Silicon Exerts Additive Effects on Phosphorus Acquisition by Potato Intercropped with Chickpea

Abstract

The role played by silicon (Si) and legume intercropping in nutrient acquisition by potato crop has been neglected in most studies. A field trial integrating potato (Solanum tuberosum L.) with chickpea (Cicer arietinum L.) in intercropping system was conducted over six (6) growing seasons in the upper midland (1552 m above sea level) agro-ecological zone of Kenya. The intercropped chickpea secreted enzyme phosphatase into the rhizosphere (5.1–27.1 mol g–1 fwt h–1) thus mobilizing organic (4.2–18.9 mg kg–1 soil) and inorganic phosphorus (6.9–42.8 mg kg–1 soil). This increased phosphorus availability and acquisition by the intercropped potato. Chickpea took up more cations than anions, resulting in net proton efflux (43–105 mmol kg soil–1) with a significant decrease in rhizosphere pH. This acidic medium enhanced Si solubilization, increasing Si+ ions, which competed with Fe3+ and Al3+ ions for specific soil phosphorus sorption sites. Provision of sustainable seed supply systems for chickpea and market linkages for water-soluble silicon are necessary for adoption of this innovation.