When is the planting time of corn in the north? How do you usually grow it?

Spring sowing corn areas in northern China generally include all of Heilongjiang, Jilin, Liaoning, Ningxia and Inner Mongolia, most of Shanxi, and part of Hebei, Shaanxi and Gansu. It is one of the main corn producing areas in China. Account for 39.2% of the national corn area, and the total output accounts for 43.8% of the national total. The planting time is usually in spring.

Spring sowing corn in northern China belongs to the humid and semi-humid climate zone in cold temperate zone, which is low-temperature and dry in winter with a frost-free period of 130-170 days. The annual precipitation is 400-800 mm, 60% of which is concentrated in July-September. The Northeast Plain has flat terrain, fertile soil, suitable temperature and sufficient sunshine in most areas, and is suitable for growing corn. It is the main producing area of corn and an important commercial grain base in China. Corn is mainly planted in dry land, and the area of corn under irrigation conditions is less than 1/5. The yield of corn in this area is very high, averaging about 6 tons per hectare. The highest yield is 15 tons per hectare.

1. Planting system

The spring sowing corn area in the north is basically an one-year system. There are three types of planting:

(1) clear seeds of corn. It accounts for more than 50% of the corn area and is distributed in the plains of the three northeastern provinces and the northern alpine areas of Inner Mongolia, Shaanxi, Gansu, Shanxi and Hebei. Due to the short frost-free period and low temperature, corn is planted in a single season, but corn plays an important role in rotation, usually with spring wheat, sorghum, millet, soybean and other crops. This situation has changed a lot since the 1970s. Due to the rapid increase of corn sown area and the difficulty of crop rotation, continuous cropping system has been developed.

(2) intercropping of corn and soybean. It accounts for about 40% of the area of this area, which is the main form of corn planting in Northeast China. Corn-soybean intercropping, making full use of the morphological and physiological differences of the two crops, improved the utilization rate of light energy, moisture, soil and air resources. Corn-soybean intercropping can generally increase grain and bean production by about 20%.

(3) interplanting spring wheat with corn. After the 1970s, the planting mode of interplanting spring wheat and corn was gradually formed in northern Shaanxi, northern Shanxi and some areas with better water and fertilizer conditions in Liaoning, Gansu and Inner Mongolia. The method of wide border sowing wheat, ridge interplanting or raising seedlings and transplanting spring corn can generally increase production by 20-30%.

two。 Main corn varieties planted

The spring sowing corn area in the north actually includes the Northeast and North China. Varieties with moderate or early maturity, low temperature tolerance and high yield are needed in Northeast China. There is basically no epidemic of virus disease and small spot disease in Northeast China, but there are large spot disease and head smut, and sometimes corn borer damage, so it is required to resist these diseases and insect pests. According to statistics, the main maize hybrids planted in Northeast China are Benyu 9, Jidan 159, Sidan 19, Zhongdan 2, Yedan 19, Danyu 13, Yedan 13 and Shendan 7, etc.

Spring sowing maize in North China suffers from serious virus diseases, in addition to stem rot, size spot and so on, so the requirements for varieties are more strict. The main cultivated varieties are Yedan 13, Yedan 12, Yedan 19, Xiyu 3, Yedan 2, Zhongdan 2 and Yandan 14.

3. Analysis of production conditions

The favorable conditions for the development of maize production in the northern spring sowing area are flat terrain, deep soil layer, fertile soil quality and rich light and heat resources. The level of agricultural production in this area is high, the yield increase potential of corn is great, and it has the advantage of commodity production.

The main factors restricting corn production in this area can be summarized as follows: first, the production areas are concentrated, the circulation is not smooth, and it is very difficult to store, transport, process and sell corn after harvest; second, the autumn frost is early, the temperature is low, and the grain is dehydrated slowly. reduce the quality grade and increase energy consumption; third, drought and little rain, insufficient irrigation facilities and water resources; fourth, low input, especially insufficient fertilizer, unreasonable ratio of nitrogen, phosphorus and potassium. Fifth, there is a lack of new varieties with stable and high yield. The strategy of stabilizing the area and increasing the yield should be adopted for the further development of maize production in this area.

4. Measures to further increase production

(1) replace new varieties. There is an urgent need to select or introduce new hybrids with early maturity, high yield, lodging resistance, suitable for close planting and mechanized operation. New varieties with fast dehydration, good quality, resistance to head smut, leaf spot, gray spot and resistance to corn borer are needed in the late filling stage.

(2) increase investment. There is a great difference in the demand for nitrogen, phosphorus and potassium between the input of chemical fertilizer and the yield of 1000 jin of corn per mu in this area. if the input of fertilizer is not increased, long-term continuous cropping corn will seriously destroy the soil fertility and make the agricultural system unsustainable. If balanced fertilization can be achieved, the yield will be greatly increased.

(3) enlarge the coverage area of plastic film. The area of maize covered with plastic film in Heilongjiang Province has reached 3 million mu. At present, the new technology of factory seedling raising and mechanized transplanting is being tested, which is one of the powerful measures to greatly increase the yield. It is also suitable to develop corn plastic film mulching technology in Shanxi, Inner Mongolia, Liaoning and Jilin provinces.

(4) to reform the grain circulation system and expand the circulation channels, while increasing drying machinery and warehousing and processing facilities. In the case of high water content of varieties, drying machines should be equipped to speed up the rate of grain dehydration after harvest, properly solve the problems of safe grain storage, transportation and circulation, improve the quality grade, and expand the export capacity. We should also pay attention to the development of post-natal processing industry, and there are many ways to protect farmers' enthusiasm for growing grain and stabilize production.