In Southern Patagonia, most of the land ranging from the mountains to the sea in contrasting environmental conditions is devoted to extensive sheep farming. Existing estimations indicate that in ecosystems under livestock use, around 85% of the nitrogen (N) returning to the soil is through animal feces and urine. However, there is a lack of information concerning the rate of nutrient return into the soil from animal feces in Southern Patagonia. In this study, we evaluated the rate of sheep faeces decomposition and nutrient (N, P, Ca and K) release in three different ecological areas of Southern Patagonia, representing a West to East environmental gradient. Samples of fresh sheep dung were collected in the field, processed in the laboratory and located in three ecological areas and subsequently collected periodically during 820 days. The remaining organic matter (OM) of decomposing faeces 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. According to the linear regressions performed, the time to reach 100% OM decomposition fluctuated between 3.7 and 4.2 years. Nutrient dynamics followed a common general trend, since nutrients were released during the first stages of decomposition, and then, fluctuations between nutrient immobilisation and release were observed. The prevailing environmental conditions among the ecological areas evaluated did not seem to involve a measurable effect on sheep faeces decomposition and nutrient release. The results obtained in this work may be useful for quantifying the return of organic matter and nutrients from sheep faeces to the soil in Southern Patagonia.

In Southern Patagonia, most of the land ranging from the mountains to the sea in contrasting environmental conditions is devoted to extensive sheep farming. Existing estimates indicate that in ecosystems under livestock use, around 85% of the nitrogen (N) returning to the soil is through animal feces and urine. However, there is a lack of information regarding the rate of nutrient return into the soil from animal feces in Southern Patagonia. In this study, we evaluated the rate of sheep faeces decomposition and nutrient (N, P, Ca and K) release in three different ecological areas of Southern Patagonia, representing a West to East environmental gradient. Samples of fresh sheep dung were collected in the field, processed in the laboratory and located in three ecological areas and subsequently collected periodically during 820 days. The remaining organic matter (OM) of decomposing faeces 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. According to the linear regressions performed, the time to reach 100% OM decomposition fluctuated between 3.7 and 4.2 years. Nutrient dynamics followed a common general trend, since nutrients were released during the first stages of decomposition, and then, fluctuations between nutrient immobilisation and release were observed. The prevailing environmental conditions among the ecological areas evaluated did not seem to involve a measurable effect on sheep faeces decomposition and nutrient release. The results obtained in this work may be useful for quantifying the return of organic matter and nutrients from sheep faeces to the soil in Southern Patagonia.

En Patagonie du Sud, le plus haut rang des montagnes de la mer dans les conditions environnementales contrastées est dévoué à l'agriculture extensive. Existing estimations indicate that in ecosystems under livestock use, around 85% of the nitrogen (N) returning to the soil is through animal feces and urine. However, there is a lack of information concerning the rate of nutrient return into the soil from animal feces in Southern Patagonia. In this study, we evaluated the rate of sheep faeces decomposition and nutrient (N, P, Ca and K) release in three different ecological areas of Southern Patagonia, represententing a West to East environmental gradient. Samples of fresh sheep dung were collected in the field, processed in the laboratory and located in three ecological areas and subsequently collected periodically during 820 days. The remaining organic matter (OM) of decomposing faeces 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. According to the linear regressions performed, the time to reach 100% OM decomposition fluctuated between 3.7 and 4.2 years. Nutrient dynamics followed a common general trend, since nutrients were released during the first stages of decomposition, and then, fluctuations between nutrient immobilisation and release were observd. The prevailing environmental conditions among the ecological areas evaluated did not seem to involve a measurable effect on sheep faeces decomposition and nutrient release. The results obtained in this work may be useful for quantifying the return of organic matter and nutrients from sheep faeces to the soil in Southern Patagonia.

في جنوب باتاغونيا، تكرس معظم الأراضي التي تتراوح من الجبال إلى البحر في الظروف البيئية المتناقضة لتربية الأغنام على نطاق واسع. وتشير التقديرات الحالية إلى أنه في النظم الإيكولوجية التي تستخدم فيها الماشية، فإن حوالي 85 ٪ من النيتروجين (N) العائد إلى التربة يكون من خلال براز الحيوان والبول. ومع ذلك، هناك نقص في المعلومات المتعلقة بمعدل عودة المغذيات إلى التربة من براز الحيوانات في جنوب باتاغونيا. في هذه الدراسة، قمنا بتقييم معدل تحلل براز الأغنام وإطلاق المغذيات (N و P و Ca و K) في ثلاث مناطق بيئية مختلفة في جنوب باتاغونيا، مما يمثل تدرجًا بيئيًا من الغرب إلى الشرق. تم جمع عينات من روث الأغنام الطازج في الحقل ومعالجتها في المختبر وتقع في ثلاث مناطق بيئية ثم جمعها بشكل دوري خلال 820 يومًا. لم تختلف المادة العضوية المتبقية (OM) من البراز المتحلل بين المناطق البيئية الثلاث. في نهاية التجربة (820 يومًا)، بلغ متوسط معدل تحلل OM 63 ٪ من المبلغ الأولي. وفقًا للانحدارات الخطية التي تم إجراؤها، تراوح وقت الوصول إلى تحلل OM بنسبة 100 ٪ بين 3.7 و 4.2 سنوات. اتبعت ديناميكيات المغذيات اتجاهًا عامًا شائعًا، حيث تم إطلاق المغذيات خلال المراحل الأولى من التحلل، ثم لوحظت تقلبات بين تجميد المغذيات وإطلاقها. لا يبدو أن الظروف البيئية السائدة بين المناطق البيئية التي تم تقييمها تنطوي على تأثير قابل للقياس على تحلل براز الأغنام وإطلاق المغذيات. قد تكون النتائج التي تم الحصول عليها في هذا العمل مفيدة لتحديد كمية عودة المواد العضوية والمغذيات من براز الأغنام إلى التربة في جنوب باتاغونيا.