Dejair Lopes de Almeida

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.

Desempenho do consórcio entre repolho e rabanete com pré-cultivo de crotalária, sob manejo orgânico

Field experiments were carried out during two consecutive years in the Integrated Agroecological Production System, in Rio de Janeiro State, Brazil, to evaluate the performance of cabbageradish intercropping under organic management on the basis of agronomic traits and Area Equivalency Index (AEI). The contribution of green manure pre-planting to the system also was evaluated. A randomized complete blocks design with seven replicates in a 2x3 split-plot factorial scheme was used. Treatments in the main plots consisted of Crotalaria juncea pre-planting or fallow. Cabbage or radish single crops and the respective intercropping were distributed in the subplots. No significant differences were detected between C. juncea and fallow as related to cabbage or radish yields in any of the systems used (single crops and intercropping). Intercropping had no effect on cabbage yield, but significantly reduced radish root yield. However, commercial standard of the harvested radish roots was not affected. An average AEI of 1,59 for the two experimental years was attained, thus indicating the viability of the cabbage-radish intercropping. The system makes possible to afford additional income for a given area cultivated with cabbage, at its conventional single-crop spacing, by including radish as a secondary crop. Intercropping also was advantageous by allowing optimization of cultural practices such as fertilization, weeding, and irrigation.

Utilização de compostos orgânicos como substratos na produção de mudas de hortaliças

Visando determinar a viabilidade da utilizacao de compostos orgânicos obtidos com palhada de Crotalaria juncea L. e capim Napier (Pennisetum purpureum Schum.) como substratos na producao de mudas de hortalicas, realizaram-se experimentos com alface (folhosa), beterraba (raiz) e tomate (hortalica de fruto). Estudou-se a eficiencia de compostos produzidos a partir dos materiais: 100% de Crotalaria Juncea; 66% de Crotalaria Juncea + 33% de Napier; 33% de Crotalaria Juncea + 66% de Napier; 100% de Napier; 33% de Crotalaria Juncea + 66% de Napier, inoculado com 5% da massa com esterco bovino; 33% de Crotalaria Juncea + 66% de Napier, inoculado com 100 L de Agrobio diluido a 5%; 100% de Napier, inoculado com 100 litros de Agrobio diluido a 5%. Como controle utilizou-se o substrato comercial Plantmax HT®. Avaliou-se altura da parte aerea, numero de folhas, producao de massa fresca na parte aerea e producao de massa seca na parte aerea. O composto produzido com a mistura de 66% de Crotalaria Juncea e 33% de Napier mostrou-se superior aos demais tratamentos para producao de mudas de alface, beterraba e tomate.

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.

Plantio direto, adubação verde e suplementação com esterco de aves na produção orgânica de berinjela.

No-tillage systems were evaluated within an eggplant (Solanum melongena) organic management in Seropedica, Rio de Janeiro State. Crotalaria juncea and Pennisetum glaucum cv. BRS 1501 were used as pre- plantings besides fallowing, in comparison to conventional system (plowing). Simultaneously, three cropping managements were tested: eggplant single-cropping, intercropping with C. juncea, and intercropping with cowpea (Vigna unguiculata cv. Maua). No differences were found among planting systems concerning eggplant yield. Crotalaria juncea was more effective than Pennisetum glaucum and fallow for soil mulch. Intercropping with leguminous species did not decrease eggplant yield. In a second study no-tillage (on C. juncea and spontaneous weeds mulchs) and conventional plowing were compared. These treatments were combined with increasing levels of poultry manure (0, 100, 200, and 400 kg ha -1 of N). In terms of biomass input, C. juncea was again superior to spontaneous weeds. Eggplant responded to organic fertilization with maximum productivity (50.6 t ha -1 ) corresponding to the highest manure level applied, compared to 36.9 t ha -1 for control plots.

Variabilidade entre genótipos de milho para eficiência no uso de fósforo

Exploiting genetic variability in maize for phosphorus (P) efficiency is one of the viable strategies to turn around the element deficiency in tropical and subtropical regions. In order to verify differences among maize genotypes on phosphorus utilization and grain yield, two experiments were conduted. First, eighteen corn genotypes (ten local varieties, six improved varieties, and two hybrids) were evaluated in two soil P levels (10 and 100 mg.kg -1 de P), under greenhouse conditions. The second experiment, five local varieties and one improved variety, and one hybrid were evaluated under field conditions at crescent levels of P fertilization (0; 8.7; 17.5; 35; 70, and 140 kg.ha -1 de P). Genetic variability was detected for P efficiency at greenhouse conditions. The local varieties (Argentino, Amarelao, Caiano de Sobralia, Asteca, Quarentao and Caiano de Alegre), the improved ones (BR 106 and BR 107), and the hybrid P 6875 were the genotypes with the highest efficiency indexes. Under field conditions, the effects of P addition in grain production and P content in the grains were observed. The genotypes exhibited different levels in response to increased nutrient availability. The local varieties Cravinho and Carioca, and the hybrid P 6875 were the most responsive, besides presenting the highest grain yield in the absence of P fertilization. Nitroflint (improved variety) and Catetao (local variety) presented the lower response to P addition and the lower grain yield without P addition.

