Sheep feces decomposition and nutrient release across an environmental gradient in Southern Patagonia

BAHAMONDE, HECTOR; GARGAGLIONE, VERONICA; PERI, PABLO LUIS

Ecología Austral

Asociación Argentina de Ecología

Año: 2017 vol. 27 p. 18 - 28

1667-7838

In southern Patagonia most of the land ranging fromthe mountains to the sea in contrasting environmental conditions is devoted to extensivesheep farming. Existing estimations indicate that in ecosystems under livestockuse, around 85 % of the nitrogen (N) returning to the soil is through animal fecesand urine. However, there is a lack of information concerning the rate of nutrientreturn into the soil from animal feces in Southern Patagonia. In this study, weevaluated the rate of sheep faeces decomposition and nutrient (N, P, Ca and K)release in three different ecological areas of Southern Patagonia representinga West to East environmental gradient. Samples of fresh sheep dung werecollected in the field, processed in the laboratory and located in threeecological areas and subsequently collected periodically during 820 days. The remaining organic matter (OM) of decomposingfaeces did not vary between the three ecological areas. At the end of the trial(820 days) the rate of OM decomposition averaged 63 % of the initial amount. Accordingto the linear regressions performed, the time for reaching a 100 % OM decompositionfluctuated between 3.7 and 4.2 years. Nutrient dynamics followed a common generaltrend, since nutrients were released during the first stages of decomposition andthen fluctuations between nutrient immobilisation and release were observed. Theprevailing environmental conditions among the ecological areas evaluated didnot seem to involve a measurable effect on sheep faeces decomposition andnutrient release. The results obtained in this work may be useful for quantifyingthe return of organic matter and nutrients from sheep faeces to the soil insouthern Patagonia.