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The increase of greenhouse gases in the atmosphere raises the average temperature of the planet, triggering problems that threaten the survival of humans. Protecting the global climate from the effects of climate change is an essential condition for sustaining life. For this reason, governments, scientists, and society are joining forces to propose better solutions that could well-rounded environmentally, social and economic development relationships. International climate change negotiations involve many countries in establishing strategies to mitigate the problem. Therefore, understanding international negotiation processes and how ratified agreements impact a country is of fundamental importance. The purpose of this paper is to systematize information about how climate negotiations have progressed, detailing key moments and results, analyzing the role that Brazil played in the course of these negotiations and the country’s future perspectives., O aumento dos gases de efeito estufa na atmosfera eleva a temperatura média do planeta, desencadeando problemas que ameaçam a sobrevivência do ser humano. A proteção do clima global frente aos efeitos das mudanças climáticas é uma condição essencial para a sustentação da vida. Por essa razão, governos, cientistas e a sociedade estão unindo forças para propor melhores soluções que possam agregar relações de desenvolvimento ambiental, social e econômico. As negociações internacionais sobre a mudança do clima envolvem muitos países no estabelecimento de estratégias para a mitigação do problema. Portanto, entender os processos internacionais de negociação e de que maneira os acordos ratificados impactam um país são de importância fundamental. O objetivo deste artigo é sistematizar informações sobre como as negociações têm procedido, detalhando momentos chave e os resultados, analisando o papel que o Brasil desempenhou no decorrer dessas negociações e as perspectivas futuras do País. &nbsp

In order to clarify the effect of mixed planting in the dynamics of phosporus (P), we assessed the fractions of this element in mixed plantings of Eucalyptus urophylla × E. grandis (Urograndis) and...

Soil, water, and nutrient loss by water erosion are among the main factors leading to land degradation, decreasing soil productivity and the provision of ecosystem services. The Cerrado-Amazon ecotone in western Brazil has suffered rapid land-use cover changes with impacts on soil erosion and land degradation. Despite the importance of the region for Brazilian agriculture and environmental conservation, studies on soil, water, and nutrient loss are still scarce. We tested integrated crop-livestock-forestry (ICLF) as a sustainable agriculture management system for the Cerrado-Amazon ecotone region. A field experiment was established in the north of Mato Grosso state to quantify total soil, water, carbon and nitrogen loss during the rainy season in 2012-2013 in plots of integrated crop-forestry (ICF), pasture (PAST), eucalyptus plantation (EUC), no-tillage crop succession (CS) and bare soil (BS). Total soil, water, carbon and nitrogen losses in BS were, on average, 96.7% higher than in ICF, EUC, PAST, and CS. ICF had significantly lower water loss than CS, EUC and PAST. Total loss of carbon (4.3 - 428.2 kg ha-1) and nitrogen (0.3 - 29.2 kg ha-1) differed significantly among treatments. The production systems with tree components (EUC and ICF) and PAST showed reduced soil and nutrients loss compared to CS. Our results demonstrated that ICLF can avoid soil quality loss and thus improve agriculture sustainability in the Cerrado-Amazon ecotone. | Resumo: A erosão hídrica é um dos principais fatores da degradação dos solos, impactando seu potencial produtivo e capacidade de provisão de serviços ecossistêmicos. O ecótono Cerrado-Amazônia, no norte de Mato Grosso, Brasil, tem sofrido intensas modificações em seu uso e cobertura com impacto na erosão e degradação do solo. Apesar da importância ambiental e agropecuária da região, estudos sobre as perdas de água, solo e nutrientes são escassos. Neste trabalho, testamos a utilidade da integração lavoura-pecuária-floresta (ICLF) para a produção agrícola sustentável no ecótono Cerrado-Amazônia. Foi implantado um experimento de campo no norte de Mato Grosso para quantificar as perdas de solo, água, carbono e nitrogênio durante o período chuvoso de 2012-2013 em parcelas de integração lavoura-floresta (ICF), pastagem (PAST), plantação de eucalipto (EUC), plantio direto com sucessão de culturas (CS) e solo descoberto (BS). As perdas totais de água, solo, carbono e nitrogênio foram, em média, 96,7% maiores em BS, quando comparadas a ICF, EUC, PAST e CS. As perdas de água e solo foram significativamente menores na ICF comparado a CS. As perdas totais de carbono (4.3 - 428.2 kg ha-1) e nitrogênio (1.05 - 10.4 kg ha-1) diferiram significativamente. Os sistemas com um componente arbóreo (EUC e ICF) e PAST tiveram menores perdas de solo e nutrientes em comparação com CS. Nossos resultados demonstraram que ICLF pode evitar a perda de qualidade de solo, melhorando a sustentabilidade da agricultura no ecótono Cerrado-Amazônia. Made available in DSpace on 2021-12-02T19:00:24Z (GMT). No. of bitstreams: 1 2021-cpamt-caz-short-term-effect-crop-livestock-forestry-system-soil-water-nutrient-loss-cerrado-amazon-ecotone.pdf: 2441861 bytes, checksum: 2412c10b0bb509387b7662ac6920409a (MD5) Previous issue date: 2021 Título em português: Efeito da integração lavoura-pecuária-floresta em fase inicial sobre as perdas de solo, água e nutrientes no ecótono cerrado-amazônia

The objective of this work was to evaluate whether balsa wood plantation and its fertilization can improve soil carbon stocks. Total carbon stocks in the soil-biomass system, at 0.0-0.30 m soil depths, were evaluated under three fertilization strategies, after three and seven years, and compared with carbon stocks from native forest and degraded pasture. At the highest fertilization level, balsa wood showed a carbon stock similar to that of the native forest (65.38 Mg ha-1) and, after seven years, it increased carbon stock by 18% in the soil, and by 42% in the soil-biomass system. Resumo: O objetivo deste trabalho foi avaliar se o plantio de pau-de-balsa e seu manejo nutricional aumentam os estoques de carbono no solo. Os estoques de carbono total do sistema solo-biomassa à profundidade de 0,0-0,30 m foram avaliados em três níveis de adubação, após três e sete anos, e comparados com mata nativa e pastagem degradada. No nível de maior adubação, o pau-de-balsa apresentou estoque de carbono semelhante ao da mata nativa (65,38 Mg ha-1) e, após sete anos, aumentou o estoque de carbono em 18%, no solo, e em 42%, no sistema solo-biomassa.

