A Note on the Effect of Fallowing On Water Storage and Loss As Determined From a Lysimeter for a Tropical Clay Soil

Abstract

A major management agronomic strategy in relatively dry areas with more than one rainy season is that of fallowing, a practice in which the soil is left uncropped and (usually) kept free of weeds for at least one rainy season. The moisture stored during this period presumably augments that available to the crop during the cropping period that follows. As pointed out by Whiteman (personal communication) the practice of fallowing can be quite attractive in areas with a bimodal rainfall distribution where the carry-over of stored moisture is higher as the intervening dry season is relatively much shorter. Where the rainfall does not exceed 300 mm in a given season and the distribution is unimodal, soil recharge may be inadequate and the practice may not be effective due to the high proportion of water lost during the intervening long, dry spell. The effectiveness of fallowing a particular soil dependslargely on the water storage capacity of the soil in relation to the remaining water balance components during the fallowing period. This note reports on a study in which a large, weighing lysimeter was used to determine water accumulation, storage, and loss from a fallow tropical clay soil. These kinds of measurement are relatively rare for the tropics.