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Teresina, Brazil

do Nascimento A.F.,University of Sao Paulo | de Sa Mendonca E.,Federal University of Espirito Santo | Leite L.F.C.,Federal University of Vicosa | Neves J.C.L.,Embrapa Mid North | Neves J.C.L.,Federal University of Vicosa
Revista Brasileira de Ciencia do Solo | Year: 2011

The aim of this study was to calibrate the CENTURY, APSIM and NDICEA simulation models for estimating decomposition and N mineralization rates of plant organic materials (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum, Stylosanthes guyanensis) for 360 days in the Atlantic rainforest bioma of Brazil. The models ́ default settings overestimated the decomposition and Nmineralization of plant residues, underlining the fact that the models must be calibrated for use under tropical conditions. For example, the APSIM model simulated the decomposition of the Stizolobium aterrimum and Calopogonium mucunoides residues with an error rate of 37.62 and 48.23 %, respectively, by comparison with the observed data, and was the least accurate model in the absence of calibration. At the default settings, the NDICEA model produced an error rate of 10.46 and 14.46 % and the CENTURY model, 21.42 and 31.84 %, respectively, for Stizolobium aterrimum and Calopogonium mucunoides residue decomposition. After calibration, the models showed a high level of accuracy in estimating decomposition and N- mineralization, with an error rate of less than 20 %. The calibrated NDICEA model showed the highest level of accuracy, followed by the APSIM and CENTURY. All models performed poorly in the first few months of decomposition and N-mineralization, indicating the need of an additional parameter for initial microorganism growth on the residues that would take the effect of leaching due to rainfall into account. Source

Araujo A.S.F.,Federal University of Piaui | Leite L.F.C.,Embrapa Mid North | De Freitas Iwata B.,Embrapa Mid North | De Andrade Lira Jr. M.,University of Pernambuco | And 2 more authors.
Agronomy for Sustainable Development | Year: 2012

Soils around the world are degraded due to inappropriate management practices. There is thus the necessity to find more conservationist agricultural systems. Agroforestry system is an alternative system that helps prevent land degradation while allowing continuing use of land to produce crops and livestock on a sustainable basis. Agroforestry system is a form of sustainable land use that combines trees and shrubs with crops and livestock in ways that increase and diversify farm and forest production while also conserving natural resources. This system enhances organic carbon accumulation in soils by the inclusion of cover crops and permanent vegetation, which is expected to increase the soil microbial biomass. The use of microorganisms aims at improving nutrient availability for plants. Currently, there is an emerging demand to decrease the dependence on chemical fertilizers and achieve sustainable agriculture and agroforestry. Arbuscular mycorrhizal fungi, plant growth-promoting rhizobacteria, and the association of rhizobia with leguminous plants are mutualistic symbioses of high economic importance for increasing agricultural production. The biological nitrogen fixation (BNF) process is an economically attractive and ecologically sound method to reduce external nitrogen input and improve the quality and quantity of internal resources. BNF by associative diazotrophic bacteria is a spontaneous process where soil nitrogen is limited and adequate carbon sources are available. However, the ability of these bacteria to contribute to increased crop yields is only partly a result of BNF. The successful use of legumes is dependent upon appropriate attention to the formation of effective symbioses with root nodule bacteria. An essential component for increasing the use of legumes is the integration of plant breeding and cultivar development, with appropriate research leading to the selection of elite strains of root nodule bacteria. An expansion of the utility of inoculants is also necessary to develop a broad conceptual framework and methodology that is supported by scientific arguments; it is destined to impact assessment of the use of new biological products in agriculture. © INRA and Springer Science+Business Media B.V. 2011. Source

Cardozo F.M.,Federal University of Piaui | Carneiro R.F.V.,Federal University of Piaui | Leite L.F.C.,Embrapa Mid North | Araujo A.S.F.,Federal University of Piaui
Spanish Journal of Agricultural Research | Year: 2016

The aim of this study was to assess the carbon pools of a tropical soil where the native forest was replaced with different pasture systems. We studied five pasture production systems, including four monoculture systems with forage grasses such as Andropogon, Brachiaria, Panicum, and Cynodon, and an agroforestry system as well as a native vegetation plot. Greater availability of fulvic acid was detected in the agroforestry system as compared with that in the other systems. Higher lability of C was detected in the Andropogon system during the dry and rainy seasons and during the dry season in Cynodon. During the dry season, all pastures systems showed deficits in the net removal of atmospheric CO2. The structure and practices of the agroforestry system enables more carbon to be sequestered in the soil as compared with the monoculture pasture, suggesting that it is an important practice to mitigate climatic change and to improve soil quality. © 2016 INIA. Source

das Chagas Oliveira F.,Embrapa Mid North | Calle Collado A.,University of Cordoba, Spain | Carvalho Leite L.F.,Embrapa Mid North
Journal of Sustainable Agriculture | Year: 2012

This article pursues two aims. The first is to assess the degree of sustainability in peasant agroecosystems through the application of the systemic approach, allowing an integrated understanding of technical, environmental, economic, and social impacts to support the agroecological transition process; the second is to comprehend the basis farmers have and the strategies they use in locally favoring the emergence of the innovations that constitute the object of analysis. The conceptual framework used ia that of the MESMIS method, which is based on a set of system attributes for agroecosystem assessment. Results indicate that innovations made by family farmers favored improvements in essential elements of system sustainability, making possible sustainable land use, assuring an increase in income, and maintenance of family employment and farm structuring. These factors cast light on the relevance of local knowledge as a key factor in policies that promote the sustainability of family systems, and as a basis for an agroecological transition process. © 2012 Copyright Taylor and Francis Group, LLC. Source

Ferreira A.C.C.,Embrapa Mid North | Leite L.F.C.,Embrapa Mid North | de Araujo A.S.F.,Federal University of Piaui | Eisenhauer N.,Friedrich - Schiller University of Jena
Land Degradation and Development | Year: 2016

Land-use change is one of the most important anthropogenic environmental change drivers affecting the biodiversity and functioning of ecosystems. However, there is limited knowledge of the consequences for soil processes in many regions around the globe. The Brazilian semi-arid ecosystem known as Caatinga has experienced the transformation from native forest into agricultural land, with heretofore unknown effects on soil processes and microbial properties. The aim of this study was to evaluate the impact of five land-use changes (to maize and cowpea cropland, grape orchard, and cut and grazed pasture) on total organic C (TOC) and total N (TN) stocks and soil microbial properties of Ultisol from Caatinga. Soil samples (0-10 and 10-20cm depth) were collected during the wet and dry periods. Split-split plot analysis of variance was used to test the effects of land use, soil depth, season and the interaction between land-use and soil depth on soil microbial properties, TOC and TN stocks. Land-use effects were more pronounced in the top soil layer than in the lower layer, while the pattern was less consistent in soil microbial properties. Land conversion from native forest to cropland may cause C losses from the soil, but conversion to pastures may even increase the potential of soils to function as C sinks. Grazed pastures showed not only high C and N stocks but also the highest soil microbial biomass and lowest respiratory quotients, all indications for elevated soil C sequestration. Thus, grazed pastures may represent a land-use form with high ecosystem multifunctionality in Caatinga. © 2016 John Wiley & Sons, Ltd. Source

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