O compartimento terrestre e o maior reservatorio de carbono no solo e armazena cerca de tres vezes mais que o compartimento atmosferico. Porem, a atmosfera tem aumentado suas concentracoes, devido as elevadas emissoes de gases de efeito estufa, decorrente principalmente do consumo de combustiveis fosseis e queimadas das florestas. O Brasil e um dos maiores emissores, especialmente de dioxido de carbono, pelo qual o setor de mudancas do uso da terra e florestas sao responsaveis majoritariamente pelas emissoes. O solo em condicoes naturais tem um equilibrio entre a entrada e saida de carbono, no entanto quando o solo e cultivado, principalmente com sistemas convencionais, ha uma perda significativa dos estoques de carbono do solo. No entanto, quando e adotado manejos conservacionistas ocorre o mecanismo de protecao fisica do carbono atraves da formacao e estabilizacao dos agregados, que dificulta o acesso dos microrganismos a decomposicao e mantem estocado no solo, o que mitiga a emissao para atmosfera. Diante do exposto, este trabalho teve como objetivo mostrar como os manejos influenciam no estoque de carbono no solo, e como e atuacao do mecanismo de protecao fisica de agregados em sistemas conservacionistas, demostrando como foram os avancos na pesquisa da interacao da materia orgânica com a formacao e estabilizacao de agregados. Stock and Mechanism of Physical Protection of Soil Carbon in Agricultural Managements A B S T R A C T The terrestrial compartment is the largest carbon reservoir in the soil and stores about three times as much as the atmospheric compartment. However, the atmosphere has increased its concentrations, due to the high emissions of greenhouse gases, mainly due to the consumption of fossil fuels and forest fires. Brazil is one of the largest emitters, especially of carbon dioxide, for which the sector of land use change and forests are responsible for the majority of emissions. Soil under natural conditions has a balance between carbon input and output, however when the soil is cultivated, mainly with conventional systems, there is a significant loss of soil carbon stocks. However, when conservation management is adopted, there is a mechanism for the physical protection of carbon through the formation and stabilization of aggregates, which hinders the access of microorganisms to decomposition and keeps them stored in the soil, which mitigates the emission into the atmosphere. In view of the above, this study aimed to show how the management influences the carbon stock in the soil, and how the mechanism of physical protection of aggregates in conservationist systems works, demonstrating how advances were made in researching the interaction of organic matter with formation and stabilization of aggregates. Key words: aggregates, carbon dioxide, greenhouse effect, crop-livestock-forest integration, organic matter

Conventional pasture management has been responsible for diffuse soil degradationin tropical pastures. However, sustainable management practices can be used to improve soil health. We tested the effect of adopting intensive and diversified pasture management systems, i.e., fertilized pasture (FP), integrated crop-livestock (ICL) and integrated livestock-forest (ILF), in comparison to conventional pasture management (CS) in Brazil. The treatments were located under contrasting climate conditions (tropical humid, tropical mesic and subtropical) and soil types (Oxisol and Ultisol). The conversion time from CS to FP, ICL and ILF ranged from 6, 3–15 and 3 years, respectively. We focus on management effects on soil chemical and biochemical properties and their interactions with the soil bacterial community structure and soil C accumulation. The results showed that pasture intensification and diversification in sites previously managed under CS, increased by 82% the soil chemical properties related to soil fertility and shifted the soil bacterial community structure. The soil biochemical properties such as microbial biomass C, geochemical P and the enzymes β-glucosidase and acid phosphatase were the most sensitive in the conversion of CS to FP, ICL and ILF. The structural equation modeling suggested that for FP, ICL and ILF there was a positive impact of soil bacterial community structure and mainly soil chemical properties on soil C accumulation. Results in the present study provided useful knowledge for the best understanding of soil-management-microbe interactions, and provide more insights into the controlling factors of soil C accumulation during management system changes in pastures sites in Brazil.

Brazil has always maintained a prominent position in negotiations within the United Nations Framework Convention on Climate Change, playing a major role in setting increasingly ambitious goals and encouraging consensus among Parties. With the purpose of reducing GHG emissions from the agricultural sector and disseminating and financing good agricultural practices, Brazil developed a platform of sustainable technologies and public policies, as the Low Carbon Agriculture Plan (the “ABC Plan”). This article reviews the main milestones of Brazil’s role in the international negotiation on climate change, how these factors affected the Brazilian agricultural sector between 2009 and 2018 and the authors’ personal view on this context. The objective is to provide an overview of Brazil’s actions regarding the agricultural sector which contribute to the voluntary commitment assumed by the Brazilian government at COPs 15 and 21 and to provide a critical analysis of how these actions are being implemented. The main results show that low carbon agriculture has been consolidated as the main Brazilian strategy for sustainable rural development,but it is vital for our country to continue with these actions., O Brasil sempre manteve uma posição de destaque nas negociações da Convenção-Quadro das Nações Unidas sobre Mudança do Clima, desempenhando um papel importante no estabelecimento de metas cada vez mais ambiciosas e no incentivo ao consenso entre as Partes. Com o objetivo de reduzir as emissões de Gases de Efeito Estufa (GEE) do setor agrícola e disseminar e financiar boas práticas agrícolas, o Brasil desenvolveu uma plataforma de tecnologias e políticas públicas sustentáveis, como o Plano de Agricultura de Baixo Carbono (o “Plano ABC”). O presente artigo faz uma revisão dos principais marcos da atuação do Brasil no âmbito da negociação internacional sobre mudança do clima, como esses fatores afetaram o setor agrícola brasileiro, entre 2009 e 2018, e a visão pessoal dos autores sobre esse contexto. O objetivo é fornecer uma visão geral das ações do Brasil em relação ao setor agrícola, que contribuem para o compromisso voluntário assumido pelo governo brasileiro nas COPs 15 e 21 e para fornecer uma análise crítica de como essas ações estão sendo implementadas. Os principais resultados mostram que a agricultura de baixo carbono se consolidou como a principal estratégia brasileira para o desenvolvimento rural sustentável, porém é vital que o país continue com essas ações.

