The Benefits and Uses of Compost Explained in Detail
What benefits does applying compost have? Do you know? The nutrient source for organic crops, under the principle that chemical fertilizers must not be used, depends entirely on the use of compost. As for the nutrient content of compost, aside from itself containing a small amount of readily available inorganic nutrients, most
What benefits does applying compost have? Do you know? The nutrient source for organic crops, under the principle that chemical fertilizers must not be used, depends entirely on the use of compost. As for the nutrient content of compost, aside from itself containing a small amount of readily available inorganic nutrients, most of the nutrients need to be released through mineralization. The rate of mineralization is limited by factors such as climate, season, moisture, and soil properties, and may not be able to supply the crop's growth needs in time. Therefore, applying compost with a higher content of readily available nutrients, such as bokashi fertilizer or liquid organic fertilizer, can immediately supply the crop's nutrient needs.
Applying compost has three functions in organic farming: (1) supplying crop nutrients, (2) improving soil physical and chemical properties, (3) activating the soil.
Applying compost has three functions in organic farming: (1) supplying crop nutrients, (2) improving soil physical and chemical properties, (3) activating the soil.
The effects of these three functions on field crops occur in sequence.
In the early stages of operating an organic farm, compost mainly supplies nutrients. After 5-6 years of operation, the soil properties will improve significantly, and yield-increasing effects will begin to appear. After ten years, the organic field soil becomes activated, and may even show static bacteria and disease resistance effects. To achieve all of the above effects of compost, operating an organic farm requires long-term perseverance and continuous effort.
After long-term application of compost to farmland, the soil properties will gradually change. First, the soil pH value, EC value, base saturation, organic matter content, and cation exchange capacity will slowly increase, and soil aggregates will gradually form, causing soil hardness and bulk density to decrease, and the soil texture will gradually become loose and easier to cultivate. As organic matter content increases, soil microorganisms become diverse and multiply in large numbers, soil activity is enhanced, the buffering capacity against harmful substances is strengthened, and the nutrients that can be mineralized also increase relatively, so the yield-increasing effect on crops gradually appears. If field management is appropriate during this period, yields can increase by about 10-30%.
However, if compost is applied improperly, over the long term the soil properties will also show negative reactions. For example, applying too much bokashi fertilizer causes the EC value and phosphorus to be too high; applying too much calcareous chicken manure compost causes pH, EC, phosphorus, potassium, calcium, and magnesium levels to be too high; long-term application of plant compost made from rice straw, weeds, and fallen leaves causes low pH and phosphate deficiency; long-term application of pig manure compost causes soil heavy metal content to be too high. When the phosphorus content in the soil is high, base saturation is high, and pH is alkaline, it is just like an elderly person who is both obese and has high blood pressure - dangerous - and soil productivity will instead be poorer. Therefore, frequently monitoring the physical and chemical properties of the soil can help you understand deviations in fertilization. Usually, after long-term careful soil cultivation, the soil properties of a healthy organic dry field fall within the following ranges: pH value is neutral, EC value is about 0.2~0.6 ms/cm, base saturation is 60~90%, calcium-magnesium equivalent ratio is 6 or below, magnesium-potassium equivalent ratio is 2 or above, soil density measured with a Yamanaka-style hardness tester is 10~20 mm, coarse porosity is 15% or below, and heavy metal content meets farmland standards. If soil properties exceed this range, soil improvement is needed, especially fertilization adjustment focused on nutrient balance.
This station's Qinan Branch has a demonstration field that, after 12 years of organic cultivation, shows significant improvement in soil properties compared with the control chemical plot, as shown in Table 1. As for its effect on yield, taking the fall 1998 crop of tender-stem lettuce as an example, the organic plot increased yield by 55% compared with the chemical plot, and for the spring 2000 corn crop, the organic plot also increased yield by 22% compared with the chemical plot. However, after long-term application of pig manure and cow manure compost, the soil properties of this plot are currently at the critical edge of high soil fertility and need to be lowered again.
The third function of compost is that after the soil is activated, it has static bacteria and disease-suppressive ability. So-called static bacteria and disease-suppressive ability means that when pathogenic bacteria enter the crop rhizosphere, the rhizosphere microorganisms have antagonistic defensive power, preventing pathogenic bacterial spores from germinating or inhibiting their reproduction, thereby protecting the crop root system from invasion. Taking this organic demonstration field at Qinan Branch as an example, for the fall 1998 crop of tender-stem lettuce, the organic plot increased yield by 55%, and part of the reason is attributable to the 12% stem rot occurrence in the control plot, while almost none occurred in the organic plot. It can be seen that only after 12 years of effort did this demonstration field slightly acquire disease-suppressive ability.
For soil to have disease-suppressive ability, in addition to relying on long-term soil cultivation, the most important reason is that through long-term application of good-quality soil compost, a stable food source is provided, the soil microbial community is thoroughly changed, and the reproduction of large numbers of beneficial and antagonistic microorganisms is induced, thereby achieving the disease-suppressive effect.
By the same reasoning, all field operations that can provide an excellent soil environment, supply microbial nutrients, and improve the living environment of soil microorganisms can be regarded as pioneering work in cultivating disease-suppressive soil. Therefore, field operations such as deep plowing, planting green manure, improving drainage, applying good-quality compost, crop rotation, mixed cropping, intercropping, and mulching can all help achieve the above goals earlier.
By the same reasoning, all field operations that can provide an excellent soil environment, supply microbial nutrients, and improve the living environment of soil microorganisms can be regarded as pioneering work in cultivating disease-suppressive soil. Therefore, field operations such as deep plowing, planting green manure, improving drainage, applying good-quality compost, crop rotation, mixed cropping, intercropping, and mulching can all help achieve the above goals earlier.