Face to face丨How to make cultivated land healthier and greener? Interview with Soil Science Expert Li Baoguo
Li Baoguo, dean of the School of Land Science and Technology, China Agricultural University, is a well-known soil scientist in my country. He has long been committed to the research, governance and protection of soil in our country.
People regard food as their heaven, and food as their foundation.
Cultivated land is the lifeblood of grain production. According to data released by the National Bureau of Statistics on December 12, the total national grain output in 2022 will be 1,373.1 billion catties, an increase of 7.4 billion catties over the previous year, and the grain output has remained stable at more than 1.3 trillion catties for eight consecutive years. .
With 9% of the world's arable land and 6% of the fresh water resources, China feeds nearly 20% of the world's population, and more than 1.4 billion Chinese people firmly hold their jobs.
However, 46% of China's arable land is distributed in hills and mountains, and less than one-fifth of the arable land has a grain yield of more than 1,000 kilograms per mu. How to make the arable land healthier and greener?
It is a question that Li Baoguo and his colleagues have been thinking about.
Reporter:
Whenever we talk about cultivated land, we always talk about whether we should use more cultivated land or protect more cultivated land. In fact, there have always been disputes about the use and protection of cultivated land. What is your mission as a soil scientist under this current situation?
Li Baoguo:
In the past, many people in our country thought that cultivated land was to be used, and they had no sense of protection. How can I improve the output of bad land through technology? If you are not good enough, I will apply more fertilizers and do everything possible to make the land more productive. To feed ourselves, because there is not enough food in the rice bowl.
We also talk about utilization now, and utilization is definitely fundamental, but there is a big difference between the utilization we talk about now and the utilization we talked about in the past, which is called sustainable utilization.
Our current grain output is, for example, 1.3 trillion catties. Can we keep it forever? To do this, we must protect these most precious resources of the soil during utilization.
Soil science experts coming out of rural areas
Land is not only Li Baoguo's career, but also the starting point of his life.
Li Baoguo was born in Xiangfen County, Linfen City, Shanxi Province in 1964. The cave dwelling where his family lived and the terraced fields on the cave dwelling are his fondest childhood memories.
Every winter and summer vacation, Li Baoguo helps his family repair the terraced fields, and when there is a drought, he also pulls water trucks to the plains to bring water back to irrigate the fields.
Compared with his parents who turned their faces to the loess all their lives and their backs to the sky, Li Baoguo has more opportunities to change his destiny.
In 1980, Li Baoguo was admitted to the Department of Soil and Agricultural Chemistry of Beijing Agricultural University, the predecessor of China Agricultural University.
When he graduated from his undergraduate degree, Li Baoguo applied for a postgraduate degree in soil science, and began to study and research on the improvement of Huanghuaihai saline-alkali land with his tutor.
Saline-alkali land is called "ringworm of the earth", and almost no grass grows on severe saline-alkali land, which is the land with the most difficulty in governance.
At that time, the instructor assigned Li Baoguo the task of digging 50 soil profiles in Shouguang, Shandong, and investigating the cultivated land resources in Shouguang.
Reporter:
What kind of workload is this?
Li Baoguo:
The front is more than one meter wide and three meters long, and the depth of the excavation should be at least one meter. After excavation, it will be described and photographed. What does the section look like? What are the layers? What are the characteristics of each layer? The phenomena of salt were all written down and described, and some groundwater was dug out and then sampled in layers.
For example, sampling from 0 to 5 centimeters, sampling from 0 to 20 centimeters, we all have this scale, 0 to 20 centimeters, 20 centimeters to 50 centimeters, 50 centimeters to 80 centimeters, and then take the samples back according to changes in soil properties, so After finishing this work, I am full of confidence in science to guide agricultural production.
After graduating with a Ph.D., Li Baoguo stayed at the school to work.
At the end of the 1990s, Huang Huaihai’s work came to an end. He began to participate in the work of desertification prevention and control in Northwest China. He traveled to many places such as Gansu, Xinjiang, Inner Mongolia, and Qinghai. Field measurement.
Reporter:
The natural conditions in these places are harsh, and you must face more hardships than in the past research process.
Li Baoguo:
It’s nothing more than poor sanitary conditions and bad food. If there is a naan with some pickles, the food is good.
Reporter:
You call this eating well, one naan and one pickle is enough.
Li Baoguo:
That's good, there are intestines.
Reporter:
It turns out that the degree of satisfaction of soil scientists is like this.
Li Baoguo:
The key question is that you have no experience with me, have you ever been to Lop Nur?
Of course you don't like this place, but I like it. I achieved the goal of our investigation, saw these natural phenomena, for example, where the salt eventually goes, and how great the power of nature is.
Protecting "Giant Pandas" in Cultivated Land
On the Northeast Plain, the black soil nourishes all things, and the accumulation of humus forms a fertile soil that is rare in the world. It is called the "giant panda" in the cultivated land.
"One liang of soil and two liang of oil", here contributes a quarter of the country's grain, and is the largest granary in China.
In 2008, Li Baoguo went to Lishu County, Jilin to inspect the local agricultural experiment station. His original purpose of building the station was to establish a monitoring point to monitor changes in the local agricultural climate and soil conditions, and to promote information agriculture.
But soon he discovered that the problem of black land degradation was more serious than imagined, and the protection of black land was imminent.
Li Baoguo:
The protection of the black land is actually because the local people have realized this problem. The wind and water erosion of the black land has been severe. After I went there in winter, I found that the land was very bare. The straw was basically removed and burned, and the soil was exposed. Very powerful, why burn straw?
To keep warm in the Northeast, the air is not good when coal is burned, and when straw is burned, the air is messed up after the soil is exposed.
