Rainfall parameters and a cover model to predict runoff and soil loss from grazing trials in the Rhodesian sandveld

Abstract

Annual runoff from a bare, sandy soil was well correlated to total seasonal precipitation quantities (P). In the case of veld treatments however, runoff was more closely related to higher precipitation levels (P50) on five of the six treatments.

Soil losses were closely related to a parameter derived from the few major storms of the season (P12–25–20). A cover model was developed to explain the variation in soil losses from the veld treatments and to improve the accuracy of prediction equations.

Uittreksel

‘n Goeie korrelaste is waargeneem tussen jaarlikse afloop vanaf ‘n kaal, sanderige grand en die totale seisoenale reënvalwaardes (P). By veld ester, is bevind dot afloop na ‘n nouer verband met die hoër reënvalpeile geneig het (P50) by vyf van die betrokke ses behandelings.

Grondverlies het ‘n noue verband getoon tot ‘n parameter wat herlei is van enkele groot storms gedurende die seisoen (P12–25–20). ‘n Bedekkingsmodel is ontwerp om die variasie in grondverlies vanaf die veldbehande‐lings te verklaar en om die akkuraatheid van die voorspellingsvergelykings te verhoog.