Biological activity of soils under systems of organic farming, agroforestry and pasture in the Amazon

Abstract

-The aim of this work was to evaluate biological indicators of soils used under the systems of organic farming, agroforestry and pasture in the south western part of the Amazon region of Brazil. The experiment was carried out at the Seridó Ecological Site, located in Rio Branco, in the state of Acre, Brazil. The experimental design was completely randomised, with five treatments (land-use systems) and six replications, with each replication consisting of four single samples. The systems of land use evaluated were: 1) native forest (control); 2) agroforestry (AFS); 3) pasture; 4) intercropped passion fruit, maize, cassava, pineapple and forage peanut; and 5) intercropped passion fruit, maize, cassava, pineapple and tropical kudzu. It was found that organic farming systems intercropped with kudzu resulted in smaller losses of C-CO 2 through edaphic respiration, and a greater accumulation of microbial biomass carbon. The intercropped organic farming system which included the forage peanut resulted in a greater loss than retention of carbon in the soil at a depth of 5-10 cm. Soil under the agroforestry system was equivalent to the soil of the control (native forest) in relation to the release and retention of carbon through biological activity. At a depth of 5-10 cm, soils under pasture presented similar microbial biomass to those under organic cultivation intercropped with tropical kudzu. However, at that depth, soils under pasture presented greater microbial biomass than those under natural forest, agroforestry or organic cultivation intercropped with forage peanut.

Biological Attributes of the Soil with Intercaled Crops and Oil Palm (Elaeis guineensis Jacq.): Sustainable Management in the Amazon

“…Many works have been developed in the southwest of the Amazon, among them [54], evaluating biological attributes in an Argisol, found higher values of RBS in the pasture area compared to areas of agricultural use and native forest, observing a great similarity between values of respiration rates between native areas and pasture areas, with significant differences for areas used as agricultural systems. These results corroborate [55], observing higher values of RBS in the pasture area when they evaluated the biological activity of soils in organic, agroforestry and pasture systems in the southwest of the Amazon. Still, [56], when investigating RBS, verified the highest values in pasture areas and three forest fragments in comparison with areas of annual and perennial crops.…”

“…In this context, research developed by several authors in the southwest of the Amazon also reported the highest values of C-BMS in the pasture area compared to areas of agricultural use and native forest. These results were attributed to fine root biomass as a factor that can influence the response of microbiological attributes in the Pa system, in addition, the age of establishment as a source of carbon accumulation [54][55].…”

Organic residue inputs influence soil biological properties in organic farming systems

“…The results of soil respiration show that, similarly with microbial biomass, the inputs of organic residue stimulated the soil microbial activity. The increase in soil microbial activity is an indicator of decomposition of organic residues and, thus, promotes a release of nutrients available for plant growth (Silva et al, 2014). Previous studies have shown an increase in soil microbial activity under an organic farming system, as measured by basal respiration (Sudhakaran et al, 2013;Silva et al, 2014).…”

Atividade biológica em solos cultivados com maracujazeiro amarelo adubados com composto orgânico / Biological activity in soils cultivated with yellow passion fruit fertilized with organic compost

“…Tabela 1 -Respiração edáfica -RES (mg C-CO2 m -2 h -1 ); Biomassa microbiana -BMS (mg.C-Cmic.kg -1 solo); Respiração Basal -RBS (mg C-CO2 kg -1 solo h -1 ) e Teor do Carbono do solo (qCO2 g kg -1 solo) de textura franco arenosa sob aplicação de diferentes volumes de composto orgânico em fundação antes do plantio de Além disso, por ser cultivo orgânico, há também naturalmente maior atividade microbiana (FREITAS et al, 2011;SAMPAIO et al, 2008), que na Amazônia estes cultivos podem ter atividade microbiana do solo semelhantes aos solos sob floresta (SILVA et al, 2014), sendo pouco alterada e detectadas em manejos conservacionistas.…”