• Authors:
    • Bielders, C. L.
    • Laloy, E.
  • Source: European Journal of Soil Science
  • Volume: 60
  • Issue: 6
  • Year: 2009
  • Summary: In order to evaluate the impact of intercrop management on runoff and erosion in a continuous maize cropping system, the plot scale, continuous and process-based erosion model (CREHDYS) developed previously must be calibrated accounting for its two main outputs: runoff and sediment loss. To do that, a global Pareto multi-objective calibration was applied to these two potentially conflicting objectives, considering daily runoff and periodical erosion rates, for two sites with different slopes and soil textures. This revealed a trade-off between both objectives. The large resulting Pareto uncertainty regarding parameters did not translate into a large predictive uncertainty of daily runoff but resulted into a large uncertainty on erosion prediction. Globally, model results were satisfactory with regard to daily runoff prediction (Nash-Sutcliffe index varying within the Pareto solution set from 0.65 to 0.91 for calibration and 0.64 to 0.77 for validation period) and relatively satisfactory for periodical erosion. However, the small number of available data points (three) for model validation in terms of periodical erosion prediction was not sufficient to ensure a proper validation. The calibrated model was in turn used to perform a scenario analysis of the long-term hydrological and erosive impact of inter-cropping period management in a continuous maize cropping system, using disaggregated rainfall. The long-term simulations mainly revealed that, with regard to the erosion prevention during the inter-cropping period, planting a winter cover crop is a better option than reduced tillage with a cultivator (0-12 cm), even if the cover is destroyed early (1 January). As compared with the situation of a bare heavily crusted soil with two semi-permanent wheel tracks, reduced tillage led to an erosion reduction from 90 to 97%, an early cover destruction (1 January) to an erosion decrease from 92 to 98% and a cover destroyed on 1 March or later to an average soil loss reduction from 96 to 99%.
  • Authors:
    • Rizzo, I.
    • Sarandón, S. J.
    • Sisterna, M. N.
    • Lori, G. A.
    • Chidichimo, H.
  • Source: Crop Protection
  • Volume: 28
  • Issue: 6
  • Year: 2009
  • Summary: Fusarium head blight (FHB) is a destructive disease of the world's wheat-growing areas. In Argentina, the area under reduced tillage has increased due to soil erosion that threatened productivity. The effect of conventional and no tillage systems on FHB combined with other agronomic practices such as nitrogen fertilization, and the influence of the environmental conditions was analysed under natural infection on different cultivars. Wheat trials were conducted in three consecutive years; maize was the previous crop in the first and wheat the previous crop in the subsequent two years of the study. The experimental design was a split plot, with tillage treatments (conventional tillage and no-till) as the main plots. Fertilizer treatments were applied as a range of urea concentrations. Fusarium head blight was observed in all three experimental years. Differences of disease expression among trials were associated with the environmental factors prevailing during the experiments. In the first year, with moderate weather conditions, the only interactions for FHB incidence were between no-till and urea split doses. Seedling emergence, seed health, thousand kernel weight and deoxynivalenol (DON) concentration did not differ suggesting that the fertilizers and genotypes did not affect disease susceptibility. Climatic conditions prevailing in the second year were more conducive to disease development and severe FHB infection was observed. Tillage and fertilization treatments did not affect the variables analysed. Only cultivars showed significant differences and DON values were high. In the third year, unfavourable conditions for disease development resulted in low disease levels and no effect or interaction among variables was observed. The results obtained would suggest that favourable weather conditions are likely to be more important than tillage practice and fertilizer treatments. Since soil conservation practices have been widely adopted in most areas of Argentina, an integrated used of all the available strategies should be considered to decrease FHB damage.
  • Authors:
    • Fernandes, C.
    • Cora, J. E.
    • Marcelo, A. V.
    • Martins, M. dos R.
