• Authors:
    • Dourado Neto, D.
    • Righi, C. A.
    • Costa, L. C.
    • Bernardes, M. S.
    • Confalone, A. E.
    • Martin, T. N.
    • Manfron, P. A.
    • Pereira, C. R.
  • Source: Ciência Rural
  • Volume: 40
  • Issue: 5
  • Year: 2010
  • Summary: Predicting crop growth and yield with precision are one of the main concerns of the agricultural science. For these purpose mechanistic models of crop growth have been developed and tested worldwide. The feasibility of an expolinear model for crop growth was evaluated on predicting growth modification on soybean ( Glycine max L. Merrill) of determined and undetermined growth cultivars, submitted to water restrictions imposed on different phenological stages. An experiment was carried out in Azul/Argentina and in Vicosa/Brazil during the growing seasons (1997/1998, 1998/1999 and 2002/2003). The expolinear model was adjusted to the dry-matter data obtained from each treatment. The model showed sensibility of R m (maximum relative growth rate of the culture - g g -1 day -1) to variation in air temperature; of C m (maximum growth rate of the culture - g m -2 day -1) to solar radiation and of T b (lost time-day) to water stress. C m values were higher without water restriction presenting, in both countries, a direct correlation with solar radiation. Without water restrictions, R m values were lower when the average air temperature during the cycle was lower. It was observed that under water stress the culture had a bias to present higher R m values. T b was lower in the irrigated treatments than in those with water deficits. The analysis of the outputs clearly shows the feasibility of the expolinear model to explain the differential growth rates of soybean as a consequence of climatic conditions.
  • Authors:
    • Ferreira, A. C. de B.
    • Lamas, F. M.
  • Source: Revista Ceres
  • Volume: 57
  • Issue: 6
  • Year: 2010
  • Summary: The objective of this work was to evaluate the production, persistence and the effect of different cover crops on weed control and cotton yield in no-tillage system. The treatments included: Pennisetum glaucum; Brachiaria ruziziensis; Sorghum bicolor; Eleusine coracana; Crotalaria juncea; Crotalaria spectabilis; Avena strigosa; Raphanus sativus; P. glaucum+ C. juncea; P. glaucum+ C. spectabilis; B. ruziziensis+ C. juncea; B. ruziziensis+ C. spectabilis; S. bicolor+ C. juncea; S. bicolor+ C. spectabilis; E. coracana+ C. juncea; E. coracana+ C. spectabilis; A. strigosa+ R. sativus; P. glaucum+ R. sativus; fallow. The cover crops were sown in late summer, after soybean harvest. The cotton cultivar BRS 269-Buriti was sown nine months later. The experiment was carried out in a randomized complete block design with four replications. Dry matter of B. ruziziensis, B. ruziziensis+ C. juncea, B. ruziziensis+ C. spectabilis and P. glaucum+ R. sativus was above 6.8 t ha -1 The dry matter produced by B. ruziziensis provided sufficient soil cover during the cotton cycle. Residues of B. ruziziensis, B. ruziziensis+ C. juncea and B. ruziziensis+ C. spectabilis reduced weed incidence until the time of cotton sowing, lasting until the initial stages of cotton development. The use of both R. sativus and A. strigosa, alone or in mixtures, resulted in reduced yield of cotton fiber.
  • Authors:
    • Paulino, J.
    • Zolin, C. A.
    • Folegatti, M. V.
    • Sanchez-Roman, R. M.
    • Bezerra, M. O.
  • Source: Informe Agropecuario
  • Volume: 31
  • Issue: 259
  • Year: 2010
  • Summary: Irrigation is important in the context of food, since each irrigated hectare is equivalent to 3-ha of irrigation in physical productivity and 7-ha in economic productivity. Given this importance and the fact that Brazil has different water availability from other countries, there was an approach to irrigated agriculture in the country, considering the irrigated area at the regional and state based on 2006 Census of Agriculture. Brazil has currently an area of 4.45 million hectares cultivated with irrigation being the largest irrigating the Southeast Region, followed by the South, Northeast, Midwest and Northeast. Among the crops, sugar cane, rice, soyabeans and maize stand out in irrigated area. The irrigation method used is more for sprinkling (no pivot), followed by flood, centre pivot, and located in the groove.
  • Authors:
    • Bayer, C.
    • Vieira, R. C. B.
    • Fontoura, S. M. V.
    • Ernani, P. R.
