GRAKO 1397

Regulation of soil organic matter and nutrient turnover in organic agriculture

Sub-project F1:  Gaseous and leaching nutrient losses in irrigation farming of fertilised sandy soils in Oman - Effects of manure quality and cropping system
Deutsche Forschungsgemeinschaft (DFG) - Research Training Group 1397
"Regulation of soil organic matter and nutrient turnover in organic agriculture"
Laufzeit: 2007-2010
Bearbeiter: Konrad Siegfried

Organic and conventional irrigation farming on the eastern coast of the arid Arabian Peninsula leads to high gaseous and leaching losses of nutrients and carbon from cultivated soils. In order to analyse such losses, the emissions NH3, N2O, CO2 and CH4 were measured on an experimental field near to the town of Sohar in the Sultanate of Oman. This was done using an INNOVA photo-acoustic infrared multi-gas monitor (INNOVA 1312-5, LumaSense Technologies A/S, Ballerup, Denmark) in a closed chamber system. Cumulative leaching losses of nitrogen (TN, NO3-N, NH4-N), phosphorous (P), potassium (K) and dissolved organic carbon (DOC) were measured by suction plates and mixed-bed ion-exchange resin cartridges (NO3-N, NH4-N, PO4-P). Seepage was estimated with the software Hydrus 1d using crop-specific evapotranspiration and hydraulic soil parameters.

The experiment on an irrigated sandy soil with four replications comprised of two types of buffalo manure, characterised by a C/N ratio of 23 with high fibre content (high-high, HH), a C/N ratio of 15 with low fibre content (low-low, LL) and a control treatment with equivalent levels of mineral nitrogen (N), phosphorous (P) and potassium (K). These three fertility treatments were combined with a crop rotation comprised of radish (Raphanus sativus) transplanted on all plots followed by cauliflower (Brassica oleracea var. botrytis) and carrot (Daucus carota ssp. sativus).


Sub-project F2: Gasförmige und sickerungsbedingte C- und N-Verluste aus gedüngten und bewässerten Ackerflächen subtropischer Bergoasen
Deutsche Forschungsgemeinschaft (DFG) - Research Training Group 1397
Laufzeit: 2007-2010
Mohammed Al-Rawahi