Effects of different tillage and cropping systems on water repellency and hydraulic properties in a tropical Alfisol of southwestern Nigeria

Abstract

This study examined the effects of growing intercrops (Sorghum, SOR (Sorghum bicolor L. Moench) in between rows of cowpea, COW (Vigna unguiculata) and soybean, SOY (Glyxine max L.Merr)) under different tillage systems on soil physico-chemical properties, soil water sorptivity (Sw), hydraulic conductivity (K), and soil hydrophobicity (R) in tropical Alfisol of Southwestern Nigeria. Results demonstrated cropping systems significantly impacted soil pH under each conventional tillage (CT), no tillage (NT), and compacted no till systems (NTC) tillage system in 2019, but not in the 2020 cropping season. Sorghum-cowpea SC) and sorghum-soybean (SS) intercropping systems under the three tillage systems had higher soil organic matter (SOM) contents than the corresponding sole sorghum (SOR) at the end of the study. Soil water sorptivity differed significantly (p < 0.001) among the cropping systems in 2019 and follows the order: SC > SS > SOY > SOR > COW while in 2020, averaged over three tillage systems, mean Sw values showed an increasing trend in the order: SOR (77.67 cm h-1/2) < COW (82.42 cm h-1/2) < SOY (88.00 cm h-1/2) < SS (88.73 cm h-1/2) < SC (98.29 cm h-1/2). In general, intercropping had a lower R than sole cropping. NTC soil was 46.48% and 56.39%; 32.47% and 41.67% more hydrophobic than soils under NT and CT in 2019 and 2020. Intercropping with legumes might have contributed to the higher K levels. Organic matter in soil improves conductivity by improving soil structure. The intercrop may have improved soil water conservation because of their shading and better soil protection. The study demonstrated that conservation tillage with intercropping could effectively enhance soil hydraulic properties.