Regional Emissions of Nitric Oxide (NO) and Carbon Dioxide (CO2) in Agroecosystems in Central West Region, Brazil
Fernandes, CEFET-BA, email@example.com
Bustamante, UnB, firstname.lastname@example.org
Kozovits, UFOP, email@example.com
Zepp, EPA, Zepp.Richard@epamail.epa.gov
The Central West Region in Brazil has been the focus of intense agricultural expansion since the 1970s and, nowadays, a large area of native cerrado has been converted to agricultural use. The expansion was accompanied by intensive use of fertilizer, irrigation and management practices. However, the consequences of these agricultural practices on NO and CO2 emissions from soil to atmosphere are still unclear. Here, we present estimates of regional emissions of NO and CO2 in a Latosol cultivated with corn, soybean, cotton and irrigated bean, under a no till system. The measurements were made from August,2003 to August,2005. NO and CO2 fluxes were measured before and after planting, after nitrogen fertilization, during the growing season and before and after harvesting. The regional emissions were estimated considering the area occupied by the crops and the cropping cycle (corn 173, soybeans 134, cotton 258 and irrigated beans 135 days). The field cotton had the highest N-NO emission per unit area (0.8 kg ha-1), followed by irrigated beans and corn (0.3 kg ha-1) and soybeans (0.2 kg ha-1). Per hectare, the field cotton and corn contributed 34.6 and 32.0 tons C-CO2, the irrigated beans 25,4 tons and the soybeans 19.4 tons C-CO2. Integrated over all cultivated fields, the highest soil emissions of NO and CO2 came from soybeans which emitted 4.6 Gt N-NO and 0.12 Tg C-CO2 from 22,854,000 ha, followed by corn with 3.7 Gt N-NO and 0.11 Tg C-CO2 from 12,297,000 ha, irrigated beans with 1.2 Gt N-NO and 0.03 Tg C-CO2 from 3,910,000 ha, and cotton with 0.9 Gt N-NO and 0.01 Tg C-CO2 from 1,152,000 ha. The results show that it is necessary for government policies to stimulate management systems that enhance sustainability and that take into account the impacts of agricultural on soil emissions of NO and CO2.
Science Theme: LC (Land Use and Land Cover Change)