Under the impact of extreme weather, how to make China's rice bowl more secure?
Continuous rainfall, increased rainfall, high temperature and high humidity, and stuffy feeling... Since the flood season began this year, extreme weather has occurred frequently in many places. It is currently in the autumn grain growing season, and my country has experienced a continuous phenomenon of "floods in the south and drought in the north". Extreme weather shocks have intensified the volatility of agricultural production and posed challenges to food security.
As a major agricultural country, China is also located in a sensitive area and a significant impact area of global climate change. How to adapt to and mitigate climate change, achieve less production reduction and more bumper harvests has become a must-answer proposition for enhancing agricultural resilience and stabilizing China's rice bowl.
Extreme weather and climate events are the most significant factor affecting the agricultural economy
The IPCC Sixth Assessment Report (AR6) pointed out that as global warming intensifies, extreme heat events increase and their intensity will increase, and the frequency of extreme heat events will increase non-linearly with the magnitude of global warming; extreme cold events will decrease and their intensity will weaken, but they will still occur from time to time. On the other hand, heavy precipitation events are likely to become stronger and more frequent. Data shows that for every 1.5 ° C global warming, the frequency of heavy precipitation occurring once in 20 years will increase by 10%, and that occurring once in a century will increase by 20%.
"Studies have shown that extreme weather and climate events occur frequently, and their impact on my country's agriculture is mainly negative, and their adverse impact on grain production will increase." Yu Weidong, chief engineer of the Institute of Meteorological Sciences of Henan Province, said.
It is understood that extreme weather and climate events that have a significant impact on agriculture are mainly divided into four categories. Temperature aspects include extreme high temperatures and extreme low temperatures; precipitation aspects include extreme heavy precipitation and extreme drought.
Yu Weidong said,"Among the common meteorological disasters in Henan Province, drought ranks first in its impact on agriculture, followed by heavy rain. However, among the several extreme weather and climate events that have occurred in recent years, extreme precipitation events have become the most significant factor affecting the local agricultural economy."
In May 2023, Henan Province encountered a rare "bad rain" in history. Large-scale continuous rainfall highly coincides with the mature harvest period of wheat. Wheat in many places experienced spot lodging, mold and germination, and summer grain output decreased by nearly 6.9% compared with the previous year.
The vivid "21.7" rainstorm caused serious corn production reductions in some areas of northern Henan. Compared with 2020, the yield per unit area of summer corn in Hebi has dropped by more than 60%, and the yield in Anyang, Xinxiang, Jiaozuo and other places has dropped by nearly 30%. In addition, extreme precipitation in the autumn of 2017 also had a negative impact on the harvest and storage of autumn grain that year.
In addition to extreme rainfall, Zhan Mingjin, who once served as deputy director of the Ecological Meteorological Center of Jiangxi Province and now deputy secretary of the Party Committee and president of Jiangxi Information Application Vocational and Technical College, proposed that extreme weather events such as high heat damage and low temperature cold damage have had a negative impact on agriculture and ecosystems.
Zhan Mingjin said that high-temperature heat damage can cause rice and other crops to bloom earlier and shorten the flowering period, and also lead to early maturity of rice. However, the crop grains are empty, resulting in a decline in yield. Crops such as tea can turn yellow and even die. At the same time, high temperatures are conducive to the reproduction of diseases and insect pests and the growth of various weeds, endangering food security. Farmers will need to apply more fertilizer to meet planting needs, which not only increases agricultural investment, but also adversely affects the soil environment. On the other hand, low-temperature and chilling injuries still occur from time to time, causing crops to suffer freezing damage or late spring cold, resulting in reduced production.
"In the context of global warming, the reversal of drought and flooding is also very extreme." Zhan Mingjin cited the Poyang Lake Basin as an example. In 2020, the water body in the Poyang Lake Basin reached a record largest area. But just two years later, Poyang Lake experienced extreme drought and shrank to its smallest area in history. The lake body was almost invisible in many places. "This extreme reversal has a huge impact on both the ecosystem of Poyang Lake and agriculture in the Poyang Lake basin." Zhan Mingjin said.
Facing the global warming trend, the adaptability of the agricultural sector needs to be improved
Extreme weather events continue to emerge around the world. Faced with the established reality of global warming, adapting to climate change in the agricultural sector has become a realistic and urgent task currently facing it.
Planting suitable crops and adjusting planting mechanisms in accordance with climate change research have become the consensus of most experts.
