Organic fertilizer, a fusion of traditional agricultural wisdom and modern ecological concepts, is an indispensable and important input for agricultural production. It not only provides comprehensive nutrients for crops but also effectively improves soil structure, enhances soil fertility, and promotes sustainable agricultural development. Understanding the types of organic fertilizers, their correct application methods, techniques for distinguishing genuine organic fertilizers, and the appropriate applications for different fertilizers is crucial for scientific fertilization and improving the quality of agricultural products.
- Main Types of Organic Fertilizer
Organic fertilizer raw materials come from a wide variety of sources and can be primarily categorized as follows:
1.1. Agricultural waste: Such as crop straw, soybean meal, cottonseed meal, mushroom residue (mushroom residue), peanut shell powder, and cassava residue. These raw materials are rich in organic matter and cellulose and are important sources of compost and commercial organic fertilizer.
1.2. Livestock and poultry manure: This includes chicken manure, cow manure, sheep manure, pig manure, and rabbit manure. This is the most common organic fertilizer raw material. Chicken manure is high in nutrients, while cattle and sheep manure has a loose texture and, after composting, produces high-quality organic fertilizer.
1.3. Industrial Processing Byproducts: Such as distiller’s grains, vinegar grains, sugar residue, furfural residue, and oil residue. These are byproducts of the winemaking, sugar production, and oil extraction industries. After harmless treatment, they can be used as organic fertilizer raw materials.
1.4. Domestic Waste and Municipal Sludge: Such as food waste, river sludge, and sewage sludge. These raw materials must undergo rigorous harmless treatment and heavy metal testing to ensure safety before use.
1.5. Green Manure: These refer to plants that are specifically cultivated and turned into the soil during their growth period, such as milk vetch and alfalfa. They effectively increase soil organic matter and nitrogen.
1.6. Biogas Fertilizer: This includes biogas slurry and biogas residue, which are the residues left after biogas fermentation. Biogas slurry is rich in fast-acting nutrients and various bioactive substances, while biogas residue is rich in organic matter. Both are high-quality organic fertilizers.
- Organic Fertilizer Application Methods
2.1 Base Fertilizer Application: This is the primary method for applying organic fertilizer. Before sowing or transplanting, apply fully decomposed organic fertilizer evenly to the soil surface and then incorporate it into the soil through tillage. This method comprehensively improves the soil and provides a continuous supply of nutrients throughout the crop’s growth period.
2.2. Topdressing: During the crop growth period, decomposed organic fertilizer (such as biogas slurry or decomposed manure) can be used as a topdressing fertilizer. For example, biogas slurry can be applied directly around the root zone or diluted and applied to the leaves to quickly replenish nutrients and promote growth.
2.3. Seedling Medium: Mix decomposed organic fertilizer (such as compost or biogas residue) with garden soil and vermiculite in a specific ratio to create a seedling medium. This provides a good growing environment for seedlings.
2.4. Seed Soaking: Soaking seeds in diluted biogas slurry can improve seed germination and seedling establishment rates and enhance the seedling’s resistance to stress.
2.5. Feed Additives: Some organic fertilizer raw materials (such as biogas slurry) can be used as feed additives for livestock, poultry, or aquaculture after processing to improve feed utilization.
- Distinguishing Authentic Organic Fertilizer
Organic fertilizer products on the market vary greatly in quality, making it difficult to distinguish genuine from counterfeit. The following methods can be used to identify genuine organic fertilizers:
3.1 Check the packaging: Authentic organic fertilizer packaging should clearly display the product name, trademark, nutrient content (organic matter ≥ 45%, total nitrogen, phosphorus, and potassium ≥ 5%), production license number, registration number, implementation standard (e.g., NY525-2021), manufacturer, address, and contact information. Be cautious when purchasing unlicensed, unlabeled, or poorly labeled products.
3.2. Observe Appearance:
Authentic organic fertilizer: It is typically dark brown or black in color, uniform in texture, granular or powdery, free of noticeable impurities, and has a characteristic earthy or fermented odor, but not a foul odor. Fake organic fertilizer may have an unusual color (such as too light or too bright), an uneven texture, and may be contaminated with inert materials such as sand or coal ash. It may also have a strong ammonia or sour odor, indicating incomplete decomposition or adulteration.
