Nitrous oxide emissions from a tropical Oxisol under monocultures and an integrated system in the Southern Amazon – Brazil

Abstract

Although agriculture and livestock systems represent important sources of N 2 O from the soil, they may also aid in emissions mitigation, mainly when integrated systems are taken into account, such as crop-livestock-forest, for food production. This work assessed the soil N 2 O emissions from a tropical Oxisol under row-crop, livestock, forest monocultures, and an integrated crop-livestock-forest system in the Southern Amazon-Brazil. Soil N 2 O emissions were measured using static chambers from November 2014 to October 2016 in four soil use systems [row-crop, livestock, forest, and integrated crop-livestock-forest (CLF)], and in a reference area under native forest fragment. For the whole period, the average of soil N 2 O fluxes was 16.9, 12.2, and 15.4 µg N 2 ON m-2 h-1 , to row-crop, livestock, and CLF systems, respectively, all with a similar average among them. The lowest fluxes were observed in the forest system and native forest fragment, with average fluxes of 4.0 and 6.3 µg N 2 ON m-2 h-1 , respectively, both lower than the agricultural systems. The largest soil N 2 O fluxes were observed throughout the rainy seasons in the row-crop, livestock, and CLF, mostly after N-fertilizer application to the soil surface or in the planted row. As a consequence, the cumulative emissions were greater in row-crop, livestock, and CLF systems, which in the averages of two cycles emitted respectively 1.40, 1.15, and 1.27 kg N 2 ON ha-1 yr-1 , all different of the forest system and native forest fragment (0.33 and 0.52 kg N 2 ON ha-1 yr-1 , respectively). Nitrogen fertilization and soil moisture influenced soil N 2 O emissions of all systems assessed in the Southern Amazon. The N 2 O emissions took place after both factors were met, corroborating the hole-in-the-pipe model. Even with more soil use intensification, once in the same area there were three cultures in succession during a year and perennial trees, CLF did not lead to greater N 2 O emissions from the soil than row-crop and livestock. Thus, CLF represents a good option for N 2 O mitigation for the edaphic and climatic conditions of the Southern Amazon.

Community resilience to natural resource vulnerability due to sand mining through the application of Integrated Farming System (IFS)

“…All result in connected systems for sustainability and resilience to climate change. In line with the results of IFS research, the integration of agriculturallivestock, livestock-forestry and agriculturallivestock-forestry cultivation activities indicated the potential values of environmental preservation (Figure 7), including reducing N2O emissions (Do Nascimento et al, 2020;Amadori et al, 2022). Similarly, the research result of Choudhury et al (2022) showed that IFS practices could reduce runoff and/or soil loss in horticultural and agroforestry systems with soil conservation measures on steep slopes.…”