José Antonio Azevedo Espindola

Decomposição e liberação de nutrientes acumulados em leguminosas herbáceas perenes consorciadas com bananeira

Evaluating the decomposition of cover crop residues added to the soil allows improving the comprehension of appropriate nutrient supply for commercial crops. This study was carried out under field conditions aiming to evaluate the decomposition and nutrient release from the shoots of perennial herbaceous legumes. The treatments were green cover crops intercropped with banana: groundnut (Arachis pintoi Krapov. & W.C. Gregory.), tropical kudzu (Pueraria phaseoloides (Roxb.) Benth.), siratro (Macroptilium atropurpureum (Sesse & Moc. ex DC.) Urb.) and spontaneous vegetation (mainly Panicum maximum Jacq.). These species were cut during the dry (April 1997) and rainy seasons (January 1998). Aboveground cover crop samples were placed in litterbags, which were distributed on the plots soil surface. Dry matter decomposition and nutrient release were monitored through collection of litterbags at 5, 10, 15, 30, 60, 90, 120 and 150 days after cutting the cover crops. Dry matter decomposition of groundnut was the fastest and the spontaneous vegetation was the slowest. The decomposition constants decreased and residue half-lives increased during the dry season. There was a faster release of N, Ca and Mg in the legumes, while spontaneous vegetation presented similar results for P. Among the chemical variables under study, the cellulose and hemicellulose contents were correlated with dry matter loss. N release was correlated with C and hemicellulose contents. Results indicate the potential of perennial herbaceous legumes for nutrient release, particularly in the case of tropical kudzu and siratro.

Bananeiras consorciadas com leguminosas herbáceas perenes utilizadas como coberturas vivas

The objective of this work was to evaluate the yield of banana plants intercropped with the perennial herbaceous legumes forage groundnut (Arachis pintoi), tropical kudzu (Pueraria phaseoloides) and siratro (Macroptilium atropurpureum). The control treatments were spontaneous vegetation (mainly Panicum maximum) and spontaneous vegetation plus nitrogen fertilizer application to banana plants. The vegetative growth of banana plants was also evaluated. Among the treatments, spontaneous vegetation and tropical kudzu promoted the highest dry matter productions; tropical kudzu had the highest amounts of accumulated and fixed N. Forage groundnut, tropical kudzu and siratro promoted the fastest vegetative growth for banana plants in this intercropped system. Tropical kudzu and siratro promoted the highest values for bunch weight and hands weight. All legume treatments result in a increase in the percentage of harvested bunches and a reduction in the harvesting time and are related to higher yields, compared to spontaneous vegetation treatment.

Organic matter quality in a soil cultivated with perennial herbaceous legumes

Using herbaceous legumes in agricultural systems yields great quantities of plant residues, allowing changes in soil organic matter quality and content over the years. This study was conducted on an Ultisol, at Seropedica, RJ, Brazil, to evaluate the effects of different perennial herbaceous legumes on soil organic matter quality. A factorial scheme with three replications was used to evaluate the species: forage groundnut cv. BR-14951 (Arachis pintoi), tropical kudzu (Pueraria phaseoloides), and siratro (Macroptilium atropurpureum). After the first cut, each plot was divided into two subplots; plants were cut and left on the soil surface or cut and removed. Soil samples of a closed area covered by spontaneous vegetation (mainly C3 plants) or by Panicum maximum were also analysed. Samples were collected from two layers (0-5 and 5-10 cm), processed for the fractionation of organic matter and the evaluation of structural characteristics of humic acids (HA). Evaluated legumes did not change total organic carbon contents, but promoted HA accumulation in the superficial soil layer. Humic acids may be used as indicators of the management effects on soil organic fractions, because there was significant incorporation of carbon and nitrogen derived from the legume residues, even for the short experimentation time (28 months). Residue management did not modify quantitative aspects of the distribution of the humified organic matter, but promoted, however, a higher condensation degree of humic acids evaluated by the elementary composition, IR and fluorescence spectroscopy.

Avaliação de coberturas mortas em cultura de alface sob manejo orgânico.

