Mitigating evaporation and desiccation cracks in soil with the sustainable material biochar

Abstract

AbstractExamining soil cracking due to evaporation and desiccation is very important as these two factors affect the permeability of soil in agricultural systems and engineering construction projects. In order to investigate the effects of a sustainable material on the evaporation and cracking of soil, biochar produced through pyrolysis with wheat straw was experimentally examined as an air‐dried additive. Soil was mixed with different amounts of biochar to produce the samples (0, 2.5, 5, 10, and 20% by weight) which were then tested. The cracking properties were subsequently examined based on variations in water loss. The development of the cracks was quantitatively analyzed by using a digital image processing technique, which provided the optimum biochar content that would mitigate evaporation and the development of desiccation cracks. The results were then plotted, and the rate of evaporation of the water in the soil samples with different biochar contents showed an approximately “step” shaped curve, in which three stages could be observed: rapid, slow and constant rates of evaporation. The rate of evaporation quickly declined with a biochar content of 5%. The fractal dimension of the cracks was also reduced with increases in the biochar content, which meant that biochar could inhibit the degree of soil cracking. The optimum biochar content was therefore 5% by weight in this study, which may effectively prevent soil cracking and reduce evaporation, thus reducing landscape irrigation costs in urban infrastructures or irrigation costs in rural agricultural farming.