Soil Carbon and Soil Respiration in Conservation Agriculture with Vegetables in Siem Reap, Cambodia.

A balance between food production and environmental protection is required to sustainably feed a growing population. The resource saving concept of conservation agriculture aims to achieve this balance through implementing simultaneously three conservation practices; no-till, continuous soil cover, and diverse species rotations. An experiment was conducted with smallholder commercial household farmers’ fields in three villages in Siem Reap, Cambodia, comparing conservation agriculture (CA) and conventional tillage (CT). Several soil quality parameters, which relate to the soils’ function as a medium for plant growth, habitat for soil microorganisms, and sink for carbon and recycler of nutrients were measured. The hypothesis was that in CA where there was high organic matter input, CA’s soil will be improved by having more soil organic carbon and nitrogen in the soil and because of having more organic carbon, soil respiration will increase. The results show that in two villages that successfully grew vegetables and cover crop (Crotolaria juncea) had significantly higher soil organic carbon and soil nitrogen with higher respiration rates based on actual soil moisture and temperature. Soil moisture of CA was found to be higher and temperature was lower  compared with  CT. Conservation agriculture may have had improved soils’ carbon content, the soils’ nutrient supplying capacity, and microclimate for soil microorganisms.