Made available in DSpace on 2020-12-10T19:45:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Fundacao de Apoio a Pesquisa do Estado de Mato Grosso Rede ILPF Empresa Brasileira de Pesquisa Agropecuaria (Embrapa) Soil organic carbon (SOC) is the main terrestrial carbon reservoir. The spatial distribution of SOC is mainly regulated by environmental factors and anthropogenic activity. Historically, land-use change has been responsible for much of the world's greenhouse gas emissions. However, carbon storage can be improved through agricultural management, either by increasing carbon inputs through higher crop yields or by delaying the release of carbon into the atmosphere. Therefore, it is essential to correctly choose which cover crops to use and how long these crops will remain in the crop rotation system. In order to clarify these issues, the objective of this work was to evaluate the chemical quality and changes in soil carbon stock between no-tillage and soybean/com crop succession systems and integrated crop-livestock systems. The study was carried out in Querencia (MT), Brazil, located in the Cerrado/Amazon ecotone. The integrated systems were studied between 2007 and 2014. These systems followed annual crop rotation and forage rotation, and were laid out as a consortium or were isolated, with the aim of producing grain and meat. In order to determine soil chemical properties, 170 sampling plots were randomized among the treatments. The highest carbon values were observed in the integrated crop-livestock systems (ICL), probably due to higher inputs of organic residues. Crop rotation with plants of different families allowed better land use and soil exploration. However, integrated production systems comprising longer pasture periods, no-tillage, and soybean/corn crop succession decreased soil carbon. When comparing carbon stocks from 2010 to 2014, only integrated production systems ICL2 and ICL3 were able to increase carbon stocks. Our results highlight the importance of length of growing and correct choice of cover crops in maintaining SOC stocks, and thus provide insights to improve SOC stocks in agricultural land in Brazil's main producing region. Univ Sao Paulo, Luiz de Queiroz Coll Agr, Dept Soil Sci, BR-13418900 Piracicaba, Brazil Univ Fed Mato Grosso UFMT, Inst Ciencias Agr & Ambientais, BR-78557267 Sinop, Brazil Brazilian Agr Res Comporat Embrapa, BR-70770901 Brasilia, DF, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Plant Hlth Rural Engn & Soils, BR-15385000 Ilha Solteira, Brazil Brazilian Agr Res Comporat Embrapa, BR-78550970 Sinop, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Soils & Fertilizers, BR-14884900 Jaboticabal, Brazil Brazilian Agr Res Comporat Embrapa, BR-86001970 Londrina, Parana, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Plant Hlth Rural Engn & Soils, BR-15385000 Ilha Solteira, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Soils & Fertilizers, BR-14884900 Jaboticabal, Brazil Fundacao de Apoio a Pesquisa do Estado de Mato Grosso: FAPEMAT. 0561074/2016

Globally, poorly managed pasture can contribute to increasing greenhouse gas (GHG) emissions. In Brazil, sustainable management systems are being proposed to reduce carbon dioxide (CO2) emissions and increase the soil C stock under degraded pasture. However, despite the potential benefits in the adoption of sustainable management systems, few studies have been carried out seeking to analyze their long-term effects on the soil C cycle. In this study, we used the DayCent model to simulate the effects of converting poorly managed pastures (PMP) to more-intensive and diversified systems of pasture management [fertilized pasture (FP), integrated crop-livestock (ICL) and integrated livestock-forest (ILF)] on long‐term soil C stocks and microbial biomass C (MBC). We also evaluated the effects of different pasture management scenarios for FP (fertilization frequency), ICL (time of implementation of the crop phase) and IFL (spacing between the tree rows). The DayCent model estimated that the conversion of PMP to FP, ICL and ILF increases the soil C stocks by 0.95, 0.04–0.70 and 0.16 Mg ha−1 yr−1, respectively. Similarly, the MBC contents also increased with conversion, mainly for ICL and ILF. In addition, the fertilization of the pasture every year (FP), the implementation of the crop phase within two years (ICL) and the spacing between the tree rows of 15 m (ILF) showed the highest soil C stocks and MBC contents. FP, ICL and IFL were also GHG sinks of 43, 57 and 116 Mg CO2eq ha−1, respectively. These results can help national initiatives associated with the recovery of degraded pasture in Brazil.

Resumo O objetivo deste trabalho foi avaliar, em condição de chuva natural, a perda de solo e água em sistemas de produção com integração lavoura-floresta ou com sucessão soja-milho. O experimento foi realizado em Latossolo Vermelho-Amarelo com textura muito argilosa, em uma região de transição Cerrado/Amazônia. Os seguintes usos e coberturas do solo foram avaliados: sistema integração lavoura-floresta; lavoura com sucessão soja-milho+braquiária; e solo descoberto. As lavouras foram cultivadas em sistema plantio direto em sucessão soja-milho+braquiária, todos os anos, independentemente do sistema de produção. A perda de solo por erosão hídrica, nos três anos avaliados, foi de 0,215 Mg ha-1 por ano, no sistema integração lavoura-floresta, e de 0,753 Mg ha-1 por ano na lavoura com sucessão soja-milho. Estes valores situaram-se abaixo do limite de tolerância, que é de 11,1 Mg ha-1 por ano, e os menores valores observados com a integração lavoura-floresta apontam para o elevado potencial conservacionista desse sistema. Abstract The objective of this work was to evaluate, under conditions of natural rainfall, the soil and water losses in crop-forest integration systems or in soybean-corn succession. The experiment was carried out in a clayey Latossolo Vermelho-Amarelo (Oxisol), in a Cerrado/Amazon transition region. The following land use and soil covers were evaluated: crop-forest integration system; soybean-corn+brachiaria succession system; and bare soil. Crops were cultivated under no-tillage in soybean-corn+brachiaria sucession, every year, regardless of the production system. In the three years of evaluation, soil losses by hydraulic erosion were of 0.215 Mg ha-1 per year, in the crop-forest integration system, and of 0.753 Mg ha-1 per year, in the soybean-corn succession system. These values were below the tolerance limit, which is of 11.1 Mg ha-1 per year, and the lowest values for crop-forest integration point towards the great conservation potential of this production system.

