The transport of water through heavy clay soils. I

Assuming a uniform heavy soil, without tilth, the water movement in which obeys diffusion laws, expressions have been deduced for four quantities, starting with a known moisture profile. (a) The moisture profile at any subsequent time in the absence of rainfall or irrigation (neglecting evaporation, transpiration, and any other source of loss of moisture). (b) The moisture profile at any subsequent time during such rainfall as causes flushing of the drains. (c) The minimum rainfall necessary to cause flushing of the drains (maximum acceptable rainfall). (d) The acceptable rainfall after a period of recovery following the previous drainage period.