Scientific Methods and Technical Key Points for Returning Wheat Straw to the Field
It is the "Three Summer" period, and farmers are all busy harvesting wheat. But how the wheat straw should be recycled after the harvest remains a problem that troubles farmers.
However, in Yongqiao District, Suzhou City, Anhui Province, Li Qingwu, head of the Huaihe Grain Industry Consortium, and his members seem especially relaxed this year: "The wheat in our fields has mostly been harvested, and in another week we can sow soybeans. Recycling wheat straw is not a problem at all here."
Li Qingwu's ease is not without reason. This year, 1,200 mu of land in the consortium is participating in a technology demonstration by the National Soybean Industry Technology System. With the breakthrough by Chinese agricultural experts in the mechanized no-till straw-mulching technology for summer soybeans after wheat stubble in the Huang-Huai-Hai region, the long-standing problem of wheat straw recycling and disposal that has troubled them will also be completely solved.
Wheat straw treatment methods are diverse,
but each has advantages and disadvantages
"Returning straw to the field benefits the country and the people," "Burning straw is prohibited; violators will be fined 2,000 and detained for 15 days." On June 11, as the reporter drove through the rural fields of Suzhou City, red banners hung across both sides of the roads could be seen everywhere.
"Now the state explicitly prohibits burning straw, but after harvesting wheat we farmers must hurry to plant the next season's crop. With burning no longer allowed, we really do not know how to handle it." Cai Jian, a staff member of the Suzhou City Agriculture Committee, told the reporter that the ban on straw burning is not welcomed by local farmers. To prevent farmers from burning straw, local village and township cadres continuously station themselves in the villages to supervise, but the effect is not ideal.
Straw is rich in organic matter, nitrogen, phosphorus, potassium, and trace elements. Practice has proved that using straw returned to the field can effectively increase soil organic matter content, improve soil structure, and fertilize the soil. Since straw has so many benefits, why are farmers unwilling to return it to the field? Why would they rather burn it all?
"On one hand, they must race against the farming season, and burning is the fastest and least troublesome; on the other hand, the technology for recycling and returning it to the field is not yet simple and mature enough." Wu Cunxiang, an expert with the National Soybean Industry Technology System and a researcher at the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences, told the reporter that at present there are mainly four ways to handle wheat straw: first, manual clearing, which is time-consuming and labor-intensive, with high labor costs; second, mechanical baling, but it requires space for safe stacking; third, straw burning, which can eliminate a certain amount of soil-borne disease but seriously pollutes the environment; fourth, crushing and returning to the field, but this has high machinery requirements, requiring high-horsepower mechanical rotary tillers to crush the straw, and if the crushing is not clean enough, manual picking is still needed.
"Not all straw is suitable for direct return to the field, and direct return of straw involves many steps and can also cause disease. The key is still to be scientific: we must look at both the method and the crop." Han Tianfu, chief scientist of the National Soybean Industry Technology System and a researcher at the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences, added that the Huang-Huai-Hai region is one of China's main soybean production areas. After wheat harvest, farmers mostly plant soybeans. If wheat straw is crushed and rotary-tilled into the soil, it will not only affect the sowing quality of soybeans, but also easily lead to problems such as moisture loss, straw decomposition competing with soybeans for nitrogen, and aggravated disease.
Scientific use focuses on the word "mulch"
As early as 2007, experts with the National Soybean Industry Technology System began thinking about the problem of wheat straw recycling. "Through long-term comparative research, we found a scientific way to return straw to the field, and finally decided to focus on the word 'mulch'." According to Han Tianfu, after 8 years of effort, the experts proposed a straw-mulch cultivation technology model for summer soybeans after wheat stubble, successfully developed a prototype machine, and formed a highly simplified wheat-stubble no-till straw-mulching precision sowing technology system that organically combines agricultural machinery, agronomy, and matched varieties.
On June 11, in Li Qingwu's demonstration field, the reporter saw a tractor pulling a no-till straw-mulching precision seeder moving quickly across the harvested wheat field. As the machine moved forward, it pulled up 30 cm-high wheat stubble together with the roots, and all the straw and part of the wheat stubble were pulled out laterally to the left. After the machine passed, several straight sowing strips were left in the field. When the machine turned back to sow the next row, the previously pulled-up wheat stubble had already been crushed and evenly covered over the sowing strip just made.
