Land is the material basis and condition for human survival and development. It has become the consensus of governments and scientific circles in various countries to realize the sustainable use of land and comprehensively improve the efficiency and benefit of land use. With the growth of world population and the improvement of social consumption level, the demand pressure on land, especially cultivated land, is increasing, resulting in the per capita cultivated land area in the world dropping from 0.52hm2 in 1970s to 0.28hm2 at the end of 20th century. The situation in China is even more serious. China has 1.30× 108hm2 cultivated land, and the per capita cultivated land is about 0. 1hm2, which is 37% of the world's per capita. There are 666 county-level administrative units whose per capita is lower than the warning line of 0.05hm2 determined by FAO, accounting for 23.7% of similar units in China. The quality of cultivated land in China is also relatively poor, and the second and third types of cultivated land account for 60%.

What contribution can earth science make to this important event involving national agriculture and the national economy and people's livelihood? Soil has always been a field of geoscience research, and soil is the basic substance that constitutes cultivated land. Earth science has initially formed a marginal science-agricultural geology, which combines pedology, element geochemistry, hydrogeology with biology and agricultural science. Obviously, academic circles should take this aspect as the research direction that needs to be developed to meet the needs of the survival and development of human society. Need to focus on the content is:

In the past, there have been many successful studies on the relationship between soil formation, material composition and physical properties and agricultural biological growth, which can provide the most suitable crops for different genetic types of soil, and suggest that in order to increase crop yield, it is necessary to supplement some specific trace elements or dope some minerals and rocks to improve the soil. It should be said that the basic conditions for China to carry out this research have been met. A regional geochemical survey of 654.38+200,000 was carried out in a country with a land area of 570× 104 km2, and the analytical data of 39 elements in more than 30 million river sediment samples were obtained. Fully developing these data will provide an important foundation for the research in this field. In addition, by exploring the relationship between soil element geochemistry and crop growth, the way to develop agriculture is explored.

In order to strengthen the geoscience research of mineral fertilizers, it is particularly necessary for China to strengthen the research of potassium fertilizer instead of soluble potassium salt. China's cultivated land is rich in nitrogen and phosphorus, but it is seriously deficient in potassium. According to statistics, K2O has a deficit of 2.3kg per mu. In the past, people have done a lot of work to convert potash feldspar, mung bean rock and other potash-bearing rocks into soluble potash fertilizer, but all of them have been shelved because they are uneconomical. Of course, importing potash fertilizer is a road that has already passed. At the same time, it is necessary to continue to do some new technological exploration. In addition, there is still a lot of room for developing new mineral fertilizers and mineral raw materials to improve soil physical properties.

In addition to improving soil, exploring the relationship between the geochemical and physical properties of soil elements and crop growth, so as to improve the fertility of cultivated land and guide crop production, geoscience research also has a broad field in the development of large agriculture, especially in the development of aquaculture.

In order to protect cultivated land, effectively use cultivated land, expand cultivated land, prevent soil erosion, desertification and salinization, and prevent floods and droughts, geoscience needs to carry out special research from the perspectives of hydrogeology, engineering geology and environmental geology. Give support to the government and relevant decision-making departments to plan and take preventive measures and provide scientific basis in time.

Geoscience research should open up a big world and form an important branch discipline serving agriculture, which should be an important direction of contemporary geoscience development.