    • Jorge, R. F.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 33
  • Issue: 2
  • Year: 2009
  • Summary: Decomposing crop residues in no-tillage system can alter soil chemical properties, which may consequently influence the productivity of succession crops. The objective of this study was to evaluate soil chemical properties and soyabean, maize and rice yield, grown in the summer, after winter crops in a no-tillage system. The experiment was carried out in Jaboticabal, Sao Paulo, Brazil on a Red Latosol (Oxisol), in a completely randomized block design, in strip plots with three replications. The treatments consisted of four summer crop sequences (maize monocrop, soyabean monocrop, soyabean/maize rotation and rice/bean/cotton rotation) combined with seven winter crops (maize, sunflower, oilseed radish, pearl millet, pigeon pea, grain sorghum and sunn hemp). The experiment began in September 2002. After the winter crops in the 2005/2006 growing season and before the sowing of summer crops in the 2006/2007 season, soil samples were collected in the layers 0-2.5; 2.5-5.0; 5-10; 10-20; and 20-30 cm. Organic matter, pH, P, K +, Ca 2+, Mg 2+, and H+Al were determined in each soil sample. In the summer soyabean/maize rotation and in maize the organic matter contents and P levels were lower, in the layers 0-10 cm and 0-20 cm, respectively. Summer rice/bean/cotton rotation increased soil K levels at 0-10 cm depth when sunn hemp and oilseed radish had previously been grown in the winter, and in the 0-2.5 cm layer for millet. Sunn hemp, millet, oilseed radish and sorghum grown in the winter increased organic matter contents in the soil down to 30 cm. Higher P levels were found at the depths 0-2.5 cm and 0-5 cm, respectively, when sunn hemp and oilseed radish were grown in the winter. Highest grain yields for soyabean in monoculture were obtained in succession to winter oilseed radish and sunn hemp and in rotation with maize, after oilseed radish, sunn hemp and millet. Maize yields were highest in succession to winter oilseed radish, millet and pigeon pea. Rice yields were lowest when grown after sorghum.
  • Authors:
    • Marinov-Serafimov, P.
  • Source: Selskostopanska Nauka (Agricultural Science)
  • Volume: 42
  • Issue: 5
  • Year: 2009
  • Summary: During the period 2006-2008 in the experimental field of the Experimental station of soybean - Pavlikeni is displayed field trial in non-irrigated conditions for establishing the efficacy and selectivity of the herbicide Diflufenikan - 500 g/l (Pelican 50 KS) in soybean agrocenosis background in natural mixed type weediness. Results obtained may be generalized in the following more important conclusions: Herbicides Diflufenikan - 500 g/l (Pelican 50SC) has relatively high selectivity (EWRS 2-3 ball) and is suitable for treatment of soybean crops after germination before sowing at a dose of culture 125 ml/ha. Herbicide effectiveness Diflufenikan - 500 g/l (Pelican 50 KS) varies from 73 to 89% on annual dicotyledonous weeds ( S. nigrum; Amaranthus spp.). Less herbicide effect (from 25 to 50%) is established under Ch. album and the least (from 8 to 52%) in the group of weeds annual Monocotyledon ( Setaria spp., Eh. crus-galli). The increase in grain yield of soybean varies from 11.3 to 106.0% compared to the control variant (control - zero) and is in direct relation to the effect achieved in the fight against weeds.
  • Authors:
    • Jorge, R. F.
    • Cora, J. E.
    • Martins, M. dos R.
    • Marcelo, A. V.
