Arid and semi-arid areas (dry lands) are prone to relatively high vegetation and general environmental degradation, translating to changes in soil physical and chemical properties. Conservation agriculture with trees presents an opportunity to reduce vegetation and soil degradation and enhancing soil characteristics- component of redressing dryland challenges of low productivity. Despite the importance of conservation farming, its adoption still remains low. We therefore set this study to assess the soil physical and chemical properties differences for conservation agriculture with trees (CAWT) and conventional tillage from a dry land context in Machakos County, Kenya. We a split plot design arranged in randomized complete block with two farming/tillage systems (conventional and conservation agriculture) as the main blocks, 10 treatments and three replicates, summing to a total of 60 plots. Three multipurpose leguminous shrub species (Calliandra calothyrsus , Cajanas cajan and Gliricidia sepium ) were planted in three different spacing at project inception in 2012 (1.5x1 m, 3x1 m, 4.5x1 m) for maize-legume intercrops. Soil samples were taken from 0-30 cm depth and analyzed for selected physical and chemical characteristics using standard laboratory methods. The data was statistically analyzed using ANOVA and means separated using LSD at p <0.05. We find significant moisture increment under conservation agriculture with trees with sole conservation agriculture retaining more moisture than sole conventional agriculture without trees (31.56 and 26.54% vol., respectively, p <0.001). Nitrogen, organic carbon, sodium and potassium are also found to be higher under conservation agriculture. In addition, cation exchange capacity was significantly (p = 0.003) higher (14.372 cmolc/kg) in conventional agriculture than in conservation agriculture (12.718cmolc/kg), and strongly correlated with clay content (r=+0.869). High salinity is also depicted for conventional farming as a result of high Electrical conductivity (CA= 0.541 dS m-1 and COA= 0.063 dS m-1). The results give reason to believe that conservation farming with integration of trees enhances soil properties in arid and semi-arid areas.
Keywords: conservation agriculture, multipurpose shrubs, soil fertility, conventional tillage, agroforestry, climate smart agriculture