    • Moraes, R. P. de
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 34
  • Issue: 6
  • Year: 2010
  • Summary: Little is known about the agronomic effectiveness of phosphate rocks in high-yielding crop rotation systems under no-till in the Center-South of the state of Parana, Brazil. This field study was undertaken to compare the effectiveness of rock phosphates and soluble P fertilizers to increase the yield of several annual crops grown in two consecutive triennial crop-rotation cycles under no-tillage. The experiment was carried out in an Oxisol, in Guarapuava, PR, from 2000 until 2006. Two phosphate rocks (PR - Gafsa and Arad) and a soluble P fertilizer (TSP - triple superphosphate) were broadcast over the soil surface at rates of 0, 40, 80 and 160 kg ha -1 P 2O 5, at the beginning of the first and the second rotation cycle of the triennial crops (oat, maize, wheat, soybean, barley and soybean). With exception of barley, crop yields were not affected in the first rotation cycle by any phosphate fertilizer regardless of type and rate, probably due to the high P contents available in the soil (8.7 mg dm -3 in the 0-10 cm layer). In the second rotation cycle, when soil available P was 4.1 mg dm -3; P application at oat sowing increased the yield of summer crops by 11% and of winter crops by 20%. The yield increment was lowest for maize (8%) and highest for barley (44%). In this cycle, TSP resulted in higher yield than PR, though only for winter crops (oat, wheat and barley), in a mean of 11%, with no difference between Gafsa and Arad. Water soluble fertilizer (TSP) was more efficient than phosphate rocks in soils under no-till system both in the short and long term. Nevertheless, it is not necessary to apply phosphates for high yields in soils with high available P contents under no-till, except for species with high P requirement, e.g., barley.
  • Authors:
    • Radmann, E. B.
    • Casagrande Junior, J. G.
    • Carpena Carvalho, F. L.
    • Gomes, C. B.
  • Source: Revista Brasileira de Fruticultura
  • Volume: 32
  • Issue: 1
  • Year: 2010
  • Summary: In a field naturally infested with ring nematode (Mesocriconema xenoplax), green covering were tested for their suppressing potential in winter and summer crops comparing to plots kept in fallow lands. Tree crop rotation system with the same plant species tested before (black oat/pig bean/millet/forage radish; forage radish/millet/white oat/corn; and white oat/dwarf velvet bean/wheat/sorghum) were evaluated for suppression potential to nematode M xenoplax for two years, using as control, plots that were kept in fallow lands. The experiments were conducted in the field in a randomized block design with six repetitions. Before and after the establishment of each plot, the nematode populations were evaluated on the number of M xenoplax/100cm3 of soil and the reproduction factor (RF=final population/initial population) of the ring nematode, where RF1,00, favoring of the reproduction. Most of the crops analyzed were unfavorable host (RF
  • Authors:
    • Peluzio, J. M.
    • Almeida, R. D. de
    • Afferri, F. S.
  • Source: Bioscience Journal
  • Volume: 26
  • Issue: 1
  • Year: 2010
  • Summary: A trial was carried out to estimate the phenotypic, genotypic and environmental correlations between eight agronomic traits, in twelve cultivars of soybean. The essays were carried out at Formoso do Araguaia, TO, in the inter-cropping of 2007. The soybean cultivars studied were DM Vitoria, MG/BR 46 (Conquista), Suprema, BRS Pintado, DM 247, BRS MG 68, BRS MG Lideranca, BRS MG Seguranca, DM 339, BRS MG Garantia, A 7002 e DM 309. The genotypic correlations presented equal signs and, in most cases were higher than their correspondent phenotypic correlations, indicating that the phenotypic values were reduced by the environment. The correlations genotypic presented equal sign and, in most of the cases, superior values to their correspondents correlations phenotypic, indicating that the expression phenotypic is reduced before the influences of the atmosphere. Selection of late flowering plants and with height insertion of the first bean would make it possible to indirectly improve grains yield due to the positive and significant correlation between these traits.
  • Authors:
    • Basso, F. C.
    • Montanari, R.
    • Passos e Carvalho, M. de
    • Andreotti, M.
    • Pariz, C. M.
    • Azenha, M. V.
    • Vercese, F.
  • Source: Ciência Rural
  • Volume: 40
  • Issue: 3
  • Year: 2010
  • Summary: The variation and the spatial dependence attributes of the following plant and soil characteristics: soyabean yield (SY) in no-till and irrigated soil; the macroporosity (MA); microporosity (MI); total porosity (TP); and bulk density (BD), in depths of 1 (0-0.10 m), 2 (0.10-0.20 m) and 3 (0.20-0.30 m), were studied in a Red Latosol of Mato Grosso do Sul, Brazil, were analysed during 2004/05, to study the variation and the linear and spatial correlations among the attributes (plant and soil) and select an index of soil physical quality with good capacity to represent the soyabean yield. A geostatistical grid to collect soil and plant data was installed, with 124 sample points, in an area of 4000 m 2. The linear relationship between soyabean yield and physical attributes of soil studied was low. So, there was a direct spatial relationship between SY and MA1 (0-0.10 m), as well as between SY and MA2 (0.10-0.20 m). The MA1 showed its best index of the soil physical quality, when it was destined to estimate the soyabean yield in no-till soil.