A cobertura morta do solo com leguminosas e gramineas e uma pratica cultural que traz beneficios aos sistemas de producao. Foi conduzido um experimento no municipio de Seropedica, estado do Rio de Janeiro, com o objetivo de avaliar o efeito de diferentes tipos de cobertura morta sobre a reinfestacao de ervas espontâneas e sobre o desempenho agronomico de alface, em cultivo orgânico. O delineamento experimental adotado foi blocos casualizados com quatro repeticoes e parcelas de oito plantas na area util. Os tratamentos foram: bagaco de cana-de-acucar (Saccharum sp.), bambu (Bambuza sp.), capim Cameroon (Penisetum purpureum), crotalaria (Crotalaria juncea), eritrina (Erythrina poeppigiana), gliricidia (Gliricidia sepium), guandu (Cajanus cajan), mucuna cinza (Mucuna pruriens) e controle (sem cobertura dos canteiros). Estimou-se a decomposicao in situ e a liberacao de nitrogenio de cada cobertura morta. Foram avaliados dois ciclos consecutivos de alface, cultivar Regina, na mesma area, visando a comparar o efeito residual das coberturas mortas. Observou-se maior acumulo de N nos residuos vegetais das leguminosas (maximo de 1.010 kg ha-1 com mucuna-cinza). Em relacao a decomposicao da cobertura morta, avaliada na colheita do primeiro ciclo de alface (35 dias apos o transplante), as leguminosas apresentaram percentuais inferiores aos das gramineas de massa seca e N remanescentes. A reinfestacao dos canteiros pelas ervas espontâneas nao diferiu significativamente entre coberturas mortas, variando entre 31 e 58 plantas m-2, mas a reducao da densidade populacional da vegetacao reinfestante chegou a 83% em comparacao ao tratamento controle. Em ambos os ciclos de cultivo da alface, a massa fresca (de 315,8 a 366,0 e de 202,9 a 225,0 g planta-1, respectivamente nos primeiro e segundo ciclos), o diâmetro da cabeca (de 30,8 a 31,7 e de 25,5 a 28,5 cm) e o teor de N (de 32,3 a 38,8 e de 28,0 a 30,3 g kg-1) foram superiores quando leguminosas foram utilizadas como cobertura morta.

Consórcios alface-cenoura e alface-rabanete sob manejo orgânico

Two experiments were carried out, in two consecutive years, at Seropedica, RJ, Brazil, aiming to evaluate the agronomic performance of intercropping of lettuce cvs. Regina 71 (smooth leaf) and Veronica (crisp leaf) with carrot (cv. Brasilia) and radish (cv. Hybrid number 19), under organic management. The amount of nutrients exported from the system by harvesting was also evaluated. The experimental design used was of completely randomized blocks, with four replications. In the first experiment, treatments consisted of lettuce with crisp leaves intercropped with carrot, lettuce with crisp leaves intercropped with radish and sole crops. In the second experiment, lettuce with smooth leaves was used instead of lettuce with crisp leaves. Intercropping of carrot and lettuce, with crisp or smooth leaf, presented land equivalent ratios higher than 1.60. Intercropping of radish and lettuce, with crisp or smooth leaf, presented land equivalent ratios of 1.54 and 1.27, respectively. Besides, the amounts of nutrients extracted by harvested products were lower than the inputs, pointing out the viability of the tested intercroppings.

Análise de fósforo em solo com leguminosas herbáceas perenes por meio de ressonância magnética nuclear

Abstract – The availability and the reserves of organic phosphorus are controlled by its mineralization rate andare also influenced by changes in soil management. The objective of this study was to evaluate the influence ofsoil covering with different leguminous plant on soil organic P by 31 P-NMR spectroscopy. Alkaline soil extractswere obtained from two depths (0–5 and 5–10 cm) of an Ultisol cultivated with herbaceous perennial leguminousplants ( Arachis pintoi , Pueraria phaseoloides , Macroptilium atropurpureum ). In an adjacent area, samples ofthe same soil cover with a secondary tropical forest and grass ( Panicum maximum ) were also collected. Theleguminous management was divided into with removal and without removal of shoot parts after cut on soilsurface. Phosphate monoesters are the dominant P species in all soil samples and P diesters accumulated on thesuperficial layer of secondary forest soil. The P amount of this fraction is higher for the legume covered soil whencompared with the grass covered soil. The permanence of leguminous plants on the topsoil after the cut promotedan increase in P diester/P monoester ratios. These findings can be accounted for an enhancement of P availabilityto plants in soils cultivated with leguminous plants.Index terms: cultivation, deforestation, cover crops.

Soil oribatid mite communities under three species of legumes in an ultisol in Brazil.

Oribatid mite densities in the topsoil and their activity at the soil surface were monitored under three species of perennial legume cover crops namely, Arachis pintoi, Macroptilium atropupureum and Pueraria phaseoloides, grass (Panicum maximum) and bare plots on three occasions in 1998 and 1999 in a derived savanna zone in Brazil. Both densities and activity at the soil surface were higher in the early but cool dry season in April 1998 than in the early wet but warm season in November 1998 and 1999. Three taxonomic groups of macropyline oribatid mites, namely Nothrus, Archegozetes and Masthermannia as well as a brachypyline taxon, Scheloribates were suggested as possible indicators of effect of legumes on soil biota because their populations increased under the legumes and/or their residues. Nothrus in particular increased in abundance more than any other taxon in the presence of residues of A. pintoi. Each legume supported a unique oribatid mite community in terms of species composition and relative abundance. The large numbers of Archegozetes trapped from all the legume and grass plots in April and November 1998 were also attributed to highly conducive conditions provided by the vegetation cover and their residues. The results suggest that the oribatid mite community of the study area was numerically stable as the peak populations of different species were not synchronized. Many taxonomic groups of pycnonotic brachypyline mites were absent. Legume cover crops, especially A. pintoi, and their residues have potential in restoring oribatid mite populations to precultivation levels.

