• 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:
    • Salado-Navarro, L. R.
    • Sinclair, T. R.
  • Source: Agricultural Systems
  • Volume: 102
  • Issue: 1/3
  • Year: 2009
  • Summary: Cropping schemes have developed in east-central Argentina for rainfed soybean (Glycine max Merr.) production that invariably employ no-tillage management. Often these schemes include growing soybean in a sequence of crops including wheat ( Triticum aestivum L.) and maize ( Zea mays L.). The full impact of various rotation schemes on soil water balance through a sequence of seasons has not been explored, although the value of these rotations has been studied experimentally. The objective of this work was to investigate through simulations, potential differences in temporal soil water status among rotations over five years. In this study, mechanistic models of soybean (Soy), maize (Maz), and wheat (Wht) were linked over a five-years period at Marcos Juarez, Argentina to simulate soil water status, crop growth, and yield of four no-till rotations (Soy/Soy, Soy/Wht, Soy/Maz, and Soy/Maz/Wht). Published data on sowing dates and initial soil water contents in the first year from a no-till rotation experiment were used as inputs to the model. After the first year, soil water status output from the model was used to initiate the next crop simulation in the sequence. The results of these simulations indicated a positive impact on soil water balance resulting from crop residue on the soil surface under no-till management. Continuous soybean and the two-year soybean/maize rotation did not efficiently use the available water from rainfall. Residue from maize was simulated to be especially effective in suppressing soil evaporation. Thus, the Soy/Maz simulation results indicated that this rotation resulted in enhanced soil water retention, increased deep water percolation, and increased soybean yields compared with continuous soybean crops. The simulated results matched well with experimental observations. The three-crop rotation of Soy/Maz/Wht did not increase simulated soybean yields, but the additional water retained as a result of decreased soil evaporation resulting from the maize residue allowed the addition of a wheat crop in this two-year rotation. Simulated soybean yields were poorly correlated with both the amount of soil water at sowing and the rainfall during the cropping period. These results highlight the importance of temporal distribution of rainfall on final yield. These models proved a valuable tool for assessing the consequences of various rotation schemes now being employed in Argentina on temporal soil water status, and ultimately crop yield.
  • Authors:
    • Steinbach, H. S.
    • Alvarez, R.
  • Source: Soil & Tillage Research
  • Volume: 104
  • Issue: 1
  • Year: 2009
  • Summary: The Argentine Pampas is one of the most important cropping regions of the World. Limited tillage systems, and specially no-till, had widespread in recent years, occupying actually around 70% of the surface devoted to annual crops. We review results produced in field experiments installed along the Pampas to determine the effect of the adoption of these tillage systems on some soil properties and crops yield. It was performed a meta-analysis of data from experiments where plow tillage (mouldboard plow), reduced tillage (chisel plow, disk plow or harrow disk) and no-till were compared. Treatments effects were contrasted by paired t-tests between groups of paired data. Soil bulk density and cone penetration resistance of the 0-20 cm layer were higher under limited tillage systems than under plow tillage. Increases of bulk density under no-till in comparison to plow tillage were generally small, averaging 4%, but cone penetration increased by 50% in many soils. The increase of bulk density was greater in soils of initial low bulk density. Neither bulk density increases nor cone penetration changes reached critical threshold for roots development. Aggregate stability and water infiltration rate were higher in soils subjected to limited tillage systems than under plow tillage. The improvement of aggregate stability was higher in poorer structured soils, with an average increase of 70% under no-till in relation to plow tillage. Under no-till infiltration rate doubled in average that of plow tillage. Soil water content during the critical periods of sowing and flowering was generally greater under limited tillage but, conversely, nitrate nitrogen levels were greater in plow tillage. Higher soil water content under no-till in relation to plow tillage may satisfied the evapotranspiration demand of 1-3 days of crops during the critical flowering period, being nitrate nitrogen in average 21 kg ha -1 lower under no-till. Soybean ( Glycine max (L.)-Merr.) yield was not affected by tillage system, meanwhile wheat ( Triticum aestivum L.) and corn ( Zea mays L.) yields were lower under reduced tillage and no-till than under plow tillage without nitrogen fertilization. Wheat and corn no-till yields were 10-14% lower that yields under plow tillage as a mean. When fertilizers were applied, wheat and corn yield differences between tillage treatments generally disappeared. The adoption of limited tillage systems in the Pampas leads to soil improvement but also generates the necessity of increase nitrogen fertilizers utilization to sustain yields of graminaceus crops.
