Antonio Eduardo Furtini Neto

Adubação verde na recuperação da fertilidade de um Latossolo Vermelho-Escuro degradado

The experiment was conducted at the Empresa de Pesquisa Agropecuaria de Minas Gerais, Nova Baden Experimental Station, in Lambari, MG, Brazil, aiming at evaluating the performance of the green manures pigeonpea (Cajanus cajan (L.) Millsp.) and sunnhep (Crotalaria juncea L.) with and without incorporation of the biomass, on the recovery of fertility of degraded soil cultivated with brachiaria (Brachiaria decumbens Stapf.). Experimental design used was of randomized block in factorial scheme of split plots with three replications, putting the biomass handling in the plots and both the legumes and brachiaria in the subplots. The three crops were cut and handled at the late flowering stage of the legumes, when samplings of the plant material were done for assessing dry matter yield, concentration and amount of nutrient. Evaluations of soil samplings at six depths (0-5, 5-10, 10-20, 20-40, 40-60 e 60-80 cm) and three periods (90, 120 and 150 days after handling) were performed. Pigeonpea stood out in the first evaluation concerning the improvements in soil fertility and sunnhep and slower mineralization, in the second. In the third evaluation, no benefits from the green manure on the chemical properties of the soil were found.

Teores críticos de fósforo em três solos para o estabelecimento de capim-Mombaça, capim-Marandu e capim-Andropogon em vasos

A pot trial was carried out in a greenhouse to evaluate the effect of phosphorus rates applied in two Oxisols (LVAd and LVd) (0, 110, 220, 330 and 560 mg dm-3 de P) and an Entisol (RQ) (0, 80, 160, 240 and 410 mg dm-3) on tillering and dry matter yield of shoot (SDM) and root (RDM) of Mombacagrass (Panicum maximum cv. Mombaca), Marandugrass (Brachiaria brizantha cv. Marandu) and Andropogongrass (Andropogon gayanus cv. Planaltina) to identify critical phosphorus rates for obtaining 90% of maximum production. Three experiments were set in complete randomized block design in a factorial scheme (five P rates x three species), with three replicates. The phosphorus rates, linearly increased the P available in soil extracted by Mehlich-1 and resin methods. The tillers number per pot and shoot dry matter changed in a quadratic form with phosphorus rates. Plants in the no P did not tiller and shoot dry matter was very low. The critical P doses, corresponding to 90% of maximum yield, for Mombacagrass, Marandugrass and Andropogongrass were respectively 236, 231 and 258 mg dm-3 in LVAd; 274, 305 e 253 mg dm-3 in LVd and 94, 171 and 163 mgdm-3 in RQ, with critical P concentration of 81, 79 and 90 mg dm-3 in the LVAd; 26, 29 e 23 mg dm-3 in the LVd e 53, 83 and 79 mg dm-3 in the RQ, respectively. Lower values for the critical P concentration occurred in LVd (soil with higher clay and silt concentrations) than in the others soils, whose concentrations corresponded to higher critical doses. In all soils P application resulted in higher yield of SDM than RDM.

Produção de biomassa e teor de macronutrientes do milheto, feijão-de-porco e guandu-anão em cultivo solteiro e consorciado

Objetivou-se determinar a producao de biomassa e o teor de macronutrientes do milheto (Pennisetum typhoides (Burm.) Stapf), feijao-de-porco (Canavalia ensiformes (L.) DC.) e guandu-anao (Cajanus cajan (L.) Millsp.) em cultivo solteiro e nos consorcios da graminea com as leguminosas, visando a producao de palha no sistema plantio direto. O trabalho foi conduzido no campo experimental do Departamento de Agricultura da Universidade Federal de Lavras (Lavras, MG, Brasil). O delineamento foi o de blocos casualizados, com cinco tratamentos e quatro repeticoes. Apenas o guandu-anao solteiro apresentou menor producao de fitomassa fresca e seca, sendo que os demais tratamentos nao diferiram entre si, pelo teste de Tukey a 5% de probabilidade. De forma geral, as leguminosas apresentaram maiores teores de N e Ca e o milheto maiores teores de S. Apenas o feijao-de-porco solteiro apresentou menor teor de P. Os maiores teores de K foram apresentados pelo milheto solteiro e consorciado com as leguminosas e pelo feijao-de-porco em consorcio com milheto. Os menores teores de Mg foram verificados para o guandu-anao.