Objetivou-se comparar o sistema de integração lavoura-pecuária-floresta com sistemas exclusivos quanto à assimilação e manutenção do carbono orgânico total (COT) e carbono lábil (CL), após o segundo ano de estabelecimento. Os tratamentos constituíram os seguintes sistemas de produção: floresta de eucalipto (EUC), pastagem com Brachiaria brizantha (PAST), lavoura de soja-milho consorciada com B. brizantha (LAV) e integração lavoura-pecuária-floresta (ILPF). Uma área de fragmento florestal nativo (Mata) e uma de pousio (Pousio) foram utilizadas como referência. A área sob cultivo de EUC obteve o menor teor de COT na camada 0-5cm, enquanto LAV e PAST apresentaram os maiores teores. Por sua vez, os teores de COT para o sistema ILPF, na camada 0-5cm, ficou em uma posição intermediária aos demais. A conversão da vegetação nativa para em cultivo agrícola e florestal contribuiu para a redução dos estoques de COT no solo em 20% na camada de 0-30 cm, representando uma perda de 17,4 Mg ha-1. O efeito do componente florestal na distribuição horizontal do estoque de COT dentro do ILPF foi favorecido no sentido sul, tendência não verificada para CL. Em curto prazo, os impactos dos sistemas conservacionistas sobre os teores de COT e CL do solo foram identificados apenas na camada superficial.Palavras-chave: agrossilvipastoril; permanganato de potássio; matéria orgânica do solo LABILE AND TOTAL CARBON POOLS IN SOIL UNDER INTEGRATED CROP-LIVESTOCK-FOREST SYSTEM IN THE CERRADO/AMAZONIA ECOTONE ABSTRACT:The aim of this experiment was to evaluate the carbon assimilation and maintenance among an integrated crop-livestock-forest system and nonintegrated systems through the pools of total soil organic carbon (COT) and labile carbon (CL) after the second year of establishment. Treatments comprised the following production systems: eucalyptus forest (EUC), Brachiaria brizantha pasture (PAST), soybean-corn tillage intercropping with B. brizantha (LAV) and integrated crop-livestock-forest system (ILPF). An area of native forest fragment (Mata) and a fallow area (Pousio) were used as references. The effects of the forest component on the COT and CL pools in the ILPF were also evaluated. The area under EUC had the lowest concentration of COT in 0-5cm layer, while LAV and PAST showed higher concentrations. Conversion of natural vegetation to cultivated systems reduced soil C stock by 20% in the 0-30 cm layer which corresponded to 17.4 Mg ha-1. The results suggest that the effect of forest component in the horizontal distribution of the TOC stock was favored in the south face of the ILPF, but this trend was not observed for CL. In a short term, the effects of ILPF on COT and CL pools were not statistically detectable.Keywords: agrosilvopastoral, soil organic matter, potassium permanganate. DOI: http://dx.doi.org/10.5935/2318-7670.v05nespa09

Several studies indicate that the use of integrated production systems, such as integrated crop-livestock-forest systems (ICLF), improves the quality of the soil and consequently the sequestration of organic carbon in the soil. In this way, this work aims to evaluate the carbon stocks in soil under different management systems in the Cerrado/Amazonia transition zone, namely: ICLF, no-tillage, pasture and eucalyptus plantation. For this, two soil samplings were done in 2011 and 2014, in the 0 - 5, 5 - 10 and 10 - 30 cm layers. Soil carbon and nitrogen stocks were analyzed. ICLF system was the treatment that obtained the highest percentage of carbon gain (7.8%) after three years of establishment which represents to an increase of 5.5 Mg·ha-1. Management systems, such as ICLF, with minimal soil disturbance combined with crop rotations that contribute to the quantity and quality of residues input, increase soil organic matter content. Carbon stock data show the potential of ICLF systems to increase soil carbon stocks. Made available in DSpace on 2017-11-02T09:01:27Z (GMT). No. of bitstreams: 1 2017cpamtmatoschangesoilcarbonstockilpfamazonregion.pdf: 1651371 bytes, checksum: 00373b12576195b9b1a56433d2284a94 (MD5) Previous issue date: 2017-10-31

We investigated the chemical and biochemical composition, residue decomposition, and mineralization rate of leguminous (Cajanus cajan, Crotalaria spectabilis, and Lablab purpureus) and spontaneous vegetation in two experimental coffee systems in southeast Brazil. The nitrogen (N) content of the shoot biomass varied from 19.3 to 45.7 g kg−1, and phosphorus (P) content ranged from 1.6 to 3.8 g kg−1. C. cajan contained the greatest values of N and P, whereas spontaneous plants had the lowest values. In both areas, spontaneous vegetation had the greatest values of carbon (C) / P, C/N, polyphenol/N, and (lignin + polyphenol) / N ratios. Decomposition rate increased in the order C. cajan < C. spectabilis < L. purpureus < spontaneous vegetation. There was no correlation between the chemical and biochemical composition and the decomposition rate under field conditions. However, the cumulative carbon dioxide (C-CO2) produced by the residues under laboratory conditions was correlated positively with initial content...

Pines (Pinus sylvestris L.) have been widely used for monoculture forest stands in north-eastern Germany. However, several studies have discussed the need to convert monoculture into mixed forest stands such as pine–oak forest. In this study, we evaluated the impact of 102 years-old pine (P. sylvestris L.) in monoculture and mixed forest stands of P. sylvestris + Quercus petraea (Matt.) Liebl. of different ages (10, 35, 106 and 124 years-old) on the dynamics of soil organic phosphorus (Po) pools. The study was carried out in the Northern German Lowlands of Brandenburg. Soil samples were taken from forest floor and two mineral soil layers at the depths of 0–10 and 10–20 cm. Different P forms of the sandy soil were obtained by sequential P fractionation, using acid and alkaline extractants. The soil total P (STP) ranged from 100 to 183 mg kg− 1 whereas total organic P (TPo) ranged from 77 to 148 mg kg− 1. STP was higher in mixed forest stand than in monoculture and decreased with soil depth. The TPo and labile-P in both soil layers increased significantly with increase in age of oak trees. In addition, TPo content was lower in mineral soil compared to the forest floor and accounted for more than 50% of soil total P in the forest stands. The most available-P fraction–labile-P predominated in the oldest pine–oak forest stand (P + O124), accounting for 29% of STP at the 0–10 cm soil depth. The largest P fraction comprised NaOH–Po and represent 62% of STP. Results showed that forest transformation from pure pine monoculture forest into pine-oak mixed forest stands promoted an increase in the TPo and P available. Furthermore, the forms of labile available P increased with age of oak trees, which are capable of maintaining larger fractions of available P under mixed forest stands.

