Soil is an important foundation for human survival and social development. The quality of soil is related to the growth and safety of agricultural products. The quality of fruit and the output of orchard all depend on the quality of soil, and more importantly, it is related to the health of people.

With the popularization of urbanization construction and the continuous increase of population in China, the soil problems in China are becoming more and more serious. We should have the courage to find out the soil problems, formulate reasonable technical solutions, improve the soil, reduce pollution, effectively improve the soil environmental quality, improve the fruit quality, and increase the output of orchards.

Soil pollutants can be roughly divided into inorganic pollutants and organic pollutants. Inorganic pollutants mainly include acids, alkalis, heavy metals, salts, compounds of radioactive elements cesium and strontium, compounds containing arsenic, selenium and fluorine. Organic pollutants mainly include organic pesticides, phenols, cyanides, petroleum, synthetic detergents, 3,4-benzopyrene and harmful microorganisms brought by urban sewage, sludge and manure.

When there are too many harmful substances in the soil, which exceed the self purification capacity of the soil, the composition, structure and function of the soil will change, the microbial activity will be suppressed, and the harmful substances or their decomposition products will gradually accumulate in the soil and be absorbed by the human body through "soil → plant → human body" or indirectly through "soil → water → human body", so as to harm the human health. This is called soil pollution.

Excessive chemical fertilizer, pesticide, agricultural film residue pollution, untreated organic fertilizer pollution, and harmful pathogen pollution often enter the cultivated soil, causing heavy metal, organic compounds and pathogenic organisms pollution in the cultivated soil. Soil pollution has also led to many serious soil problems.

1、 Soil acidification and salinization

Due to the excessive use of physiological acid fertilizer and chemical nitrogen fertilizer for a long time, the acid-base balance in the soil was destroyed. Soil acidification will accelerate soil impoverishment, activate soil harmful heavy metals, increase soil harmful microorganisms, especially parasitic fungi, and cause serious soil borne diseases. Due to the excessive use of chemical fertilizers for a long time, the salt in the soil is constantly accumulated, especially nitrate. These salts accumulate to the surface along with the soil moisture, resulting in the alkalization of soil surface salt, the destruction of soil structure, and the deterioration of physical, chemical and biological properties.

2、 Soil dystrophy

In order to pursue high yield, excessive application of nitrogen, phosphorus and potassium fertilizer blindly, no or less application of organic fertilizer and medium and trace element fertilizer, resulting in enrichment of nitrogen and phosphorus in the soil, depletion of medium and trace elements such as potassium, silicon, calcium, magnesium, boron, zinc, iron and molybdenum in the soil, resulting in imbalance in the ratio of nitrogen, phosphorus and potassium, and imbalance in the nutrition ratio between macroelements and medium and trace elements. This leads to the antagonism of soil nutrient elements, which is fertilized but useless.

3、 Soil organic matter decreased significantly

Compared with the 1980s, in 2015, the contents of total nitrogen, available phosphorus and available potassium of cultivated land soil in China increased significantly, and the content of soil carbon showed an increasing trend. However, some areas still have problems such as the obvious decrease of soil organic matter, the aggravation of soil acidification and alkalization. According to the statistics of the National Agricultural Technology Extension Service Center of the Ministry of agriculture and rural areas, the organic carbon content of some cultivated land in the three northeast provinces, the eastern part of Inner Mongolia, Fujian, Guangdong, Xinjiang, Qinghai, Tibet and other places has decreased significantly. The organic carbon content of black soil in the three provinces of Northeast China decreased by 21.9%, that in Fujian, Guangdong and Hainan decreased by 16.0%, that in Qinghai Tibet decreased by 13.3%, and that in Northwest China decreased by 10.5%, which seriously reduced soil fertility.

According to the investigation, there are many reasons for the decline of soil fertility, but it is mainly due to the excessive development of agriculture in recent years and the substantial increase in output. In particular, a large number of elemental fertilizers are applied and organic fertilizers are not properly supplied to the soil, resulting in the decline of soil organic matter content and the weakening of soil microbial flora diversity and function, resulting in the "sub-health" state of the soil. To sum up, first, the organic matter in the soil can not be supplemented if the farmyard manure is not applied or less applied for a long time; The second is the excessive application of chemical fertilizers and the high yield beyond the soil load, resulting in the reduction of soil organic matter content.

