José Luiz Rodrigues Torres

Produção de fitomassa por plantas de cobertura e mineralização de seus resíduos em plantio direto

The objective of this work was to evaluate dry biomass production, decomposition rate and macronutrients release (N, P, Ca, Mg and S) of cover crops cultural residues, in a no-till savanna soil. The cover crops tested were: pearl millet (Pennisetum americanum sin. typhoides), brachiaria grass (Brachiaria brizantha cv. Marandu), sorghum [Sorghum bicolor (L.) Moench], pigeon pea [Cajanus cajan (L.) Millsp.], sunn hemp (Crotalaria juncea L.) and black oat (Avena strigosa Schreb), compared to a fallow plot (control). The experiment was carried out in an Oxisol, medium texture. A randomized block design, in a split-plot array in time, with four replications, was used. Dry biomass production was evaluated 110 days after sowing. Decomposition rate was evaluated by litter bags containing cultural residues. Millet and sunn hemp are the cover crops (grass and legume) with the highest dry biomass production and N accumulation, in the two evaluation periods. The highest decomposition rate and nutrient release occurred at 42 days after desiccation. The highest values of half life were observed in dry period.

Dinâmica do potássio nos resíduos vegetais de plantas de cobertura no Cerrado

Crop residue production, plant residue maintenance and their decomposition are important factors in the understanding of nutrient recycling process. To evaluate K accumulation and release a study with eight cover crops types was developed: pearl millet (Pennisetum americanum sin. tiphoydes), brachiaria grass (Brachiaria brizantha), sorghum (Sorghum bicolor L. Moench), pigeonpea (Cajanus cajan (L.) Millsp), sunn hemp (Crotalarea juncea) and black oats (Avena strigosa Schreb), fallow land and conventional culture (control) in the experimental area of CEFET-Uberaba-MG, in a Cerrado area. The dry mass production, crop residue decomposition in litter bags and K release were evaluated. A mathematical model was used to describe residue decomposition and K release, which calculates the decomposition constant (k) and half-time life. Pearl millet, sorghum and the sunn hemp were the cover crops that produced most dry matter while K accumulation was highest in the grasses. K release was highest in pearl millet, oats, brachiaria grass and sunn hemp in the first 42 days after handling. Brachiaria grass had the shortest half-time life and the highest K release rate.

Qualidade do fruto e produtividade do abacaxizeiro em diferentes densidades de plantio e lâminas de irrigação

The objective of this work was to evaluate the effect of different planting densities and two irrigation levels on the fruit quality and productivity of pineapple (Ananas comosus (L.) Merril). A randomized block experimental design was used with six planting densities and two irrigation levels, with five replicates. Fruit weight, firmness, and juice yield were evaluated. The diameters of the fruit and of the stalk were also measured. The primary fruit, ratoon fruit, and the total fruit yield were calculated. The increase in planting density caused a decrease in the average fruit weight, diameter of the fruit and of the stalk, juice yield, and primary crop. However, plant density did not affect fruit firmness. The higher irrigation rate did not influence the fruit weight average, the diameter of the fruit and of the stem, or the primary crop, but did cause a decrease in fruit firmness and juice yield in the 35,714 and 71,429 plants ha -1 populations. The total fruit productivity increased with plant density and was not influenced by irrigation rate.

Alterações dos atributos físicos de um Latossolo Vermelho submetido a diferentes sistemas de manejo

O cultivo do solo pode alterar alguns atributos fisicos em relacao ao solo nao cultivado. Diante disso, neste estudo objetivou-se verificar as alteracoes provocadas pelos sistemas de uso do solo sobre alguns atributos fisicos de um Latossolo Vermelho no Triângulo Mineiro. Os tratamentos utilizados foram: Campo nativo (CN) (testemunha); preparo convencional do solo (PC); pastagem irrigada de braquiaria sob pastejo rotacionado tipo VoIsin (PT) e Semeadura direta (SD). Utilizou-se o delineamento inteiramente casualizado, com 4 repeticoes, onde foram avaliados os seguintes atributos fisicos: densidade do solo (Ds), volume total de poros (VTP), microporosidade (MI), macroporosidade (MA), condutividade hidraulica saturada (Kθ, resistencia mecânica do solo a penetracao (RP) e o indice de sensibilidade (Is). Nas areas sob PC, SD e PT nao foram observadas alteracoes significativas com relacao aos atributos fisicos avaliados. Para as profundidades avaliadas so ocorreram diferencas significativas entre as profundidades de 0,0 - 0,05 e a de 0,15 a 0,20 m para os parâmetros Ds e VTP. PC, SD, PT e CN apresentaram valores medios de volumes de MA proximos ou superiores daquele considerado ideal (0,33 dm-3dm-3). Apenas no CN nao ocorreu valores maiores que 2 MPa. No CN, PC, e SD nao ocorreram limitacoes ao desenvolvimento das culturas ate a profundidade de 0,08 m. O Is calculado para os atributos CC e Kθ nos sistemas PC e PT demonstraram o efeito prejudicial desses sistemas de manejo sobre a estrutura do solo, quando comparados ao SD.

