• Authors:
    • Denmead,O. Tom
    • Kinsela,Andrew S.
    • Reynolds,Jason K.
    • Melville,Michael D.
    • Macdonald,Bennett C. T.
    • White,Ian
  • Source: Soil Research
  • Volume: 49
  • Issue: 6
  • Year: 2011
  • Authors:
    • Cockfield, G.
    • Maraseni, T. N.
  • Source: Agricultural Systems
  • Volume: 104
  • Issue: 6
  • Year: 2011
  • Authors:
    • Mollah, M.
    • Partington, D.
    • Fitzgerald, G.
  • Source: Crop and Pasture Science
  • Volume: 62
  • Issue: 10
  • Year: 2011
  • Summary: Carbon dioxide (CO2) is the most important greenhouse gas, predicted to increase globally from currently 386 to 550 μmol mol–1 by 2050 and cause significant stimulation to plant growth. Consequently, in 2007 and 2008, Australian grains free-air carbon dioxide enrichment (AGFACE) facilities were established at Horsham (36°45′07″S lat., 142°06′52″E long., 127 m elevation) and Walpeup (35°07′20″S lat., 142°00′18″E long., 103 m elevation) in Victoria, Australia to investigate the effects of elevated CO2, water supply and nitrogen fertiliser on crop growth. Understanding the distribution patterns of CO2 inside AGFACE rings is crucial for the interpretation of the crop growth data. In the AGFACE system, the engineering performance goal was set as having at least 80% of the ring area with a CO2 concentration [CO2] at or above 90% of the target concentration at the ring-centre for 80% of the time. The [CO2] was highly variable near the ring-edge where CO2 is emitted and declined non-linearly with the distance downwind and wind speeds. Larger rings maintained the target [CO2] of 550 μmol mol–1 at the ring-centres better than the smaller rings. The spatial variation of [CO2] depended on ring size and the gap between fumigation and canopy heights but not on wind speeds. The variations in the inner 80% of the rings were found to be higher in smaller rings, implying that the larger rings had more areas of relatively uniform [CO2] to conduct experiments.
  • Authors:
    • Rodriguez, L. C.
    • May, B.
    • Herr, A.
    • Farine, D.
    • O'Connell, D.
  • Source: Energy Policy
  • Volume: 39
  • Issue: 4
  • Year: 2011
  • Authors:
    • Blanco-Canqui, H.
  • Source: Soil Use and Management
  • Volume: 27
  • Issue: 1
  • Year: 2011
  • Summary: Soil water repellency (SWR) is an intrinsic and dynamic soil property that can influence soil hydrology and crop production. Although several land use systems have been shown to induce water repellency in soil, the specific effects of no-till cropping on SWR are poorly understood. This article reviews the impacts of no-till on SWR and identifies research needs. No-till cropping generally induces 1.5 to 40 times more SWR than conventional tillage, depending on soil type. This may result from near-surface accumulation of hydrophobic organic C compounds derived from crop residues, microbial activity and reduced soil disturbance. While large SWR may have adverse impacts on soil hydrology and crop production, the level of SWR under no-till relative to conventional tillage may contribute to aggregate stabilization and intra-aggregate C sequestration. More research is needed to discern the extent and relevance of no-till induced SWR. This includes: (1) further assessment of SWR under different tillage systems across a wide range of soil textures and climates, (2) comparison of the various methods for measuring SWR over a range of water contents, (3) inclusion of SWR in routine soil analysis and its use as a parameter to evaluate management impacts, (4) assessment of the temporal and spatial changes in SWR under field conditions, (5) further assessment of the impacts of the small differences in SWR between no-till and conventionally tilled soils on crop production, soil hydrology and soil C sequestration, and (6) development of models to predict SWR for different tillage systems and soils.
  • Authors:
    • Blanke, M. M.
