Transport and Transformation of Urea in Soil under Multiple-pit Irrigation

LI Jingling; YANG Wenhui; SUN Xihuan; CHEN Pan; FENG Huijun

doi:10.13522/j.cnki.ggps.2017.06.007

Abstract：In order to improve nitrogen use efficiency in multiple-pit-storage fertigation and protect ecological systems, we experimentally investigated the movement and transformation of urea in laboratory using six plexi-glass boxes filled with soils. The pits were placed at the four corner of each box, and the movement of water and urea from the pit to the soil was measured. The results showed that the water was found mainly in the depth of 20~80 cm and the soil in 0~10 cm depth was relatively dry. At the same depth, water content in the proximity of the pit was higher than that in soil outside the zero-flux plane. The urea distributed mainly in soil proximal the pit and water content in soil outside the zero-flux plane was much lower than that inside the plane. Urea hydrolysis was completed in nine days and its hydrolyzing rate peaked seven day after the irrigation commenced. The hydro-lysis rate decreased with time in a power law. The ammonia distributed mainly in 40~60 cm depth, and its concen-tration at 20 cm from the pit was higher than that in soil outside the zero-flux plane. The spatial distribution of ni-trate was opposite to that of ammonia. The ammonia showed a bigger increase in depths of 40~60 cm and 60~80 cm at 20 cm from the pits and zero flux plane, but the nitrate increased faster in 90~100 depth.