Soil fertility is an important indicator of soil fertility, which is the ability to measure the variety of soil nutrients required to provide crop growth. The comprehensive performance of a variety of basic soil properties, is the difference between the soils from the essential features of soil parent material and other natural body and soil as the material basis of natural resources and agricultural means of production. The soil fertility can be divided into natural and man-made soil according to the cause of formation. The former refers to in five major soil forming factors (climate, biology, parent material, topography and age) under the influence of the formation of fertility, mainly exist in uncultivated natural soil; the latter refers to long-term under artificial cultivation, fertilization, irrigation and other various farming activities affect the fertility, mainly in farming land soil.

1, sensory identification: General acidic soil wet paste rotten, dry to form larger lumps, put bitter taste in the little entrance. In alkaline soil, after the rain, the surface crust, dry loose. The loose soil into the water to stir the muddy, clarify the clarification of the liquid to boil dry, the bottom has a little cream. Of or for red or yellow soil is acid, such as yellow soil, upland soil, red soil land etc.. The general red soil pH value was 4.56.0, soil acidity, pH value is 4.05.5.

In recent years, the safety of the tongue can be said to be the public's most concerned about the topic. In recent years, cadmium rice, heavy metals and other food safety incidents have let us begin to realize that we have been on the soil has been contaminated, and harmful substances have been with food, drinking water is the end of our table. But how serious is the problem of soil pollution?

Soil biological indicators, soil physical indicators and soil chemical indicators are important components of soil quality indicators. With people's cognition and understanding of the soil, the attention of the soil is no longer confined to the soil water, gas, heat, plant nutrition elements, etc., the soil microbial indicators are also more and more attention. The function of microorganism in soil is mainly expressed in the following aspects:

Nobel (Pauling Linus), twice Pauling prize winner, said: "every disease, every kind of disease can be traced to the lack of minerals." Today we encountered most of the problems are began to the grain in the lack of mineral land planted, and eat the food of animal.

With the contradiction between population and resources, the quality of soil and land resources has become increasingly serious. Since 1960s, the world has been concerned about this issue. And China is very serious, China's arable land accounts for only around 10% of the population is only 22%, China's per capita arable land area a few years ago had been reduced to the 1.4 acres, only 40% of the world average level, the red line of 18 million mu of arable land is broken alarm has been sounded, also the 18 million mu of tillage geology is accelerated decline. The area of arable land decreased and the quality of the decline, what we take to ensure food security, the problem is worrying.

In recent years, similar to the Hunan cadmium rice event aspects of agricultural product safety accident prone, the safety of agricultural products has become the focus of attention. Hunger breeds discontentment, we all cannot do without meals. Up to the national leaders, to the ordinary people are increasingly concerned about the quality and safety of agricultural products. And many times the safety of agricultural products at the national level that the two sessions on the proposed research, stressed. Soil acidification is one of the important reasons leading to the serious soil borne diseases. The soil borne diseases cause the use of pesticides and the quality of agricultural products. According to statistics from related departments, the main vegetable planting area of 3 million mu, the soil borne diseases occurrence area 3.5 million acres around, each big city vegetable is particularly serious.