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Biochar amendment of fluvio‐glacial temperate sandy subsoil: Effects on maize water uptake, growth and physiology

Ahmed, F., Arthur, E., Plauborg, F., Razzaghi, F., Kørup, K., Andersen, M. N.
Journal of agronomy and crop science 2018 v.204 no.2 pp. 123-136
agricultural productivity, biochar, biomass, bulk density, corn, crop yield, drought, drying, field capacity, flowering, gravitropism, greenhouse experimentation, irrigation rates, leaf water potential, nitrogen, phosphorus, photosynthesis, porosity, sandy soils, soil water, soil water content, stomatal conductance, straw, subsoil, subsoiling, water content, water holding capacity, water uptake
Coarse sandy soils have poor water retention capacity, which may constrain crop growth during drought. We investigated the effect of biochar amendment to subsoil on crop physiological processes and maize yield, comparing irrigated and drought conditions. A two‐year greenhouse experiment was conducted with one‐time application of straw biochar at concentrations of 0%, 1%, 2% and 3% (B0, B1, B2 and B3). Maize was planted twice in the same large pots one week and again 12 months after biochar application. Plants were fully irrigated until flowering; thereafter, half of them were subjected to drought. Our results indicate B2 and B3 increased soil water content at field capacity. Leaf water potential, stomatal conductance, photosynthesis and transpiration were maintained in B2 and B3 during the drying cycle in year one and in all biochar levels in year two. In the first year, B3 induced negative root geotropism and significantly reduced vegetative biomass under both irrigation schemes. Cob biomass was significantly reduced by B1 under full irrigation. In year two, B3 significantly increased cob biomass under drought. Nitrogen uptake was significantly reduced by B2 in year one, but increased significantly in B3 in year two. In both years, P uptake was significantly increased by B2 and B3. Furthermore, K uptake was significantly increased in B2 in year one and in all biochar treatments in year two. Overall, biochar improved water content of coarse sandy soil due to decreased bulk density and increased porosity after biochar amendment, consequently, improving crop physiological processes including transpiration and photosynthesis. Significant effects on yields tended to be more negative in the first year, and neutral to positive in the second year suggesting the enhancement of biochar effects with ageing. The positive effect in the second year shows biochar's potential for improving agriculture productivity in drought‐prone regions.