  • Source: Soil & Tillage Research
  • Volume: 104
  • Issue: 1
  • Year: 2009
  • Summary: The adaptation of no-tillage system in tropical regions depends on the suitable choice of summer and winter crops which should contribute to improvement of soil properties. The aim of the present study was to determine the effect of crop sequences on soil aggregation and contents of organic C and polysaccharides in aggregates of a Rhodic Eutrudox under no-tillage. The treatments consisted of the combination of four summer crop sequences and seven winter crop sequences. The summer crop sequences were: maize monocrop ( Zea mays L.) (MM); soybean monocrop ( Glycine max (L.) Merrill) (SS); crop sequence of soybean/maize/soybean/maize (SM); crop sequence of rice ( Oryza sativa L.)/bean ( Phaseolus vulgaris L.)/cotton ( Gossypium hirsutum L.)/bean (RB). The winter crops were: maize, sunflower ( Helianthus annuus L.), radish ( Raphanus sativus L.), pearl millet ( Pennisetum americanum (L.) Leeke), pigeon pea ( Cajanus cajan (L.) Millsp), grain sorghum ( Sorghum bicolor (L.) Moench) and sunn hemp ( Crotalaria juncea L.). The highest total organic C, total polysaccharides and dilute acid-extracted polysaccharides contents were found in 2.00-1.00 mm water-stable aggregates and the lowest contents were found in
  • Authors:
    • Ray, J.
    • Smith, R.
    • Castlebury, L.
    • Mengistu, A.
    • Bellaloui, N.
  • Source: Plant Disease
  • Volume: 93
  • Issue: 10
  • Year: 2009
  • Summary: Phomopsis longicolla is a major seed pathogen of soybean ( Glycine max) in hot, humid environments. The objective of this study was to monitor the infection and development of P. longicolla on vegetative and reproductive tissues of six cultivars and to determine the relationship between this infection and subsequent seed infection and seed germination. Cultivars were grown for 3 years (2002 to 2004) without irrigation or with irrigation applied at pre- plus postflowering or at postflowering growth stages. P. longicolla was isolated most frequently from leaf, stem, pod, root, and seed. Diaporthe phaseolorum and three unidentified Phomopsis sp. were also isolated. Diaporthe aspalathi, which previously has not been reported on soybean, was also recovered from leaf samples. These isolates, however, were recovered very infrequently. Recovery of P. longicolla from roots was much lower than from leaves, stems, and pods in all years and irrigation environments. The recovery of P. longicolla from seed was affected by irrigation environments. Seed from irrigated plots had more P. longicolla than that from nonirrigated plots. Isolation of P. longicolla from seed was negatively correlated with percentage of seed germination in irrigated environments but not in the nonirrigated environment. Pod infection was correlated with seed infection in all three irrigation environments. Even though infection of leaves and stems increased with increasing moisture availability, such infection did not consistently correlate with seed infection. Seed germination and seed infection were negatively correlated with percent hard seed. This study provided the first demonstration of the seasonal progression of P. longicolla on soybean cultivars grown under three irrigation environments.
  • Authors:
    • Monteiro, J. E. B. A.
  • Source: Agrometeorologia dos cultivos: o fator meteorológico na produção agrícola
  • Year: 2009
  • Summary: This book brings together a broad base of information on 32 major Brazilian agricultural crops and their relations with climate. The focus of the book is not on the methodologies and applications of agrometeorology per se, but rather restricts its focus to crops and traits that determine yield as a function of the environment. The crops included are rice, castor oil, sunflowers, pineapples, soyabeans, triticale, maize, potatoes, barley, peanuts, oats, onions, canola, wheat, cotton, beans, sugarcane, Pinus, black wattle ( Acacia mearnsii), tropical and temperate grapes, coconuts, citrus, bananas, sisal, cocoa, coffee, apples, Jatropha, Eucalyptus and the fodder plants Cynodon, Brachiaria and Panicum. The contents of the book are divided into three main parts, I. Introduction, II. Temporary crops and III. Permanent crops, with each chapter within parts II and III dedicated to a particular crop, and covering: (1) the main features of farming and phenology; (2) agrometeorological productivity constraints - water availability, temperature, solar radiation, photoperiod and wind; and (3) adverse events - hail and rainstorms, droughts and dry spells, winds and gales, frost, and too much rain and over-prolonged drought. The book was organized by the National Institute of Meteorology and had the collaboration of 105 researchers from 37 Brazilian institutions (federal and state), research centres, institutes and universities.
  • Authors:
    • Ferreira, R. S.
    • Moraes, J. C.
