Estimativas da curva de retenção da água e da produtividade agrícola em solos da Zambézia, Moçambique

Abstract

Soil water retention and aeration play an important role in plants germination and development for agricultural production. Besides that, these edaphic properties are essential for crop irrigation manegement and desing. Unfortunately, information on soil water retention and aeration of soils from the province of Zambézia, Mozambique, Africa are scarce, making it difficult to manage and to establish public policies for the water use.Traditional procedures for measuring soil hydraulic properties are usually expensive and laborious and due to it pedotransfer functions (PTFs) are alternative estimation tools. This study aimed to assess scenarios of available water (AW) and drainable porosity (DP) fractions in soils of province of Zambézia-Mozambique, generated from PTFs, in order to subsidize the analysis of agricultural production. A data set composed of 406 sample points comprising granulometric fractions and bulk density data of the assessed soils was built. These data were Applied in 11 parametric PTFs selected in the literature, by these 6 were not sucessful for yielding estimates due to prediction errors. However, 5 PTFs showed convergent estimation data and were applied to estimate the parameters of the van Genuchten equation to represent the soil water retention curve (SWRC). With these parameters, AW and DP fractions were calculated for the soils of the province of Zambézia by the volumetric water content at saturation, field capacity and permanent wilting points. The 5 PTFs that generated convergent simulations and scenarios were Rosetta 3.0, Splintex 2.0, GH, ZW and RB, with mean AD values (0.202, 0.239, 0.277, 0.253 and 0.180 cm3 cm-3, respectively) and DP (0.117, 0.159, 0.214, 0.07 and 0.185 cm3cm-3). Using the AW and DP data obtained via PTFs, crop yields were simulated using the aquaCrop model, with 4 PTFs generating convergent scenarios of crops productivity showing that the evaluated soils of textural classes listed as loam, sand loam, sandy, sandy clay loam, and sandy loam have satisfactory water retention capacity and drainable porosity for the production of a dry agricultural crops such as cassava, sweet potato, boer beans and peanuts