Investigating the Changes of Saturated Hydraulic Conductivity and Water Repellency Under the Influence of the Particle Size of Cattle Manure

Animal manure is used to increase the productivity of agricultural products and improve soil properties. Pathogenic microorganisms present in animal manure cause environmental pollution. Therefore, it is necessary to investigate the effect of cattle manure granulation on physical characteristics such as hydraulic conductivity and hydrophobicity of manure in order to be a basis for other researches on water and soil pollution. The aim of this research is to investigate the effect of cow manure size on saturation hydraulic conductivity and hydrophobicity of cow manure. For this purpose, four granulation treatments were prepared (D1-1-2, D2-0.5-1, D3-0.25-0.5 and D4>0.25 mm smaller). Saturated hydraulic conductivity was done by constant load method and water repellency test was done by water drop penetration time method. The obtained results showed that by reducing the size of cow dung particles, saturated hydraulic conductivity decreases significantly at a statistical level of 1%. Respectively, the highest and lowest saturation hydraulic conductivity was related to treatment D4 with hydraulic conductivity of 1.6 cm/min and D1 with hydraulic conductivity of 0.063 cm/min. The reason for this is to reduce the pore size in small grains. Reducing the particle size of cow dung increases water repellency. The highest and lowest degree of water repellency is related to treatment D1 and treatment D4, respectively. The reason for this is the presence of microbial particles rich in fatty acids in smaller granulation treatments. It seems that the use of coarse-grained cow manure in agriculture is a more appropriate option than fine-grained cow manure due to its higher hydraulic conductivity and lack of hydrophobicity.