Plantio direto de alface adubada com cama de aviário sobre coberturas vivas de grama e amendoim forrageiro

The agronomic viability of no-tillage system for lettuce was evaluated, using grass and legume as cover crop under organic management. A randomized complete block design with split plot arrangement was used. Plot treatments were conventional soil tillage (control), bahia grass and perennial peanut cultivated for living cover crops on no-tillage system. Split-plot treatments were doses of poultry manure (0; 7; 14 and 28 t ha-1) in three application periods. Lettuce cv. Vera yield was not affected by tillage system neither by cover crop. The quadratic model was the most appropriate to describe the variation of yield. The greatest yield estimated by regression models was 348 g plant-1 with 23 t ha-1 of poultry manure bed. On the no tillage system, using bahia grass or perennial peanut, the estimated yield by regression models was similar to the conventional soil tillage system, with a yield of 55,99 t ha-1 using 23,4 t ha-1 of poultry manure bed.A viabilidade agronomica do plantio direto de alface cv. Vera foi avaliada sobre coberturas vivas perenes de graminea e leguminosa em sistema de manejo orgânico. Empregou-se o delineamento de blocos casualizados, dispostos em parcelas sub-divididas. Os tratamentos nas parcelas constaram de plantio em sistema de preparo convencional do solo (controle), plantio direto sobre cobertura viva de grama batatais e plantio direto sobre cobertura viva de amendoim forrageiro. Os tratamentos nas subparcelas constaram de adubacao com doses de cama de aviario aplicada em cobertura (0; 7; 14 e 28 t ha-1), parceladas em tres epocas. Observou-se que a producao de cabeca de alface nao foi influenciada pelo modo de plantio e nem pela especie de cobertura viva sobre a qual foi realizado o plantio direto. Modelo quadratico mostrou-se adequado para descrever a variacao observada dos valores de producao de cabeca de alface em relacao a doses. O rendimento maximo estimado pelo modelo de regressao para a massa fresca media de alface foi de 348 g planta-1 para a dose de 23 t ha-1 de cama de aviario. O plantio direto de alface sobre cobertura viva de grama batatais e amendoim forrageiro acarretou desempenho semelhante ao desta hortalica, em sistema de preparo convencional do solo, com nivel maximo de produtividade de 55,99 t ha-1 de massa fresca estimado pelo modelo de regressao.

Growth and yield of common bean cultivars at two soil phosphorus levels under biological nitrogen fixation

The genotypic differences on growth and yield of common bean (Phaseolus vulgaris L.) in response to P supply were evaluated in a field experiment under biological N2 fixation. Eight cultivars were grown at two levels of applied P (12 and 50 kg ha-1 of P ¾ P1 and P2 respectively), in randomized block design in factorial arrangement. Vegetative biomass was sampled at three ontogenetic stages. The effects of genotype and phosphorus were significant for most traits, but not the genotype ´ phosphorus interaction. The cultivars presented different patterns of biomass production and nutrient accumulation, particularly on root system. At P1, P accumulation persisted after the beginning of pod filling, and P translocation from roots to shoots was lower. The nodule senescence observed after flowering might have reduced N2 fixation during pod filling. The responses of vegetative growth to the higher P supply did not reflect with the same magnitude on yield, which increased only 6% at P2; hence the harvest index was lower at P2. The cultivars with highest yields also presented lower grain P concentrations. A sub-optimal supply of N could have limited the expression of the yield potential of cultivars, reducing the genotypic variability of responses to P levels.

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.

Effect of seed phosphorus concentration on nodulation and growth of three common bean cultivars

Abstract An experiment was conducted in the greenhouse to evaluate the effects of seed phosphorus (P) concentration on growth, nodulation, and nitrogen (N) and P accumulation of three common bean (Phaseolus vulgaris L.) cultivars. Seeds were produced under low or high soil P levels, and soaked, or not, in 200 mM KH2PO4 solution. The experiment had a 3×3×2×2 factorial block design: three cultivars (ICA Col 10103, Carioca and Honduras 35), three levels of applied P (15, 30 and 45 mg P kg−1 soil), two native seed P concentrations, and two seed soaking treatments. Plants were harvested at flowering. Soaked seeds increased the number, dry mass and P content of nodules, but did not affect plant growth. Plants originated from seeds with high native P concentration presented higher shoot dry mass and nodule number and mass at every soil P level, and were less responsive to increased soil P supply, than plants from low seed P. In plants from seeds with high P, soil P levels did not alter significantly root dry mas...