Teresina, Brazil
Teresina, Brazil

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do Nascimento A.F.,University of Sao Paulo | de Sa Mendonca E.,Federal University of Espirito Santo | Leite L.F.C.,Federal University of Viçosa | Neves J.C.L.,Embrapa Mid North | Neves J.C.L.,Federal University of Viçosa
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.


Sagrilo E.,Embrapa Mid North | Sagrilo E.,Wageningen University | Jeffery S.,Wageningen University | Hoffland E.,Wageningen University | Kuyper T.W.,Wageningen University
GCB Bioenergy | Year: 2015

Soil amendment with pyrogenic organic matter (PyOM), also named biochar, is claimed to sequester carbon (C). However, possible interactions between PyOM and native soil organic carbon (SOC) may accelerate the loss of SOC, thus reducing PyOM's C sequestration potential. We combined the results of 46 studies in a meta-analysis to investigate changes in CO2 emission of PyOM-amended soils and to identify the causes of these changes and the possible factors involved. Our results showed a statistically significant increase of 28% in CO2 emission from PyOM-amended soils. When grouped by PyOM C (PyC):SOC ratios, the group of studies with a ratio >2 showed a significant increase in CO2 emissions, but those with a ratio <2 showed no significant effect of PyOM application on CO2 emission. Our data are consistent with the hypothesis that increased CO2 emission after PyOM addition is additive and mainly derived from PyOM's labile C fractions. The PyC:SOC ratio provided the best predictor of increases in CO2 production after PyOM addition to soil. This meta-analysis highlights the importance of taking into account the amount of applied PyC in relation to SOC for designing future decomposition experiments. © 2014 John Wiley & Sons Ltd.


Cardozo F.M.,Federal University of Piauí | Carneiro R.F.V.,Federal University of Piauí | Leite L.F.C.,Embrapa Mid North | Araujo A.S.F.,Federal University of Piauí
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.


Araujo A.S.F.,Federal University of Piauí | 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.


Leite L.F.C.,Embrapa Mid North | Oliveira F.C.,Embrapa Mid North | Arajo A.S.F.,University Federal Do Piau | Galvo S.R.S.,Embrapa Mid North | And 2 more authors.
Australian Journal of Soil Research | Year: 2010

No-tillage and organic farming are important strategies to improve soil quality. This study aimed to quantify the effects of the tillage systems and organic management on total organic carbon (TOC), labile C (CL), and biological indicators in an Acrisol in north-eastern Brazil. Five systems were studied: NV, native vegetation; NT/ORG, no-tillage plus organic fertiliser; NT/CHE, no-tillage plus chemical fertiliser; NT/CHE/ORG, no-tillage plus organic and chemical fertiliser; CT/CHE, conventional tillage plus chemical fertiliser. Soil samples were collected in the 00.10 and 0.100.20m depths. TOC stocks were higher in NT/CHE/ORG (00.10m, 14.0Mg/ha; 0.100.20m, 13.0Mg/ha) and NT/ORG (00.10m, 12.6Mg/ha; 0.100.20m, 11.6Mg/ha) than in CT/CHE and NV systems. C L stocks were higher in NT/ORG (3.61Mg/ha) at 00.10m and in NT/ORG, NT/CHE, and NT/CHE/ORG at 0.100.20m. At 00.10m, microbial biomass C content was higher in the NT/CHE/ORG (190mg/kg) and NT/ORG (155mg/kg). Soil microbial respiration rate was similar in all systems. However, qCO2 was higher in the NT/CHE and CT/CHE systems, suggesting a stress in the soil microbial biomass. No-tillage and organic management promoted positive changes in soil organic carbon and soil microbial properties and improved soil quality. © 2010 CSIRO.


Ferreira A.C.C.,Embrapa Mid North | Leite L.F.C.,Embrapa Mid North | de Araujo A.S.F.,Federal University of Piauí | 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.


Araujo A.S.F.,Federal University of Piauí | Cesarz S.,Friedrich - Schiller University of Jena | Leite L.F.C.,Embrapa Mid North | Borges C.D.,University of Sao Paulo | And 2 more authors.
Soil Biology and Biochemistry | Year: 2013

Human activities, such as land use change, cause severe land degradation in many ecosystems around the globe with potential impacts on soil processes. Restoration practices aim at reverting such impacts and reconstituting the biotic composition and functioning of an ecosystem to its initial condition. The aim of this study was to monitor soil microbial properties in degraded lands in Northeast Brazil and to compare those with land under restoration. Soil samplings were conducted in 2009, 2010 and 2011 in two different seasons (wet and dry season) at sites differing in degradation status: native vegetation (NAT), moderately degraded land (MDL), highly degraded land (HDL), and land under restoration for four years (RES). Soil microbial properties showed pronounced fluctuations between seasons with higher levels of functioning in the wet than in the dry season. Soil microbial biomass and enzymes had significantly higher values under native vegetation than in degraded land, while restored land mostly corresponded to native vegetation. Soil microbial biomass, respiratory quotient and enzyme activities were more strongly affected by land degradation than soil chemical properties. Soil microbial properties varied more between seasons and years in highly degraded land than under native vegetation suggesting a buffering effect of the native vegetation on soil microbial processes. However, land degradation effects on soil microbial properties were significant in both seasons. Moreover, our results indicate that the land restoration practice applied here shifted soil microbial community composition as indicated by soil microbial stoichiometry. Our results indicate that land degradation strongly deteriorates soil microbial properties and their stability in time, but that land restoration practices likely are successful in promoting the recovery of some soil microbial functions, even after only four years. However, shifts in soil microbial community composition in restored lands may have significant feedback effects on element cycles. © 2013 Elsevier Ltd.