Níveis de adubação nitrogenada nas características morfológicas e produtividade do jiló

The experiment was conducted at the Rural Federal University of Rio de Janeiro, Brazil, fron July to December, 1993. The effects of different levels of nitrogen (0; 24; 48; 72 and 96 kg.ha-1 of N) was evaluated over some morphological characteristics of the fruit and over yield of the jilo, cultivar Tingua. Harvest began 105 days after sowing date, in 10-day intervals. The diameter, length, medium weight and total yield of fruits were evaluated. The jilo plant responds positively to the nitrogen fertilizer application, increasing the yield up to 35,7%, in relation to the control plot, in spite of non statistical differences among nitrogen levels; the morphologic characteristics suffered no influence from N levels.

Fertilidade e carbono total e oxidável de Latossolo de Cerrado sob pastagem irrigada e de sequeiro

The sprinkler irrigation on pasture can increase the forage production and improve soil chemical conditions. The aim of this study was to evaluate soil fertility and oxidizable and total carbon contents in Oxisol of the Cerrado under pasture area Tifton 85 (Cynodon spp), irrigated and dryland. The experimental design was completely randomized. Soil samples were collected in the 0-5, 5-10, 10-20 and 20-40cm depth, to evalueted the tenors of Ca, Mg, Al, P, K, Na, H + Al, total organic carbon (TOC) and determined the pH values. The samples were chemically fractionated with potassium dichromate to obtain fractions with different degrees of lability: F1>F2>F3>F4. The irrigated area had the highest Ca and Mg tenors in relation to the no-irrigated area, except for Mg, 10-20cm depth. It was observed difference for the TOC, and the highest values were verified in the irrigated area, due to higher contribution of stem and root biomass at all depths. This pattern was also observed for fractions F1 and F2. The irrigation increases the concentration of TOC, being this increase most noticeable in the more labile fractions (F1 and F2) and also provides improved soil fertility by increasing the concentration of Ca and Mg.

Production, decomposition of residues and yield of maize and soybeans grown on cover crops

The residues of cover plants and crops left on the soil surface can influence decomposition, nutrient cycling and follow crop yield. The objective was to evaluate the production of dry biomass (BD), of residues decomposition rate and yield of maize and soybean grown on different soil covers. The experimental design was a randomized block scheme banded, with four covers: Brachiaria, sun hemp, pearl millet and fallow period in autumn/winter, with maize and soybean crop in the spring/summer. We evaluated BD, decomposition through bags of decomposition and yield of maize and soybeans. Pearl millet and sunhemp were the covers which produced more of BD in the fall/winter period. the rate of decomposition of plant residues in maize and soybeans is slow in the dry period and accelerated in the rainy period; maize yield was higher when grown on sunhemp and brachiaria in the years evaluated, while for soybeans there were no differences on any measured coverage; maize and soybeans have grain yields higher than the regional average when grown on different soil covers.

Geostatistical techniques applied to spatial distribution of macroorganisms in soybean crop

State University of Campinas (Unicamp) School of Agricultural Engineering (Feagri), Av. Cândido Rondon, 501 - Barao Geraldo

Análise das caracteristicas quantitativas e qualitativas da microbacia do córrego barreiro, afluente do Rio Uberaba

The association of qualitative and quantitative methods in the study of hydrographic microbasins is fundamental to investigate factors that influence the various forms of relief and identification of homogeneities in the area. In order to performe morphometry and to evaluate water quality of the microbasin of Barreiro stream,it was performed the morphometric characterization of the area, which was carried out on a topographical map of IBGE (Sheet Uberaba) at 1:100,000 scale, by using curvimeter, planimeters and AutocadMap2000i computer program. It was observed that the microbasin has a total area of 10.97 km 2 , and a perimeter of 14.33 km, with length of the main channel of 6.11 km and drainage network for 3 rd order, with dendritic pattern; Kc of 1.21, Ic of 0.76 and Kf of 0.23 indicates the elongated form of the microbasin, determining the non-propensity to inundations in the area; the area has aptitude for agriculture. The stream water was inappropriate for human and animal consumption inasmuch as it was contaminated with fecal coliform in the study period.