The conversion of silvopasture to different land use systems cause effective changes in soil carbon distribution, due to disturbances in soil aggregation promoted by soil management and changes in crop residues inputs and decomposability. We evaluate the C and N stocks, and organic C fractions in soils under continuous arable land (AR) and silvopasture with apple trees and grass (SP); and after 4 years of conversion from silvopasture to arable land (SP-AR) and grassland (SP-GL). Total N (TN) and organic C (TOC), as well as microbial biomass carbon (CMB), light fraction (CLF) and heavy fraction (CHF) were evaluated at two different depths (0–10 and 10–20 cm). After 4 years of conversion, SP-AR and SP-GL presented C and N stocks similar to the observed for SP when the 0–20 cm depth was considered. However, AR presented TOC and TN stocks around 21 and 10% lower than SP, respectively. SP-AR tended to present the lowest CMB stocks and was positively correlated with salt extractable organic C (r 2 = 0.60, P

The objective of this work was to evaluate the C and N stocks and organic-C fractions in soil under mixed forest stands of Scots pine (Pinus sylvestris L.) and Sessile oak (Quercus petraea [Matt.] Liebl.) of different ages in NE Germany. Treatments consisted of pure pine (age 102 y), and pine (age 90-102 y) mixed with 10-, 35-, 106-, and 124-y-old oak trees. After sampling O layers, soils in the mineral layer were taken at two different depths (0-10 and 10-20cm). Oak admixture did not affect total organic-C (TOC) and N stocks considering the different layers separately. However, when the sum of TOC stocks in the organic and mineral layers was considered, TOC stocks decreased with increasing in oak age (r 2 = 0.58, p < 0.10). The microbial C (C MB ) was not directly correlated with increase of oak age, however, it was positively related with presence of oak species. There was an increase in the percentage of the C MB -to-TOC ratio with increase of oak-tree ages. On average, light-fraction C (C LF ) comprised 68% of the soil TOC in upper layer corresponding to the highest C pool in the upper layer. C LF and heavy-fraction C (C HF ) were not directly affected by the admixture of oak trees in both layers. The C HF accounted on average for 30% and 59% of the TOC at 0―10 and 10-20 cm depths, respectively. Despite low clay contents in the studied soils, the differences in the DCB-extractable Fe and Al affected the concentrations of the C HF and TOC in the 10―20cm layers (p < 0.05). Admixture of oak in pine stands contributed to reduce topsoil C stocks, probably due to higher soil organic matter turnover promoted by higher quality of oak litter.

Differences in soil P among silvopasture, grassland, and arable lands have been well established. Nevertheless, most of the reports compare soil properties under long-term sites. Thus, there exists little information on the effect of the conversion of silvopasture to arable or grassland use on soil P pools. The objective of the study was to determine the impact of converting silvopasture system (SP) into arable cropping and grassland system on the distribution of P pools and potential P bioavailability. We compared the following systems: SP system, SP converted to arable cropland (SP-AL), SP converted to grassland (SP-GL), and for comparative purposes, a long-term arable cropland (AL). The P fractionation was performed by a sequential extraction scheme, using acid and alkaline extractants on samples collected from the 0?10 and 10?20 cm soil layers. It was assumed that the large variations in soil-P fractionations are caused by the different management practices associated with land conversion. The results of P fractionation showed a dominance of calcium-bound P, HCl-extractable Pi constituted up to 36% of the soil total P (TP). However, the type of land use did not affect this P fraction. On the other hand, the reduction in labile-Pi and NaOH-Pi fractions observed at the SP-AL site may have led to the decline in readily available P. The soil total organic P (TPo) content was 8% and 17% lower at SP-AL compared to SP and SP-GL site, respectively. Labile organic-P (labile-Po) content was markedly higher at SP site compared to arable soils, and was ≈ 10% of TPo. The NaOH-Po constituted the highest fraction of the organic-P pool (55%?79% of TPo) across all the study systems, and was positively correlated with TPo (p < 0.01). The study indicates that conversion of SP system in temperate regions to arable cropping with conventional tillage seems to result in the reduction of P availability compared to SP, indicating SP as an important land-use practice.

Water erosion is one of the main factors driving soil degradation, which has large economic and environmental impacts. Agricultural production systems that are able to provide soil and water conservation are of crucial importance in achieving more sustainable use of natural resources, such as soil and water. The aim of this study was to evaluate soil and water losses in different integrated production systems under natural rainfall. Experimental plots under six different land use and cover systems were established in an experimental field of Embrapa Agrossilvipastoril in Sinop, state of Mato Grosso, Brazil, in a Latossolo Vermelho-Amarelo Distrófico (Udox) with clayey texture. The treatments consisted of perennial pasture (PAS), crop-forest integration (CFI), eucalyptus plantation (EUC), soybean and corn crop succession (CRP), no ground cover (NGC), and forest (FRS). Soil losses in the treatments studied were below the soil loss limits (11.1 Mg ha-1 yr-1), with the exception of the plot under bare soil (NGC), which exhibited soil losses 30 % over the tolerance limit. Water losses on NGC, EUC, CRP, PAS, CFI and FRS were 33.8, 2.9, 2.4, 1.7, 2.4, and 0.5 % of the total rainfall during the period of study, respectively.

