Irene Maria Cardoso

Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization

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.

Selection of native trees for intercropping with coffee in the Atlantic Rainforest biome

A challenge in establishing agroforestry systems is ensuring that farmers are interested in the tree species, and are aware of how to adequately manage these species. This challenge was tackled in the Atlantic Rainforest biome (Brazil), where a participatory trial with agroforestry coffee systems was carried out, followed by a participatory systematisation of the farmers experiences. Our objective was to identify the main tree species used by farmers as well as their criteria for selecting or rejecting tree species. Furthermore, we aimed to present a specific inventory of trees of the Leguminosae family. In order to collect the data, we reviewed the bibliography of the participatory trial, visited and interviewed the farmers and organised workshops with them. The main farmers’ criteria for selecting tree species were compatibility with coffee, amount of biomass, production and the labour needed for tree management. The farmers listed 85 tree species; we recorded 28 tree species of the Leguminosae family. Most trees were either native to the biome or exotic fruit trees. In order to design and manage complex agroforestry systems, family farmers need sufficient knowledge and autonomy, which can be reinforced when a participatory methodology is used for developing on-farm agroforestry systems. In the case presented, the farmers learned how to manage, reclaim and conserve their land. The diversification of production, especially with fruit, contributes to food security and to a low cost/benefit ratio of agroforestry systems. The investigated agroforestry systems showed potential to restore the degraded landscape of the Atlantic Rainforest biome.

Decomposition and nutrient release of leguminous plants in coffee agroforestry systems

SUMMARY 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.

Mycorrhizal associations in agroforestry systems

Agroforestry systems can be a viable alternative to the preservation of natural resources while contributing to sustainable food production in the tropics. These perennial systems promote beneficial biological interactions between micro-organisms and plant species, especially those formed by arbuscular mycorrhizal fungi and roots. Mycorrhizal fungi increase the soil volume explored by the roots, increase nutrient absorption by the plants, protect the root system against pathogens, toxic elements and certain heavy metals, help the formation and maintenance of soil structure, increase the input of soil carbon, and contribute to the maintenance of biodiversity. Agroforestry systems have the potential to maximize the benefits associated with AMF, which in turn could mitigate negative interactions between trees and annual crops. This beneficial impact between agroforestry management and mycorrhizal action may be depicted as a particular form of symbiosis, and deserves more study.

Learning by doing: a participatory methodology for systematization of experiments with agroforestry systems, with an example of its application

Participatory research methods have helped scientists to understand how farmers experiment and to seek partnerships with farmers in developing technologies with enhanced relevance and adoption. This paper reports on the development of a participatory methodology to systematize long-term experimentation with agroforestry systems carried out in a hotspot of biodiversity by non-governmental organizations and local farmers. A methodological guide for systematization and techniques used for Participatory Rural Appraisal formed the basis of our work. We propose an analytical framework that recognizes systems of reflexive and learning interactions, in order to make the learned lessons explicit. At the process level, the main lessons and recommendations are as follows. It is important to establish partnerships to conduct innovative and complex experimentation with agroforest. Participatory systematization allows us to improve the methodological aspects of design, implementation and management of on-farm participatory experimentation. It also serves to synthesize the main findings and to extract lessons from agroforestry systems experiments. It fosters the technical improvement of agroforestry systems. It creates possibilities for reflection on agroforestry systems by farmers, extensionists and researchers, as well as their learning with respect to management of such systems. The findings are placed in the context of current theory on participatory experimentation in agriculture. Extractive and interactive approaches help to produce rich insights of mutual interest through collaboration by identifying local, regional and global convergences, complementarities, and conflicts of interest; which affect the advance of new eco-friendly technologies, to both improve the livelihoods and to reverse biodiversity loss and environmental degradation.

Characteristics, residue decomposition, and carbon mineralization of leguminous and spontaneous plants in coffee systems.

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 contents of N and P and negatively with polyphenol/N and (lignin + polyphenol) / N ratio (P < 0.01) throughout the sampling period. The low nutrient content, especially for N, of spontaneous vegetation is compensated by the greater decomposition rate under natural conditions than that of introduced species. Management of the spontaneous plants is therefore an attractive alternative for sustainable agriculture.

