Herbivore effect in the assemblages of phytoliths incorporated to soils from cow dung

Abstract

Phytoliths represent an important fraction of soil's components and they are incorporated through different agents. One of the sources of phytoliths to soils and sediments is dung. In particular, in agroecosystems, the incorporation of phytoliths from dung may be of importance, since pastures (grasses) belong to one of the highest producer families. The main objective of this work was to compare the content and state of phytoliths in rumen and dung samples from cows in relation to the phytoliths produced in the forage plants eaten. Secondly, we analyzed if phytolith assemblages differed between dung collected in different pastures in Pampean region, Argentina. Phytoliths from rumen and dung samples from five fistulated cows were compared with the main forage species eaten (Festuca arundinacea). Also, dung of three different pastures (two naturals and one controlled) were compared. Phytoliths of plants and dung were extracted by a calcination technique, while rumen samples were treated with hydrogen peroxide. In rumen and dung samples, the morphologies derived from Festuca arundinacea plants had different stages of degradation: the acute bulbosus and the papillate were the most degraded, while the rondels remained with little wear. A high percentage of phytoliths remained unidentified, probably due to their degradation state. Through phytolith morphometric analysis, it was possible to identify that the principal organ eaten by cows was the inflorescence. The dung belonging from different pastures was differentiated by their phytolith content, although the unidentified morphotypes predominated. Dung allow the incorporation of new morphologies and a high amount of degraded phytoliths to soils, modifying its permanent stock of phytoliths.