An Approach for the Calculation of the Biomass Production of Short Growing Periods in the Rangelands of Northern Kenya

Abstract

Investigations on the soil plant water relationship were carried out in the semiarid thorn bush Savannah of Ngare Ndare, Isiolo District, Northem Kenya, to develop an approach for the determination of the biomass production on the basis of the soil:water balance. In order to determine the growth-effective rainfall, the soil-water balance of the short rain periods was correlated with the subsequent growing periods. During the study period, the growth effective rainfall of the different rain periods amounted to an average of 75% of the total rainfall. Due to the highly adapted natural plants of this dwarf shrub bushland, the daily water consumption of the vegetation was below 2 mm/day. High growth effectivity of the rainfall and low water consumption led to long growing periods even after light rainfalls. Based on these observation5, a formula for the calculation of the duration of the growing periods based on daily rainfall and evaporation data was developed.