Qualidade da matéria orgânica de solos sob cultivo de café consórciado com adubos verdes

The input of organic residues associated with the humification process promotes improvement of soil properties and enables the sustainability of the production system. Aside from supplying the coffee with nutrients, pulse crops can improve the quality of soil organic matter by forming humic substances. The purpose of this study was to evaluate the effect of green manures legumes on the quality of humic substances in soils under coffee under two environmental conditions in the region of Zona da Mata, in Minas Gerais. The species forage peanut, calopo, stylosanthes, velvetbean and spontaneous species were grown for four years on two family farms. After four years, soil was sampled and the humic substances were extracted and purified to obtain fulvic acids (FA) and humic acids (HA). The elemental sample composition (CHNO analyzer), UV-visible, infrared and thermogravimetry of the purified material were analyzed. The results showed that HA have a higher molecular weight, hydrophobicity, condensation, and aromatic compounds with higher C content, providing greater structural stability than FA. The humic substances in the environment facing south, with lower light incidence, lower temperatures and higher humidity, were structurally more stable and decay-resistant than the humic substances extracted from soil northwest-oriented soil surfaces. In the treatment with calopo, FA contained low C and high O levels, characterizing compounds of lower structural stability than FA in the treatments with stylosanthes, velvetbean and spontaneous species. In HA, the use of legumes showed similar results.

O conhecimento local e a etnopedologia no estudo dos agroecossistemas da comunidade quilombola de Brejo dos Crioulos

This work sought to identify, rescue and value the traditional knowledge about soil and environment, establishing a relationship of this knowledge with scientific knowledge of academic slant. To this end, it was the stratification of the environment of the marron territory of Brejo dos Crioulos, based on local criteria and pedological conventional method, considering the soil and its interface with other environmental components. Associated with the characterization of agroecosystems, with interpretation and recognition of the logic of traditional knowledge use and management of natural resources, by contacting the maroons recognize the best time (time), the environment (soil, moisture, microclimate), the species and variety, combining activities, and casting a set of practices that allow the survival of their families. The community of Brejo dos Crioulos dominates its own system of stratification of environments, whose identity enables comprehensive reference to scientific knowledge and articulation academic. The construction of identification keys of environments based on the criteria of the maroons, combined with information obtained based on local knowledge, to deepen the characterization of environments and mapping of soils contributed to a better understanding of the strategies of agrifood maroon, achieving results that can support planning processes and definitions of public policies for sustainable land use territory of maroon.

Etnobotânica de Leguminosae entre agricultores agroecológicos na Floresta Atlântica, Araponga, Minas Gerais, Brasil

O trabalho apresenta a riqueza de Leguminosae utilizada por 21 agricultores tradicionais em sistemas agroflorestais (SAFs) cafeeiros e fragmentos florestais na Floresta Atlântica, municipio de Araponga, Minas Gerais, Brasil, e as categorias de uso, importância relativa e similaridade das especies entre os SAFs. Os dados foram obtidos atraves de entrevistas semiestruturadas e observacao participante, entre agosto de 2005 e novembro de 2006, durante caminhadas direcionadas em sete SAFs e fragmentos florestais no entorno do Parque Estadual da Serra do Brigadeiro. Os agricultores citaram 59 especies de Leguminosae; 86% sao nativas da Floresta Atlântica, utilizadas em praticas culturais antigas, como para fazer carro de boi. Foram estabelecidas 12 categorias de uso, das quais as mais importantes foram adubo e lenha (21 spp cada). Nos SAFs, as especies que adubam o solo (18 spp) sao as mais utilizadas, e na floresta, para lenha e tecnologia (17 spp). O indice de importância relativa mostrou que na floresta, Piptadenia gonoacantha apresentou 83% de concordância quanto ao uso da madeira para cercar pastagem, enquanto nos SAFs, Inga edulis obteve 100% como alimento. Os SAFs estudados apresentam pouca similaridade em especies (0,42 da escala Sorensen), devido a capacidade de selecao dos agricultores, proporcionando entao, espacos para a conservacao de especies uteis de Leguminosae.

Nutrients release from powder phonolite mediated by bioweathering actions

PurposeSilicate rock powders have been appointed as possible nutrient alternative sources which might enhance the agricultural sector sustainability. However, the application of those materials directly in soil presents as main limitations the low content and solubility of the mineral nutrient sources. In this perspective, the aim of the present study was to evaluate, in a bioweathering perspective, the conjunct application potential of phonolite with organic composts over the nutrients release in soil, as well as the production and nutrition of brachiaria grass (Urochloa decumbens). In addition, it was sought to assess the composting process effectiveness in improving the nutrient release from this rock.MethodAn experiment was conducted with five treatments (control; enriched compost with powder rock at 10%; mixed compost with powder rock at 10%; solely powder rock; solely compost) and four repetitions.ResultsThe alternative sources positively influenced the productivity, as well as the K and Si contents at the aerial part of the brachiaria grass and the nutrient release in soil. However, the conjunct applications of powder phonolite with organic composts were the source which the best promoted the total nutrient biorelease to soil.ConclusionNevertheless, there was no evidence that the composting process promotes the phonolite bioweathering. On the other hand, the conjunct application of powder phonolite with organic composts, either as an initial component to the composting pile or additive to the stabilized composts, is a strategy which enhances the nutrient biorelease of the mineral source.