The loose, rough surface of newly tilled soil readily allows rain water to infiltrate into the soil - unless a crust forms. High temperatures in July and August cause high water loss through evaporation and transpiration from plants. Soil water stores are at their lowest. Soil water levels begin to recharge as temperatures drop and evaporation and transpiration slow. Organisms Warming temperatures, air from tillage, and food from a plowed-down crop trigger a high level of activity.
Organisms give off heat, carbon dioxide, and nutrients as they consume residue.
In late summer, organisms from bacteria to earthworms are less active and reproduce less because of the lack of water. Microbial activity increases in response to greater soil moisture and new food in the form of roots and residue from harvested crops. Plants Tillage triggers weeds to sprout. As crop roots begin to grow, they continually contribute organic matter to the soil. They exude organic compounds and slough off dying cells.