Oliveira F.D.C.,Embrapa Mid North | Calle Collado T.,University of Cordoba, Spain | Carvalho Leite L.F.,Embrapa Mid North
Agricultural Systems | Year: 2013

This paper seeks to analyze an endogenous development scheme implemented by farming families, involving innovations in the organic production of watermelons; this was a novel local initiative reflecting the creative drive of the farmers themselves, against a background marked by considerable political and institutional uncertainty. The scheme was evaluated in terms of a set of systemic properties measured by multidimensional indicators for farming systems. Data on the selected indicators were collected by field observations, monitoring of production units, and direct semi-structured interviews with farmers. In general terms, the innovations prompted improvements in the various components of extensive environmental and social sustainability, enabling a more sustainable land use through chemical, physical and biological improvements to the soil in the farming systems studied, ensuring increased incomes and the maintenance of family employment, strengthening the farmers' resources and improving their control over resources, and reducing the degree of dependency in relations between the farming unit and the broader context. © 2012 Elsevier Ltd.


de Araujo A.S.F.,Federal University of Piauí | Eisenhauer N.,Friedrich - Schiller University of Jena | Nunes L.A.P.L.,Federal University of Piauí | Leite L.F.C.,Embrapa Mid North | Cesarz S.,Friedrich - Schiller University of Jena
Land Degradation and Development | Year: 2015

Land degradation reducing vegetation cover may affect the soil surface-active fauna because both aboveground and belowground invertebrates depend on complex plant communities. In this study, we evaluated the effect of land degradation and restoration on soil fauna in northeast Brazil. Sites differed in degradation status: native vegetation, moderately degraded land, highly degraded land, and land under restoration for 4years. Araneae and Coleoptera densities were significantly higher in natural vegetation and restored land (8±4 ind./trap and 41±21 ind./trap, respectively) than in degraded lands (-73% and -81%, respectively). The density of Formicidae was significantly higher in natural vegetation (206±181 ind./trap) than in highly degraded land (32±24 ind./trap), while restored land (51±10 ind./trap) and moderately degraded land (37±14 ind./trap) did not differ significantly from the other degradation levels. The density of Orthoptera did not follow the aforementioned patterns, while invertebrate groups mostly had highest densities in natural land and restored land. Linear regressions showed a strong negative relation between faunal density and soil bulk density, and a positive relation with soil organic matter due to an increase in plant cover. Our results indicate that land degradation simplifies soil surface-active invertebrate communities with pronounced decreases in the density of Araneae, Coleoptera, and Formicidae, but that land restoration practices may recover the density of soil fauna even after only 4years. Araneae, Coleoptera, and Formicidae respond sensitively to land degradation and restoration practice and are suggested as indicator groups for restoration success. © 2013 John Wiley & Sons, Ltd.


Sagrilo E.,Embrapa Mid North | Rittl T.F.,Wageningen University | Hoffland E.,Wageningen University | Alves B.J.R.,Embrapa Agrobiology | And 2 more authors.
Geoderma Regional | Year: 2015

Soil amendment with biochar has been claimed as an option for carbon (C) sequestration in agricultural soils. Most studies on biochar/soil organic carbon (SOC) interactions were executed under laboratory conditions. Here we tested the stability of biochar produced in a traditional kiln and its effects on the stocks of native SOC under field conditions. The biochar was characterized using pyrolysis-gas chromatography-mass spectrometry, and then added to an Oxisol under savannah climate. This soil was amended with 0, 5, 10, 20 and 40 Mg ha- 1 of biochar in a randomized complete block design with four replications and cultivated with soybean over four cropping seasons (CSs; 120 days each). Soil samples from the 0-10 cm top layer were collected at the end of the first and fourth CSs and analyzed for CO2 emissions, isotopic C abundance (13C/12C ratio) and enzymatic activity (fluorescein diacetate and dehydrogenase). The biochar showed a low degree of thermal modification. Its relative decomposition rate was higher (k = 0.32-1.00 year- 1) than generally claimed (k = 0.005-0.0005 year- 1), and higher than the decomposition of native SOC (k = 0.22 year- 1). Addition of biochar did not affect the stocks of native SOC. Our findings highlight the need for critically reviewing the potential of locally produced biochar to sequester C. © 2015 Elsevier B.V.

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