    • Costa, R. R.
  • Source: Ciência e Agrotecnologia
  • Volume: 33
  • Issue: 5
  • Year: 2009
  • Summary: Studies were conducted to evaluate the effect of the application of inducers on the resistance of 2 soyabean cultivars to the whitefly Bemisia tabaci Biotype B. The seeds of the soyabean cultivars IAC-19 and MONSOY-8001 were previously treated with captan. The following treatments were tested: irrigating the soil around the plants of each pot with 250 ml solution of 1.0% silicic acid (T1); spraying of the plants, to the 'point of dripping', with a solution of 0.3% acibenzolar-S-methyl (T2); spraying of the plants, to the 'point of dripping', with a solution of 0.24% pyraclostrobin+epoxiconazole (T3); and control (T4). The plants were infested with 100 adult whiteflies that were released 8 days after applying the treatments. The number of ova on the abaxial face of each leaf, which was marked for further evaluation of nymphs, tannin and lignin contents and dry weight of the aerial parts and roots. There was no difference for the number of ova and nymphs among the soyabean cultivars. Nevertheless, the average survival rate of B. tabaci was lower on cultivar IAC-19. The application of silicon or acibenzolar-s-methyl induced an increase in lignin content in the soyabean cultivar IAC-19.
  • Authors:
    • Doré, T.
    • Lucas, P.
    • Faloya, V.
    • Montfort, F.
    • Motisi, N.
  • Source: Field Crops Research
  • Volume: 113
  • Issue: 3
  • Year: 2009
  • Summary: Biofumigation is increasingly viewed as a potentially useful technique for controlling soil-borne crop pathogens, but its efficacy has not systematically been demonstrated at field scale. We investigated the differences in efficacy observed in the field, by analysing the mechanisms by which a Brassica cover crop can act as a biofumigant crop in the prevention of soil-borne disease development. We hypothesised that the biofumigant crop might have a negative effect on soil-borne pathogens whilst growing, and that the pulverisation of this crop and the incorporation of its residues into the soil may enhance this effect. We tested this hypothesis by carrying out three field experiments in 2006, 2007 and 2008 in which Brassica juncea (brown mustard) was managed in different ways within a sugar beet-winter wheat rotation and analysing effects on sugar beet root rot caused by Rhizoctonia solani. Three treatments were studied: mustard pulled out at flowering (MP), mustard crushed at flowering and incorporated into the soil (MC) and bare soil (BS) as a control. We assessed the effect of each treatment on root rot incidence and severity at harvest. Over the 3 years of the experiment, disease incidence was significantly higher on BS plots than on the other plots and was significantly higher on MP plots than on MC plots. MC treatment gave a significantly lower mean conditional severity (severity calculated for diseased beets only) than the BS and MP treatments. Mustard residue incorporation was consistently effective at decreasing disease incidence from year to year (43, 44 and 47% efficacy, as determined by comparison with the disease incidence on BS plots, in 2006, 2007 and 2008, respectively), but the efficacy of growing mustard was variable (36, 16 and 39% efficacy in 2006, 2007 and 2008, respectively). These findings provide insight into the mechanisms by which biofumigant crops may affect soil-borne diseases. These findings have implications for the possible use of biofumigant crops as a biological method for controlling soil-borne diseases at the field scale. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Haller, W. T.
    • Mudge, C. R.
  • Source: Weed Technology
  • Volume: 23
  • Issue: 1
  • Year: 2009
  • Summary: The effects of flumioxazin in irrigation water were evaluated on four row crop species (corn, cotton, soybean, and wheat) and three ornamental species (begonia, impatiens, and snapdragon). Plants were overhead irrigated one time with flumioxazin at concentrations of 0, 10, 25, 50, 100, 200, 400, 800, 1,600, and 3,200 g ai/L in water equivalent to 1.27 cm. Ornamental plant tolerances on the basis of a 10% reduction in dry weight (effective concentration 10 [EC 10]) were as follows: impatiens (40)