Due to the influence of the height, the general irrigation equipment is difficult to achieve the irrigation of corn. But the "Rain star" hose reel irrigation machine can be very good for irrigating corn. Take North China as an example to analyze the corn irrigation technology.

The irrigation period and irrigation amount depend on the following points: the amount of water required during each fertility period, precipitation, and the soil water content at that time. For most parts of North China, the large horn period of maize is the critical start period of water demand, and the tasseling - silking stage is the critical period of water demand, these two periods are in the rainy season and generally do not require irrigation. but it requires irrigation during sowing and grouting periods. 

The impact on yield for Irrigation during sowing and grouting periods and  irrigation methods are described as follows:

一、Irrigation during seedling period

１．Effect of Irrigation on Yield in the Seedling Period

Appropriate soil moisture (Soil moisture content accounts for 70% ~ 80% of field water capacity) can not only ensure the timely sowing of corn and ensure the survival rate, but also create conditions for seedlings to flourish. There is a drought in the early summer of North China, the precipitation in June is less than 50 mm, droughts occur 47 percent of the time, therefore, summer corn sowing often lacks water, affecting the sowing time and survival rate, thus affecting the yield. According to the test, summer corn is planted every night during the suitable sowing period, and the yield per Mu will be reduced by more than 10 kilograms. Therefore, for timely early sowing, irrigation should be carried out when sowing. In the past, after the wheat harvest, if there is insufficient moisture, it will carry out irrigation, the time is long and uneven, often causing the corn to miss the suitable sowing period. Irrigate by hose reel irrigation, the time is fast and uniform, water saving, the terrain requirements are not strict, can ensure that all seedlings. Pre-sowing sprinkler irrigation increased seedling rate by 50 per cent and increased yield by about 30 per cent.

２．Method of irrigation during seedling period

Soil water content needs to be test before sowing. irrigation is required if the moisture content of the field is less than 70% There are two methods:

（１）Irrigation before sowing: start irrigation immediately after wheat harvest. The amount of irrigation should be determined according to the soil moisture at that time, so as to ensure the emergence of seedlings. Under normal circumstances, irrigation of 30mm, approximately equivalent to about 20 cubic meters of water per mu. We can also increase the soil moisture by irrigating the yellow water before wheat harvest.

（２）Spray irrigation after sowing: time is urgent during the three summers, in order to improve the seeding progress, you can also irrigate after sowing.But be sure toirrigate immediately after sowing, so as to avoid early sowing and early emergence and large, small seedling phenomenon. Generally, the irrigation is 25mm, which is about 17 cubic meters of water per mu. In the actual production, due to the time, manpower, material resources are very tight, should be reasonable arrangement, two methods can be used, part of the first sprinkling irrigation after sowing, the other part of the first sowing after sprinkling irrigation, this can improve the seeding progress, and can ensure the emergence of seedlings. The above two methods should pay attention to the uniformity of irrigation, otherwise it will affect the survival rate.　

二、Irrigation during grouting

１．Effect of sprinkling irrigation on yield during grouting。In north China, maize is not used to watering during grout period 。One is due to low yield, low density, on the other hand, more autumn rain. Maize yield is higher in recent years, large density, less rain, just by precipitation can't be satisfy the need of the maize growth, Water requirements per mu yield 500 kilograms of summer corn is 223 ~ 256 mm in the period of flowering and ripening, and this period (late August to the end of September). The average rainfall in Beijing is only 85.8 mm, even the groundwater added is far from enough to meet the demand, especially in the year of autumn drought. Generally, the grouting period requires irrigation. The results showed that 20mm irrigation during grouting period can increased the 1000-grain weight by 22 ~ 46 g and 40 ~ 80 kg.With the increase of irrigation, 1000-grain weight and yield also increased, but the increase range was different, from 20mm to 30mm, with a large increase, while from no irrigation to 20mm and from 30mm to 40mm, with a small increase, so 30mm was better.　

２．The method of irrigation In the middle and later stage of growth, maize plants are tall, height is generally about 2 meters.  It only needs to add an elevated frame to the position of the Rainstar's gun to meet the requirements of sprinkler height.