How does the presence of humus affect the soil?

[1] The amount of rain and snow fall has an effect on the amount of soil moisture. Too little moisture means stressed soils, soil food web, and plant roots. Too much moisture means waterlogged soils, rot, and bacterial and fungal diseases. [2] The level of heat, humidity, light, and wind has an effect on the rate of soil evapotranspiration rates. High levels, particularly in the absence of protective ground cover, means more moisture lost to soil through high evapotranspiration rates. [3] The amount of organic matter ka humus has an effect on soil drainage, fertility and structure. Low levels of humus means stressed soils lacking in some or more of the 16-17 nutrients whose presence indicates healthy soil. [4] The absemce or presence of slope has an effect on moisture infiltrating and percolating through soil; pooling; or running off. Ground at the downslope of an incline may pool moisture so that soil becomes waterlogged. Ground at the top of an incline may loose moisture to run-off.