Os sistemas de manejo do solo modificam a dinâmica do fósforo alterando o conteúdo das diferentes formas de P. Objetivou-se avaliar o efeito de sistemas de cultivo em longo prazo (16 anos de plantio) sobre as diferentes formas de P no solo. Os tratamentos constaram de combinações entre dois sistemas de cultivo: milho exclusivo (M) e milho consorciado com feijão (MF), com duas doses (0 e 40 m^3 ha^-1 ano^-1) de adubo orgânico (AO), e três doses (0, 250 e 500 kg ha^-1) de N–P–K, 4–14–8 (AM). Solo sob um fragmento de Floresta Atlântica foi utilizado como referência de um estado em equilíbrio. Os valores de P orgânico total (Pot) variaram de 184,2 a 280,2 e de 147,9 a 282,9 mg kg^-1, em amostras de solo das camadas de 0–10 e 10–20 cm, respectivamente, sendo os maiores valores observados para combinação 500 kg ha^-1 + adubação orgânica, correspondendo, em média, a 26,4 % do P total no solo. Houve tendência da relação C/Pot manter-se constante, entre os tratamentos, constatando-se aumento dos valores de Pot com o aumento do teor de carbono orgânico total no solo. O adubo mineral promoveu incremento do P na biomassa microbiana (Pbm) apenas no sistema de milho exclusivo. Em média, o aumento do Pbm foi de 262 e 164 % para o sistema que recebeu o composto orgânico no sistema de milho exclusivo e consorciado com feijão, respectivamente. Em média, a fração de P orgânico solúvel em meio ácido correspondeu a 90 % do Pot predominando sobre a fração solúvel em base. Nos tratamentos com 500 kg ha^-1 de 4–14–8 e 500 kg ha^-1 + composto orgânico, no sistema de consórcio, foram obtidos aumentos nos valores de P total lábil de 53 e 157 %, respectivamente, comparados aos da testemunha. O P orgânico lábil (Pol) correspondeu, em média, a 3,7 % do Pot para os sistemas de cultivo, já para a Floresta Atlântica, esta relação foi de 10,7 %, nas duas profundidades. Os aumentos nos teores das formas mais lábeis de P, proporcionados pela adubação orgânica, evidenciam a importância deste sistema de manejo no favorecimento da ciclagem de P. Soil management systems affect the P dynamics in content and forms. The aim of this work was to measure the effect of several cultivations systems in the long term (16 years) on the different soil P forms. The treatments consisted of combinations of the two cultivation systems: sole corn (C) and corn-bean intercrop (CB), with two levels (0 and 1) of organic fertilizer (OF), at rates of 0 and 40 m^3 ha^-1 year^-1 and three levels (0, 1, 2) of mineral fertilizer (MF) N–P–K, in the doses 0, 250 and 500 kg ha^-1 of the formula 4–14–8. An area under Atlantic Forest was used as reference of a balanced state. The values of total organic P (Pto) changed from 184.2 to 280.2 and from 184.4 to 282.9 mg kg^-1 in 0–10 and 10–20 cm deep soil, respectively. The highest values were observed for 500 kg ha^-1 of mineral fertilizer + organic fertilizer, corresponding on average to 26.4 % P in the soil. The C/Pto ratio of the treatments tended to be constant. An increase of the Pto values with the increase of the soil organic carbon content was observed. The mineral fertilizer promoted P increment in the microbial biomass (Pmb) in the sole corn crop system. The increase of Pmb was 262 and 164 % of the system that received the organic compost in the sole corn crop and corn-bean intercrop, respectively. On average, the fraction of organic soluble P corresponded to 90 % Pto, prevailing over the basic soluble fraction. The 500 kg ha^-1 of mineral fertilizer and 500 kg ha^-1 of mineral fertilizer + organic fertilizer treatments in the intercrop system caused increases in the total labile P (Plt) values of 53 and 157 %, respectively, compared to the reference. The labile organic P fraction (Plo) corresponded to 3.7 % of Pto for the cultivation systems; for the Atlantic Forest soil this relationship was 10.7 % at both depths. The increments in the contents of most labile P forms, owing to the organic manure, demonstrate the importance of this management system for an improvement of the P cycle.

In temperate regions, cultivation of Robinia pseudoacacia L. has recently received considerable attention because it is a fast-growing species for biomass and bioenergy production, while acting as a potential carbon (C) sink to counterbalance carbon dioxide (CO2) emissions and an alternative to agricultural crops on marginal sites. The objective of our work was to compare total organic carbon (TOC), total nitrogen (TN), and organic C fractions in postlignite mining soils under different development stages of R. pseudoacacia. Soil samples from three different depths (0–3, 3–10 and 10–30 cm) were taken in plantations 2, 3, 4, and 14 years old (R2, R3, R4, and R14, respectively). The TOC and TN contents increased with increasing tree age in all layers (P < 0.01). In the top 30 cm, TOC and TN stocks ranged from 11.7 to 59.8 Mg C ha−1 and from 0.30 to 2.61 Mg N ha−1 at R2 and R14, respectively. The rate of C sequestration was calculated to be 4.0 Mg C ha−1 year−1. Microbial biomass C and N were strongly correl...

Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and (lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants. Leguminosas utilizadas como adubos verdes são consideradas uma fonte importante de nutrientes para a cultura do cafeeiro, especialmente em solos com baixa disponibilidade de nutrientes. Experimentos de campo foram realizados com o objetivo de avaliar as taxas de decomposição e liberação de nutrientes de leguminosas empregadas como adubos verdes em cafezais sob sistemas agroflorestais na Zona da Mata de Minas Gerais. Os teores iniciais de N e P nos materiais vegetais variaram de 25,7 a 37,0 e de 2,4 a 3,0 g kg-1, respectivamente. As relações lignina/N, lignina/polifenol e (lignina+polifenol)/N apresentaram baixos valores para todas as espécies estudadas. As maiores perdas de matéria seca ocorreram nos primeiros 15 dias de avaliação, quando 25 % do material foi decomposto. Entre 15 e 30 dias de avaliação, houve redução da taxa de decomposição em ambas as propriedades. Na propriedade de Pedra Dourada (PD), a constante de decomposição k aumentou na sequência C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. Já em Araponga (ARA), não houve diferença nas taxas de decomposição das leguminosas estudadas. As taxas de liberação de N variaram entre 0,0036 e 0,0096 d-1. Cerca de 32 % do total de N no material vegetal foi liberado nos primeiros 15 dias. Até os 360 dias, foram liberados pelos adubos verdes, em média, 77,5 % do N em Araponga e 88,5 % em Pedra Dourada. O P apresentou a maior velocidade de liberação, variando de 0,0165 a 0,0394 d-1. As taxas de decomposição e liberação de nutrientes não se correlacionaram com as composições química e bioquímica iniciais, porém as diferenças climáticas entre as duas áreas modificaram as constantes de decomposição dos resíduos das leguminosas.

