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

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On July 13, Lianzhu Village, Henan Tuan Town, Quzhou County, Hebei Province, 200 mu double-season corn demonstration square began harvesting. "This is the earliest spring corn harvested in Hebei Province and even North China." Chen Xinping, director of the "Double Season Corn Experimental Demonstration Project" and professor of the School of Resources and Environment of China Agricultural University, said.

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. "In recent years, the climate has warmed, and the accumulated temperature of 260 ° C has increased in Hebei in spring. On this basis, we use plastic film seeding 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-season corn can save water by 30%~50%

In 2012, the high-yield and high-efficiency modern agricultural research base of China Agricultural University (Quzhou) began to carry out double-season corn experiments, that is, to explore the replacement of the traditional "winter wheat-summer corn" planting mode by "spring corn-summer corn". This experiment focuses on the improvement and adjustment of planting structure in North China in the future under the condition of climate and resource environment change, and explores the establishment of ecological conservation agriculture that can not only increase yield, but also save water, fertilizer and fallow cultivation.

The biggest problem in agricultural production in North China is water shortage. From sowing to harvesting, winter wheat needs to be watered at least three times and at most four or five times, consuming a lot of groundwater. In Hengshui City, some counties and districts have issued subsidies to allow farmers to give up planting wheat and plant other crops instead, so as to avoid groundwater over-exploitation. "It only needs one or two waters to replace winter wheat planting with spring corn. Summer corn generally does not need watering when it is sown in the rainy season in July. In this way, two waters can be saved all year round, and the water saving can reach 30%~50%." Cui Zhenling, associate professor at the School of Resources and Environment of China Agricultural University, made a comparison.

However, the spring maize varieties in the double-season maize model are not randomly selected. After many trials, the double-season corn experimental demonstration project team selected the spring corn variety "Demei" widely planted in the northeast high latitude area. This kind of spring corn is cold-resistant 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 in mid-July (Hebei area) and mature in mid-November.

Double-cropping maize can produce a 4-month fallow period

In the traditional planting mode, because of the large amount of summer corn stalks, it is more troublesome to deal with. In order 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 it to the field mechanically. Double-season corn stalks, isn't it more difficult to deal with?

"The double-season corn model can easily realize the full amount of corn stalks returned to the field." Cui Zhenling said, Spring corn "De Meiya" Suitable for dense planting, Straw thin easy to dry, Can be harvested directly mechanical crushing return to the field, Does not affect summer corn sowing; Summer corn mature in mid-November, Because there is no need to rush farming time, Can wait for straw dry before harvest and straw return operation.

It should be noted that the corn stalks of the second season are not ploughed after breaking, but directly covered on the ground. This is because there is a 4-month idle period between summer corn harvest and spring corn planting in the following year. If the soil is exposed, it will cause problems such as loss of organic matter in the surface layer of the soil, weakening of moisture content and dust emission. More importantly, four months of fallow was achieved in winter, when land productivity was at its lowest, restoring fertility on the one hand and optimizing land use on the other.

Under the double-season corn mode, the straw that "people see and annoy" becomes an indispensable treasure for covering the ground and protecting cultivated land.

K fertilizer application rate of double cropping maize could be reduced by 50 kg K 2O/hm2

The total amount of corn straw returned to the field can also greatly reduce the amount of potassium fertilizer. In Huang-Huai-Hai region, K fertilizer application rate can be reduced by 50 kgKO 22O/hm and maintained at 90kgKO 22/hm22 in two seasons of a year. This is because the potassium in corn plants is mainly concentrated in the stems, and the stalks buried in the soil can release most of the potassium in a very short time.

The reduction of potash fertilizer is of special significance to China. "China's potash reserves account for only 1.6% of the world's total, while the consumption is 20% of the world's total, and fluctuations in imported potash prices have become an important factor affecting China's fertilizer market." The full amount of corn stalks returned to the field in double seasons is an efficient substitute technology for potassium fertilizer. If it is widely promoted in Huang-Huai-Hai region, it will help alleviate the situation of China's dependence on potassium fertilizer imports." Sinochem Fertilizer Co., Ltd. potash business unit deputy general manager Guo Qiang said.

Double-cropping maize can increase yield by 20%~30%

Double-season corn can save water, fertilizer and fallow. How about its yield? The experimental data of Quzhou "Double High Base" of China Agricultural University from 2012 to 2014 show that under the condition of conventional water and fertilizer management, the yield of double-season corn is as high as 1.5 tons/mu, which is 12% higher than that of high-yield farmers planting winter wheat-summer corn and 20%~30% higher than that of ordinary farmers.

The 200 mu double-season corn demonstration party uses the contracted land of Fan Changyong, secretary of the Party branch of Lianzhu Village. He told reporters: "The drought is very heavy this year, and the wheat harvest in our village is not very good." However, the spring corn harvest of the demonstration side is not bad, 650 kilograms per mu of real estate. Now that the summer corn has been sown, the rain has been better these few days, and the yield will be higher this season."

Through the processes of film mulching sowing and temperature accumulation, short growth period spring corn stubble, summer corn straw crushing and covering the ground surface, spring ploughing straw deep ploughing, etc., the ingenious combination of water resources, climatic conditions and variety selection, mechanized operation, conservation tillage technology and other factors in time and space has been realized, and the project team has completed the technical integration of the whole double-season corn mode. "It can be said that the double-season corn 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 Season Corn"

Each of the techniques in the two-season corn model seems ordinary and nothing special. However, these conventional technologies are scientifically and skillfully combined to create a groundbreaking planting model, which is really "the most unusual, easy but difficult". However, the reporter still has some puzzles after the interview, fortunately get detailed answers from relevant experts.