How to use straw when composting?

Straw is the waste left over after we harvest wheat, rice, and other crops. However, as we all know, due to the special characteristics of straw, it can play a very important role in the process of making compost.

The working principle of straw composting is the process of mineralization and humification of organic matter such as crop straw by a series of microorganisms. In the early stage of composting, the mineralization process is the main process, and the later stage is dominated by the humification process. Through composting, the carbon-nitrogen ratio of the organic matter can be narrowed, the nutrients in the organic matter can be released, and the spread of germs, insect eggs, and weed seeds in the composting material can be reduced. Therefore, the decomposing process of compost is not only a process of decomposition and resynthesis of organic matter but also a process of harmless treatment. The speed and direction of these processes are influenced by the composition of the compost material, the microorganisms, and its environmental conditions. High-temperature composting generally goes through the stages of heating, cooling, and fertilizing.

The conditions that straw compost must meet:

Mainly in five aspects: moisture, air, temperature, carbon-nitrogen ratio, and pH.

• Moisture. It is an important factor affecting the activity of microorganisms and the speed of composting. The composting material is easily decomposed by microorganisms after it absorbs water, expands, and softens. Generally, the moisture content should be 60%-75% of the maximum water holding capacity of the composting material.
• Air. The amount of air in the compost directly affects the activity of microorganisms and the decomposition of organic matter. Therefore, to adjust the air, the method of first loosening and then tight stacking can be adopted, and ventilation towers and ventilation ditches can be set up in the compost, and the compost surface can be covered with covers.
• Temperature. Various types of microorganisms in compost have different requirements for temperature. Generally, the suitable temperature for anaerobic microorganisms is 25-35 °C, for aerobic microorganisms, 40-50 °C, for mesophilic microorganisms, the optimum temperature is 25-37 °C, and for high-temperature microorganisms. The most suitable temperature is 60-65 ℃, and its activity is inhibited when it exceeds 65 ℃. The heap temperature can be adjusted according to the season. When composting in winter, add cow, sheep, and horse manure to increase the compost windrow temperature or seal the heap surface to keep warm. When composting in summer, the windrow temperature rises quickly, then turning the compost windrow, and water can be added to reduce the windrow temperature to facilitate nitrogen preservation.
• Carbon to nitrogen ratio. Appropriate carbon-nitrogen ratio (C/N) is one of the important conditions for accelerating compost decomposing, avoiding excessive consumption of carbon-containing substances, and promoting the synthesis of humus. High-temperature composting mainly uses the straws of cereal crops as raw materials, and its carbon-nitrogen ratio is generally 80-100:1, while the carbon-nitrogen ratio required for microbial life activities is about 25:1, that is to say when microorganisms decompose organic matter, every 1 part of nitrogen, 25 parts of carbon need to be assimilated. When the carbon-nitrogen ratio is greater than 25:1, due to the limitation of microbial activities, the decomposition of organic matter is slow, and all the decomposed nitrogen is used by the microorganisms themselves, and effective nitrogen cannot be released in the compost. When the carbon-nitrogen ratio is less than 25:1, microorganisms multiply quickly, materials are easily decomposed, and effective nitrogen can be released, which is also conducive to the formation of humus. Therefore, the carbon-nitrogen ratio of grass straw is relatively wide, and the carbon-nitrogen ratio should be adjusted to 30-50:1 when composting. Generally, human manure equivalent to 20% of compost material or 1%-2% nitrogen fertilizer is added to meet the needs of microorganisms for nitrogen and accelerate the decomposing of compost.
• Acidity and alkalinity (pH). Microorganisms can only operate within a certain range of acid and alkali. Most microorganisms in the compost require a neutral to the slightly alkaline acid-base environment (pH 6.4-8.1), and the optimum pH is 7.5. Various organic acids are often produced in the process of composting, creating an acidic environment and affecting the reproductive activities of microorganisms. Therefore, an appropriate amount (2%-3% of the strawweight) of lime or plant ash should be added during composting to adjust the pH. Using a certain amount of superphosphate can promote the compost to mature.

Main points of straw high-temperature composting technology:

1. Ordinary composting method:

• Choose a venue. Choose a place close to the water source and convenient for transportation. The size of the compost depends on the site and the amount of materials. The ground is pounded, then a layer of dry fine soil is placed on the bottom, and a layer of uncut crop stalks is placed on top as an aerated bed (about 26 cm thick).
• Handling straw. Straw and other organic materials are stacked on the bed in layers, each layer is about 20 cm thick, and human feces and urine are poured layer by layer (less at the bottom and more at the top). , so that the bottom is in contact with the ground, pull out the wooden stick after stacking, and the remaining holes are used as ventilation holes.
• Compost material ratio. The ratio of straw, human and animal manure, and fine soil is 3:2:5, and 2-5% calcium-magnesium-phosphate fertilizer is added to mix compost when ingredients are added, which can reduce the fixation of phosphorus and improve the fertilizer efficiency of calcium-magnesium-phosphate fertilizer significantly.
• Regulates moisture. Generally, it is advisable to hold the material in hand if there are droplets. Dig a ditch about 30 cm deep and 30 cm wide around the compost, and cultivate the soil around to prevent the loss of manure.
• Mud seal. Seal the heap with mud for about 3 cm. When the heaped body gradually sinks and the temperature in the heap slowly drops, turn the heap, mix the poorly decomposed materials at the edges with the internal materials evenly, and pile them up again. If the material is found to have white bacteria When the silk body appears, add an appropriate amount of water, and then re-seal it with mud. When it is half-decomposed, press it tightly and seal it for later use.
• The sign of the compost being decomposed. When fully decomposed, the color of the crop straw is dark brown to dark brown, the straw is very soft or mixed into a ball, and the plant residue is not obvious. Grasp the compost by hand to squeeze out the juice, which is colorless and odorless after filtering out.

2. Fast-rot composting method:

• Choose a venue. Choose a place close to the water source and convenient for transportation. The size of the compost depends on the site and the amount of materials. If you choose flat ground, you should build a 30 cm high soil ridge around it to prevent running water.
• Handling straw. Generally divided into three layers, the thickness of the first and second layers is 60 cm, the thickness of the third layer is 40 cm, and the mixture of straw decomposing agent and urea is evenly sprinkled between the layers and on the third layer, straw decomposing agent and urea The dosage of the mixture is 4:4:2 from bottom to top. The stacking width is generally required to be 1.6-2 meters, the stacking height is 1.0-1.6 meters, and the length depends on the amount of material and the size of the site. After stacking, it is sealed with mud (or film). 20-25 days can be rotten and used, the quality is good, and the effective nutrient content is high.
• Material and ratio. According to 1 ton of straw, 1 kg of straw decomposing agent (such as “301″ bacterial agent, rot straw spirit, chemical ripening agent, “HEM” bacterial agent, enzyme bacteria, etc.), and then 5 kg of urea (or 200- 300 kg of decomposed human feces and urine) to meet the nitrogen required for microbial fermentation, and adjust the carbon-nitrogen ratio reasonably.
• Regulate moisture. Before composting, soak the straw with water. The ratio of dry straw to water is generally 1:1.8 so that the moisture content of the straw can reach 60%-70%. The key to success or failure.