The assessment of the carbon (C) sequestration potential of different land use systems is receiving increasing attention within the European Union forced by aspects of optimum humus content of soils and the debate on climate change. Short rotation coppice crops (SRC) emerge as a promising land use option both for bioenergy production and C sequestration. In this study, C storage in the biomass and the soil under four SRC systems of Robinia pseudoacacia L. was investigated. The plantations were established on reclamation sites in the mining district of Lower Lusatia in 1995, 2005, 2006, and 2007. Samples were collected in the winter of 2007 and 2009. Average aboveground dry matter (DM) production ranged from 0.04 to 9.5 Mg ha−1 year−1 for 1–14 years of growth, respectively. Total stocks of soil organic carbon (SOC) at 0–60 cm depth after 2 and 14 years of growth were 22.2 ± 11.3 and 106.0 ± 11.7 Mg ha−1, respectively. Interpreting the data as a false chronosequence, the average rate of soil C sequestration in the 0–60 cm layer was 7.0 Mg ha−1 year−1. Hot water extractable carbon (HWC) that represents the labile fraction of SOC was highest in the oldest plantation (1.4 Mg ha−1 for the 0–30 cm layer). The relative proportion of HWC in SOC, however, did not change substantially between diffe­rent aged SRC, indicating that with time, because of increasing stocks, C became increa­singly stabilized within the soils. Overall, plantations of R. pseudoacacia seem to be a promising land use option for post-mining areas due to their high capacity for sequestering C within biomass as well as a high potential to increase soil C stocks on marginal sites.

O objetivo deste trabalho foi avaliar o impacto da adubação orgânica e mineral sobre a estabilidade de agregados e a distribuição de C, N e P, em classes de agregados de um Argissolo Vermelho-Amarelo. Os tratamentos consistiram de 0 e 40 m³ ha-1 por ano de adubação orgânica e de 0, 250 e 500 kg ha-1 de adubação mineral N-P-K da fórmula 4-14-8. Uma área sob floresta atlântica foi utilizada como referência. Amostras foram coletadas nas camadas de 0-10 e 10-20 cm. Houve predomínio da classe de agregados entre 4 e 2 mm, que correspondeu a 39,7% do total de agregados separados por via seca no tratamento com composto orgânico. Os teores de C orgânico total para adubação orgânica foram 17,5 e 36,7% maiores para as classes 4-2 e 0,105-0,25 mm. A adubação orgânica contribuiu para teores de N e P totais de 43 e 38,7% (0-10 cm) e 35,4 e 36,8% (10-20 cm), maiores que os dos tratamentos sem adubo orgânico. A relação carbono/nitrogênio se manteve constante entre as classes de agregados de um mesmo tratamento, enquanto a de carbono/fósforo reduziu com o uso de adubo orgânico ou mineral, em relação à mata nativa. Os índices de estabilidade de agregados se correlacionaram positivamente aos teores de carbono orgânico total da classe 4-2 mm. The aim of this work was to evaluate the effect of mineral and organic fertilization on the soil-water aggregate stability and on the distribution of C, N and P in different classes of aggregates in an Acrisol. The treatments were 0 and 40 m³ ha-1 per year of organic fertilizer and 0, 250 and 500 kg ha-1 of mineral fertilizer N-P-K of the formula 4-14-8. An area under Atlantic forest was used as reference. Soil samples were collected at 0-10 and 10-20 cm depths. The distribution of aggregates showed the highest values from 4 to 2 mm. In the organic fertilizer treatment, the aggregates 4-2 mm corresponded to 39.7% of the total on the soil. For the aggregates 4-2 and 0.105-0.25 mm, the total organic carbon contents were 17.5 and 36.7% higher in the organic fertilizer treatments. The organic fertilization contributed to values of N and P of 43 and 38.7% (0-10 cm) and 35.4 and 36.8% (10-20 cm), which were higher than the treatments without organic fertilizer. The carbon/nitrogen ratio did not vary among the aggregate classes in the same treatment. However, the carbon/phosphorus ratio was reduced with the use of organic and mineral fertilizer. The indexes of aggregates stability were positively correlated with the content of total organic carbon in the 4-2 mm.

A 15-year experiment in a clayey Red-Yellow Podzolic in the tropical highlands of Vicosa, Brazil, was studied in 2000, aiming to evaluate the impact of different management systems (no tillage, disk plowing, heavy scratcher + disk plowing, and heavy scratched) on the total organic carbon (TOC), total nitrogen (TN), and several organic carbon pools. A natural forest, adjacent to the experimental area, was used as reference. The greatest TOC and TN as well as microbial biomass C ([C.sub.MB]), light fraction C ([C.sub.FL]), and labile organic carbon ([C.sub.L]) stocks were observed in the Atlantic Forest, compared with all other systems. The long-term cultivation ([+ or -] 70 years) of this area, prior to the installation of the experiment, has led to soil degradation, slowing the C recovery. No tillage had the higher C and N stocks and greater CE pool at the surface (0-10 cm), indicating improvement in soil nutrient status, although none of the systems presented potential to sequester C-C[O.sub.2]. Sustainable tropical agricultural systems should involve high residue input and conservative soil management in order to act as a C-C[O.sub.2] sink. The C stocks in the [C.sub.MB], [C.sub.FL], and [C.sub.L] compartments were more reduced in relation to the natural vegetation with higher intensity management than the TOC stocks. This result indicates that these C compartments are more sensitive to changes in the soil management.

The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis) to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation. C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun. O uso de adubos verdes pode contribuir para a redução da erosão do solo, o aumento da sua matéria orgânica e a disponibilidade de N para o café produzido na Zona da Mata de Minas Gerais. Objetivou-se avaliar o potencial de produção de biomassa, acúmulo de nutrientes e mineralização de N de quatro leguminosas (Arachis pintoi, Calopogonium mucunoides, Stylozanthes guyanensis e Stizolobium aterrimum) cultivadas nas entrelinhas de café sob diferentes condições edafoclimáticas. A produção de biomassa de C. mucunoides foi influenciada pelo sombreamento do café. Houve tendência de maior mineralização de N para C. mucunoides, comparado com as outras leguminosas, em razão das menores concentrações de polifenóis e da relação polifenol/N. Por ocasião do primeiro corte, A. pintoi apresentou baixa produção de biomassa e fixação de N. A longo prazo, o teor de celulose foi o principal fator controlador da mineralização de N. As características bioquímicas, o acúmulo de nutrientes e a produção de biomassa foram altamente influenciados pela altitude e orientação das áreas de estudo em relação ao sol.

