Part 1: Definition of organic fertilizer, what is organic fertilizer?
Organic fertilizer, commonly known as farmyard manure, includes various animal and plant residues or metabolites, such as human and animal feces, straw, animal remains, and slaughterhouse waste.
Organic fertilizers include cake fertilizers (rapeseed cake, cottonseed cake, soybean cake, sesame cake, castor cake, tea seed cake, etc.); compost; fermented manure; stable manure; biogas manure; and green manure.
Organic fertilizers primarily improve soil physical and chemical properties, promote plant growth, and enhance the circulation of soil ecosystems by supplying organic matter.
Under favorable conditions, these elements are mineralized by soil microorganisms and returned to the soil for utilization by crops.
Cake fertilizers include rapeseed cake, cottonseed cake, soybean cake, sesame cake, castor cake, and tea seed cake.
Mud fertilizers include uncontaminated river mud, pond mud, ditch mud, harbor mud, and lake mud.
Purely natural mineral fertilizers, including potassium ore powder, phosphate rock powder, calcium chloride, natural potassium magnesium sulfate fertilizer, and other natural substances that have not undergone chemical processing, are natural.
Such products must be certified organic and produced in strict accordance with organic standards before they can be used in organic agriculture.
Narrow Definition of Organic Fertilizer
Specially refers to a type of fertilizer made from various animal wastes (including animal manure; animal processing waste) and plant residues (cake fertilizers; crop straw; fallen leaves; dead branches; peat, etc.) using physical, chemical, biological, or a combination of these techniques, and undergoing specific processing techniques (including but not limited to composting, high temperature, and anaerobic treatment) to eliminate harmful substances (pathogens, insect eggs, weed seeds, etc.) to achieve harmlessness standards. This fertilizer complies with relevant national standards (NY 525-2012) and regulations.
Strictly speaking, unfermented human feces and urine, various livestock and poultry manures, tree branches, crop straw, firewood, fallen leaves, etc. can only be considered organic matter, not organic fertilizer. Just like raw rice, noodles, oil, and meat—they are merely food, not food, and certainly not meant to be eaten directly.
Part 2: What are the functions of organic fertilizers, and how do they contribute to agricultural production?
A. Improving Soil Fertility
95% of trace elements in soil exist in an insoluble form and cannot be absorbed by plants. However, microbial metabolites contain large amounts of organic acids. These, like hot water added to ice cubes, quickly dissolve essential trace elements like calcium, magnesium, sulfur, copper, zinc, iron, boron, and molybdenum, transforming them into nutrients that can be directly absorbed and utilized by plants, greatly increasing the soil’s fertility capacity.
The organic matter in organic fertilizers increases the organic matter content in the soil, reducing soil cohesion and enhancing the water and fertilizer retention of sandy soils. This creates a stable aggregate structure, enabling the soil to effectively coordinate fertility.
Using organic fertilizers will make the soil looser and more fertile.
B. Improve Soil Quality and Promote Soil Microbial Growth
Organic fertilizers can promote the proliferation of soil microorganisms, particularly beneficial microorganisms such as nitrogen-fixing bacteria, ammonifying bacteria, and cellulolytic bacteria.
These beneficial microorganisms can decompose organic matter in the soil, increase soil aggregate structure, and improve soil composition.
The beneficial microorganisms in organic fertilizers can also inhibit the growth of harmful pathogens, reducing the need for pesticides. If applied continuously for many years, they can effectively suppress soil pests, saving labor, money, and pollution.
Furthermore, organic fertilizers contain various active enzymes secreted by animal digestive tracts and enzymes produced by microorganisms. When applied to the soil, these substances can significantly increase soil enzyme activity.
Long-term and sustained use of organic fertilizers can improve soil quality. By fundamentally improving soil quality, there is no need to worry about not growing high-quality fruits.
C. Provides comprehensive nutrients for crops and protects their roots and stems.
Organic fertilizers contain a large number of nutrients, trace elements, sugars, and fats that plants need.
The CO2 released by the decomposition of organic fertilizers can serve as a fuel for photosynthesis. Organic fertilizer also contains 5% nitrogen, phosphorus, and potassium, and 45% organic matter, providing comprehensive nutrition for crops.
It’s also worth mentioning that organic fertilizer decomposes in the soil and transforms into various humic acids. Humic acids are high-molecular-weight substances with excellent chelating and adsorption properties. They effectively mitigate the toxic effects of heavy metal ions on crops, prevent them from entering the plant, and protect the roots and stems of plants.
D. Enhances Crop Resistance to Disease, Drought, and Waterlogging
Organic fertilizer contains vitamins and antibiotics, which can enhance crop resistance and reduce or prevent disease.
When applied to the soil, organic fertilizer increases its water retention capacity, enhancing crop resistance to drought in drought conditions.
It also loosens the soil, improves the ecological environment for crop roots, promotes root growth, strengthens root vitality, improves crop resistance to waterlogging, reduces plant mortality, and increases the survival rate of agricultural products.
E. Improving Food Safety and Greenness
The government has long stipulated that excessive use of inorganic fertilizers must be limited in agricultural production, and that organic fertilizers are the primary source of fertilizer for producing green food.
Because organic fertilizers contain a relatively complete range of nutrients and are completely non-toxic, harmless, and pollution-free natural substances, they provide the necessary conditions for producing high-yield, high-quality, and pollution-free green food.
Humic acid, as mentioned earlier, can mitigate the harmful effects of heavy metal ions on plants, which in turn reduces the harmful effects of heavy metals on humans.
F. Improving Crop Yields
The beneficial microorganisms in organic fertilizers utilize organic matter in the soil to produce secondary metabolites, which contain a large number of growth-promoting substances.
For example, auxin promotes plant elongation, abscisic acid promotes fruit ripening, and gibberellins promote flowering and fruit set, increasing the number of flowers and fruit retention, boosting yields, and ensuring plump, fresh-colored fruits. They can also bring fruits to market earlier, ultimately increasing production and income.
G. Reduce nutrient loss and improve fertilizer utilization
The actual utilization rate of chemical fertilizers is only 30% to 45%. Some of the lost fertilizer decomposes and is released into the atmosphere, some is lost through soil erosion, and some is trapped in the soil, unable to be directly absorbed and utilized by plants.
When organic fertilizers are applied, beneficial biological activity improves soil structure and increases its water and nutrient retention capacity, thereby reducing nutrient loss. Combined with the phosphorus and potassium dissolution of beneficial microorganisms, the effective utilization rate of chemical fertilizers can be increased to over 50%.
