(1) Land resource degradation

It is mainly manifested in the continuous development of large-scale soil erosion, land desertification and salinization, and large areas of land distributed near towns with relatively concentrated industries are polluted by solid waste and sewage.

First of all, soil erosion is becoming more and more serious. According to rough estimation, the area of soil erosion in China was about110.6 thousand square kilometers in the early days of the People's Republic of China, and it expanded to10.8 thousand square kilometers in the early 1990s, accounting for almost 1/6 of the national land area. The average annual loss area increases by 5-6 million mu. There are more than 600 million mu of cultivated land in China that are harmed by soil erosion, which is equivalent to 1/3 of the total cultivated land area. It is estimated that the annual soil loss in China is 5 billion tons, accounting for112 of the world's total loss, of which the sediment injected into the ocean is about 2 billion tons, which also accounts for112 of the world's total land sediment. Relatively fertile topsoil and a large number of nutrients such as nitrogen, phosphorus and potassium are lost. The most serious situation is the loess plateau and the middle and upper reaches of the Yangtze River, followed by rocky mountainous areas in the north, red soil hilly areas in the south and black soil areas in the northeast. The area of soil erosion in the Loess Plateau is 430,000 square kilometers, accounting for 70% of the total area of the Plateau. The annual soil erosion is as high as 65.438+63 million tons, and the erosion modulus in the most seriously eroded gully region can reach 5000 tons per square kilometer per year. In recent ten years, the comprehensive management of small watersheds has eased the situation. The area of soil erosion in the Yangtze River basin was 360,000 square kilometers in the 1950s, and it expanded to 740,000 square kilometers in the 1980s, accounting for 4 1% of the total area of the whole basin, and the annual erosion reached an astonishing record of 3 billion tons. Therefore, the reasons for the worsening trend are: first, steep slope reclamation; Second, excessive logging; Third, overgrazing; Fourth, large-scale capital construction lacks soil and water conservation measures. Pay attention to strengthening the construction of shelter forests and soil and water conservation forests.

Secondly, the area of desertification is expanding. China is one of the countries with serious desertification hazards. The area of desertification land in China is about 334,000 square kilometers, including 6,543.8+0.2 million square kilometers that existed long before human history, 50,000 square kilometers of modern desertification land formed in recent 50 years and 6,543.8+0.6 million square kilometers of land with potential desertification risks. If desert and Gobi are added, it is 6.5438+0.533 million square kilometers, accounting for 654.38+05.9% of the land area. Today, the harm of desertification is still developing. In 1950s and 1970s, desertification land expanded by 1.56 square kilometers every year, and increased to 2 1.000 square kilometers in 1980s. There are 59 million mu of cultivated land and 73.95 million mu of grassland in1/kloc-0 provinces in northwest, north and northeast China, which are often threatened by desertification. Natural factors (dry climate, sparse vegetation, loose surface composition, etc. ) only provides the possibility for the formation of desertification, while human intensive activities and unreasonable utilization methods (over-cultivation, over-grazing, over-logging, etc. ) is the main contributing factor. In recent years, efforts have been made to build "Three North" shelterbelts, adjust the industrial structure in semi-agricultural and semi-pastoral areas, and improve land use patterns to curb the vicious spread of desertification.

Salinization is also an important problem affecting soil quality. There are about 65.438+48.7 million mu of saline land in China (including 554 million mu of modern saline soil and 260 million mu of potential saline soil). The cultivated land in China is 654.38 billion mu, accounting for more than 5%.

With the expansion of city scale, the development of industry, the rise of township enterprises and the extensive use of pesticides, the problem of land pollution is becoming more and more serious. It is estimated that there are 60 million mu of cultivated land polluted by the "three wastes" of large industrial and mining enterprises, 28 million mu of cultivated land polluted by township enterprises and 240 million mu of cultivated land seriously polluted by pesticides, totaling 328 million mu. If measures are not taken as soon as possible, land pollution will have serious consequences.

(2) serious loss of cultivated land.

As a big agricultural country, China has a tradition of "cherishing soil as gold" since ancient times. This is because "there is soil and food". In order to meet people's food needs, we must cherish cultivated land. However, since the reform and opening up, due to the needs of development and construction and the influence of market economy, all walks of life have reached out to the land. Under the impact of this flood, a large number of cultivated land in all parts of the country have been used for other purposes. The sharp decline in cultivated land directly weakened the grain production capacity. According to the survey, from 1980 to 1985, the average annual decrease is 7.38 million mu. During 1986 ~ 1990, the average annual loss of cultivated land was 3.53 million mu; After 1990, due to the decentralization of land examination and approval authority, multi-head land grant and out-of-control management, 199 1 to 1995 suffered an annual loss of 5 million mu, mainly in the southeast coastal provinces and cities. Generally speaking, from 1980 to 1995, * * lost about 8/kloc-0.0 million mu of cultivated land. If 75% of cultivated land is used for growing grain, the yield per mu is 400 kilograms, which is equivalent to reducing the grain production capacity by as much as 25 billion kilograms every year.

