The integrated technology is mature and double-cropping corn can be planted in the North China Plain.

On July 13, the demonstration side of 200 mu double-season corn in Lianzhu Village, Lianzhu Town, Quzhou County, Hebei Province began to harvest. "this is the earliest spring corn harvested in Hebei Province and even in North China." Said Chen Xinping, a professor at the School of Resources and Environment of China Agricultural University, who is in charge of the double-season Maize experiment and demonstration Project.

Due to the low temperature in spring, spring corn in Hebei Province is generally sown in late April or early May and harvested in late August. "the climate has warmed in recent years, and the accumulated temperature in Hebei has increased by 260 ℃ in spring. On this basis, we use plastic film sowing technology to advance the sowing time of spring corn to mid-March, so that it can be harvested in mid-July. " Chen Xinping explained.

Double cropping corn can save water by 30% to 50%.

In 2012, the High-yield and High-efficiency Modern Agricultural Research Base of China Agricultural University (Quzhou) began to conduct a double-cropping corn experiment, that is, to explore the replacement of "spring corn-summer corn" to the traditional "winter wheat-summer corn" planting model. This experiment focuses on the improvement and adjustment of planting structure in North China in the future under the change of climate, resources and environment, and explores the establishment of ecological conservation agriculture which can not only increase yield, but also save water, fertilizer and fallow.

The biggest problem in agricultural production in North China is the lack of water. From sowing to harvesting, winter wheat needs to be irrigated at least and four or five water at most, which consumes a lot of groundwater. Some counties and districts in Hengshui City have granted subsidies to farmers to give up planting wheat and plant other crops to avoid continued overexploitation of groundwater. "it only takes one or two water to replace winter wheat with spring corn, and summer corn generally does not need to be watered during the rainy season in July. In this way, two water can be saved in the whole year, and water saving can reach 30% to 50%." Cui Zhenling, associate professor at the School of Resources and Environment, China Agricultural University, made a comparison.

However, the spring corn varieties in the double-cropping corn model are not randomly selected. After many experiments, the double-season corn experiment and demonstration project team selected the spring maize variety "Demeya", which is widely planted in the high latitudes of Northeast China. This kind of spring corn is cold-tolerant and has a short growth period. It is sown in mid-March and harvested in mid-July, so that the summer corn of the second season can be sown at the latest in mid-July (Hebei region) and mature in mid-November.

Double cropping corn can produce a fallow period of 4 months.

In the traditional planting mode, because of the large amount of summer corn straw, it is more troublesome to deal with it. In order to rush to plant winter wheat, farmers often harvest summer corn before it is fully mature, and the straw is still green, so it is difficult to return to the field mechanized. Double-cropping corn has twice the amount of straw, isn't it more difficult to deal with?

"the double-cropping corn model can easily realize the full return of corn straw to the field." Cui Zhenling said that spring corn "Demeya" is suitable for close planting, and the straw is thin and easy to dry, and it can be mechanically crushed and returned to the field at harvest time, without affecting the sowing of summer corn; summer corn matures in mid-November, because it is no longer necessary to rob the farm. you can wait until the straw is dry before harvesting and returning the straw to the field.

It should be noted that after the corn straw is broken in the second season, it is not ploughed, but directly covered to the surface. This is because there is a free period of four months from summer corn harvest to spring corn sowing next year. If the soil is exposed, it will cause problems such as the loss of organic matter on the surface of the soil, the weakening of soil moisture and dust. More importantly, four months of fallow was achieved in the winter when the land output rate was the lowest. On the one hand, the soil fertility was restored, on the other hand, the optimal use of land was realized.

In the double-cropping corn model, the "annoying" straw has become an indispensable treasure to cover the surface and protect cultivated land.

Double cropping corn can reduce the amount of potash fertilizer 50kgK2O/hm2.

