Fluxo de óxido nitroso (N2O) do solo em um sistema agroflorestal em Tomé Açu, nordeste do Pará

Abstract

The study on the emission of nitrous oxide (N2O) from soil in agricultural systems contributes to the understanding of global climate change, which could aid in minimizing negative impacts on the environment. The importance of this gas due to its direct relationship with the global greenhouse effect and to stratospheric ozone depletion. Some agricultural practices performed in agroforestry systems, when managed correctly can help curb these negative impacts. The use of legumes in these systems has become increasingly common, but its relationship with N2O emissions is still not well understood. Given the importance of processes and factors contributing to the increase in N2O emissions, this study aimed to examine the contribution of legume species (Inga edulis Mart.) And non-legume (Theobroma cacao) in nitrous oxide emissions from soil to the atmosphere through the use of static cameras and different climatic characteristics in an agroforestry system in the city of Tome Açu northeastern state of Para the experiment was conducted in an area of agroforestry (SAF) located in Tome Acu ( PA ) ( 02 ° 33'38 , 5 " S , 48 ° 21'36 , 1 " W ) within the February/2013 August/2012, totaling 11 field campaigns, a fortnightly basis. Static chambers of circular type (diameter = 300 mm ) and rectangular ( 37.5 cm x 57 cm ) were used to determine the emission of N2O from the soil, with the aid of polypropylene syringes with a volume of 20 ml and transferred to flasks borosilicate. The N2O concentration was determined by gas chromatography using a gas chromatograph Varian CP 3800 gas model with an electron capture detector. The variation of N2O emissions were 2.74 to 42.54 mg N m-2 h-1 pulses to and from 1.65 to 30.46 mg N m-2 h- 1 for non-legumes. Higher emissions were observed in the wet season compared to the dry season. The gravimetric soil moisture, soil temperature and inventory of plant residues on the soil were the factors that most N2O emissions from the soil.