Changes in Physico-Chemical Properties of a Sandy Loam Soil Depending on the Particle Size of Hazelnut Shell-Derived Biochar

Abstract

This study evaluated the effects of hazelnut shell-derived biochar particle sizes on the soil’s physical and chemical properties, and on various nutrient contents present in the sandy loamy soils. For this purpose, an incubation experiment in the plastic high tunnel has been performed under sixteen treatments (control-only soil), and at four incubation times (30, 60, 90, and 120 d), by using three different biochar sizes (≤ 1, 1 - 2, and 2 - 4 mm). The addition of 1 - 2 and 2 - 4 mm biochar during the incubation time decreased the bulk density in the soil by 26%. The particle size ≤ 1 mm on the other hand, increased the available water content, percentage of aeration porosity, and macropore, but decreased the micropore percentage in the soil. The soil’s pH has been the highest at 1 - 2 mm, 120 d sample, organic matter content at ≤ 1 mm, 120 d sample, and total nitrogen at ≤ 1 mm, 60 d sample. Regarding the available phosphorus and extractable potassium contents, the most effective particle size has been ≤ 1 mm and the incubation period has been 90 d for P and 60 d for K. The reduction in biochar particle size decreased the soil’s micro element content. The results showed that among all applications ≤ 1 mm biochar particle size was the most effective size on many physico-chemical properties of sandy loam soils. Also, a potential study related to the subject of this research focusing on the effects of different textures of particle sizes derived from hazelnut shell biochars.