Is returning straw to the field wrong?, Intensified pests and diseases Reporter | Agriculture | Straw
Half month talk reporters conducted research in some agricultural counties and found that after more than 10 years of large-scale straw returning, the organic matter content of farmland soil increased and soil fertility improved, laying the foundation for stable and high-yield grain production. At the same time, some agricultural management entities have reported that improper straw returning operations have led to the exacerbation of diseases, pests, grass damage, and freezing damage in crop growth in some areas, which urgently needs to be taken seriously.
There weren't so many pests and diseases before
A specialized agricultural service company located in the main grain producing area of central China, providing cultivation services for approximately 100000 acres of arable land in the area. In recent years, the head of the company has noticed an increase in pests and diseases in local grain production. "The incidence of diseases and pests has increased early, and the frequency of occurrence has increased." The person in charge said that wheat needs to be insecticided four times a season, which used to only require one or two times. Corn used to be treated with medicine at most once, but now it also needs to be treated two or three times, and the further south, the more obvious the increase in diseases and pests.
The increase in pests and diseases is directly related to the large-scale return of straw to the field. The person in charge believes that there are a large number of bacteria and insect eggs inside the straw. When the temperature and humidity are suitable, the straw becomes an "incubator" and the pests and diseases are exacerbated. At the same time, if the straw is not crushed enough, buried not deeply, and unevenly distributed in the cultivation layer, it is not conducive to crop rooting and water and fertilizer transportation, which can easily aggravate frost damage.
During visits to multiple agricultural counties, the Half Month Talk reporter found that many farmers hold this view, believing that improper straw returning to the field can exacerbate diseases, pests, grass damage, and frost damage.
A farmer from an agricultural planting cooperative in a certain area along the Yellow River told a reporter from Half Moon Talk that the wheat she planted last year was treated with medicine six times, and the corn was treated with medicine four times. "There weren't so many pests and diseases before," she said. A person in charge of a seed company not far away said that local wheat is generally treated with more than 4 times of pesticide, while corn needs to be treated with about 3 times of pesticide. "This is mainly because straw is prohibited from burning and returning to the field, which was not obvious at first but is becoming more and more obvious now. There are bacteria and insect eggs in the soil of the entire plot.".
Another person in charge of a seed industry company that has been engaged in agriculture for more than 50 years said that in early March, he visited the grain fields of several major grain growers in the local area and found that most of them had a shortage of seedlings and broken ridges, which was related to improper straw returning to the field. "Poor straw crushing, no deep plowing or raking, breeding diseases and pests, and also affecting crop rooting.".
Grassroots agricultural technicians generally believe that the benefits of returning straw to the field outweigh the drawbacks, but improper returning operations are related to the exacerbation of frost damage, pests and diseases. "In recent years, soil borne diseases such as stem rot have become more serious, and the source of the disease is on straw. However, there are many factors that affect its incidence, such as seed resistance, agricultural climate, temperature and humidity, etc. Without long-term specialized research, it is difficult to have scientific data support." said a researcher at the Agricultural Technology Extension Center of a major grain producing county in central China.
The causes of improper land return are complex
"Given that there are few ways to ban straw burning and utilize it as a resource, returning straw to the field is currently the main way of utilization." said Ru Zhengang, a wheat breeding expert and professor at Henan University of Science and Technology. There are corresponding operating standards for straw returning to the field, such as crushing degree, deep plowing degree, appropriate temperature and humidity, and the application of appropriate nitrogen fertilizer for catalytic decomposition. However, due to multiple factors, the returning operation, which should have been crushing, deep plowing, raking, timely watering, and appropriate application of nitrogen fertilizer, has been simplified to crushing and rotary tillage in some areas, resulting in prominent side effects of straw returning to the field.
——Some farmers lack scientific knowledge. Currently, many farmers adopt rotary tillage to bury their straw. Compared to deep plowing depths of 30 to 40 centimeters, rotary tillage depths are only 15 to 20 centimeters. The straw is buried shallowly and unevenly distributed, and if crushed roughly, it is easy to expose the surface, increasing the difficulty of decomposition. Poor straw decomposition can easily breed diseases and pests, and affect crop rooting and soil water and fertilizer transportation.
The person in charge of the seed industry company, which has been engaged in agriculture for more than 50 years, conducted a survey on the agricultural knowledge of about 600 large grain growers in the local area and found that one-third of them were proficient in research, one-third had only partial knowledge, and one-third knew very little. "With the transformation of production and operation models, agriculture is no longer a labor-intensive industry, but a knowledge and technology intensive industry. Taking straw returning as an example, many farmers' cultivation models have lagged behind.".
——Deeply plowing the soil increases planting costs. A professional agricultural planting cooperative in the Yellow River region manages 13000 acres of arable land locally, with most of the arable land adopting rotary tillage operations. "We have also noticed that when rotary tillage straw is returned to the field, wheat does not take root well and has poor contact with the soil." The manager of the cooperative's base said that if rotary tillage is changed to deep plowing, the cost of one acre of land will increase by 50 to 60 yuan, and the profit of one acre of wheat will only be 400 to 500 yuan. Farmers are unwilling to pay this amount of money.
——Small scale farming affects farming methods. Another specialized planting cooperative has transferred more than 2000 mu of farmland in a place in the north, and entrusted 50000 mu of farmland. The head of the cooperative has been awarded the national exemplary individual in grain production. "We adopt deep plowing for the land we transfer ourselves, but small farmers are more concerned about costs and benefits and do not pay attention to farming methods." The person in charge said that 70% of the entrusted farmland is rotary plowing operation. Firstly, some plots are small and it is inconvenient for large machinery to enter the operation. Secondly, the cost of deep plowing is high and small farmers do not accept it. Moreover, deep plowing does not immediately take effect and requires long-term persistence. At the same time, there are not many or strong specialized agricultural service organizations, and some individual operated agricultural machinery organizations are loose and without standards, with uneven operational levels, which also affects the quality of straw returning to the field.
——The amount of straw has increased significantly, making digestion difficult. According to the Half Month Talk reporter, the planting density of crops has significantly increased now. For example, corn has increased from 3000 plants/mu more than 10 years ago to 6000 plants/mu, and the amount of straw has increased significantly. If all of it is still returned to the field, it will exceed the land's digestibility.
Expand straw utilization channels
Many parties believe that comprehensive measures are needed to address the "side effects" of improper straw returning to the field.
According to research conducted by reporters from Half Month Talk, in addition to the livestock industry being able to absorb some straw, the utilization methods of straw based bio materials, oil production, ethanol production, etc. are limited in their ability to absorb straw due to factors such as immature technology, high costs, and difficulties in mass production. Therefore, it is necessary to further increase scientific and technological research efforts.
Due to the many factors that affect the occurrence of pests and diseases, it is difficult for grassroots agricultural technology centers to scientifically understand the relationship between the increase of pests and diseases and a certain factor. Relevant scientific research institutions need to conduct long-term tracking research in order to provide reference for optimizing and adjusting cultivation methods.
Grassroots interviewed cadres also reported that banning straw burning is one of the key tasks throughout the year, which consumes a lot of manpower, material resources, and financial resources. If there are any fire spots, cadres will be held accountable and their rewards will be deducted. In addition, air pollution is a visible form of pollution, while soil pollution and pesticide residues are invisible and easily overlooked. Some grassroots cadres believe that straw burning has certain benefits in killing bacteria and insect eggs and saving costs. Can we weigh the pros and cons and explore the organized, phased, and localized burning of some straw when atmospheric diffusion conditions are good.
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