  • Authors:
    • Hilbert, J.
    • Huerga, I.
    • Donato, L.
  • Source: Central theme, technology for all: sharing the knowledge for development. Proceedings of the International Conference of Agricultural Engineering, XXXVII Brazilian Congress of Agricultural Engineering, International Livestock Environment Symposium - ILES V
  • Year: 2008
  • Summary: The present study is focus on the final energy balance of bioenergy production in Argentina using soybean, sunflower, rapeseed, corn and sorghum as feedstocks. The balance considers the difference between the energy contained per unit and the amount used for its generation in all the different steps from sowing to final destination. For direct energy consumption costomaq software was employed using local fuel consumption forecast for each field labor. Particular attention is paid to the energy consumption in the agricultural steps considering the distinctive no till system spread out in Argentina that has a very low energy input. Direct and indirect energy were considered in the different steps of bioethanol and biodiesel generation. Industrial conversion consumption was based on international literature data. Comparisons were made between tilled and no till practices and considering or not the energy contained in co products. Results indicate a balance ranging from 0.96 to 1.54 not considering the co products. If co products were introduced the balances ranged between 1.09 and 4.67.
  • Authors:
    • Barfoot, P.
    • Brookes, G.
  • Year: 2008
  • Authors:
    • Eriksen-Hamel, N. S.
    • Angers, D. A.
  • Source: Soil Science Society of America Journal
  • Volume: 72
  • Issue: 5
  • Year: 2008
  • Summary: While the adoption of no-till (NT) usually leads to the accumulation of soil organic C (SOC) in the surface soil layers, a number of studies have shown that this effect is sometimes partly or completely offset by greater SOC content near the bottom of the plow layer under full-inversion tillage (FIT). Our purpose was to review the literature in which SOC profiles have been measured under paired NT and FIT situations. Only replicated and randomized studies directly comparing NT and FIT for >5 yr were considered. Profiles of SOC had to be measured to at least 30 cm. As expected, in most studies SOC content was significantly greater (P < 0.05) under NT than FIT in the surface soil layers. At the 21- to 25-cm soil depth, however, which corresponds to the mean plowing depth for the data set (23 cm), the average SOC content was significantly greater under FIT than NT. Moreover, under FIT, greater SOC content was observed just below the average depth of plowing (26-35 cm). On average, there was 4.9 Mg ha(-1) more SOC under NT than FIT (P = 0.03). Overall, this difference in favor of NT increased significantly but weakly with the duration of the experiment (R-2 = 0.15, P = 0.05). The relative accumulation of SOC at depth under FIT could not be related to soil or climatic variables. Furthermore, the organic matter accumulating at depth under FIT appeared to be present in relatively stable form, but this hypothesis and the mechanisms involved require further investigation.
  • Authors:
    • Diaz-Zorita, M.
    • Penon, E.
    • Coviella, C.
    • Ciocco, C.
    • Lopez, S.
  • Source: Spanish Journal of Agricultural Research
  • Volume: 6
  • Issue: 1
  • Year: 2008
  • Summary: Biological nitrogen fixation (BNF) is of key importance in the N balance of soybean ( Glycine max) crops. A number of authors have suggested that a negative balance may occur under high yield conditions. Few studies have measured the contribution of BNF to soil N in the pampas region. The aims of the present study were to compare three BNF determination methods - two isotopic methods using sorghum or a non-nodulating soybean isoline as a reference crop, and one involving the calculation of the difference in N content between the nodulating and non-nodulating soybean isolines - and to estimate the N balance in soybean crops raised under conventional tillage and no tillage practices. The study was performed in 2004-2005; a complete randomised block design was used with three replicates (plot dimensions 3*7 m). The different methodologies estimated BNF to account for 45-58% of total plant N, equivalent to 94 to 123 kg N ha -1. Depending on the methodology for estimating the BNF the soil N balance varied between -7 and 22 kg N ha -. With an average grain yield of 1,618 kg ha -1 and a BNF accounting for approximately 50% of total plant N (i.e., 115 kg N ha -1), the soil N balance was slightly positive (14 kg ha -1) and independent of the tillage practice. The tillage systems had no effect (P
  • Authors:
    • Buschiazzo, D. E.
    • Alvarez, R.
    • Bono, A.
    • Cantet, R. J. C.
