Provision of nitrogen as ammonium rather than nitrate increases silicon uptake in sugarcane

Silicon (Si) is important in mitigating abiotic and biotic plant stresses, yet many agricultural soils, such as those of the rainfed production areas of the South African sugar industry, are deficient in plant-available Si, making Si supplementation necessary. Means to maximise Si uptake via the roots from applied silicon sources and thereby enhance crop yields have not yet been fully explored. In a new study published in AoB PLANTS, Keeping et al. found that reduction of rhizosphere pH through provision of nitrogen fertilizer to sugarcane as ammonium rather than nitrate increased silicon uptake from a low-silicon soil amended with calcium silicate slag. They propose that ammoniacal fertilizers have potential for enhancing the solubilisation of silicate slags by acidifying the rhizosphere and increasing silicic acid solubility and availability for plant uptake.