The reason for the decrease of cultivated land is due to the adjustment of industrial structure and disaster damage within agriculture. Since the reform and opening up, it has turned to a new era with economic construction as the center, changing the single management idea of "taking grain as the key link" in the past. However, the agricultural structure has been adjusted according to market requirements, and the comprehensive development of planting, animal husbandry, forestry, fishery and sideline has promoted the adjustment of land use layout, and the land for grain production has generally decreased. In this regard, although some economic benefits have been achieved, due to the neglect of social and ecological benefits and the lack of macro-control and management, some new problems have emerged, such as digging fish ponds and planting fruit trees on cultivated land, which has occupied too much grain field area. It is estimated that during the period of 1986 ~ 1995, about 70 million mu of land was destroyed due to agricultural restructuring, occupation and disasters. Fortunately, the cultivated land reclaimed and reclaimed in the same period in China can generally offset this loss.

The other is the permanent loss of cultivated land caused by non-agricultural construction. Of course, construction needs land, but many development and construction are blind. For example, cities are expanding without restrictions, development zones are being built blindly, rural residential sites are seriously exceeding the standard, luxury cemeteries are being built, adobe bricks are being burned, and open-pit mining is being carried out.

1978, there were only 16 1 cities and less than 2,900 market towns in China. By 1995, there were 640 cities in China, and the number of established towns soared to 16992. The rapid expansion of cities and towns surrounded the suburban countryside, occupying a large area of fertile fields and vegetable gardens. For example, since the Pearl River Delta opened to the outside world, as of 1995, the planned urban built-up area has an area of 9,500 square kilometers, which can accommodate 654.38 billion urban population. In fact, the urban population of Guangdong Province is only 654.38+0 billion, even if all of them are concentrated in the cities and towns of the Pearl River Delta, the land occupied is more than enough. It can be seen that large-scale urban construction wastes too many fertile fields and vegetable gardens.

In the early 1990s, the wind of building development zones was set off all over the country, and all localities competed to build nests to attract phoenix. Many places attract investment at the expense of land, gather "land wealth", disregard the overall situation of the country, go on projects indiscriminately, occupy cultivated land indiscriminately, and even copy and sell land at will to make profits from it. From 65438 to 0992, there were more than 9,000 development zones in provinces, cities, counties and townships, covering an area of more than 24 million mu, of which 80% were cultivated land. The vast majority of development zones are too large in scale, but the actual development lags behind, so there are useless circles, resulting in a large area of cultivated land being abandoned. According to the investigation in the beginning of 1995, nearly 2 million mu of land in China has been requisitioned and left idle, and some cultivated land has been seriously damaged and it is difficult to recover, resulting in many farmers having nowhere to find their production and life. In addition, the disorderly construction of the compound of the township enterprise circle and the "roadside shops" along the highway also occupies a lot of cultivated land.

Rural housing construction is scattered, and land use generally exceeds the standard. At present, the per capita land use of rural residential areas in China has reached 190 square meters, exceeding the prescribed maximum standard of 150 square meters by 27%, and * * * covers an area of 5 1 10,000 mu.

It is also worth noting that graves occupy cultivated land. For example, there are 53 operating cemeteries approved by Jiangsu Province and 76 public welfare cemeteries11. In addition, there are countless illegal cemeteries, and more than 300,000 graves are built every year. Another example is Wenzhou City, Zhejiang Province, which has always paid attention to grave repair, with an average of 1 0.5 million new graves every year, covering an area of110,000 square meters. Grass-roots governments in some places even put forward the idea of "building cemeteries if you want to be rich" as a way to develop local economy, so parks in some places have also been changed into cemeteries.

It is particularly noteworthy that in recent years, in the reduction of cultivated land in China, high-quality cultivated land around towns and along traffic lines has been occupied, and paddy fields in the south have been occupied. Reclaiming wasteland is difficult to compensate for the loss of these cultivated lands. In a word, the country is facing a very severe situation of protecting cultivated land.

(3) The contradiction between population and cultivated land supply and demand is prominent.

The population of China accounts for 22% of the world, and the cultivated land accounts for 7% of the world. This is a country with a large population and relatively little cultivated land. Especially with the development of economic construction, non-agricultural land is increasing, cultivated land is decreasing year by year, and population is increasing year by year, so the contradiction between supply and demand of population and cultivated land is intensifying.

