• Authors:
    • Silva, M.
    • Goncalves, M.
    • Souza, C.
    • Souza, L.
    • Marchetti, M.
    • Mercante, F.
    • Lourente, E.
  • Source: SEMINA-CIENCIAS AGRARIAS
  • Volume: 31
  • Issue: 4
  • Year: 2010
  • Summary: Soil management practices exert important influence on biological and biochemical properties of soil. This work aimed to valuate the impact of crop rotation on soil biochemical and microbiological attributes, as well and influence on corn crop yield. The experiment was carried out during 2005/06 crop season, in Dourados - MS, Brazil. Experimental design was randomized blocks with treatments established in sub-divided plots with tree replications, which seasons were plots and management systems were sub-plots. Studied seasons were winter and summer and no tillage systems were represented by five crop rotation schemes, which involved the cultures of hairy vetch, bean, oat, forage turnip, soybean, crotalaria, corn, sorghum, pearl millet, sunflower and, in conventional tillage, with corn in winter and with soybean in summer. Native vegetation constituted one treatment and, with conventional tillage, it was used as ecosystem of reference as control for comparison between possible alterations in chemical and microbiological attributes with the establishment of a system more conservationist for soil management. There was a positive correlation among Norg, Corg, Porg and C-BMS contents with chemical attributes of soil fertility, which shows interdependence between chemical and biology of soil. The elimination of native vegetation and the substitution for cultivation system after that reduce the C-BMS. In Cerrado conditions, studied cultivation systems increased phosphorus content in soil. Crop rotation influenced corn yield after the cultivation of determined species as crotalaria and vetch in crop rotation.
  • Authors:
    • Weeks, C.
    • Robertson, M.
    • Oliver, Y.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 2
  • Year: 2010
  • Summary: The practice of long fallowing, by omitting a year of cropping, is gaining renewed focus in the low rainfall zone of the northern agriculture region of Western Australia. The impetus behind this practice change has been a reduced use of pasture breaks in cereal crop rotations, and the belief that a fallow can improve soil water accumulation and thus buffer the negative effects of dry seasons on crop yields. We evaluated the benefits of long fallowing (full stubble retention, no weed growth allowed) in a continuous wheat sequence via simulation modelling with APSIM at two rainfall locations and five soil types. The simulated benefits to long fallowing were attributable to soil water accumulation only, as the effects on soil nitrogen, diseases or weeds were not evaluated. The long-term (100 years) mean wheat yield benefit to fallowing was 0.36-0.43 t/ha in clay, 0.20-0.23 t/ha in sand and loam, and 0-0.03 t/ha in shallow sand and shallow loams. Over the range of seasons simulated the response varied from -0.20 to 3.87 t/ha in the clay and -0.48 to 2.0 t/ha for the other soils. The accumulation of soil water and associated yield benefits occurred in 30-40% of years on better soils and only 10-20% on poorer soils. For the loam soil, the majority of the yield increases occurred when the growing-season (May-September) rainfall following the fallow was low (30 mm), although yield increase did occur with other combinations of growing-season rainfall and soil water. Over several years of a crop sequence involving fallow and wheat, the benefits from long fallowing due to greater soil water accumulation did not offset yield lost from omitting years from crop production, although the coefficient of variation for inter-annual farm grain production was reduced, particularly on clay soils during the 1998-2007 decade of below-average rainfall. We conclude that under future drying climates in Western Australia, fallowing may have a role to play in buffering the effects of enhanced inter-annual variability in rainfall. Investigations are required on the management of fallows, and management of subsequent crops (i.e. sowing earlier and crop density) so as to maximise yield benefits to subsequent crops while maintaining groundcover to prevent soil erosion.
  • Authors:
    • Kidd, C.
    • Ruchs, C.
    • D'Antuono, M.
    • Rayner, B.
    • Peirce, J.
    • Reeves, A.
  • Source: Plant Protection Quarterly
  • Volume: 25
  • Issue: 1
  • Year: 2010
  • Summary: Skeleton weed is under an eradication program in Western Australia. There was concern that should the weed establish over large areas of the sandier soils in the cereal growing areas of Western Australia; the treatments to eradicate/control the weed would affect the cropping rotations. This is because the persistence of the herbicides clopyralid and picloram used for skeleton weed control would suppress lupins and other legumes which are a major part of cropping rotations in Western Australia. A cropping rotation experiment was established during 2002 in South Australia in an area heavily infested with skeleton weed. For six years crops were grown in a continuous rotation which included lupins in 2004 and 2006. Regular use of the herbicides clopyralid and picloram in the cereal phase and clopyralid as a pre-sowing application in the legume phase significantly reduced skeleton weed density without any deleterious impact on narrow leaf lupins ( Lupinus angustifolius).
