Evaluation of the variation of selected chemical and physical soil properties under different ages of Faidherbia Albida Canopies

Abstract

The aim of this study was to investigate the variation of selected chemical and physical soil properties under different ages of Faidherbia albida (F.albida) tree canopy. Three (3) sites identified were Chongwe, Kasisi and Shimabala. From these sites, soils were randomly collected under and outside the canopies both for analysis and for a green house pot experiment. The collected soils were analysed for pH, soil organic carbon (SOC), available nitrogen (N), total nitrogen (%N), available phosphorus (P), potassium (K), bulk density, infiltration rate {!) and aggregate stability . To compare the dry matter yields of maize on soil collected from different ages as well as outside canopy, test crop maize was grown in the greenhouse pots for eight (8) weeks. After 8 weeks, the above ground portions were harvested, dried and weighed. The results of the study showed that there was a general improvement of the chemical and physical properties of soils with increasing age though some variations were also observed in some sites. Statistical analysis for Chongwe showed that there was a significantly higher pH value with increase in age (p=0.006). In addition, the SOC was significantly higher (p=0.04) under the canopy compared to outside the canopy though there were no significant differences between the different ages (p=0.139). There were also significantly higher amounts of P for soils collected under canopy than outside the canopy (p=0.046) while among the different ages, there was no significant difference (p=0.066).There was also no significant difference between dry matter for soils collected under and outside canopy (p=0.677) and between the different ages (p=0.387). For Shimabala, a significantly higher K under than outside the canopy (p=0.027) was observed but there was no significant difference among different ages (p=0.947). There was also no significant difference between %N under and outside canopy (p=0.199) and there were no significant differences between the different ages (p=0.8]6). Moreover, Higher stability of aggregates was observed under compared to outside canopy (p=0.009). For Kasisi, there was a significantly high bulk density outside than under canopy (p=<.001).There was also no significant difference between available N for soils collected under and outside canopy (p=0.074). Generally it was observed that the albida effect was realised as early as three (3) years and that the contribution of the F.albida generally increased with age.