Yu Weidong suggested that a census of agricultural climatic resources and agricultural meteorological disaster risk zoning should be done first. Based on the results of the census and zoning, crops and varieties should be planted according to local conditions to achieve the effect of seeking benefits and avoiding disadvantages.
"Agriculture emphasizes good weather. Climate change not only has negative impacts, but also its favorable aspects must be seen and utilized." Zhan Mingjin pointed out that climate change will significantly improve light, temperature and precipitation conditions. On the basis of good research and judgment, early rice can be sown early to extend the growing season; some areas where single-season rice are planted can plant double-season rice to increase yields.
It is understood that Jiangxi Province has carried out pilot demonstration projects for early rice sowing. In 2022, 83 demonstration sites in Jiangxi Province covering an area of more than 600,000 acres will conduct early rice sowing experiments. Data shows that the yield of early-sown farmland has increased significantly, with the average yield per mu being 29.4 kilograms higher, the increase in production rate reaching 8.0%, and the average income per mu is about 100 yuan.
Strengthening monitoring and early warning of agricultural meteorological disasters will also help enhance agriculture's ability to cope with extreme weather. At present, my country's meteorological forecasting capabilities have been enhanced, forecast accuracy has been continuously improved, and meteorological early warning has continued to play a leading role in disaster prevention and response.
"At present, my country's weather forecasting capabilities are generally excellent, but it is necessary to open up the 'last meter' at the service level to effectively transmit early warning information to farmers. Our current services are all targeted at large crops. For example, Jiangxi Province pays more attention to major crops such as rice, rapeseed, citrus, and navel orange. However, there are some niche crops with high economic value and small planting range, such as white tea, alpine vegetables, etc., which are difficult for the meteorological department to pay attention to. They can provide small-scale, high-value, and characteristic economic crops through farmers 'purchase of services or project cooperation. Provide escort." Zhan Mingjin said.
Yu Weidong believes that the "resilience" of agricultural production and disaster prevention and reduction capabilities should also be improved through the construction of high-standard farmland.
He introduced that the meteorological department of Henan Province has been deeply integrated into the province's high-standard farmland construction work in recent years. Documents such as the "Henan Province High-Standard Farmland Construction Plan (2021-2030)" and the "Guidelines for the Construction of Meteorological Support System in the High-Standard Farmland Demonstration Zone of Henan Province" issued in 2022 all propose to focus on improving the climate adaptability of high-standard farmland from the perspective of meteorology. "The construction of high-standard farmland itself has requirements for rainstorms and drainage standards that occur once in 5-10 years. It can also have a series of safeguard measures for disasters such as droughts and floods, so as to achieve stable yields and stable yields."
Develop organic agriculture to mitigate climate change
Agriculture is not only deeply affected by climate change, it is also an important factor affecting the climate. In addition to improving the sustainability of agricultural production and adaptability to climate change, how can agriculture mitigate climate change?
In the eyes of many experts, organic agriculture without the use of chemical fertilizers and pesticides is one of the important ways.
"Organic agriculture places more emphasis on systematicness and the systematic cooperation of crops. It will have a stronger ability to respond to disasters than a single crop, so it has a stronger ability to resist meteorological disasters." Zhan Mingjin said.
Xu Xiangbo, associate researcher at the Institute of Geographical Sciences and Resources, Chinese Academy of Sciences, said that organic agriculture has a great contribution to emission reduction compared with traditional agriculture based on chemical fertilizers and herbicides.
"From the perspective of greenhouse gas emissions, chemical fertilizers contribute 60%-80% to carbon emissions from the front-end production process of agricultural materials in full life cycle agricultural production to field planting, and the pesticide production process also contributes about 10%. One requirement for organic agriculture is not to use chemical fertilizers and pesticides, and organic fertilizers are used to replace chemical fertilizers, reducing greenhouse gas emissions." Xu Xiangbo said.
To promote low-carbon development of agriculture, the carbon sequestration potential of farmland soil deserves attention. Xu Xiangbo said that the organic matter content index of farmland soil can reflect the carbon sink level of the soil. The use of organic fertilizers in organic agriculture increases organic matter in soil, helps increase farmland soil carbon sinks, improves agricultural production's ability to adapt to climate change, and makes positive contributions to the global response to climate change.
"The price of agricultural products in organic agriculture is relatively high, which can lead small farmers to achieve greater benefits through small-scale planting. This is also one of the many contributions of organic agriculture to mitigate climate change, develop sustainable agriculture, and increase farmers 'income." Xu Xiangbo said.
