(*) Summary:  Agricultural activities have long been identified as major contributor to environmental degradation. Consequently, Identification of appropriate tillage system and soil ameliorant becomes a necessity. This study involves the use of diffident tillage methods and rates of manure (organic and inorganic) with the aim of determining their impacts on soil physical quality and isotopic fractionation. Extensive tillage system impacts negatively on soils by destroying soil structure leading to surface sealing, puddlings and increased erosion risks as well as increasing carbon emission to the atmosphere. Stable isotope technique, which is now gaining popularity in soil studies due to its strong potential in providing information that are more difficult to obtain by most other methods, was employed to identify some of these risks. Results obtained using this technique showed that conventional tillage (CT) increased isotope fractionation by causing more δ18O depletion at the soil surface. This implies an increased evaporation and reduced water infiltration because soil water for the analysis was sampled at evaporative front.  Also, more soil 13C and 15N enrichment were observed under CT compared with zero tillage indicating increased rate of soil organic carbon and nitrogen mineralization which could potentially contribute to increased green house gas emission (GHG). Application of poultry manure in this study however, helped in carbon sequestration as 13C isotopic depletion was observed where manure was applied compared with unmanured plots.   Reduced tillage intensity along with organic manuring is therefore required to increase soil productivity and sustainability while maintaining a healthy soil environment.

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(**) Biodata:  Dr. Mutiu A. Busari obtained his Bachelor and Master Degrees at the University of Agriculture, Abeokuta (UNAAB), Nigeria. He is currently on his PhD program at the University of Agriculture, Abeokuta, Nigeria in conjunction with ICTP as a fellow under the ICTP/IAEA Sandwich Training Educational Program (STEP). He is also an Assistant Lecturer at UNAAB. He has published 3 articles in peer-reviewed journals and 2 conference proceedings. His main research interests are amelioration of degraded soil, mitigation of environmental pollution and application of isotopes in agriculture.