"You may not know that with just one pass, the machine has already completed multiple operation steps including lateral straw clearing, lateral deep fertilization, precision sowing, closed herbicide application, and straw mulching." Chen Haitao, an expert with the National Soybean Industry Technology System and a professor at Northeast Agricultural University, told the reporter that the no-till straw-mulching precision sowing technology for summer soybeans after wheat stubble mainly solves the problems of difficult wheat stubble straw handling and poor soybean sowing efficiency. And with this set of machinery, both problems can be smoothly solved.
Under Chen Haitao's guidance, the reporter brushed aside the soil clods covered with wheat straw and dug down 8 cm, where soybean seeds were seen. Each seed was spaced the same distance apart, about 8-10 cm. "After the wheat straw is crushed, it is directly covered on the ground. For soybeans, it is like a quilt for the season and can save water and preserve soil moisture; for the next crop after soybeans, wheat, the wheat straw has already decomposed and can fully serve as fertilizer for the next season. This gives full play to the role of wheat straw and achieves scientific return to the field. And precision mechanical dibbling also helps soybeans emerge early, with strong and uniform seedlings." Chen Haitao explained.
"After mechanical wheat harvest, the stubble is high and the straw is scattered in the field, seriously affecting the sowing quality of soybeans. But now, with just one machine, we farmers can do it completely effortlessly, not only recycling the wheat straw well but also planting soybeans well. It is really too convenient." Wang Bingyin of the Suzhou City Academy of Agricultural Sciences, who was inspecting the mechanical operation in the demonstration field, said with sincere emotion.
Soybean yields increase by 20 kg per mu; the technology is of great significance for promotion
Farmer Ji Yongmin in Suixi County began using this new technology model last year. He calculated an account for the reporter: "Using this technology helped me solve the problems of seedlings and labor, and after the soybeans are planted, basically no more management is needed. Last year, my soybeans increased by 40 kg per mu, and I also saved 7-10 labor-days. The seedlings emerge early, uniformly, evenly, and strongly, and later there is no need to thin or space the seedlings."
Since 2012, this technology has been recommended by the Ministry of Agriculture as a main promotion technology and has been comprehensively demonstrated and promoted in major summer soybean production areas such as Henan, Shandong, Hebei, Jiangsu, and Anhui. According to estimates, covering the ground with wheat straw not only saves the amount of pesticide and chemical fertilizer used per mu, but also increases soybean yield, with an average increase of 15-20 kg per mu and an efficiency increase of 70-140 yuan. In 2013, at the Xinxiang Experimental Base of the Chinese Academy of Agricultural Sciences, the soybean variety XA12938 planted with this new technology even set a record of 311.2 kg.
"This technology system is a soil fertility-building system based on straw return and a highly simplified cost-saving production system. It effectively solves the long-standing problems in agricultural production in our Huang-Huai-Hai region: wheat straw handling, soybean seedling protection, and soil fertility building." Cai Jian said to the reporter with emotion, "The experts used new technology to help us solve the grassroots problems of banning straw burning and utilizing straw. I think that once we promote this technology on a large scale and over a wide area, straw burning will certainly no longer exist."
So, is this technology actually easy to promote? Is the cost of the seeder actually high? "Our technology is very easy to apply. As long as a general seeder is slightly modified and adjusted according to crop characteristics and sowing requirements, it can be done. Now, this technology can be used not only for soybeans but also for peanuts and corn." Wu Cunxiang told the reporter that at present some private enterprises in China have already produced such no-till straw-mulching precision seeders, priced at around 10,000 yuan, and if farmers buy one, after enjoying agricultural machinery subsidies, they only need to spend a few thousand yuan.
"Returning straw to the field is a major matter for farmers. To achieve scientific return and utilization of wheat straw, our technology must be up to the task." Han Tianfu said that in the future, researchers will continue scientific and technological research on optimizing and utilizing the technology.