Since the 1970s, China has carried out family planning and strictly controlled population growth, with remarkable results, and the annual growth rate has declined. However, due to the large population base, it still increases by1200 ~150,000 people every year. Since the promulgation of 1987 Land Management Law, the reduction of cultivated land has eased slightly, but it is still difficult to reverse the trend of intermittent reduction of several million mu every year. Looking ahead, the balance between population and cultivated land will become more serious.

Part of the reason is the shortage of cultivated land reserve resources in China. According to the data of the Ministry of Land Reclamation in 1980s and the summary of previous comprehensive investigation reports in remote areas organized by China Academy of Sciences, there are nearly 50 million mu of wasteland suitable for agriculture with good development conditions and high quality in China, mainly distributed in Heilongjiang and eastern Inner Mongolia. The wasteland suitable for farming is about1.200 million mu, with limited development conditions and medium quality; There are also a large number of wasteland suitable for agriculture with poor quality, but it is difficult to use for a while because of its remote distribution, inconvenient development or difficult development conditions. Some are distributed in the agro-pastoral ecotone or agro-pastoral ecotone. If cultivated indiscriminately, it will destroy grazing grassland or forest slope, and even destroy ecological balance. It can be seen that the actual arable wasteland in China does not exceed 200 million mu at best. According to the reclamation coefficient of 0.5, the net cultivated land is only 1 100 million mu, and the reserve resources of cultivated land are insufficient. Moreover, the development of new cultivated land will be limited by capital investment, technical feasibility and the characteristics of wasteland resources, and the development progress is not fast enough to meet the demand in time.

At present, the per capita arable land in 1/3 provinces and regions is less than 1 mu, and the per capita arable land in Shanghai, Zhejiang, Fujian, Guangdong, Hunan and other provinces and cities in the southeast is less than 0.6 mu. According to the regulations of FAO, to satisfy a person's survival, at least 0.8 mu of arable land is needed to produce food. Below this figure, food supply cannot be guaranteed safely. In China, the per capita arable land in 666 counties is below the warning line of 0.8 mu, mainly distributed in densely populated southeast provinces. The lack of food in the southeast depends on the support of North China and Northeast China. In the past, the situation of transferring grain from south to north is now reversed.

The carrying capacity of land population is an important issue in the relationship between man and land. On the one hand, it is directly related to the total amount of food that can be supplied by land resources, on the other hand, it is related to the consumption level and quality of life of the population. Generally speaking, the ability of cultivated land to produce food depends on many factors, including the quality and fertility of land, sowing area and multiple cropping index, crop structure and variety, farming technology and management, the application of science and technology, and the input of human, financial and material resources. According to estimates, by the year 2000, the population of China will be close to 654.38+300 million. If the per capita grain consumption is 400 kilograms, the grain demand will be 520 billion kilograms, which can be roughly balanced. The maximum population carrying capacity in China is 654.38+0.5 ~ 654.38+0.6 billion people. If the population reaches1600 million by the middle of the 20th century, it is predicted that the annual per capita grain consumption may increase to 450 kilograms due to the improvement of living standards, so * * * will need 720 billion kilograms of grain. From 520 billion kilograms in 2000 to 720 billion kilograms in 2050, the average annual output needs to increase by 4.4 billion kilograms, and the task is arduous. If there are slight changes or mistakes in various related factors affecting grain production, it will inevitably lead to grain shortage and the prospect is not optimistic. Therefore, we must do everything possible to make better use of land to increase grain output and strictly control population growth.

Resources/cz/czdl/dgjc/3/tdzy/2693 _ sr.htm

Countermeasures:

Countermeasures for the Development and Utilization of Land Resources in China

(1) Effectively protect the existing cultivated land.

In view of the decreasing cultivated land and the increasingly acute contradiction between people and land, we must vigorously publicize and conscientiously implement the basic national policy of "cherishing and rationally utilizing every inch of land and effectively protecting cultivated land" and comprehensively promote the protection, development and rectification of cultivated land by legal and economic means. In order to strengthen the construction of land legal system, deepen the reform of land management system, strengthen the enforcement of farmland protection, and resolutely stop the indiscriminate occupation of farmland, the National People's Congress Standing Committee (NPCSC) successively deliberated and promulgated the People's Republic of China (PRC) Land and Land Management Law and the Regulations on the Protection of Basic Farmland in the 1980s, improved the farmland protection system, demarcated basic farmland protection areas nationwide, and established the restraint and reward and punishment mechanism for farmland protection. 1997 May 18, China * * * Central Committee and the State Council issued the notice of "Further Strengthening Land Management and Effectively Protecting Cultivated Land", demanding to strengthen macro-management of land, further strictly control the examination and approval management of construction land, strictly control the scale of urban construction land, strengthen rural collective land management, strengthen the management of state-owned land assets, strengthen the supervision and inspection of land management law enforcement, and strengthen the organization and leadership of land management. These legal measures have played a certain role and should be further publicized to effectively protect cultivated land.