Determinação de cádmio, cobre, cromo, níquel, chumbo e zinco em fosfatos de rocha

The possibility of food chain transfer is a matter of concern on studies related to heavy metals in mineral fertilizers. The objective of this paper was to determine the content of heavy methods and to compare three extraction procedures (Embrapa, 1999; USEPA 3051A and USEPA 3050B) for Cd, Cr, Cu, Ni, Pb, and Zn in national and imported rock phosphates. The quantification of the trace elements content was performed by air-acetylene flame atomic absorption spectroscopy. Among the studied phosphates, the thermophosphate presented significantly greater concentrations of Cd, Cr, Cu, Ni, and Zn whereas Cu, Ni, Pb, and Zn were found in greater contents in the natural phosphate 2. The reactive phosphate 3 presented the greatest quantity of Cd (145±13 mg kg-1) and the natural phosphate 2, the highest quantity of Pb (234±9 mg kg-1). The tested methods can be applied in studies concerning heavy metals in phosphate fertilizers.

CRESCIMENTO INICIAL DE ESPÉCIES FLORESTAIS DE DIFERENTES GRUPOS SUCESSIONAIS EM RESPOSTA A DOSES DE FÓSFORO

Objetivando avaliar a resposta de especies florestais ao fornecimento de P, conduziu-se um ensaio sob condicoes de casa de vegetacao, cultivando-se mudas das especies arboreas pioneiras (aroeira - Lithraea molleoides; aroeirinha - Schinus terebinthifolius; jacare - Piptadenia gonoacantha; sabia - Mimosa caesalpiniaefolia; sesbânia - Sesbania virgata), climax exigente em luz (jatoba - Hymenaea courbaril), e climax tolerantes a sombra (guanandi - Calophyllum brasiliensis; ipe-amarelo - Tabebuia serratifolia; oleo-balsamo - Myroxylon peruiferum). Utilizaram-se cinco doses de P, correspondentes a 0, 100, 250, 500 e 800 mg dm-3 de P. Foram avaliados o diâmetro do caule, a altura e a materia seca de raizes, parte aerea e total das plantas. As especies pioneiras foram mais responsivas ao fornecimento de P, indicando a necessidade do suprimento deste nutriente para o adequado desenvolvimento destas especies. As especies climax mostraram-se pouco sensiveis ao suprimento de P, refletindo um baixo requerimento na fase de mudas. Diferencas em relacao a taxa de crescimento e ao tamanho das sementes podem estar ligadas ao comportamento contrastante observado para especies pioneiras e climax.

Resposta diferencial de linhagens de feijoeiro ao nitrogênio

It was evaluated 100 breeding lines of common bean in the presence and absence of N in cover in four conditions aiming at identifing the lines of beans which would be tolerant to nitrogen (N) stress and/or also responsive to this nutrient. In each condition there were two distinct experiments with and without N, in a 10 x 10 triple lattice design, being the plot constituted by a line with three meters of length. It was estimated the index of efficiency of nitrogen utilization, through the average grains yield. The obtained yield with N was 12% above the one without N, in the average of the four conditions. By decomposing the effect of levels for each line, in 77% of them there was no answer to the nitrogen fertilization in cover. This, only 22 lines positively responded to nitrogen fertilization and among them the efficiency of N utilization ranged from 11.3 to 18.3kg of grains per kg of applied N.

Formas de fósforo em solo sob plantio direto em razão da profundidade e tempo de cultivo

O objetivo deste trabalho foi estudar, pelo metodo de extracao sequencial, as alteracoes das formas de P em amostras de solo sob plantio direto (PD) por diferentes tempos de cultivo, em duas profundidades, em relacao as amostras de solos de areas adjacentes nunca cultivadas (referenciais). As amostras de solo foram coletadas nas profundidades de 0-5 e 5-10 cm de um Neossolo Quartzarenico, com um ano de PD; de dois Latossolos Vermelho distroficos com tres e cinco anos de PD; e de dois Latossolos Vermelho distroferricos, com sete e 11 anos de PD, e das respectivas areas adjacentes nunca cultivadas. O metodo de fracionamento de P foi eficiente para avaliar os efeitos do manejo na dinâmica das alteracoes das formas de P no solo. As formas de P dos solos apresentaram tendencia de reducao com a profundidade. Com o tempo de cultivo sob PD, em uma mesma classe de solo, a participacao das formas de P nao-labeis em relacao ao P total tendeu a diminuir, sendo acompanhada por um aumento relativo das formas mais labeis.

