Assessment of Soil Quality in Paddy Fields at Dakawa Irrigation Scheme, Morogoro, Tanzania

Abstract

Soil quality, a measure of a soil’s capacity to function, can be assessed using indicators based on physical, chemical, and biological properties. A soil quality assessment for soils used for rice production was conducted at the Dakawa Irrigation Scheme, located in Mvomero District, Morogoro, Tanzania. Eight disturbed soil samples, together with twenty-four undisturbed core soil samples, were obtained from two pitches (blocks 18 and 23) for laboratory analysis. The soil texture was identified as sandy clay loam for both pitches, and the pH levels in all layers of all pitches were rated as medium (5.7-7.0) to very high (7.0-8.6). The levels of organic carbon (OC) and organic matter (OM) were found to be very low, especially in the first layer for pitch one, where the average OM was 1.49% and OC was 0.83% and pitch two demonstrated OM of 1.34% and the OC was 1.08%. Average bulk density for all pitches was very high which cause soil compaction, all layers in each pitch has B.D> 2g/cm³, for the case of permeability was very low ranges from 1.922 x 10^-5 to 3.712 x 10^-7 cm/s for pitch one and 1.2436 x 10^-5 to1.89 x 10^-7 cm/s. The cation capacity exchange (CEC) and exchangeable bases were rated as low to medium in all blocks. According to soil taxonomy and the world reference base for soil resources, the soil at the Dakawa Irrigation Scheme is classified as Vertic Calciusteps, fluvisols and Haplic Vertic combisols, respectively. It is recommended to increase the organic matter in the soil by applying organic matter. Additionally, the use of rice husk as a soil amendment should also be taken into consideration to control permeability and compaction.