Organic Compost Compost Maturity More Commonly Used Test Methods

The maturity of the finished compost is related to the effect of the finished organic fertilizer on the crops after entering the soil. There are many methods of compost maturity testing, but some are limited by the nature of the raw materials, or difficult to operate. I found a few simple and effective methods to reflect the degree of decay, to share with you.

Seed Germination Experiment
The ultimate goal of composting livestock manure to produce efficient organic fertilizer is that the finished organic fertilizer can promote plant growth and increase crop yields. Uncooked manure is toxic to plants and will inhibit plant growth, so the seed germination test is recognized as a more sensitive and effective and most responsive method for evaluating the toxicity and maturity of organic manure to plant growth.

The organic fertilizer is extracted with water, and the extract is compared with distilled water for the experiment. If the germination rate is less than 50% compared with the control group, the fertilizer is considered unripe and phytotoxic, and if it is greater than 50%, the organic fertilizer can be considered ripe, and the germination rate of organic fertilizer with higher compost ripeness should be more than 80%.

Oxygen Consumption Rate
In the compost heating period and high temperature period, the microbial activity is high and requires more oxygen, in the late composting period, the microorganisms remaining in the humus enter the dormant period, their life activity is weakened, organic matter degradation almost stops, and the rate of oxygen consumption also decreases. Therefore, we can consider that the oxygen consumption rate represents the composting process.

In practice, the oxygen content of the raw material can be measured with a portable dissolved oxygen detector.

C / N
C / N is the ratio of total carbon to total nitrogen content of the compost pile and is one of the most common and important indicators to evaluate the degree of decay. The most appropriate C / N is 25:1 - 35:1 at the beginning of composting and decreases as the microorganisms continue to consume the carbon source. Compost maturity can be determined using the C/N ratio of the final product to the C/N ratio of the initial material, with a ratio below 0.6 indicating that the compost is mature.