As an important resource in agricultural production, the rational use of organic fertilizer is of great significance to soil improvement, crop yield increase and environmental protection. However, in actual application, many farmers still have misunderstandings about organic fertilizer, which leads to poor results or even counterproductive results. This article will systematically explore the precautions for the use of organic fertilizer to help farmers apply it scientifically and give full play to the benefits of organic fertilizer.
- Characteristics and advantages of organic fertilizer
Organic fertilizer refers to fertilizers derived from animal and plant residues or excrement, which are formed after fermentation and decomposition. Compared with chemical fertilizers, organic fertilizers have the following significant advantages:
a. Improve soil structure: Organic fertilizers can increase the content of soil organic matter, promote the formation of aggregate structure, and improve the soil’s ability to retain water and fertilizer.
b. Provide comprehensive nutrition: Contains nitrogen, phosphorus, potassium and a variety of trace elements, and the nutrient release is slow and lasting.
c. Enhance biological activity: Provide energy and nutrition for soil microorganisms and promote the reproduction of beneficial microorganisms.
d. Reduce environmental pollution: Reasonable use can reduce the amount of chemical fertilizers and reduce non-point source pollution.
- Preparation before using organic fertilizer
Determination of maturity: Unripe organic fertilizer may carry pathogens, eggs and weed seeds, and continued fermentation in the soil will produce high temperature and harmful gases, which will harm the root system of crops. Fully decomposed organic fertilizer should be dark brown, without odor, loose texture, and about 30% water content. It can be simply tested by the “plastic bag method”: put the sample into a sealed plastic bag and place it in the sun. If there is no gas expansion in the bag, it is fully decomposed.
a. Quality inspection:
Heavy metal content: Especially for organic fertilizer made from urban sludge and livestock and poultry manure, lead, cadmium, mercury, arsenic and other indicators need to be tested.
Salt content: Some livestock and poultry manure has a high salt content, and long-term use may cause soil salinization.
Antibiotic residues: The manure of large-scale farms may contain veterinary antibiotics, which affects the balance of soil microorganisms.
b. Nutrient content determination:
Organic fertilizers from different sources have large nutrient differences. Generally, livestock and poultry manure has a high nitrogen content (0.5-2.5%), and compost is relatively rich in phosphorus and potassium. It is recommended to conduct simple testing for each batch to avoid blind application.
- Key points of scientific application technology
a. Application period:
Base fertilizer is the main one: It is best to apply it 15-20 days before sowing or transplanting to fully integrate the fertilizer with the soil. It is recommended to apply it in autumn for field crops to facilitate the decomposition of organic matter.
Topdressing supplement: For crops with a long growth period, decomposed liquid fertilizer can be applied with quick-acting fertilizer during the critical growth period.
b. Application method:
Deep application and covering the soil: Avoid surface spreading, generally 15-20cm deep, which can reduce nutrient volatilization and facilitate root absorption.
Concentrated application: Fruit trees can be applied in annular trenches, and vegetables can be applied in holes to improve local fertilizer efficiency.
Combined with improvers: lime is applied to acidic soils, sulfur is added to alkaline soils, and pH value is adjusted to promote nutrient release.
c. Dosage control:
According to soil conditions: poor soil can be increased appropriately, and fertile soil maintains balance. Generally, the annual dosage per mu is 3-5 tons, and facility vegetables can be increased to 8-10 tons.
Consider crop needs: leafy vegetables require more nitrogen, so poultry manure can be used more; fruit trees require a large amount of potassium, so straw compost is suitable.
Avoid excessive use: excessive organic fertilizer may cause nitrogen leaching, phosphorus fixation, and imbalance of trace elements such as copper and zinc.
- Specific precautions for different types of organic fertilizers
a. Livestock and poultry manure:
Chicken manure: high nutrient concentration, but also high salt and uric acid content, needs to be fully decomposed and should not be used alone for consecutive years.
Pig manure: fine texture, contains more fast-acting nutrients, suitable for topdressing.
Cow manure: high fiber content, good soil improvement effect, but slow nutrient release, should be applied early.
b. Crop straw:
High C/N ratio (e.g. straw is about 60:1), direct return to the field will cause microorganisms to compete with crops for nitrogen, so nitrogen fertilizer should be supplemented or accelerated decomposition agents should be used.
Straw from fields with serious pests and diseases needs to be treated with high-temperature composting before use.
c. Commercial organic fertilizer:
Choose products from regular manufacturers, check the registration number and test report.
Pay attention to indicators such as organic matter content (≥30%) and moisture (≤30%).
Biological organic fertilizers also need to pay attention to the number of effective live bacteria (≥20 million/g).
With the development of organic agriculture and green food production, the scientific application technology of organic fertilizers will continue to improve. It is recommended that farmers establish fertilization files, record the source, dosage and effect of organic fertilizers, and gradually form an optimization plan suitable for local conditions. At the same time, attention should be paid to the development of new organic fertilizer products (such as biochar-based fertilizers, enzymatic amino acid fertilizers, etc.), and the fertilization level should be improved with the times. Only by correctly understanding the characteristics of organic fertilizers and following scientific application principles can we achieve the strategic goal of “storing grain in the land” and promote sustainable agricultural development.