4、 Soil hardening

Due to the lack of soil organic matter in cultivated land and unreasonable cultivation and irrigation, a large amount of chemical fertilizer is applied, soil acidification, soil secondary salinization, which destroys soil agglomeration and leads to soil hardening. It affects the development of plant roots and the absorption of nutrients.

5、 Soil microbial activity decreased

The microorganisms in the soil are mainly bacteria, generally accounting for 70% ~ 90% of the total number of soil microorganisms, followed by actinomycetes and fungi, and less algae and protozoa. Soil is the habitat for microorganisms to live and breed. Soil microorganisms are an important part of soil ecosystem and the main component of biological fertility.


As the multiple cropping index in China is too high, which leads to excessive fertilization and unreasonable fertilization, as well as a large number of pesticides, the number of soil microbial communities in some areas of China has dropped sharply, the soil fertility has deteriorated seriously, and the fertilizer absorption and utilization rate has declined. In some areas, there have been different degrees of fertilizer damage, drug damage and the phenomenon of "dead shed" in vegetable greenhouses.

Since the 1980s, due to excessive re cultivation and neglect of organic fertilizer, China's soil organic matter has decreased. Affected by soil salinization and acidification, and the antibiotic residues in organic fertilizer made of livestock and poultry manure, the microbial activity in some soils in China has decreased, the soil ecological environment has deteriorated, and the soil microbial community structure and diversity have been in recent years.

6、 Soil erosion

Soil erosion of cultivated land mainly includes water erosion, wind erosion and tillage erosion. It is mainly due to the excessive reclamation of slope land, especially the slope land with a slope of more than 15 degrees, and the frequent disturbance of surface soil cultivation, resulting in water and soil loss. Secondly, there is a lack of protective tillage measures such as slope to terrace, horizontal ditch cultivation and plant hedge after reclamation. Instead, the land is dug and ploughed at will, which not only causes tillage erosion, but also intensifies wind erosion and water erosion. Long term soil and water loss leads to soil desertification, soil thinning, nutrient loss, reduction of water and fertilizer conservation capacity, soil impoverishment and reduction of cultivated land area. To a certain extent. So how can we improve the many problems faced by the soil to improve the soil quality.

Improving and protecting soil is a shortcut to return to ecological industry and increase production and income

The first promising solution is to reduce the use of chemical fertilizer and adopt biological fertilizer. Biological fertility (microorganisms) can redox and complex the harmful metals in the soil, and has great potential to degrade organic pollutants (including solid and liquid). Moreover, it has the obvious advantages of complete remediation, no secondary pollution, low energy consumption and environmental safety. It has opened a new way for the remediation of heavy metal, pesticide residues, oil and industrial waste pollution.

Increasing the application of soil conditioner, organic fertilizer, organic-inorganic compound fertilizer, bio organic fertilizer, microbial agent, etc. will not only improve the soil and fertilize, but also loosen the soil, improve the soil structure, maintain water and fertilizer, and promote the growth of roots; It also has the effects of improving the living environment of soil microorganisms, stimulating crop growth points, high stress resistance, and resistance to repeated cropping.

In addition, the soil is deeply ploughed every 1-2 years to break the bottom layer of the plow. Improve soil structure and increase soil permeability. Using straw returning to the field, planting green manure and other measures to increase the content of soil organic matter. Improve soil aggregate structure and soil microbial environment.

Improve the planting system, adopt measures such as rotation of stubble or regular fallow, etc. * balance soil nutrients and restore soil fertility, reduce pathogenic microorganisms, and increase soil disease resistance and purification capacity.

For the plot with serious water and soil loss, terraces shall be built or green manure plants with fertilizer, water and soil conservation shall be planted to reduce water and soil loss* It is a large agricultural production country. According to the requirements of sustainable development, ecological agriculture is a major direction of future development. It has its unique advantages in terms of economic benefits and ecological benefits. In order to achieve sustainable development, improve the quality of fruits, increase the output of orchards greatly, and scientifically manage soil problems, it is of great significance.


Source: 3O organic agriculture