  • Authors:
    • Bartosik, R.
  • Source: Julius-Kühn-Archiv
  • Issue: 425
  • Year: 2010
  • Summary: Concerning grain production, South America is divided in two main regions: (1) the Mercosur region (Argentina, Brazil, Uruguay and Paraguay) which produces more than 250 million tonnes of grains and oilseeds, and (2) the Andes Mountain region countries, which are net importers of these products. The main challenges related to grain postharvest that South America is facing are to minimize the quality and quantity losses; improve the food safety; enhance the capability for segregation and traceability of identity preserved (IP) grains; and incorporate technology to maintain the overall efficiency of the postharvest system. Among the critical points affecting the efficiency of the system are the shortage of permanent storage capacity; large storage structures which affects the segregation of IP grains; deficient transportation system (roads and railroads); poor management of integrated pest control system; and unsatisfied demand of formal and informal education in suitable grain postharvest technologies and practices. However, the region remains highly competitive in producing and delivering food for the rest of the world and it has demonstrated high capacity for incorporating cost efficient grain handling technologies. As a result, one of the main changes in the region was the appearance of the silobag system for temporary storage of dry grain and oilseeds. Each silobag can hold approximately 200 tonnes of wheat and with the available handling equipment is quite simple to load and unload. During the 2008 harvest season, more than 33 million tonnes of grain were stored in these plastic bags in Argentina (including corn, soybean, wheat, sunflower, malting barley, canola, cotton seed, rice, lentils, sorghum, beans and even fertilizers). The silobag technology is also being adopted not only in neighbor countries, but also in countries around the world such as the USA, Mexico, South Africa, Australia, Russia and Ukraine, among others.
  • Authors:
    • Sousa, D. M. G. de
    • Rein, T. A.
  • Source: Informações Agronômicas
  • Issue: 126
  • Year: 2009
  • Summary: Soyabean monoculture with inadequate agricultural practices has resulted in losses of soil organic matter in the Brazilian cerrado, especially in sandy soils. This has led to erosion, reduced cation exchange capacity and water storage, and diminished fertilizer use efficiency. One of the ways of avoiding the loss of soil organic matter is to reduce tillage, as in the system of direct (as opposed to conventional) planting, and the use of this system is growing in the cerrado region. This paper reviews work that has been done on the correction of soil acidity and fertilizing with macronutrients in the direct planting system, both before and after crop establishment. The section on soil acidity discusses both surface (0-20 cm) and subsurface (20-60 cm) acidity, and the effects of correction with limestone or gypsum under conventional and no tillage systems, and on cotton and soyabean yields under a direct planting system. The section on fertilizers looks at the effects of liming, conventional and no tillage systems and dry farming on soil macronutrient content (with particular reference to nitrogen, phosphorus and potassium) and crop yield (with data for maize). Soil organic matter content is also compared under conventional and no tillage systems.
  • Authors:
    • Andreotti, M.
    • Benett, C. G. S.
    • Buzetti, S.
    • Valderrama, M.
    • Arf, O.
    • Sa, M. E. de
  • Source: Pesquisa Agropecuaria Tropical
  • Volume: 39
  • Issue: 3
  • Year: 2009
  • Summary: The objective of this study was to evaluate the effect of doses and sources of nitrogen and phosphorus, on the production components and grain yield, on irrigated common beans cultivated in a Cerrado area of Selviria, Mato Grosso do Sul State, Brazil (20degrees22′S, 51degrees22′W, altitude 335 m). The experimental design was a randomized block, with 4 doses of top-dressed N (0 kg ha -1, 40 kg ha -1, 80 kg ha -1, and 120 kg ha -1) and 2 sources (urea and coated urea), and 4 doses of phosphorus (0 kg ha -1, 50 kg ha -1, 100 kg ha -1, and 150 kg ha -1 of P 2O 5) and 2 sources (triple super phosphate and coated triple super phosphate), at sowing, with 4 repetitions. Nitrogen and phosphorus content in leaves, pod/plant number, grain/plant number, mass of 100 grains, and grain yield were evaluated. The sources of N, as well as the sources of P 2O 5, did not differ, as related to the number of pods per plant, grains per plant, mass of 100 grains, and grain yield. The doses of N influenced linearly the leaf N content, as well as the grain yield. The doses of P increased linearly the leaf P content and the grain yield, up to the 120 kg ha ′1 dose.