  • Source: Soil Science Society of America Journal
  • Volume: 72
  • Issue: 4
  • Year: 2008
  • Summary: Tillage systems may affect soil C sequestration, with a potential impact on crop productivity or organic matter mineralization. We evaluated crop yield, C inputs to the soil, and in situ CO 2-C fluxes under no-till and conventional tillage (disc tillage) during the 3- to 6-year period from the installation of an experiment in an Entic Haplustoll of the Semiarid Pampean Region of Argentina to elucidate the mechanisms responsible for possible management-induced soil organic matter changes. Yield and biomass production were greater under no-till than disc tillage for all the crops included in the rotation (oat + hairy vetch ( Vicia villosa ssp. villosa), maize, wheat and oat). This result was attributed to the higher soil water content under no-till. Carbon inputs to the soil averaged 4 Mg C ha -1 year -1 under no-till and 3 Mg C ha -1 year -1 under disc tillage. Soil temperature was similar between tillage systems and CO 2-C emission was approximately 4 Mg C ha -1 year -1, with significant but small differences between treatments (~0.2 Mg C ha -1 year -1). Carbon balance of the soil was nearly equilibrated under no-till; meanwhile, greater C losses as CO 2 than inputs in crop residues were measured under conventional tillage. Organic C in the soil was 5.4 Mg ha -1 higher under no-till than the disc tillage treatment 6 years after initiation of the experiment. Results showed that in our semiarid environment, C sequestration occurred under no-till but not conventional tillage. The sequestration process was attributed to the effect of the tillage system on crop productivity rather than on the mineralization intensity of soil organic pools.
  • Authors:
    • Simon, M.
    • Monaco, C.
    • Cordo, C.
  • Source: Australasian Plant Pathology
  • Volume: 36
  • Issue: 3
  • Year: 2007
  • Summary: Two Septoria Monitoring Nursery sets were tested for resistance in the field during three consecutive years. Different concentrations of oat grains covered with mycelia of Septoria tritici were applied as inoculum. The position of the disease on the plants and the severity of the Septoria leaf blotch infection were recorded at two growth stages. A comparison between leaf pulverisation and grain application as a source of conidia was made in the last year. The percentages of necrotic lesions and pycnidial coverage were recorded on the upper three leaves of the plants at the same growth stages as for previous years. With grain inoculation, the infection reached the 7th leaf of the plants with the maximum concentration applied at tillering stage. The best concentration to obtain the highest discrimination among resistances is 120 g/m 2. In the comparison of inoculation techniques, the results showed a higher necrosis and pycnidial coverage following leaf pulverisation than with the grain application treatment.
  • Authors:
    • Duarte, G.
    • Diaz-Zorita, M.
    • Barraco, M.
  • Source: Wheat Production in Stressed Environments Developments in Plant Breeding
  • Volume: 12
  • Year: 2007
  • Summary: Wheat ( Triticum aestivum L.) grain yields under no-till production systems have been shown to be reduced in the presence of maize ( Zea mays L.) residues. It has been suggested that sowing a greater density of wheat seeds or removing maize residues from the planting rows contributes to avoid this problem. However, the causal factors and the mechanism that produce reductions in wheat yields are no clearly defined. Our objective was to determine the effects of different volumes of maize or soybean [ Glycine max (L.) Merrill] residues on no-tillage wheat establishment and production under field conditions on a Typic Hapludoll from the Pampas region of Argentina. The study was performed during the 2002, the 2003 and the 2004 growing seasons. Two treatments [residue volume (0, 4, 8 and 16 Mg ha -1) and crop residue (maize and soybean)] were imposed after sowing wheat at low and high plant densities, (301 and 396 seed ha -1, respectively). The previous crop was sunflower ( Helianthus annus L.) and the residues were applied on the soil surface immediately after planting and fertilizing with 125 kg ha -1 of Nitrogen. Independently of the quality of the residues and the sowing density, wheat plants m -2, spikes m -2 and grain yields ha -1 decreased when residue volume increased. In general, lower soil temperatures values and variability were observed when increasing the volume of residues. The presence of large amounts of maize or soybean residues causes the reduction in no-tillage wheat productivity (plant stand and numbers of spikes). However, only maize residues causes significant reductions in grain yields, independently of the seeding rate. The absence of significant differences in soil temperature measurements between residues allows us to think that the effects on surface soil temperature are not the main factor explaining the reduction in wheat grain yields in the presence of maize residues. Increasing the seeding rate can contribute to ameliorate the grain yield reduction in the presence of maize residues but further research is required for explaining the reasons for the behavior of the crop.