Straw and biochar effects on soil properties and tomato seedling growth under different moisture levels

A greenhouse experiment was conducted to evaluate the effects of wheat straw and its biochar on tomato seedling growth and soil physicochemical properties under different moisture levels. Treatments included control (no amendments, CK), three biochar amendments (B1: 1%, B2: 3% and B3: 6% w/w) and three straw amendments (S1: 1%, S2: 3% and S3: 6% w/w), under two moisture levels (M1: 40% water holding capacity (WHC) and M2: 70% WHC). The straw and biochar had contrasting effects on soil physiochemical properties and physiology of tomato seedlings. The B1 treatment significantly increased the soil urease activity (15%) and decreased the activity of dehydrogenase and β glucosidase enzymes (67% and 56%), as compared to the S1 treatment, especially for the high moisture condition. Biochar significantly improved shoot and root dry weights, biomass and altered chlorophyll contents. Plant antioxidants, superoxide dismutase (SOD), Peroxidase (POD) activities and malondialdehyde (MDA) were significantly decreased in biochar treatments, however, an increasing trend was observed for straw treatments. The current findings suggest that application of high amount of biochar (6%) or low amount of straw (1%) would be a reasonable management practice in semi-arid regions to improve soil physiochemical properties and the physiology of tomato seedlings.