  • Authors:
    • Pop, A.
  • Source: Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca
  • Volume: 67
  • Issue: 1
  • Year: 2010
  • Summary: The strategy for suppressing weeds in a minimum tillage system has to be prior and different from the classical soil tillage system. A tremendous importance must be taken for the indirect methods of weed suppressing, especially crop rotation method. The soil tillage system and weed suppressing methods play a key role for the entire weeding soybean. Especially at the first stages of plant development all the weeding crops are extremely sensible for weed activity. The most common weed species that infestate soybean crops are: Avena fatua, Echinochloa crus-galli, Setaria sp., Digitaria sanguinalis, Sorghum halepense, Agropyron repens, Amaranthus retroflexus, Chenopodium album, Galinsoga parviflora, Xanthium sp., Abutilon teophrasti, Polygonum sp., Cirsium arvense, Convolvulus arvensis. The present results where obtained in Jucu experimental plots, property of the Agricultural Faculty of Cluj-Napoca. The eco-pedological conditions consisted in: faeoziom soil with a humus content of 4.72% and a pH of 6.8, multi annual precipitation with values between 550-650 mm and the average thermal regime of 8.0-8.2C. For soybean crop, applying the minimal tillage systems, an increase in weeds number, especially of perennial di-cotyledonated ones, is observed. The weeding degree is 10,5-18,4% higher in unconventional variants. The percent of perennial di-cotyledonated weeds is 10% for plough variants and reaches 14-18% in minimal tillage systems variants. In similar working conditions and same dosage of herbicides, the higher degree of weeding in unconventional variants can be put on the working system.
  • Authors:
    • Rosolem, C.
    • Olibone, A.
    • Olibone, D.
    • Prando, M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 34
  • Issue: 3
  • Year: 2010
  • Summary: In soils with physical and/or physical hydric restrictions for root growth, it may be a viable strategy to increase crop productivity by increasing water storage potential through improvements in water infiltration. Accordingly, the objective of this study was to determine water infiltration in a Hapludult in three crop rotations under no-tillage, with and without initial chiseling. Crop rotations consisted of: millet/soybean/sorghum/maize/sorghum; millet/soybean/Brachiaria ruziziensis/corn/Brachiaria ruziziensis; and millet/soybean/Brachiaria ruziziensis+castor bean/corn/Brachiaria ruziziensis+castor bean. Water infiltration in soil was evaluated in the field, using concentric discs at the soil surface and at depths of 0.10 and 0.20 m, in 2006 and 2007. After the first year, chiseling led to increased infiltration of water into the soil. Water infiltration was greatest in the crop rotation system with Brachiaria ruziziensis+castor bean. The activity of root systems of crops in the plots without chiseling increased the rate of water infiltration into the soil.
  • Authors:
    • Bradford, S.
    • Crohn, D.
    • Poss, J.
    • Shouse, P.
    • Segal, E.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 137
  • Issue: 3/4
  • Year: 2010
  • Summary: A nutrient management plan (NMP) field experiment was conducted to investigate the fate of nitrogen (N), phosphorus (P), potassium (K) and salts in a semi-arid environment (San Jacinto, CA). Our mechanistic approach to study NMP performance was based on comprehensive measurements of water and N mass balance in the root zone. A cereal crop rotation (wheat-rye hybrid to sorghum, Triticum aestivum L.- Secale cereale L. to Sorghum bicolor L. Moench) that does not fix atmospheric N was employed during 2007, whereas a legume crop (alfalfa, Medicago sativa L.) that forms nodules to fix N was used in 2008. Blending (2007 and 2008) and cyclic (2007) dairy wastewater (DWW) application strategies (no statistical difference in 2007) were implemented to meet crop water and N uptake. The high content of salts in DWW and accurate application of water to meet evapotranspiration ( ET) yielded salt accumulation in the root zone. Leaching these salts after the fallow period resulted in the flushing of nitrate that had accumulated in the root zone due to continuous mineralization of soil organic N. This observation suggested that a conservative NMP should account for mineralization of organic N by (i) leaching salts following harvests rather than prior to planting and (ii) maintaining soils with low values of organic N. For the wheat-rye hybrid-sorghum rotation, losses of nitrate below the root zone were minimal and the soil organic N reservoir and P were depleted over time by applying only a fraction of the plant N uptake with DWW (28-48%) and using DWW that was treated to reduce the fraction of organic N (3-10%), whereas K accumulated similar to other salts. Conversely, with alfalfa approximately 15% of the applied N was leached below the root zone and the soil organic N increased during the growing season. These observations were attributed to fixation of atmospheric N, increased root density, and applying a higher fraction of plant N uptake with DWW (76%). Collectively, our results indicate that NMPs should accurately account for water and nutrient mass balances, and salt accumulation to be protective of the environment.