  • Source: Acta Horticulturae
  • Issue: 916
  • Year: 2011
  • Summary: Technological innovations appear under-utilised in many fruit tree crops, whereas viticulture, citriculture and vegetable crops have largely automated planting, pruning, thinning and harvesting and integrated GPS and/or GIS in their cultivation practises. As a consequence of the trend from pedestrian to tall orchards, innovation and technology is required to overcome shading, particularly in the lower part of the tree canopy. Types, properties and prices are presented of reflective ground covers (textile, aluminium and paper) as well as organic alternatives (lime, straw) as well as titanium dioxide and bio-degradable white line marker paint with additives. To combat sunburn, kaolin, carnauba-wax and other products are available, which can be combined with evaporative cooling. Mechanisation includes new machinery for mechanical thinning, pruning and harvesting to save labour. An autonomous prime mover (APM) is being developed for camera systems for assessment of flowering intensity, alternate bearing, fruit set, June drop, leaf nutrient status, pest and disease control and yield estimation/prediction. The two approaches for better light utilisation in row systems include reducing the spacing of every row from the current 14 feet (4.3 m) to 10-12 feet (3.0 to 2.6 m) or maintaining the spacing of a centre row at 14 feet (4.3 m) or ease of access, but narrower row spacing either side to less than 10 feet (3.0 m) The OTR (over the tree rows) developed by Washington State University and two commercial European multi-row sprayers are presented and new harvesting techniques with pre-sorting in the orchard.
  • Authors:
    • Costa, M. S. S. de M.
    • Pivetta, L. A.
    • Steiner, F.
    • Costa, L. A. de M.
    • Castoldi, G.
    • Gobbi, F. C.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 6
  • Issue: 4
  • Year: 2011
  • Summary: Crop systems and fertilization sources can affect the chemical properties of the soil and, consequently, its fertility. With the aim of evaluating the effect of such management practices, soil samples collected at 0.0-0.10; 0.10-0.20; and 0.20-0.40 m in depth were collected and analyzed in the second year of an experiment installed in 2006 in a Rhodic Hapludox under no-till farming, located in the Agronomic Experimental Station of UNIOESTE, in the city of Marechal Candido Rondon, Parana, Brazil. The experiment consisted of two crop systems (with and without rotation of cover crops) and three fertilization sources (mineral, organic and mineral+organic). The organic and mineral+organic fertilizations consisted of the application of animal manure alone and animal manure mixed with mineral fertilizer, respectively. The values of pH, exchangeable potassium (K +) and cation exchange capacity (CEC) were not affected by the different crop systems, related to the application of different fertilization sources. However, they did influence the organic matter contents (OM), potential acidity (H ++Al 3+), exchangeable aluminum (Al 3+), phosphorus (P), calcium (Ca 2+), magnesium (Mg 2+), and the bases sum and saturation (V%). The organic and mineral+organic fertilizations, with animal manure promoted the highest increase in soil Ca and Mg.
  • Authors:
    • Rosolem, C. A.
    • de Fatima Esteves, J. A.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: Water soluble phosphates are the most often used phosphorus sources in fertilizers for ease of P release to the soil. However, in tropical soils, much of this P is adsorbed to soil particles and becomes unavailable to plants. Conversely, reactive phosphates may be slow initial releasers of the nutrient, but be released continually to the developing crops, reducing soil P fixation. The aim of this study was to investigate the application of two P sources to triticale and assess the residual effect of fertilization on pearl millet in no tillage. Soil fertility, dry matter and grain yields, phosphorus content and amount in plants and straw were determined. The experiment was conducted in an Oxisol. Three treatments were applied in April of the first year: (1) without application of P 2O 5, (2) application of 80 kg ha -1 P 2O 5 as triple superphosphate and (3) application of 80 kg ha -1 P 2 O 5 of reactive phosphate (Arad). Triticale (* Triticosecale Wittmack) was planted and grown until grain harvest. In September, after harvest of triticale, pearl millet ( Pennisetum glaucum (L.) R. Brown) was planted to increase the amount of straw on the soil surface. At flowering in November, pearl millet was desiccated. Soluble phosphate, which was applied to the soil surface, increased soil P contents down to the 5-10 cm soil layer, and triticale benefited from P fertilization with higher yields. Despite the increase in available phosphorus in the soil provided by soluble phosphate, P application to triticale did not increase dry matter production, P content and amount in the shoots of the pearl millet grown in sequence.
