How do soil temperature and moisture affect the decomposition of plant material?

In the context of vegetable farming, soil temperature and moisture are critical factors that dictate the rate at which micro-organisms decompose plant material.1

Plant material decomposes most rapidly when the soil is warm and well supplied with moisture. These conditions facilitate the metabolic activity of the micro-organisms responsible for breaking down organic matter into carbon dioxide and releasing nutrients back into the soil.1

The influence of these factors is summarized as follows:

• Moisture: Adequate moisture is essential for decomposition. If the soil is dry when plant material—such as green-manure crops or crop residues—is turned under, little to no decomposition will occur until rain or irrigation provides the necessary water.1
• Temperature: Warm soil temperatures promote faster microbial activity. Conversely, unfavorable soil temperatures can retard biological processes.12
• Material Quality: Beyond environmental conditions, the rate of decomposition also depends on the type of crop and its stage of growth. More succulent, green material decomposes more quickly than dry, mature material.1

Maintaining proper soil organic matter is a fundamental practice in vegetable farming, as it serves as a vital source of plant nutrients.1