• Authors:
    • Degrande, P.
    • Soria, M.
  • Source: Revista Brasileira de Milho e Sorgo
  • Volume: 10
  • Issue: 2
  • Year: 2011
  • Summary: Pest species that are enhanced by cover crops used in no-tillage farming can cause damages to subsequent crops of economic importance planted into cover crops stubble. In the 2006/2007 growing season, in Dourados, MS, Brazil, a study was carried out to assess the arthropod fauna in three soybean no-tillage systems: unseeded vegetation-soybean, pearl millet-soybean and sorghum-soybean. During the soybean pre-planting season and the early soybean season, the incidence of pests and natural enemies was assessed in 1 m 2 of the cover crops and later on their respective stubble with soybean seedlings in development using a wood made frame square ("wood square" sampling method). The most abundant species at the soybean pre-planting season were caterpillars of Mythimna ( Pseudaletia) sequax and Mocis latipes (Lepidoptera: Noctuidae), and adults and nymphs of the predator Doru luteipes (Dermaptera: Forficulidae), showing a significant population increase on the pearl millet green cover crop. After the cover crops desiccation the incidence of Lagria villosa (Coleoptera: Lagriidae) species was significant on sorghum and pearl millet stubble and the genus Agrotis sp. (Lepidoptera: Noctuidae) on sorghum cover. Thus, the bioecology of pests and natural enemies associated with pearl millet as cover crop might be considered on the development of Integrated Pest Management (IPM) programs in conservation farming systems.
  • Authors:
    • Klein, V.
    • Denardin, J.
    • Escosteguy, P.
    • Spera, S.
    • Santos, H.
  • Source: Revista Agrarian
  • Volume: 4
  • Issue: 14
  • Year: 2011
  • Summary: The goal of the work was to evaluate the effects of soil tillage and crop rotation systems in the restrictive chemical attributes and plant production of grain crops of two layers of soil. The experiment was carried out in Passo Fundo, RS, Brazil, after more than two decades without limestone application. The design was randomized blocks, schedule of split plots, with three modes of soil tillage and crop rotations. It was evaluated the effect on grain yield and dry matter of the shoot of winter ( Triticum aestivum, Avena sativa and Vicia sativa) and summer ( Glycine max and Sorghum bicolor) crops. The effect of these factors in soil chemical attributes has also been evaluated according to the layer of soil (0 to 6.7 and 6.8 to 20 cm). The effects of soil tillage and crop rotation influenced the grain yields of crops of wheat and sorghum only, in addition to the mass of the shoots of soybean crop. Chemical soil attributes were not influenced by the interaction of factors studied, being little influenced by crop rotation. In all treatments, the results indicated a surface layer (0 to 6.7 cm) with a nutrient concentration, and other subsurface (6.8 to 20 cm) compacted and acid. In the surface layer the values of chemicals attributes were appropriated for the developing cropping evaluated. There were no differences between the amounts of organic matter and the particulate fraction. In the layer subsurface, in all treatments, the attributes of the soil acidity were restrictive to plant development.
  • Authors:
    • Denardin, J.
    • Klein, V.
    • Escosteguy, P.
    • Spera, S.
    • Santos, H.
  • Source: Revista Agrarian
  • Volume: 4
  • Issue: 14
  • Year: 2011
  • Summary: The objective of this paper was to evaluate the effects of different soil tillage and crop rotation systems in the restrictive physical attributes and plant production of grain crops of two layers of soil. The experiment was carried out in Passo Fundo, RS, Brazil, a dystrophic Red Latosol, after more than two decades without application of limestone. Treatments tested were three soil tillage and three crop rotations, to assess the effect on grain yield and dry mass of shoots of crops. The effect of these treatments on the soil physical attributes (soil bulk density, soil porosities, natural clay, soil mechanical resistance and saturated soil hydraulic conductibility) was also measured by the soil layers analyzed. The interaction between management of soil and crop rotation influenced the yield of grain crops of wheat and sorghum, in addition to the mass of air part and soybean crop. Soil physical attributes were not influenced by the interaction of factors studied, being little influenced by crop rotation. In all treatments, physical attributes results indicated a layer (0 to 6.7 cm) not compacted and another (6.8 to 20 cm) compacted. In the 0 to 6.7 cm layer, the differences of physical attributes were not important between the treatments. In the compacted layer, the notill has zero value for least limiting water range thus being considered restrictive to the development of plants.
  • Authors:
    • Costa, M.
    • Castoldi, G.
    • Pivetta, L.
    • Steiner, F.
    • Costa, L.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 6
  • Issue: 3
  • Year: 2011
  • Summary: The organic carbon is a major component of the soil organic matter, and its stock is influenced by the type of management system used. This study aimed to evaluate the effect of two cropping systems, with and without cover crop rotation, associated to three fertilization sources (mineral, organic and mineral+organic) in the organic and residual carbon contents of an Oxisol, in no-tillage system. Soil samples were collected at 0.0-0.10, 0.10-0.20 and 0.20-0.40 m depth in the first, second and third years of the experiment, installed in 2006. The crops sequence in the rotation system with cover crops was oat+vetch+turnip/corn/wheat/mucuna+brachiaria+crotalaria/corn/soybean, and in the following system it was wheat/corn/wheat/soybean/corn/soybean. The organic and mineral+organic fertilizers consisted in the sole application of organic fertilizers and combined with mineral fertilizer. The organic and residual carbon contents were not affected by the different cropping systems. The organic and mineral+organic fertilizers promoted increases in the organic and residual carbon contents. The system of crop succession fertilized with mineral fertilizer resulted in higher losses of soil carbon.
  • Authors:
    • Machado, V.
    • Lopes, J.