  • Authors:
    • Fontaneli, R. S.
    • Santos, H. P. dos
    • Spera, S. T.
    • Tomm, G. O.
  • Source: Acta Scientiarum. Agronomy
  • Volume: 32
  • Issue: 1
  • Year: 2010
  • Summary: Soil physical characteristics were evaluated, after eight years (1995 to 2003), on a typic Hapludox located in Coxilha, Rio Grande do Sul State, Brazil. Six crop production systems were evaluated: system I (wheat-soybean/black oat+common vetch pasture-corn); system II (wheat-soybean/black oat+common vetch+annual ryegrass pasture-corn); system III (wheat-soybean/black oat+common vetch pasture-pearl millet pasture); system IV (wheat-soybean/black oat+common vetch+annual ryegrass pasture-pearl millet pasture); system V (wheat-soybean, white oat-soybean/black oat+common vetch pasture-pearl millet pasture); and system VI (wheat-soybean/white oat-soybean/black oat+common vetch+annual ryegrass pasture-pearl millet pasture). Soil bulk density and resistance to penetration increased from deeper layer (10-15 cm) to top layer (0-5 cm). In the systems I, V and VI, total porosity decreased and soil bulk density resistance to penetration increased from the deeper layers to top layer surface, due to higher intensity of livestock activities. After eight years of use, the production systems under no-till, involving annual winter and summer pastures and crops, did not promoted soil degradation, in constraining levels, on soil physical attributes.
  • Authors:
    • Rosa Becker, A.
    • Camilo Bedano, J.
    • Dominguez, A.
  • Source: Soil & Tillage Research
  • Volume: 110
  • Issue: 1
  • Year: 2010
  • Summary: No-till (NT) has been recognized as a management system of low environmental impact when applied in combination with crop residue mulch and rotations involving cover crops. It has been suggested, however, that, if these conditions are not met, NT may result in physical, chemical and biological soil degradation. This study evaluates the effect of NT on the litter decomposition process and on soil macrofauna communities and how changes in soil physical, chemical, and physicochemical properties affect litter decomposition and soil macrofauna. We hypothesised (1) that macrofaunal abundance, richness and diversity would be lower in NT soils than in natural grasslands; (2) that this would be a consequence of unfavourable physical and chemical soil conditions and high inputs of agrochemicals; and (3) that these changes in macrofauna would influence soil functioning, reducing litter decomposition rate. The study was conducted during winter and spring 2007 on Typic Haplustolls from southern Cordoba, Argentina (32 degrees 41' and 32 degrees 50'S; 63 degrees 58' and 63 degrees 44'W). Macrofauna was sampled twice in NT and in natural grasslands (NA) - as a reference situation - by extracting five soil monoliths of 25 cm x 25 cm x 30 cm at each plot. Soil properties were measured using standard methods. The decomposition rate was determined by the litterbag method, using a 2 mm and a 10 mm size meshes to evaluate litter decomposition mediated by macrofauna. NT greatly reduced richness (from 33 species in NA to 12 species in NT) and abundance (from 1870 ind/m(2) in NA to 475 ind/m(2) in NT) of macroinvertebrates, confirming our first hypothesis. Changes in macrofauna community under NT were mainly explained by high compaction and low organic matter content, confirming our second hypothesis. The reduction in earthworm abundance may also be explained by the influence of the intense use of toxic agrochemicals. No-till increased surface horizon bulk density (from 1.22 to 1.33 g/cm(3)) and decreased organic matter content (from 3.51% to 2.58%) and pH (from 6.74 to 6.01) compared with NA. The litter decomposition rate was lower in NT, confirming our third hypothesis, and it was correlated with low earthworms abundance and activity. We conclude that in our study area the capacity of soils under NT to maintain ecosystem functions would be at risk. (C) 2010 Elsevier B.V. All rights reserved.
