Description
More frequent and longer drought periods are predicted to threaten agricultural yield. The capacity of soils to hold water is a highly important factor in controlling drought stress intensity for plants. Biogenic amorphous silica (bASi) pools in soils are in the range of 0–6% and are suggested to help plants resist drought. In agricultural soils, bASi pools declined to values of ~1% or lower) due to yearly crop harvest, decreasing the water-holding capacity of the soils. Here, we assessed the contribution of bASi to the water-holding capacity (WHC) of soil. Consequently, ASi was mixed at different rates (0, 1, 5, or 15%) with different soils. Afterward, the retention curve of the soils was determined via the Hyprop method. Here we show that bASi substantially increases the soil water holding capacity by forming silica gels with a water content at saturation above 700%. An increase of bASi by 1% or 5% (weight) increased the water content at any water potential and plant available water increased by up to > 40% or > 60%, respectively. Our results suggest that soil management should be modified to increase bASi content, enhancing available water in soils and potentially decreasing drought stress for plants in terrestrial ecosystems.