Crescimento, acúmulo de fósforo e frações fosfatadas em mudas de sete espécies arbóreas nativas

This work aimed to compare growth, phosphorus (P) uptake and distribution of P-fractions in seedlings of seven tree species classified as pioneers (Lithraea molleoides, Shcinus terebinthifolius, Mimosa caesalpiniaefolia, Sesbania virgata) or climaxes (Hymenaea courbaril, Calophyllum brasiliensis, Myroxylon peruiferum) and cultivated under five doses of P (0, 100, 250, 500 and 800 mg dm-3 of P) in a greenhouse. Up to ninety days after germination, the plants were harvested, and dry matter, P-content and P-fractions (total-P, inorganic-P and organic- P) in the leaves were determined. The tree species presented a wide behavior variation regarding P-fertilization, with the pioneer species being more efficient in producing dry matter and absorbing P. The biomass production of the pioneer species Lithraea molleoides was directly related to P accumulation. Its proportions of inorganic-P and organic-P remained unaffected by the increased availability of P. The growth of the Shcinus terebinthifolius, Sesbania virgata and Hymenaea courbaril did not keep up with P uptake, which was mainly accumulated as inorganic-P in the first species and as organic-P in the two last ones. Climax species Calophyllum brasiliensis and Myroxylon peruiferum presented a larger proportion of organic-P, however, the P uptake and plant growth were little affected by P-fertilization.

Eficiência nutricional de clones de eucalipto na fase de mudas cultivados em solução nutritiva

The objectives of this study were to evaluate the biomass production and nutritional efficiency of seedlings of eucalyptus clones in nutrient solution, to characterize the macronutrient uptake, translocation and utilization efficiency. The experiment was carried out in a greenhouse using seedlings of six eucalyptus clones (58, 386, GG100, I042, I144, and VM1), grown in nutrient solution. The treatments, represented by the six clones, were distributed in a completely randomized design, with four replications. The eucalyptus clones differed from each other in biomass production and in nutritional efficiency. Differences were detected in the uptake efficiency, translocation and utilization of the macronutrients in relation to the different eucalyptus clones, as well as in function of the nutrient. In a general way, the clones can be ranked for nutritional efficiency in the following sequence: I144 > 386 > 58 ≈ GG100 > VM1 > I042. Clone I144 was most efficient, mainly for N, P, K, Mg and S, with higher uptake and utilization efficiency of these nutrients in biomass production. Clone I042 was inefficient in uptake and utilization of all macronutrients, compromising biomass production. VM1 stood out among the other clones as the most efficient in the translocation of all macronutrients to the aerial part of the eucalyptus seedlings. The differences identified in this study in terms of nutritional efficiency of eucalyptus clones in the seedling phase suggest the possibility of selection of eucalyptus genotypes for distinct soil fertility conditions.

Crescimento e nutrição da braquiária em função de fontes de fósforo

Avaliaram-se, em casa de vegetacao, as contribuicoes de diferentes fontes de fosforo (P) aplicadas em amostras de Latossolo Vermelho distroferrico (LVdf) (350 mg dm-3 de P2O5) e de Neossolo Quartzarenico (NQ) (200 mg dm-3 de P2O5), coletadas nos municipios de Lavras (MG) e Itutinga (MG), respectivamente, na producao de materia seca, no teor e acumulo de P na parte aerea e raiz da Brachiaria brizantha cv. Marandu. Tambem foi avaliado o indice de eficiencia agronomica (IEA) das fontes. O experimento foi conduzido em um delineamento experimental inteiramente casualizado, em esquema fatorial 2x4 (dois solos e quatro fontes de fosforo (Superfosfato Triplo (ST), Fosfato Reativo de Arad (FR), Fosfato Natural de Araxa (FA), e uma mistura ST+FR - na relacao (1:1), com quatro repeticoes. A dose de fosforo foi baseada no teor de P2O5 total das fontes. Para a producao total de materia seca e o acumulo total de P, as fontes de maior solubilidade, como o ST, FR e a mistura ST/FR foram mais eficientes, principalmente no primeiro, terceiro e quarto cortes no LVdf e em todos os cortes no NQ. O teor total de P na braquiaria ao final do ultimo corte foi maior quando se aplicaram as fonte FR e ST+FR para o LVdf e, ST e ST+FR para o NQ. As fontes de fosforo influenciaram o IEA nos dois solos, que foi maior para as fontes de maior solubilidade.