  • Authors:
    • Dercon, G.
    • Nziguheba, G.
    • Iwuafor, E. N. O.
    • Berkhout, E. D.
    • Franke, A. C.
    • Vandeplas ,I.
    • Diels, J.
  • Source: Experimental Agriculture
  • Volume: 46
  • Issue: 4
  • Year: 2010
  • Summary: Integrated crop-livestock farming in the Guinea savanna of West Africa is often assumed to lead to synergies between crop and livestock production, thereby improving the overall productivity and resilience of agricultural production. Whether these synergies actually occur remains poorly studied. On-farm trials were conducted in northern Nigeria over a period of four years to assess the agronomic and economic performance of maize-legume systems with and without the integration of livestock (goats). Groundnut-maize rotations with livestock achieved the highest carry-over of nutrients as manure from one season to the next, covering approximately one-third of the expected N, P and K uptake by maize and reducing the demand for synthetic fertilizers. However, the advantage of lower fertilizer costs in rotations with livestock was offset by higher labour costs for manure application and slightly lower values of maize grain. Overall, no clear agronomic or economic benefits for crop production were observed from the combined application of manure and synthetic fertilizer over the application of synthetic fertilizer only, probably because the amounts of manure applied were relatively small. Legume-maize rotations achieved higher cereal yields, a better response to labour and fertilizer inputs, and a higher profitability than maize-based systems with no or only a small legume component, irrespective of the presence of livestock. Livestock at or near the farm could nevertheless make legume cultivation economically more attractive by increasing the value of legume haulms. The results suggested that factors other than crop benefits, e.g. livestock providing tangible and non-tangible benefits and opportunities for animal traction, could be important drivers for the ongoing integration of crop and livestock production in the savanna.
  • Authors:
    • Kuhn, A.
    • Hiepe, C.
    • Judex, M.
    • Gaiser, T.
  • Source: Agricultural Systems
  • Volume: 103
  • Issue: 9
  • Year: 2010
  • Summary: Upscaling of crop models from the field scale to the national or global scale is being used as a widespread method to make large-scale assessments of global change impacts on crop yields and agricultural production. In spite of the fact that soil fertility restoration and crop performance in many developing countries with low-input agriculture rely strongly on fallow duration and management, there are only few approaches which take into account the effect of fallowing on crop yields at the regional scale. The objectives of this study were to evaluate the sensitivity of maize yield simulations with the Environmental Policy Integrated Climate (EPIC) model to fallow availability at the field and regional scale and (2) to present a novel approach to derive a model-based estimate of the average fallow availability within a typical catchment of the sub-humid savanna zone of West Africa. Therefore, the EPIC model has been validated at the field scale and then incorporated into a spatial database covering a typical catchment within the sub-humid savanna zone of West Africa with 121 sub-basins. Maize-fallow rotations have been simulated within 2556 quasi-homogenous spatial units and then aggregated to the 10 districts within the catchment assuming three different scenarios of fallow availability: 100% of the bush-grass savanna area is available and used in fallow-crop rotations (FU100), 50% of the bush-grass savanna area is available and used in fallow-crop rotations (FU50) and 25% of the bush-grass savanna area is available and used in fallow-crop rotations (FU25). A new aggregation procedure has been developed which is based on changes in the frequency of fallow-cropland classes within the sub-basins to render the simulation results in the spatial database sensitive to changes in fallow availability. Comparison of the average simulated grain yield with the mean yield over the catchment shows that the simulations overestimate maize yields by 62%, 44% and 15% for scenario FU100, FU50 and FU25, respectively. The best agreement between simulated and observed crop yields at the district scale was found when using the assumption that 25% of the savanna is available as fallow land under the present cropping patterns, which corresponds to a fallow-cropland ratio of 0.9. Comparison with farm surveys shows that the combination of remote sensing and dynamic crop modelling with yield observations provides realistic estimates of effective fallow use at the regional scale. (C) 2010 Elsevier Ltd. All rights reserved.