3.3. Hand Twisting Test: Take a small amount of fertilizer and rub it between your hands. High-quality organic fertilizer feels soft, has a certain amount of moisture, but is not sticky, and has a fine powder. If it feels hard, rough, or gritty, it may have been mixed with a large amount of sand.
3.4. Water Solubility Test: Take a small amount of fertilizer and stir it in clean water. Genuine organic fertilizer will not dissolve completely, with organic matter suspended or precipitated, and the water will appear slightly turbid but not black or smelly. If it dissolves quickly and the water becomes clear, it may be a fake chemical fertilizer. If the water becomes black and smells bad, it indicates that the raw materials are low-quality or poorly decomposed.
3.5. Combustion Test (Use with caution): Take a small amount of fertilizer and ignite it. Organic fertilizer will not ignite easily and will produce a smell similar to burning paper and ash. If it ignites easily and has a pungent odor, it may contain a large amount of untreated, flammable organic matter or chemicals.
- Suitable Applications for Different Organic Fertilizers
Different types of organic fertilizers are suitable for different crops and soil conditions due to their nutrient content, physical properties, and specific effects.
4.1 Livestock and Poultry Manure (Chicken Manure, Cow Manure, Sheep Manure):
Suitable Applications: Suitable as a base fertilizer for most field crops (such as wheat and corn), vegetables (such as tomatoes and cucumbers), and fruit trees (such as apples and pears). Chicken manure is high in nutrients and suitable for crops with high fertilizer requirements; cow and sheep manure has a loose texture and is more suitable for improving heavy clay soils or as a raw material for seedbed soil.
Precautions: It must be fully decomposed, otherwise it can easily burn roots and breed pests and diseases. Chicken manure, which is high in salt, should not be used continuously or in large quantities on saline-alkali land or in greenhouses.
4.2 Composting Agricultural Waste Such as Straw, Mushroom Residue, and Peanut Shell Powder:
Suitable Applications: Particularly suitable for improving soil structure and increasing soil organic matter content. Applying large amounts of this type of compost is particularly effective in areas with compacted soils from years of continuous cultivation, or when establishing new orchards or vegetable gardens. Mushroom residue is rich in calcium, silicon, and other elements, which are beneficial for improving the disease resistance and quality of fruit and vegetable crops.
Note: Due to its high carbon-to-nitrogen ratio, direct application will compete with crops for nitrogen. It must be composted and thoroughly decomposed.
4.3 Biogas Liquid and Biogas Residue:
Applications: Biogas liquid is an excellent, fast-acting topdressing and foliar fertilizer suitable for topdressing rice, corn, vegetables, and fruit trees, and can also be used for seed soaking. Biogas residue can be used as a base fertilizer or in preparing seedling soil. It is widely used in ecological farms and planting areas with biogas digesters.
Note: Biogas liquid should be diluted before use to avoid damage from excessive concentrations. Biogas residue has a moderate fertilizer effect and should be applied early.
4.4 Green Manure:
Applications: Suitable for soil improvement in orchards, tea plantations, and fallow land. Planting green manure between fruit tree rows or during the winter fallow period can effectively increase soil nitrogen and organic matter content and suppress weeds after mulching.
Note: It’s important to carefully time mulching, generally around flowering time, to achieve optimal nutrient and biomass production.
4.5 Commercial organic fertilizers (based on soybean meal, oil residue, etc.):
Suitable for: They offer high and stable nutrient content and are suitable for crops of high economic value, such as flowers, high-end vegetables, valuable fruit trees, and Chinese medicinal herbs. They can be used as a base fertilizer or topdressing, offering long-lasting effects and significantly improving product quality.
Note: Choose reputable brands and ensure their organic matter and nutrient content meet standards.
In summary, the appropriate selection and use of organic fertilizers not only provides balanced nutrition for crops but also fundamentally improves soil health, achieving green, efficient, and sustainable agricultural development. In practice, organic fertilizers should be strategically combined and applied precisely according to soil conditions, crop needs, and fertilizer characteristics to maximize their effectiveness.