The use of sunn hemp as green manure intercropped with taro

An experiment was carried out in Mage, Rio de Janeiro State, Brazil, to evaluate the performance of taro (Colocasia esculenta) intercropped with sunn hemp (Crotalaria juncea), used as green manure. A randomized blocks design with four replicates was used and the soil of the field plots was classified as Haplic Gleysol. Treatments consisted of taro (1) intercropped with unpruned sunn hemp, (2) intercropped with sunn hemp cut at soil level, (3) intercropped with sunn hemp pruned at its mid-height, and (4) in monoculture. The taro was planted in double rows spaced by 1.0 m. The planting furrows had a space of 0.5 m, with rhizomes placed at every 3.0 m. The experimental plot consisted of four 3.0 m rows and the useful area corresponded to the five central plants in each of the two central rows. The sunn hemp was sown in parallel lines in the spaces between the taro double rows, 120 days after planting the taro. When the sunn hemp was cut at soil level, an accumulation of 211 kg ha-1 of N was observed. Besides this, the sunn hemps biomass promoted the cycling of an average 17 kg ha-1 of P, 85 kg ha-1 of K, 151 kg ha-1 of Ca, and 27 kg ha-1 of Mg. Worth mentioning, it represented also a deposition of 6.85 Mg ha-1 of dry substance. Even when pruned at its mid-height, the sunn hemp still provided 60% of nutrients relatively to the treatment in which it was cut at soil level. In addition to the nutrient supply, the use of taro intercropped with sunn hemp cut at soil level or pruned at mid-height represented efficient alternatives for controlling the spontaneous vegetation and for reducing taro leaf burning by solar radiation, without compromising the yield of taro. In all intercropping systems, taro plants had a larger leaf area and were taller than plants in monoculture.

Evaluation of perennial herbaceous legumes with different phosphorus sources and levels in a Brazilian Ultisol

This study was carried out under field conditions with the aim of evaluating the period of time necessary for soil cover, dry matter production and accumulation of nutrients by perennial herbaceous legumes with different phosphorus sources at different levels. Four legumes were evaluated: calopo ( Calopogonium mucunoides Desv.), forage groundnut ( Arachis pintoi Krap. & Greg.), siratro ( Macroptilium atropurpureum (OC.) Urb.) and tropical kudzu ( Pueraria phaseoloides (Roxb.) Benth.). Each of these species received different phosphorus (P) sources and levels: no phosphate fertilization; 44 and 88 kg of P ha −1 applied as rock phosphate; and 44 kg of P ha −1 as triple superphosphate. Calopo, siratro and tropical kudzu completely covered the soil surface 129 days before forage groundnut. Phosphate fertilization did not increase the dry matter production of any species. The legumes forage groundnut, siratro and tropical kudzu showed desirable characteristics that promote their use as cover crops, such as high dry matter production and shoot accumulation of nitrogen (N) and potassium (K). Forage groundnut had the highest proportion of N derived from the atmosphere at the end of the rainy season, while there were no significant differences between the legumes at the end of the dry season. There was an elevation of soil pH and calcium+magnesium (Ca+Mg) contents, associated with a reduction of aluminum (Al) content, in the surface soil layer (0–5 cm) for siratro in relation to groundnut and tropical kudzu. Tropical kudzu promoted higher soil organic C contents when compared to groundnut.

Produção de cebola orgânica em função do uso de cobertura morta e torta de mamona

A cebola e uma hortalica consumida em grande quantidade e tem sua producao concentrada no âmbito da agricultura familiar, sendo responsavel pela geracao de emprego e renda para grande numero de produtores rurais que tem no cultivo desta especie sua unica fonte de renda. E crescente a demanda por tecnologias para producao de cebola adequadas a agricultura familiar, com enfase em tecnicas agroecologicas. Neste aspecto, destaca-se a utilizacao de coberturas mortas e adubos orgânicos. O objetivo deste trabalho foi avaliar o efeito de diferentes coberturas mortas, associados a doses crescentes de torta de mamona aplicadas em cobertura, na producao total e no diâmetro dos bulbos de cebola produzidos em sistema orgânico. Observou-se efeito significativo da cobertura morta na producao total e nas diferentes classes de diâmetro de bulbo. Nao foram observados efeitos significativos da adubacao com a torta de mamona e da interacao entre cobertura e adubacao com torta de mamona. O efeito benefico da cobertura morta na produtividade e na qualidade da cebola foi, provavelmente, decorrente da manutencao de maior umidade e da reducao da amplitude termica do solo.