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Research Project: MANAGING WATER AVAILABILITY AND QUALITY TO MAINTAIN OR INCREASE AGRICULTURAL PRODUCTION, CONSERVE NATURAL RESOURCES, AND ENHANCE ENVIRONMENT

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Dynamics of soil carbon, nitrogen and soil respiration in farmer’s field with conservation agriculture Siem Reap, Cambodia

Author
item Edralin, Don - North Carolina Agricultural And Technical State University
item Sigua, Gilbert
item Reyes, Manuel - North Carolina Agricultural And Technical State University

Submitted to: International Journal of Plant and Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2016
Publication Date: 5/9/2016
Citation: Edralin, D.I., Sigua, G.C., Reyes, M.R. 2016. Dynamics of soil carbon, nitrogen and soil respiration in farmer’s field with conservation agriculture Siem Reap, Cambodia. International Journal of Plant and Soil Science. 11(1):1-13.

Interpretive Summary: While tillage has been recognized to be beneficial to farmers, it is believed to come with cost to the farmers themselves, the environment, and natural resource base that are depended upon by farming. The rapid decline in soil organic matter caused by tillage results in mineralization of nutrients for plant use, with significant source of carbon emissions, but it also leads to soil crust formation, soil compaction and reduction in water infiltration leading to high potentials of soil erosion. This calls for a new paradigm of sustainable agricultural production that balances increase food production with conservation and enhancement of natural resources. Additional information that are essential for determining where and why conservation tillage and/or conservation agriculture does work in delivering different ecosystem services while increasing crop production are still needed. A study was conducted in farmer’s field to evaluate the effect of conservation agriculture (CA) and conventional tillage (CT) on soil carbon, nitrogen and soil respiration in three villages of Siem Reap, Cambodia. Soil organic carbon, soil total nitrogen and soil respiration for at least in two villages were significantly affected by tillage management. The soil quality was improved in villages under CA compared with villages under CT by increasing soil organic carbon (10.2 to 13.3 megagram per hectare, Mg/ha) and soil nitrogen (0.9 to 1.1 Mg/ha) because of much higher soil moisture (15.7 to 20.0%) retained in CA and with reduced soil temperature (30.4 to 32.4 degree centigrade, oC) during the dry period. Additionally, field soil respiration was higher in CA (55.9 kilogram carbon dioxide–carbon per hectare, kg CO2-C/ha/day) than in CT (36.2 kg CO2-C/ha/day), which indicates more microbial activity and increased mineralization of soil organic carbon for nutrient release. Our results have suggested that CA may have had improved soils’ carbon and nitrogen contents, nutrient supplying capacity and microclimate for soil microorganisms. Moreover, results of our study supported the overall concept and/or premise of CA. Conservation agriculture is a concept of crop production that aims to save resources, strives to achieve acceptable profits with high and sustained production levels, while at the same time conserving the environment. The soil’s functions of supporting plant growth and sink of carbon and recycler of nutrients was likely improved in agroecosystem with CA than in system with CT.

Technical Abstract: The years of intensive tillage in many countries, including Cambodia, have caused significant decline in agriculture’s natural resources that could threaten the future of agricultural production and sustainability worldwide. Long-term tillage system and site-specific crop management can affect changes in soil properties and processes, so there is a critical need for a better and comprehensive process-level understanding of differential effects of tillage systems and crop management on the direction and magnitude of changes in soil carbon storage and other soil properties. A study was conducted in farmer’s field to evaluate the effect of conservation agriculture (CA) and conventional tillage (CT) on soil carbon, nitrogen and soil respiration in three villages of Siem Reap, Cambodia. Soil organic carbon (p=0.01), soil total nitrogen (p=0.01) and soil respiration (p=0.10) for at least in two villages were significantly affected by tillage management. The soil quality was improved in villages under CA compared with villages under CT by increasing soil organic carbon (10.2 to 13.3 megagram per hectare, Mg/ha) and soil nitrogen (0.87 to 1.11 Mg/ha) because of much higher soil moisture (15.7 to 20.0%) retained in CA and with reduced soil temperature (30.4 to 32.4 degree centigrade, oC) during the dry period. Additionally, field soil respiration was higher in CA (55.9 kilogram, kilogram carbon dioxide–carbon per hectare, kg CO2-C/ha/day) than in CT (36.2 kg CO2-C/ha/day), which indicates more microbial activity and increased mineralization of soil organic carbon for nutrient release. The soil’s functions of supporting plant growth and sink of carbon and recycler of nutrients was likely improved in agroecosystem with CA than in system with CT. Our results have suggested that CA may have had enhanced soils’ carbon and nitrogen contents, nutrient supplying capacity and microclimate for soil microorganisms in three villages with agricultural production.