    • Souza, R.
    • Souza, C.
    • Teixeira, C.
  • Source: Informe Agropecuario
  • Volume: 32
  • Issue: 260
  • Year: 2011
  • Summary: The successful implementation and establishment of the no-tillage (NT) system is directly related to the maintenance of straw on the soil surface. The system of crop rotation also contributes to the success of NT. In the Cerrado (Minas Gerais, Brazil), the high temperature and rainfall mainly during the first six months accelerate straw decomposition and hinder the cultivation of crops during the winter. This paper presents various crop management options to promote the success of NT in the Cerrado region. Most notable is the oversowing of millet in soyabean and Santa Fe system, which involves a mixture of grasses and perennial crops, such as sorghum, millet and maize.
  • Authors:
    • Souza, R. F. de
    • Medeiros, M. A. de
    • Marouelli, W. A.
    • Resende, F. V.
  • Source: Horticultura Brasileira
  • Volume: 29
  • Issue: 3
  • Year: 2011
  • Summary: The efficient use of water and the environmental diversity are crucial to the balance and sustainability of the organic production system of tomatoes. The present study aimed to evaluate the organic production of tomato cultivated as a single crop and in consortium with coriander, under sprinkler and drip irrigation. The experiment was carried out at an organic production area on the Federal District of Brazil. The experimental design was randomized blocks with treatments arranged in a 2*2 factorial (two irrigation systems * two cropping schemes). No significant interaction between the both factors occurred, and there was no significant effect of the cropping scheme over the evaluated variables. Although the crop cycle has been reduced when tomato was drip irrigated, the fruit yield was not affected by the irrigation systems. The larger reduction in the stand of plants observed under sprinkler irrigation has been compensated by an increase in the number of fruits per plant, without a change on the fruit mass. The smaller volume of soil explored by the tomato roots associated with the higher incidence of South American tomato pinworm ( Tuta absoluta) and mainly powdery mildew ( Leveillula taurica) may have limited the yield of drip irrigated tomato. The fruit decay rate on sprinkle irrigated plants was twice the rate found on the drip irrigated system.
  • Authors:
    • Knies, A. E.
    • Streck, N. A.
    • Radons, S. Z.
    • Martins, J. D.
    • Carlesso, R.
  • Source: Ciência Rural
  • Volume: 41
  • Issue: 6
  • Year: 2011
  • Summary: The plastochron, which is the time interval between the appearance of two successive nodes and the final node number (FNN) are important variables of the vegetative development in soybean. The objective of this study was to determine the plastochron and the FNN of soybean ( Glycine max (L.) Merrill) cultivars sown in different dates under irrigated conditions in a subtropical location. A field experiment was carried out in Santa Maria, RS, Brazil during 2005/2006 growing season, with three sowing dates (09/11/2005, 09/12/2005 and 28/01/2006). It was used 15 soybean cultivars recommended for the Central and North Argentina, and South and Southeast Brazil. The variables measured were the number of nodes (NN) and the (FNN) on the main stem. The plastochron was estimated by the inverse of the slope of the linear regression between NN and the thermal time (base temperature=10degreesC) accumulated since plant emergence. The late sowing resulted in lower plastochron and FNN, probably because of the lower photoperiod under which the plants were submitted in the node phase, a typical response of short day plants.
  • Authors:
    • da Silva Matos, E.
    • de Lima, P. C.
    • Souto, R. L.
    • Cardoso, . M.
    • de Sá Mendonça, E.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 42
  • Issue: 5
  • Year: 2011
  • Summary: 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.
  • Authors:
    • Ralish, R.
    • de Lima, G. P.
    • Rosa, D. M.
    • Pereira Nóbrega, L. H.
    • Mauli, M. M.
  • Source: Brazilian Archives of Biology and Technology
  • Volume: 54
  • Issue: 4
  • Year: 2011
  • Summary: This study analyzed possible interferences associated to the amount of crop residues produced by the black oats and the consortium of black oats, common vetch and forage turnip on weeds incidence and soil seed bank. It was a field trial with seven treatments and five replications. The cover crop was sown at throwing, cut at 100 days and residues were put on each respective plot, using a proportion of normal amount of produced straw, either its half and double. The heaviest weights were obtained from cover crop consortium and their application decreased weeds incidence in such area. The seeds bank and other analyzed parameters did not show statistical differences. According to these results, it was concluded that winter cover crop could be used in crops rotation with soybean.
  • Authors:
    • Pereira, L. G. R.
    • de Oliveira, P. T. L.
    • Voltolini, T. V.
    • Turco, S. H. N.
    • de Araújo, G. G. L.
    • Mistura, C.
    • Menezes, D. R.
  • Source: Revista Ceres
  • Volume: 58
  • Issue: 2
  • Year: 2011
  • Summary: This study was carried out to evaluate the influence of climatic factors on performance and physiological responses of sheep fed on different protein supplements in grazing Tifton 85 ( Cynodon spp.) irrigated in conditions of Brazilian semiarid climate. A total of 28 male Santa Ines * SPRD (undefined breed), castrated lambs, with initial weight of 28 kg, received three different sources of protein in the supplement (soybean meal, cotton cake and urea) and a control treatment, only on grass. The parameters evaluated were: dry matter intake, average daily gain, physiological parameters [respiratory rate (FR), surface temperature (TS) and rectal temperature (TR)] and environmental parameters. Under the climatic conditions imposed by the experiment, the period of the afternoon led the animals to a condition of high heat stress, regardless of the diet. Supplementation affected roughage intake without changing sheep performance, making it economically unfeasible. Protein source derived from cotton cake and used in the supplement for the lambs in grazing increased FR, influencing their thermal comfort.