Studying the effects of two different biochars on soil water repellency

Water repellency is one of the important physical properties of soil that affects the soil moisture curve, hydraulic conductivity, and so on. The aim of present study is to investigate the effects of adding natural and artificial biochars on water repellency and some other physical and chemical properties of soil. This study was conducted in factorial design with various levels of additives (natural and waste compost biochars) in a randomized complete block design in three repetitions. The considered factors are natural biochar in four levels (0, 1, 3 and 5%) and municipal waste compost biochar in four levels (0, 1, 3 and 5%) with the total of 16 treatments. The water repellency of natural and municipal waste compost biochar was measured by means of the water drop penetration time (WDPT) test and the actual time required for infiltration ( ) was recorded for each 16 treatments. The results showed that increasing the percentage of applied biochars increased . The highest amount of  belongs to treatments No. 5 and 16 were 156 and 170 s, respectively, which increased by 98 and 99 times in comparison with the control treatment. 12 of 16 treatments were classified as wet table or non-water-repellent soil, one treatment in slightly and three treatment as strongly water repellent soil. In general, it can be said that application of biochars, especially the natural biochar, in terms of water repellency does not cause any infiltration problem. Also, it can be concluded that bulk density had an average decrease rate of 4.3% and organic matter and pH had an average increase of 2.2 and 1.8 percentage respectively.