existing problems

(A) low utilization rate of cultivated land

Judging from the results of agricultural land classification in Gansu Province, the output of cultivated land is closely related to natural and human factors. In recent years, with the improvement of agricultural production modernization, human factors have played an increasingly important role. Human factors mainly include socio-economic conditions, scientific and technological level and farming system. Socio-economic conditions affect the input level of cultivated land and determine the classification of cultivated land; The level of science and technology affects the advancement and backwardness of technical means and the utilization of cultivated land. These are comprehensively reflected in the output level of cultivated land.

According to the survey data of agricultural land classification, the average proportion of effective irrigation area in Gansu Province is only 27%, and the proportion of irrigation protection area is also low. Many cultivated lands with good natural conditions in Hexi Corridor have been degraded because they can't fully satisfy irrigation. The planting index of cultivated land is also low, farmers' awareness of making full use of light and heat resources to increase biological yield is weak, farming technology is backward, the degree of mechanization is low, and the labor force is tight during busy farming, so it is difficult to give consideration to multiple cropping, intercropping and interplanting, rationally match crop varieties and make better use of soil fertility and light energy resources. Rain-fed agriculture is dominant, subject to natural rainfall, extensive planting and poor harvest still account for a large proportion.

(2) Cultivated land, especially fertile land, cannot be effectively protected.

Cultivated land is the base for producing agricultural and sideline products. At the current level of science and technology, most of the food people depend on depends on cultivated land. To some extent, cultivated land is the food and clothing parents of human beings. Although the per capita cultivated land in Gansu Province is higher than the national average, the quality of cultivated land is poor and the output level is low, and the problem of food and clothing has not been solved in some poverty-stricken areas. At present, many cultivated land has not been effectively protected, especially the cultivated land with good quality is occupied in large quantities, which greatly offsets the achievements of agricultural infrastructure construction. The reduction of cultivated land is mainly reflected in construction occupation, agricultural structure adjustment, conversion of cultivated land to other uses or land destruction by disasters. According to the data of agricultural land classification for the balance of cultivated land occupation and compensation in Gansu Province, there are more cultivated land with good quality in all kinds of construction, especially when farmers build houses and township enterprises build on the spot, they occupy more good cultivated land along Sichuan, tableland and highway. Although a part of cultivated land is increased through land development every year, the increased area is basically the same as the decreased area, but its quality is hard to make up, and its maturity and output level are far less than the original cultivated land.

(3) The virtuous circle of cultivated land utilization has not yet formed.

The material and energy circulation in cultivated land utilization basically got rid of the pure natural ecological circulation system and became an artificial ecosystem highly controlled by human beings. What we are pursuing is a virtuous cycle system with high efficiency, high output, soil fertility can be restored and supplemented, and sustainable utilization. From the analysis of agricultural land classification results, it is found that there are many short-term behaviors in Gansu Province, such as reusing cultivated land and neglecting farming, emphasizing development and neglecting management, and attaching importance to applying chemical fertilizer and neglecting organic fertilizer, which leads to the decline of soil fertility and soil hardening. In some places, instead of actively enriching soil fertility, organic matter is decomposed in a leisure way, and cultivated land nutrients are released, so that light and heat resources cannot be effectively and fully utilized. The arid and barren land in Gansu province is all over the country, and some saline-alkali low-yield fields are caused by improper irrigation methods. There are many people and few land in mountainous areas, and organic fertilizer itself is insufficient. In addition, due to the lack of fuel, farmers use the roots of crops and even livestock manure as fuel, and the source of fertilizer is even poorer. They have to rely on chemical fertilizers or even white water to sow, and the organic matter and nutrients in the cultivated soil have a further downward trend. According to the second soil survey in Gansu Province, the content of soil organic matter in mountainous cultivated land has dropped below 10g/kg, and the contents of total nitrogen, available nitrogen and available phosphorus are also decreasing, and the soil structure is getting worse and worse.

(D) The ability of agricultural production to resist natural disasters is poor.

The natural disasters that are most harmful to the utilization of cultivated land mainly include drought, frost, hail, rainstorm, sandstorm, pests and diseases. In addition, the soil erosion caused by heavy rain in Longdong, Longnan and Longdong is more serious, and the sandstorm disaster in Hexi area is also more prominent. Soil erosion resulted in poor farmland soil and reduced the output of agricultural products.

(e) Limited arable land, high population pressure and low food possession.

Population, cultivated land and grain are closely related and often affect the overall situation. Among them, people and cultivated land are the foundation and key factors. In the relationship between man and land, man is the dominant factor. First, the population growth is too fast, resulting in a rapid decline in per capita arable land; Second, the influence of human behavior, people can protect cultivated land, improve soil, increase grain output, or do the opposite, wasting and destroying cultivated land resources. Grain in Gansu Province is increasing year by year, but it fluctuates greatly due to disasters, and the per capita grain growth is slow.