The choking of pore‐space in the soil and its relation to runoff and erosion

Abstract

The identification and evaluation of all factors influencing runoff and erosion on the erosive lands of the nation are manifestly studies of the most fundamental importance, especially in so far as they may be made to yield definite information upon methods of control over this insidious tendency upon cultivated lands. Investigations in progress at our Soil Erosion Experiment Stations have rather clearly shown that we may divide the factors that are mainly responsible for preventing or provoking erosion into two broad categories, namely: (1) The protective effects of dense covers of vegetation of one kind or another, and (2) the almost certain destruction that follows the exposure of cultivated slopes to natural conditions of rainfall. Thus it is a fact that increasing the slope on Kirvin fine sandy loam‐soil— which is the most extensive and probably the most erosive soil‐type in the East Texas—Louisiana‐Arkansas sandy‐land region served by the Erosion Station at Tyler, Texas—from 8 3/4 per cent to 16 1/2 per cent does not appreciably affect the almost perfect erosion‐control provided by the use of a dense Bermuda sod. However, under conditions of clean cultivation, as with cotton, the same change in slope on the same soil greatly increases the soil‐loss which already is excessive under such conditions on slopes of more than six or seven per cent.