Effect of tunneler dung beetles on cattle dung decomposition, soil nutrients and herbage growth

Abstract

AbstractTwo field experiments were conducted to evaluate effects of dung beetles on cattle dung decomposition, soil nutrients and herbage growth. On an orchardgrass (Dactylis glomerataL.) pasture, three treatments, each composed of 1 kg of cattle dung, were placed in a randomized block design. For each treatment, dung beetles of three tunneler species were released at a density of 0, 40 or 80 beetles per dung sample in the 2000 experiment and 0, 40 or 120 beetles per dung sample in the 2001–2002 experiment. The respective weights and nutrient contents in the dung sample remnants were measured for 56 days; nutrients in the soil beneath the dung samples were also measured for the same period in the 2001–2002 experiment. Additionally, herbage yield along with the dung weight and nutrients were measured over 2 years in the 2001–2002 experiment. In both the 2000 and 2001–2002 experiments, the greater the dung beetles released, the greater the decomposition and loss of nutrients from the dung. Inorganic nitrogen (N) in the soil of beetle‐released plots increased considerably until the seventh day according to the beetles released. That pattern in the soil reflected the N loss from the dung. Trends of available phosphorus (P) and exchangeable potassium (K) in the soil were not explained so clearly as the case of N. Yield and N and P uptakes of herbage around the dung were significantly larger in the beetle‐released plot than in the no‐beetle released plot in September of the first year in the 2001–2002 experiment. In other seasons (July 2001 and May, July and September 2002), however, significant relationships between yield and nutrient uptakes of herbage and dung beetle activities were not detected. These results indicate that dung beetles promoted dung decomposition and nutrient transfer from the dung to soil, however, subsequent effects on herbage growth were not clear under field conditions.