The role of dung beetle species in nitrous oxide emission, ammonia volatilization, and nutrient cycling

This study evaluated the role of dung beetle species alone or associated under different species on nitrous oxide (N 2 O) emission, ammonia volatilization, and the performance of pearl millet [ Pennisetum glaucum (L.)]. There were seven treatments, including two controls (soil and soil + dung without beetles), single species of Onthophagus taurus [Shreber, 1759] (1), Digitonthophagus gazella [Fabricius, 1787] (2), or Phanaeus vindex [MacLeay, 1819] (3); and their assemblages (1 + 2 and 1 + 2 + 3). Nitrous oxide emission was estimated for 24 days, when pearl millet was planted in sequence to assess growth, nitrogen yield (NY), and dung beetle activity. Dung beetle species presented greater N 2 O flow of dung on the 6th day (80 g N 2 O-N ha −1 day −1 ) compared to soil and dung (2.6 g N 2 O-N ha −1 day −1 ). Ammonia emissions varied with the presence of dung beetles ( P < 0.05), and D. gazella had less NH 3 − N on days 1, 6, and 12 with averages of 2061, 1526, and 1048 g ha −1 day −1 , respectively. The soil N content increased with dung + beetle application. Dung application affected pearl millet herbage accumulation (HA) regardless of dung beetle presence, and averages ranged from 5 to 8 g DM bucket −1 . A PCA analysis was applied to analyze variation and correlation to each variable, but it indicated a low principal component explanation (less than 80%), not enough to explain the variation in findings. Despite the greater dung removal, the largest species, P. vindex and their species combination, need to be more studied to get a better understanding about their contribution on greenhouse gases. The presence of dung beetles prior to planting improved pearl millet production by enhancing N cycling, although assemblages with the three beetle species enhanced N losses to the environment via denitrification.