At present,the earliest historical site of organic fertilizer accumulation and utilization in the world can be traced back to Sumerian civilization 6000 years ago.As early as before the Qin and Han Dynasties,China also used the practice of organic fertilizer to raise land.The relevant agricultural books of previous dynasties described in detail the types,functions,accumulation and application methods of organic fertilizer.In the Qing Dynasty,there were 10 categories and more than 100 kinds of organic fertilizers in China.In 1990,the Ministry of agriculture carried out a national investigation and Research on organic fertilizer,which was divided into 10 categories and 433 varieties.
From ancient times to the 1970s,the fertilizer used in agricultural production mainly depended on organic fertilizer,which basically maintained the stability of the yield per unit area of rice and wheat,and increased slowly.In the mid-20th century,due to the popularization and application of chemical fertilizer,the status of organic fertilizer decreased day by day.The proportion of organic fertilizer application in the total fertilizer application in China was 99.9%in 1949,91.0%in 1957,80.7%in 1965,66.4%in 1975,47.1%in 1980,43.7%in 1985,36.7%in 1990,31.4%in 2000 and 25%in 2003.
Due to the extensive use of chemical fertilizer,great changes have taken place in agricultural production.While bringing huge economic benefits and meeting the needs of rapid population growth,its negative effects are becoming more and more obvious,such as the decline of soil fertility,the deterioration of environmental quality,food quality and safety accidents,etc.Therefore,people pay more and more attention to organic fertilizer.
However,the unreasonable use of organic fertilizer will also have a negative impact on soil quality,environmental quality and food safety.If not paid enough attention,its side effects will even exceed that of chemical fertilizer.Soil quality refers to the ability of soil to maintain crop production capacity,maintain environmental quality and promote animal and plant health.Therefore,the use of organic fertilizer will strongly affect soil quality from both positive and negative aspects.
In modern agricultural production,the application of organic fertilizer is not only directly related to soil quality,crop yield and quality,water and atmospheric environmental quality,but also an important link between planting and aquaculture.It also plays an important role in promoting material circulation and energy transformation in farmland ecosystem and biosphere.In order to give full play to the positive role of organic fertilizer and minimize its negative effects,we must have a clear understanding of the characteristics of various organic fertilizers,their transformation process in soil and their impact on soil,environmental quality and crops,so as to formulate scientific application specifications.