This study aimed to evaluate the effects of soil texture, fertilizer formulation and nitrogen dose on the characteristics of upland rice production, and to compare the Agronomic Efficiency Index (AEI) of formulations of biochar-urea pellets (BUPs). The treatments comprised four fertilizers (three formulations of BUP and urea) and five nitrogen doses (0, 75, 150, 300 and 600 mg dm-3), analyzed in two soil (sandy and clay). For each soil texture, a greenhouse experiment was established as a randomized block design with a 5 x 4 factorial arrangement and four replicates. Chlorophyll index, plant height, number of tillers and panicles, dry mass of aerial parts and of grains were all affected significantly by soil texture, fertilizer formulation and nitrogen dose and/or by the interactions between these sources of variation. The results demonstrated that the performances of BUPs are highly dependent on soil texture. Under sandy soil, application of BUP-based fertilizers contributed to the increase or maintenance of grain production compared to that of urea alone. Whereas under clayey soil the performance of BUPs exceeded that of urea only at low nitrogen doses. Compared to urea, BUPs were more efficient under sandy soil, with potential to increase AEI. KEYWORDS: organomineral fertilizers; wood sawdust; pyrolysis; N-leaching. Uso de pellets de biochar-ureia para reduzir as perdas de nitrogênio RESUMO: Este trabalho objetivou avaliar os efeitos da textura do solo, formulações e doses de nitrogênio em características do arroz de terras altas, e comparar o Índice de Eficiência Agronômica (AEI) das formulações de pellets de biochar-ureia (BUP’s). Os tratamentos foram: quatro fertilizantes (três formulações de BUP e ureia) e cinco doses de nitrogênio (0, 75, 150, 300 and 600 mg dm-3), avaliados em dois solos de textura distinta. Para cada solo (arenoso e argiloso), foi conduzido um experimento em casa-de-vegetação em blocos casualizados em um arranjo fatorial 5 (doses) x 4 (fertilizantes), com quatro repetições. O índice de clorofila, altura de plantas, número de perfilhos, número de panículas, massa seca de parte aérea, massa seca de grãos tiveram diferenças significativas em função da textura do solo, fertilizantes e doses de N e/ou pelas interações entre esses fatores. Os resultados demonstraram que o desempenho dos BUP’s foi dependente da textura do solo, com melhores respostas no solo arenoso em relação à ureia, com potencial de elevar a eficiência agronômica da adubação nitrogenada. PALAVRAS-CHAVE: fertilizantes organominerais, pó de serra, pirólise, lixiviação de N. This study aimed to evaluate the effects of soil texture, fertilizer formulation and nitrogen dose on the characteristics of upland rice production, and to compare the Agronomic Efficiency Index (AEI) of formulations of biochar-urea pellets (BUPs). The treatments comprised four fertilizers (three formulations of BUP and urea) and five nitrogen doses (0, 75, 150, 300 and 600 mg dm-3), analyzed in two soil (sandy and clay). For each soil texture, a greenhouse experiment was established as a randomized block design with a 5 x 4 factorial arrangement and four replicates. Chlorophyll index, plant height, number of tillers and panicles, dry mass of aerial parts and of grains were all affected significantly by soil texture, fertilizer formulation and nitrogen dose and/or by the interactions between these sources of variation. The results demonstrated that the performances of BUPs are highly dependent on soil texture. Under sandy soil, application of BUP-based fertilizers contributed to the increase or maintenance of grain production compared to that of urea alone. Whereas under clayey soil the performance of BUPs exceeded that of urea only at low nitrogen doses. Compared to urea, BUPs were more efficient under sandy soil, with potential to increase AEI. KEYWORDS: organomineral fertilizers; wood sawdust; pyrolysis; N-leaching. Uso de pellets de biochar-ureia para reduzir as perdas de nitrogênio RESUMO: Este trabalho objetivou avaliar os efeitos da textura do solo, formulações e doses de nitrogênio em características do arroz de terras altas, e comparar o Índice de Eficiência Agronômica (AEI) das formulações de pellets de biochar-ureia (BUP’s). Os tratamentos foram: quatro fertilizantes (três formulações de BUP e ureia) e cinco doses de nitrogênio (0, 75, 150, 300 and 600 mg dm-3), avaliados em dois solos de textura distinta. Para cada solo (arenoso e argiloso), foi conduzido um experimento em casa-de-vegetação em blocos casualizados em um arranjo fatorial 5 (doses) x 4 (fertilizantes), com quatro repetições. O índice de clorofila, altura de plantas, número de perfilhos, número de panículas, massa seca de parte aérea, massa seca de grãos tiveram diferenças significativas em função da textura do solo, fertilizantes e doses de N e/ou pelas interações entre esses fatores. Os resultados demonstraram que o desempenho dos BUP’s foi dependente da textura do solo, com melhores respostas no solo arenoso em relação à ureia, com potencial de elevar a eficiência agronômica da adubação nitrogenada. PALAVRAS-CHAVE: fertilizantes organominerais, pó de serra, pirólise, lixiviação de N.

Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and (lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants. Made available in DSpace on 2011-11-14T18:48:34Z (GMT). No. of bitstreams: 1 2011AP08.pdf: 768878 bytes, checksum: 2e291c35ca12ae8e4351e794a13fb25c (MD5) Previous issue date: 2011-10-26

O objetivo deste trabalho foi avaliar o impacto da adubacao organica e mineral sobre a estabilidade de agregados e a distribuicao de C, N e P, em classes de agregados de um Argissolo Vermelho-Amarelo. Os tratamentos consistiram de 0 e 40 m3 ha.1 por ano de adubacao organica e de 0, 250 e 500 kg ha.1 de adubacao mineral N.P.K da formula 4.14.8. Uma area sob floresta atlantica foi utilizada como referencia. Amostras foram coletadas nas camadas de 0.10 e 10.20 cm. Houve predominio da classe de agregados entre 4 e 2 mm, que correspondeu a 39,7% do total de agregados separados por via seca no tratamento com composto organico. Os teores de C organico total para adubacao organica foram 17,5 e 36,7% maiores para as classes 4.2 e 0,105.0,25 mm. A adubacao organica contribuiu para teores de N e P totais de 43 e 38,7% (0.10 cm) e 35,4 e 36,8% (10.20 cm), maiores que os dos tratamentos sem adubo organico. A relacao carbono/nitrogenio se manteve constante entre as classes de agregados de um mesmo tratamento, enquanto a de carbono/fosforo reduziu com o uso de adubo organico ou mineral, em relacao a mata nativa. Os indices de estabilidade de agregados se correlacionaram positivamente aos teores de carbono organico total da classe 4.2 mm.