving measure. According to the research, under the condition that the soles are irrigated with water (the water in winter is better), the water irrigation effect in winter is worse, and the water-saving water irrigation effect in booting stage is the best. Under the condition of poor soil moisture before winter, the irrigation effect with winter water and booting water is more obvious. Therefore, in the case of water shortage, it is an important measure to improve water use efficiency and achieve high yield and high efficiency to ensure water use in the critical period of wheat.

3. Harden the canal to reduce leakage.

Leveling land and improving irrigation quality; Backbone canals (ditches) should be equipped with anti-seepage facilities, and efforts should be made to return water to the fields. When surface irrigation is used, the land should be leveled, because the levelness and boundary specifications of the land have a great relationship with the irrigation quality and efficiency. Land leveling can improve irrigation efficiency by 30 ~ 50% and save water by more than 50%.

4. Adopt advanced irrigation technology.

In areas where water resources are relatively scarce and economic conditions are relatively good, advanced irrigation technologies such as sprinkler irrigation, drip irrigation, infiltration irrigation and pipeline irrigation are effective ways to save water. According to research, sprinkler irrigation can save water by 20% ~ 40% compared with ground irrigation; The water consumption coefficient of wheat (the water consumed to produce 0.5 kg grain) is only 25% ~ 30% of that of border irrigation; Infiltration irrigation saves about 40% water than border irrigation, and drip irrigation saves 4 ~ 6 times water than border irrigation. Moreover, these advanced irrigation techniques are generally not easy to cause soil hardening and nutrient leaching, which is beneficial to the coordination of soil water, fertilizer, gas and heat and the activity of microorganisms, and promotes nutrient transformation, thus improving wheat yield.

5, irrigation combined with other agronomic measures.

After irrigation in wheat field, timely intertillage, loosening soil and plastic film mulching can prevent water evaporation, improve water use efficiency and save water.