Dietary Tannins Reduce Soil Respiration after Goat Manure Application on an Irrigated Sandy Soil in Oman
Mariko Ingold1, Sibylle Faust2, Philipp Holz1, Aboud Fayad1, Andreas Buerkert1
1University of Kassel, Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics, Germany
The combined hot and moist conditions of irrigated agriculture on sandy soils in northern Oman lead to high gaseous carbon (C) and nitrogen (N) losses and impedes the accumulation of soil organic matter due to its high microbial turnover. In the millennia old oasis in Oman, goat manure is traditionally used as fertiliser and soil conditioner, which is, however, often of poor quality. By altering the goat’s diets using condensed tannins, organic matter can be stabilised and N retention of soils improved. To investigate the effect of dietary tannins on soil respiration after application of manure to soil, a two-year field experiment was conducted on a sandy alluvial soil in the Al-Batinah Plain/northern Oman with the following treatments: mineral fertiliser (MIN); goat manure (GM); tannin-enriched goat manure (TM). GM was obtained from goats fed a basal diet of 50% hay, 47% maize and 3% soybean and TM from goats additionally fed 3.4% Quebracho tannins to the basal diet and applied to radish at 2.6 and 2.8 t C ha-1 year-1 in 2011 and 2012, respectively. CO2 emissions were analysed on field using a portable multi-gas monitor (Innova 1312, LumaSense Technologies A/S) at 1-7 day intervals starting with manure application in February until harvest end of March (n=453).
Keywords: Goat manure, radish cultivation, soil respiration, subtropics, tannins
Contact Address: Mariko Ingold, University of Kassel, Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics, Steinstrasse 19, 37213 Witzenhausen, Germany, e-mail: ingolduni-kassel.de