The total amount of double-season corn straw returning to the field can also greatly reduce the amount of potash fertilizer. In Huang-Huai-Hai area, the amount of potash fertilizer can be reduced to 50kgK 22O/hm, and it can be maintained at 90kgKO/hm22 in two seasons a year. This is because the potassium in the corn plant is mainly concentrated in the stalk, and the straw buried in the soil can release most of the potassium in a very short time.

The reduction of potash fertilizer is of great significance to our country. "China's potash reserves account for only 1.6% of the world's potash reserves, while the consumption is 20% of the world's. The fluctuation of imported potash prices has become an important factor affecting China's chemical fertilizer market. The full return of double-cropping corn straw to the field is an efficient alternative technology for potash fertilizer. if it is popularized in a large area in Huang-Huai-Hai region, it will help to alleviate the situation of China's dependence on imports of potash fertilizer. " Guo Qiang, deputy general manager of potash fertilizer division of Sinochem Chemical Fertilizer Co., Ltd., said.

Double cropping corn can increase yield by 20% to 30%.

Double-cropping corn can save water, fertilizer and fallow, what is its yield? The experimental data of "double High Base" of China Nongdaqu week from 2012 to 2014 show that under the condition of conventional water and fertilizer management, the yield of double-cropping corn is as high as 1.5 tons per mu, 12% higher than that of high-yielding farmers growing winter wheat and summer corn, and 20% higher than that of ordinary farmers.

The 200-mu demonstration side of double-cropping corn used the contracted land of Fan Changyong, secretary of the party branch of Lianzhu Village, who told reporters: "the drought is very serious this year, and the wheat harvest in our village is not very good. However, the spring corn harvest of the demonstrator is not bad, with a yield of 650 kg per mu. Now that summer corn has been sown, Rain Water is better these days, and the yield will be higher this season. "

Through the process of film-mulched sowing and grabbing temperature, short-growing spring corn stubble, summer corn straw crushing to cover the surface, spring ploughing and soil preparation straw deep turning and so on, it realized the ingenious combination of water resources, climatic conditions and variety selection, mechanized operation, conservation tillage technology and other factors in time and space, and the project team completed the technical integration of the whole double-cropping corn model. "it can be said that the double-cropping maize model has matured and has the conditions for large-scale popularization in the North China Plain." Chen Xinping is very confident.

Reporter's notes

Four questions about "double cropping Corn"

Each of the techniques in the double-cropping corn planting model looks common and nothing special. However, the scientific and ingenious combination of these conventional technologies has created a breakthrough planting pattern, which can be said to be "the most extraordinary and seemingly ordinary, as easy but difficult". However, the reporter still had some puzzles after the interview, and fortunately he got a detailed answer from the relevant experts.

First, since the growth period of spring corn (Demeya) is short and the yield is high, why not continue planting in the second season? Demeia is a density-tolerant variety, which can grow 6000 trees per mu of land, while Hebei's traditional spring corn has only 4000 trees. But its disease resistance is poor, so it is not suitable to grow in the high temperature of Huang-Huai-Hai region in summer.

Second, why should we pay attention to the sowing date of summer corn in the double-cropping corn model in mid-July? Traditional summer corn in North China is usually sown in June, and the latest sowing time is in mid-July. The summer corn sowing of double-season corn is stuck at this time, and there are more Rain Water in July, so there is no need to water at the seedling stage.

Third, China's North China Plain is the largest "funnel area" in the world. Since there is such a shortage of water, why not promote drip irrigation? The cost of drip irrigation equipment is high, and if the increase in yield caused by drip irrigation does not exceed 20%, it will not be cost-effective for farmers, unless there is a special shortage of water. Therefore, double-cropping corn has the cost advantage of saving water.

Fourth, since returning straw to the field can basically maintain the balance of potassium in the soil, can we apply less or no potash fertilizer? Potassium mainly exists in the stem of the plant, which can improve the folding resistance of the stem. Increasing the level of potassium supply is one of the necessary measures to enhance the lodging resistance of maize and achieve high yield.