The impact of climate change has become increasingly severe in drylands, resulting in heat stress and water deficiency and, consequently, reducing agricultural production. Biochar plays an important role in improving soil fertility. The properties of sandy soils where water deficiency occurs with a greater frequency need to be enhanced by biochar amendments to increase the water retention capacity (WRC). Few studies have reported the effects of biochar on the readily available water (RAW) of these soils or an evaluation of the optimal application rate of the biochar. In this study, we aimed to assess the effect of different biochar types and application rates on the soil properties related to water retention. Under laboratory conditions, we amended sandy soil with four different types of biochar (woodchip (WBC), waterweed of Ludwigia grandiflora (WWBC), poultry litter (PLBC) and bagasse (BBC)) at rates of 0%, 5%, 10%, 15%, 25%, 50%, 75% and 100%. Soils treated with zeolite and perlite, both conventional materials, were arranged for a comparative study. The water content in the amended soils was recorded at saturation, field capacity, wilting point and oven-dry. Our results show a reduction in the bulk density by increasing the amendment rate across all biochar types. Although the WRC increased with the application rate, the RAW reduced and peaked at a 5% (v/v) biochar content for almost all the biochar types. WBC and WWBC showed the highest RAW increments of 165% and 191%, respectively, at a 10% (v/v) rate. In most cases, higher rates (such as 75% (v/v) of PLBC) caused negative effects on the RAW. Following these results, it is clear that both the biochar type and the application rate significantly influence the hydrological properties and the RAW capacity of sandy soils. A 5% (v/v) biochar amendment could significantly improve the readily available water to mitigate drought in sandy agricultural soils.

This study investigated the effect of the interaction between wood vinegar and biochar feedstock on total biomass, fruit weight (yield), and sugar content of tomato plants (Solanum lycopersicum L.). An experiment was conducted in two locations with six different biochar types produced from either plant or animal feedstock. Each biochar was incorporated into soil (1:2500 g/g) along with chemical fertilizer. Wood vinegar was diluted with water (1:200 mL) and applied once weekly for the vinegar treatment. Biochar application resulted in a higher yield and biomass of the chicken manure biochar owing to its high ammonium-nitrogen content. Vinegar application increased the yields of the plant feedstock, which was particularly evident for most of the yield parameters with the bamboo biochar. Regardless of treatment, yield and biomass were not significantly different between the animal and plant feedstock. The sugar content was higher for the chicken manure and animal litter biochar, which was attributed to better pH conditions. The combination of plant feedstock biochar and vinegar application for improving the yield of tomatoes is promising. In contrast, vinegar application could potentially limit the yield and fruit sugar content of tomato plants treated with animal feedstock biochar. Highlights: • The soil was amended with biochar, with or without vinegar application. • The chicken manure biochar plants had the highest yield and biomass. • Vinegar application increased the yield of the plant feedstock. • Plant and animal feedstock plants had similar yield and biomass. • The pH of the animal feedstock was better because of higher CO₂ and MgO contents. • Fruit sugar content for animal feedstock plants was better due to higher phosphorus.