  • Authors:
    • Alleoni, L. R. F.
    • Murphy, D. V.
    • Caires, E. F.
    • Garbuio, F. J.
    • Jones, D. L.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 5
  • Year: 2011
  • Summary: The short-term effects of surface lime application and black oat ( Avena strigosa Schreb.) residues, with or without N fertilization, were evaluated in a long-term no-till (NT) system on a sandy clay loam, a kaolinitic, thermic Typic Hapludox from the state of Parana, Brazil. The main plot treatments were: control and dolomitic lime applied on soil surface at 8 Mg ha -1. Three treatments with crop residues were evaluated on the subplots: (i) fallow, (ii) black oat residues, and (iii) black oat residues after N fertilization at 180 kg ha -1. Black oat dry biomass was not affected by the treatments during 3 yr. Surface liming increased soil pH, microbial biomass, microbial activity, and bacterial/fungal ratio at the soil surface (0-5 cm), resulting in increased amino acid turnover, water-soluble humic substances formation, and N mineralization and nitrification. While the application of black oat did increase the soil pH, overall it had much less effect on soil biological processes and C and N pools than did lime. We concluded that black oat cannot replace the need for lime to optimize crop production in these tropical NT systems. In the long term, however, black oat should aid in the amelioration of acidity and replenishment of soil organic C pools and should help reduce erosion. Overall, this study suggests that overapplication of inorganic fertilizer N may occur in some tropical NT systems. Further experiments are required in NT systems to investigate the use of slow-release N fertilizers in combination with lime and black oat as a mechanism to reduce acidification and promote sustainability.
  • Authors:
    • Gruber, S.
    • Möhring, J.
    • Claupein, W.
  • Source: Soil & Tillage Research
  • Volume: 115
  • Year: 2011
  • Summary: Ten years of a long-term field experiment using different strategies of conventional and conservation tillage in SW Germany were evaluated for soil mineral nitrogen (SMN) and soil moisture content. Treatments analysed were combinations of stubble tillage (S) or no stubble tillage with primary tillage P: mouldboard plough, CP: chisel plough, RTT: rototiller, NT: no-till, and VAR: alternating SIP or S/CP. Best management practices were used for crop rotation, fertilisation and plant protection. CP, VAR and NT resulted in 18.7-19.0% gravimetric water content in spring. Partially significantly lower water content was observed in spring under S/P and CP with 18.2%; P and S/RTT resulted in 18.5%. Autumn soil moisture ranged from 15.3 to 15.8% and did not significantly differ between the treatments. Interactions between treatment and depth were not significant. There was no clear trend for spring soil moisture. No treatment showed a particular response to dry or wet season. Total SMN ranged between 8 and 49 kg ha(-1) in spring and 5-26 kg ha(-1) in autumn; significant effects of the treatments or interactions of treatment x depth did not occur. The effect of the season was most relevant for the amount of SMN, probably as a result of different conditions for mineralisation. Downward movement of nitrogen in spring was low in all treatments if catch crops were grown in the previous autumn. Overall, different soil tillage methods had little effect on soil moisture and soil SMN under temperate conditions. Seriously adverse effects of any tillage treatment in terms of nitrate leaching or reduced mineralisation seem unlikely. Similarly, the tillage systems did not exhibit obvious advantages or disadvantages in terms of soil water content. An exception may have been the higher water content in autumn in 0-30 cm under high soil disturbance which provided more suitable conditions for germination of the following crop. The decision of whether or not to adopt conservation tillage in temperate climates seems not to be primarily dependent on soil moisture and nitrogen mineralisation or on nitrogen leaching.