• 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:
    • Harris, H.
    • Masri, S.
    • Makhboul, R.
    • Pala, M.
    • Singh, M.
    • Ryan, J.
    • Sommer, R.
  • Source: Journal of Agricultural Science
  • Volume: 148
  • Issue: 2
  • Year: 2010
  • Summary: The Mediterranean region is experiencing unrelenting land-use pressure, largely driven by population growth. Long-term cropping system trials can guide crop and soil management options that are biophysically and economically sustainable. Thus, an extensive cereal-based rotation trial (1983-98) was established in northern Syria, to assess various two-course rotations with durum wheat ( Triticum turgidum Desf.). The alternative rotations were: continuous wheat, fallow, chickpea ( Cicer arietinum), lentil ( Lens culinaris), medic ( Medicago spp.), vetch ( Vicia sativa) and watermelon ( Citrullus vulgaris) as a summer crop. Ancillary treatments were: nitrogen (N) fertilizer application to the cereal phase (0, 30, 60 and 90 kg N/ha) and variable stubble grazing management (zero or stubble retention, moderate and heavy grazing). Both phases of the rotation trial occurred each year. The soil is a fine clay, thermic Calcixerollic Xerochrept. Seasonal rainfall was the dominant factor in influencing overall yields. Rotations significantly influenced yields, being highest for fallow (2.43 t/ha), followed by watermelon (similar to fallow), vetch, lentil, medic and chickpea, and least for continuous wheat (1.08 t/ha). Overall, yields increased consistently with added N, but responses varied with the rotation. The various stubble grazing regimes had little or no effect on either grain or straw yields. While the trial confirmed the value of fallow and the drawbacks of continuous cereal cropping, it also showed that replacing either practice with chickpea or lentil, or vetch for animal feed, was potentially a viable option. Given favourable economics, legume-based rotations for food and forage could contribute to sustainable cropping throughout the Mediterranean region.
  • 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:
    • Yifru, A.
    • Taye, B.
  • Source: World Journal of Agricultural Sciences
  • Volume: 6
  • Issue: 5
  • Year: 2010
  • Summary: A study to examine soil fertility status was conducted in the highlands of Southeast Ethiopia situated within latitude 0707′N and longitude 4010′E at altitude 2200 m to 2400 m above sea level. Twenty five farmers who are knowledgeable about soils of the area are purposively selected to provide insight into different soil fertility management practices. Local methods used to identify different soils and to assess the fertility status. Farmers used soil color, texture, water holding capacity, fertilizer requirement (inherent fertility) and workability as a criteria to identify different soil types. However, soil color and texture were commonly used by farmers to describe soil quality. Farmers preferred black and clay soils to white and sandy soils due to their high water holding capacity and inherent fertility. Besides, soil samples were randomly collected from the farmer's field under continuous cereal production systems. The study made up thirty-two sites and each site covered 400 m 2 sampling area. Composite samples of surface and subsurface soils were collected using special auger from three depths (0-10, 10-20, 20-30 cm). The laboratory analysis result indicated the soils are low in cation exchange capacity, low to medium in organic matter, slightly acidic to neutral, very high in base saturation, low to medium in exchangeable bases and moderate in both total nitrogen and available phosphorus. These soils are low to moderate in fertility that requires quite reasonable management. As a summary, the combined effect of both qualitative (local indicators of soil fertility) and quantitative (technical indicators of soil fertility) information would result in better assessment of soil fertility pattern and soil fertility management strategies to ensure food security program.
  • Authors:
    • Ginovart, M.
    • Josa, R.
    • Sole, A.
  • Source: International Agrophysics
  • Volume: 24
  • Issue: 2
  • Year: 2010
  • Summary: In an experiment conducted in NE Spain, cereals and legumes were rotated for seven cycles using two different tillage techniques - conventional tillage and direct drilling (no-tillage: NT). Straw was removed after harvesting in both tillage systems. With NT, more than 30% of the soil surface was still covered by residues (stubble) at sowing. The soil was Calcic Cambisol and the climate aridity index was 0.76. The climatic water balance was negative, at -187 mm y(-1) from 1950 to 1980. The aims of the study were to determine the effect of tillage system on 2-D macroporosity by micromorphology, and bulk density (excavation method) of the upper layer of the ploughed horizon. To identify differences, either parametric or nonparametric statistical tests were performed depending on sample size. Direct drilling with residue removal affected bulk density, macroporosity and mean macropore area in the top 10 cm of the profile. The same effects were observed under conventional tillage. The upper layer of the studied horizon had higher total porosity than the layer beneath with both treatments. The upper layer of the horizon showed unfavourable physical conditions with direct drilling.
  • Authors:
    • Grant, C.
    • Khakbazan, M.
    • Mohr, R.