(2) Realize the dynamic balance of total cultivated land.

It is an arduous task to ensure that the cultivated land is reduced as little as possible and try to increase it, but it is the requirement of social and economic sustainable development.

The solution to the shortage of cultivated land is nothing more than extension development, that is, reclamation and expansion of cultivated land, and connotation mining potential. As mentioned above, there are not many reserve resources of cultivated land in China, so it is impossible to increase grain output mainly by expanding planting. But on the basis of effectively protecting the existing cultivated land, we should devote ourselves to fully tapping the land potential, that is, changing the utilization mode of land resources from extensive to intensive. According to the typical survey data of 1.980 collected by the National Land Use Planning Institute of the State Bureau of Land Management, the minimum investment of 1 mu of wasteland in the northeast swamp reclamation is 1.58 yuan, and the highest investment is 360 yuan in the southeast coastal beaches. Only 14 yuan per mu is needed for the transformation and management of low-and medium-yield fields, such as the Loess Plateau, and the highest is 235 yuan, such as the arid areas in northwest China. It can be seen that under the realistic conditions, the cost of tapping the potential of low-and medium-yield fields is much lower than that of reclaiming wasteland to expand cultivated land area, so it is also a more feasible method. At present, the average yield per mu is less than 400 kg, accounting for 83.2% of all cultivated land, with great potential. Among them, the middle-yield fields are mostly flat land with mild flood or saline-alkali soil, or gentle slope land with mild soil erosion. Once improvement measures are taken to eliminate its limiting factors, it will be easier to achieve the effect of increasing production. If investment funds permit, we should also transform labor-intensive low-and medium-yield fields, especially poor areas, which is conducive to the implementation of poverty alleviation work.

Improving the multiple cropping index of cultivated land is another important measure to tap the potential. The greatest feasibility is in the warm temperate zone (such as the south of the Huang-Huai-Hai Plain) and subtropical zone (such as the shallow hills in the south), with good water conditions. At present, the national average multiple cropping index is 1.55%. If we can increase 1 percentage point, it is tantamount to expanding the planting area by 20 million mu. If the national average multiple cropping index can be raised to 1.60%, the sown area will be increased to 1 100 million mu, which is equivalent to developing all cultivated land and wasteland with good conditions, which shows its great role.

There are other ways to tap the potential of land use. For example, scattered rural residential land currently accounts for more than 87% of the total land used by urban and rural residents. In recent years, it has become a common phenomenon for farmers to expand their homesteads, such as strengthening consolidation, properly focusing on building new countryside, and implementing returning farmland to forests, which has great potential. Another example is that 80% of the existing more than 20 million township enterprises are scattered in small natural villages, which not only expands the pollution sources, but also is not conducive to the unified construction of infrastructure. If the appropriate centralized layout is combined with the construction of small towns, it can promote rural urbanization and industrialization, facilitate management and enterprise cooperation, and save a lot of land. Another example is the reclamation of various abandoned land, the renovation of destroyed land, or the leveling and transformation of fragmented and irregular land, in order to improve its utilization rate and revitalize existing land.

(3) Adjust measures to local conditions and make rational use of land.

① Formulate land use planning and strengthen macro-control and management. Through planning, we can adjust measures to local conditions, foster strengths and avoid weaknesses, and give full play to the potential of land resources in various regions; According to the requirements of national modernization, developing production and ensuring life, we should coordinate the relationship between land use departments, not only to maintain the necessary cultivated land area, but also to ensure the necessary construction land: pay attention to the combination of economic benefits with social benefits and ecological benefits.

(2) Rational utilization and protection of cultivated land must be carried out simultaneously, completely changing the situation of heavy utilization and light cultivation, and improving the production capacity of land resources.

③ Adhere to land conservation and intensive management. There are many forms to develop land-saving agriculture (including saving water, energy and time), such as developing forest-grain intercropping, fruit-forest intercropping, combination of agriculture and animal husbandry, combination of agriculture and animal husbandry, combination of agriculture and fishery, etc., so as to give full play to the comprehensive benefits of land ecosystem.

④ Relying on scientific and technological progress, increasing land investment, improving production conditions and developing efficient, high-quality and sustainable agriculture.