Reporter:
When I was a child, I had this impression that I couldn't open my eyes when burning straw.
Li Baoguo:
Moreover, the hotels in the county town smelled very bad, the smell of coking coal and sulfur. They went there in winter, and when they went there in the spring of the following year, they always encountered sandstorms.
Reporter:
What is the black soil here like?
Li Baoguo:
Most of them are exposed, without protective tillage. When planting, they plow and rake the ground. In this kind of weather, the wind blows very hard. So at that time, PM10 was completely off the table, and burning straw was called PM2. .5 off the meter, when the wind blows, it is PM10 off the meter, that's how the black soil is lost.
Under natural conditions, vegetation on grasslands and meadows withers and decays, gradually turning into soft black soil rich in organic matter. The land is gradually degraded.
Li Baoguo consulted a large amount of information and found that the international experience in controlling black soil is to implement conservation tillage technology, that is, to reduce soil disturbance to the top layer of black soil, return the field by straw mulching, increase surface cover, no-till and less-tillage, so that the cultivated land can as close as possible to the natural state.
Li Baoguo:
Why does the straw cover the ground?
The stalks are relatively long, cross each other, and there are high stubbles, so the stalks can be kept on the surface, thus playing the role of soil protection.
After the straw rots, it supplements the nutrients of the soil or the organic matter of the soil, which imitates the formation process of natural black soil.
In China, farming civilization runs through a long history of 5,000 years. People have come to a conclusion from the day-to-day labor from spring to autumn, that is, only intensive farming can obtain returns from the land.
From the perspective of farmers, the conservation tillage promoted by Li Baoguo is tantamount to "lazy man farming", which will lead to a decrease in yield.
Reporter:
How difficult is it to break a habit and establish a new concept?
Li Baoguo:
It is difficult, and it is called a farming revolution in foreign countries.
Reporter:
Are there any big objections?
Li Baoguo:
Certainly no farmer is willing to do this, only the village party secretary is willing to do this, because the land is not plowed, and the straw is returned to the field, which saves a lot of processes. It used to be that traditional machines enter the field six to seven times, but ours may be Two to three times, the cost of the machinery alone can save seventy or eighty yuan, which is so much money per mu. The village party secretary thinks this is okay, but we have to give him a guarantee that if the production is reduced, we will compensate you.
Starting from a 225-mu experimental field in Gaojia Village, Lishu Town, Lishu County, a new farming method has quietly sprouted on the land of Lishu County, and the domestic no-tillage seeder specially used for conservation tillage has also emerged as the times require.
It can complete the actions of ditching, sowing, covering soil and fertilizing at one time without plowing or deep rotary tillage as much as possible.
Driven by cooperatives, more and more farmers, especially large growers, have begun to join the ranks of conservation tillage.
Reporter:
Is there no obstacle for him to accept this point of view?
Li Baoguo:
He didn’t know this point of view at the beginning. First of all, he didn’t know that there was such a method of farming, but once he knew it, he thought it was okay, and he doubted whether this technology could be done properly. Can you guarantee me germination?
Can you guarantee that my last pests, diseases and weeds will not happen?
Can you guarantee that the final output will be the same as the original conventional output?
After the cost increases, the cooperative can accept the cost.
But after we promise him that the output is low, I will compensate you for this part.
Reporter:
How do you have the confidence to guarantee his standard?
Li Baoguo:
Because we definitely have confidence in this technology, we have read a lot of literature, as long as the technology is in place, there is no problem.
After 10 years of continuous monitoring, the effective water supply of the soil in the Lishu black soil protection test plot has increased by 50-70 mm, and the organic matter content in the 0-20 cm plow layer has increased by 12.9%. Conservation tillage reduces straw burning by more than 1 million tons per year. Reduced the use of chemical fertilizers by 3,000 tons, effectively reducing agricultural non-point source pollution.
The grain yield is similar to that of traditionally cultivated land, and even exceeds that of traditionally cultivated land in dry years.
Increasing production and saving costs are strong guidance for farmers. The "pear tree model" of "planting in wide and narrow rows, full coverage of straw, less tillage and no tillage" has gradually been recognized by the society and academic circles.
In 2021, with the approval of the state, black soil protection will be promoted to a national project.
As one of the founders of the "Pear Tree Model" for black soil protection, Li Baoguo has participated in legislative discussions many times.
From August 1, 2022, the "Black Soil Protection Law of the People's Republic of China" will be officially implemented.
This is the first black land protection law at the national level, which provides legal protection for the protection and utilization of black land.
Nowadays, the concept of conservation farming that respects the laws of nature is becoming more and more popular, and the technology of conservation farming has also been extended from the black soil to the North China Plain, the southern region, and along the "Belt and Road".
Compared with the laboratory, Li Baoguo still prefers to work in the field. Observing, taking pictures, and sampling are almost necessary procedures for every business trip he has to do in the field.
Reporter:
Your father said at the time that if you don’t pass the college entrance examination, you will go home to farm. Did you ever think that your research in this field is actually farming on the land of the motherland, or is it related to farming?
Li Baoguo:
My father’s so-called farming refers to this piece of land. The job I am doing now may be to care about every piece of land in the motherland, every piece of cultivated land.
Reporter:
As a cultivator, he is gratified, right?
Li Baoguo:
For me and my father, the soil is the foundation. The soil provides us with a place to live and everything we live in. Every high-rise building in our city is also built on the foundation of the soil. This soil What sustained your past is actually sustaining our present.
We hope to have a bright future, so we must protect the land of our motherland, because it is the lifeblood of food production and the source of all human life.
(CCTV news client reporter丨Wang Ning)