  • Source: López-Francos A. (comp.), López-Francos A. (collab.). Economics of drought and drought preparedness in a climate change context. Zaragoza : CIHEAM / FAO / ICARDA / GDAR / CEIGRAM / MARM, 2010 (Options Méditerranéennes : Série A. Séminaires Méditerranéens;
  • Issue: 95
  • Year: 2010
  • Summary: The objective of this paper was to study the impact of drought and adaptation measures on the economics of production for some major crops grown in Western Canada. Crop yields, yield variability, and crop losses were analyzed to quantify drought impacts and statistical models were developed to estimate the relationship between yield and growing season precipitation for wheat, canola, oats, and barley. The linear and quadratic precipitation terms were found to have the correct sign and to be significantly related to yield (p
  • Authors:
    • Honeycutt, C. W.
    • Griffin, T. S.
    • Larkin, R. P.
  • Source: Plant Disease
  • Volume: 94
  • Issue: 12
  • Year: 2010
  • Summary: Seven different 2-year rotations, consisting of barley/clover, canola, green bean, millet/rapeseed, soybean, sweet corn, and potato, all followed by potato, were assessed over 10 years (1997-2006) in a long-term cropping system trial for their effects on the development of soilborne potato diseases, tuber yield, and soil microbial communities. These same rotations were also assessed with and without the addition of a fall cover crop of no-tilled winter rye (except for barley/clover, for which underseeded ryegrass was substituted for clover) over a 4-year period. Canola and rapeseed rotations consistently reduced the severity of Rhizoctonia canker, black scurf, and common scab (18 to 38% reduction), and canola rotations resulted in higher tuber yields than continuous potato or barley/clover (6.8 to 8.2% higher). Addition of the winter rye cover crop further reduced black scurf and common scab (average 12.5 and 7.2% reduction, respectively) across all rotations. The combined effect of a canola or rapeseed rotation and winter rye cover crop reduced disease severity by 35 to 41% for black scurf and 20 to 33% for common scab relative to continuous potato with no cover crop. Verticillium wilt became a prominent disease problem only after four full rotation cycles, with high disease levels in all plots; however, incidence was lowest in barley rotations. Barley/clover and rapeseed rotations resulted in the highest soil bacterial populations and microbial activity, and all rotations had distinct effects on soil microbial community characteristics. Addition of a cover crop also resulted in increases in bacterial populations and microbial activity and had significant effects on soil microbial characteristics, in addition to slightly improving tuber yield (4% increase). Thus, in addition to positive effects in reducing erosion and improving soil quality, effective crop rotations in conjunction with planting cover crops can provide improved control of soilborne diseases. However, this study also demonstrated limitations with 2-year rotations in general, because all rotations resulted in increasing levels of common scab and Verticillium wilt over time.
  • Authors:
    • Jauhiainen, L.
    • Peltonen-Sainio, P.
  • Source: Agricultural and Food Science
  • Volume: 19
  • Issue: 4
  • Year: 2010
  • Summary: The balance between applied and harvested nitrogen (yield removed nitrogen, YRN %) is a recognized indicator of the risk of N leaching. In this study we monitored the genetic improvements and environmental variability as well as differences among crop species (spring cereals and rapeseed) in YRN in order to characterize changes that have occurred and environmental constraints associated with reducing N leaching into the environment. MTT long-term multi-location field experiments for spring cereals (Hordeum vulgare L., Avena sativa L. and Triticum aestivum L.), turnip rape (Brassica rapa L.), and oilseed rape (B. napus L.) were conducted in 1988-2008, covering each crop's main production regions. Yield (kg ha(-1)) was recorded and grain/seed nitrogen content (N(grain), g kg(-1)) analyzed. Total yield N (N(yield), kg ha(-1)) was determined and YRN (%) was calculated as a ratio between applied and harvested N. A mixed model was used to separate genetic and environmental effects. Year and location had marked effects on YRN and N(yield). Average early and/or late season precipitation was often most advantageous for N(yield) in cereals, while in dry seasons N uptake is likely restricted and in rainy seasons N leaching is often severe. Elevated temperatures during early and/or late growth phases had more consistent, negative impacts on YRN and/or N(yield) for all crops, except oilseed rape. In addition to substantial variability caused by the environment, it was evident that genetic improvements in YRN have taken place. Hence, YRN can be improved by cultivar selection and through favouring crops with high YRN such as oat in crop rotations.
  • Authors:
    • Meca, A. V.
    • Popescu, N.
  • Source: Annals of the University of Craiova - Agriculture, Montanology, Cadastre Series
  • Volume: 40
  • Issue: 2
  • Year: 2010
  • Summary: Within our country conditions the wheat, rye, barley, oilseed rape and pea-oat fodder are sown in autumn. They may be grown after crops that are harvested during summer or perennial crops or pastures that are included is crop rotation schemes. In the conditions of our country, crops that are harvested during the summer are: pea-oat fodder, pea, early potato, barley and wheat. After harvesting these crops, there must be done, immediately, the summer plowing because the soil is still moist, resulting a good quality plowing. Any delay conducts to diminishing the yields. Usually, the summer plow is made at 18-20 cm depth. Deeper plow are not necessary on most soil types from our country. Twenty cm deeper plow is need only on clayey soil that easily compacts, when the soil is highly infested by weeds, covered by high straw or when in the last year there was made a shallow plow. Summer plow, no matter the depth must be done along with harrow after plow. During the fall, till drilling, the soil has to be harrowed in order to destroy weeds and to maintain soil loosened.