In the process of organic fertilizer production, windrow turning serves as the critical link connecting raw material pretreatment with the final maturation and composting stage. The turning operation—typically executed using a windrow compost turner—may appear simple on the surface; however, it carries the core mission of safeguarding fermentation quality and enhancing fertilizer grade, making it an indispensable component of organic fertilizer production. Its objective is not merely to mix the materials; rather, through scientifically controlled turning, it aims to create optimal conditions for microbial activity, facilitate the efficient decomposition of organic matter, and ultimately yield high-quality, safe organic fertilizer.
The primary objective of windrow turning is to regulate the temperature of the fermenting materials and control the composting process. Organic fertilizer fermentation relies on the metabolic activity of microorganisms; as these microorganisms become active, they release substantial amounts of heat, causing the temperature within the compost pile to rise. If the pile is not turned in a timely manner, the internal temperature will continue to climb—potentially exceeding 65°C. Such excessively high temperatures can inhibit the activity of beneficial microorganisms, or even lead to their death, thereby stalling the composting process. Windrow turning effectively mixes the high-temperature materials from the pile's interior with the cooler materials from the surface, maintaining the overall temperature within an optimal range of 55–60°C. This temperature range serves a dual purpose: it effectively eliminates pathogens, insect eggs, and weed seeds present in the materials, while simultaneously ensuring the continuous and efficient metabolic activity of the microorganisms.
Secondly, windrow turning replenishes oxygen and expels harmful gases, thereby ensuring that microorganisms can engage in aerobic respiration. The maturation of organic fertilizer typically involves aerobic fermentation, wherein microorganisms utilize aerobic metabolism to efficiently break down organic matter and convert it into nutrients that can be absorbed by crops. As fermentation progresses, the oxygen within the compost pile is gradually depleted, leading to the generation of harmful gases such as carbon dioxide and hydrogen sulfide. If the materials remain undisturbed for too long, an anaerobic environment will develop; this fosters the proliferation of harmful microorganisms, causing the materials to rot, deteriorate, and emit foul odors. Windrow turning disrupts the compacted structure of the pile, introduces fresh air to replenish the oxygen supply, and simultaneously expels harmful gases, thereby creating a favorable living environment for beneficial microorganisms.
Furthermore, windrow turning promotes the uniform maturation of the materials and enhances the uniformity of nutrient distribution within the fertilizer. During the initial piling of raw materials, moisture and nutrient distribution often tend to be uneven: the surface layers may be relatively dry with slow nutrient decomposition, while the interior layers remain moist with rapid nutrient decomposition. Through the process of windrow turning, materials, moisture, and microorganisms are thoroughly blended, ensuring a consistent rate of maturation throughout the entire pile. This prevents issues such as localized under-maturation or over-maturation, while simultaneously facilitating the uniform distribution of nutrients and enhancing the overall quality of the organic fertilizer.
In summary, windrow turning serves as a pivotal mechanism for regulating the fermentation environment of organic fertilizers and guaranteeing the quality of maturation; it directly impacts the safety, nutrient content, and application efficacy of the final product. Only through scientific and standardized windrow-turning practices can the efficient conversion of organic matter be achieved, yielding high-quality organic fertilizers that provide robust support for the green and sustainable development of agriculture.
