• Authors:
    • Liu Qian
    • Zhang TingWei
    • Liu ChangZhong
  • Source: Guizhou Agricultural Sciences
  • Issue: 6
  • Year: 2010
  • Summary: The results from studying the effect of inter-cropping of wheat with different crops on occurrence quantity of wheat aphid at flowering and filling stage of wheat showed that the aphid occurrence quantity of inter-cropping of wheat with maize or Helianthus annuus or soybean significantly lower than wheat single cultivation, there was significantly difference in aphid occurrence quantity among three inter-cropping patterns and the aphid occurrence quantity of wheat/maize inter-cropping pattern was the lowest, followed by wheat/ Helianthus annuus inter-cropping pattern.
  • Authors:
    • Meinhardt, C. G.
    • Nelson, K. A.
    • Smoot, R. L.
  • Source: International Journal of Agronomy
  • Volume: 2010
  • Year: 2010
  • Summary: Field research (2003-2005) evaluated the effect of wheat row spacing (19 and 38 cm) and cultivar on double-cropped (DC) soybean response, 38-cm wheat on relay-intercrop (RI) response, and wheat cultivar selection on gross margins of these cropping systems. Narrow-row wheat increased grain yield 460 kg ha -1, light interception (LI) 7%, and leaf area index (LAI) 0.5 compared to wide rows, but did not affect DC soybean yield. High yielding wheat (P25R37) with greater LI and LAI produced lower (330 kg ha -1) soybean yields in an RI system than a low yielding cultivar (Ernie). Gross margins were $267 ha -1 greater when P25R37 was RI with H431 Intellicoat (ITC) soybean compared to Ernie. Gross margins were similar for monocrop H431 non-coated (NC) or ITC soybean, P25R37 in 19- or 38-cm rows with DC H431 NC soybean, and P25R37 in 38-cm rows with RI H431 ITC soybean in the absence of an early fall frost.
  • Authors:
    • Burdick, B.
    • Smoot, R.
    • Nelson, K.
  • Source: Crop Management
  • Issue: July
  • Year: 2010
  • Summary: Soybean seeded [ Glycine max (L.) Merr.] early into standing wheat ( Triticum aestivum L.) using relay intercropping (RI) and seed-coat technology may reduce mechanical damage and soybean interference to wheat. Field research at Novelty from 2003 to 2005 and Albany in 2004 evaluated effects of seed coat technology on wheat and soybean response, and gross profits of RI soybean using seed coat technology compared with selected full season (FS) wheat or soybean and double crop (DC) wheat-soybean. Wheat grain yield in the absence of soybean was 10 bu/acre greater in narrow (7.5-inch) than wide (15-inch) rows. Relay intercropped Intellicoat (ITC) treated 5143 soybean delayed germination and increased 15-inch wheat grain yields 8 bu/acre compared to non-coated (NC) 5143. At Novelty, RI 5143 ITC yield was similar in all three years and 7 bu/acre greater at Albany than 5143 NC. In 2005, dry conditions in mid- to late June reduced RI stands and yields compared to DC soybean at Novelty. Double-cropped 5143 NC soybean had greater gross profits than RI 5143 ITC when wheat and soybean prices were high. However, RI 5143 ITC gross profits were greater when soybean prices were high and wheat prices were low. The RI system using ITC maintained soybean yields and did not reduce wheat yields due to mechanical damage or soybean interference compared to non-coated or fungicide-only coating.
  • Authors:
    • Haar, M.
    • Lindquist, J.
    • Wortman, S.
    • Francis, C.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 25
  • Issue: 4
  • Year: 2010
  • Summary: While weed management is consistently a top priority among farmers, there is also growing concern for the conservation of biodiversity. Maintaining diverse weed communities below bioeconomic thresholds may provide ecosystem services for the crop and the surrounding ecosystem. This study was conducted to determine if weed diversity, density and biomass differ within and among organic and conventional crop rotations. In 2007 and 2008, we sampled weed communities in four long-term crop rotations near Mead, Nebraska using seedbank analyses (elutriation and greenhouse emergence) and above-ground biomass sampling. Two conventional crop rotations consisted of a corn ( Zea mays) or sorghum ( Sorghum bicolor)-soybean ( Glycine max)-sorghum or corn-soybean sequence and a diversified corn or sorghum-sorghum or corn-soybean-wheat ( Triticum aestivum) sequence. Two organic rotations consisted of an animal manure-based soybean-corn or sorghum-soybean-wheat sequence and a green manure-based alfalfa ( Medicago sativa)-alfalfa-corn or sorghum-wheat sequence. Species diversity of the weed seedbank and the above-ground weed community, as determined by the Shannon diversity index, were greatest in the organic green manure rotation. Averaged across all sampling methods and years, the weed diversity index of the organic green manure rotation was 1.07, followed by the organic animal manure (0.78), diversified conventional (0.76) and conventional (0.66) rotations. The broadleaf weed seedbank density in the tillage layer of the organic animal manure rotation was 1.4*, 3.1* and 5.1* greater than the organic green manure, diversified conventional and conventional rotations, respectively. The grass weed seedbank density in the tillage layer of the organic green manure rotation was 2.0*, 6.1* and 6.4* greater than the organic animal manure, diversified conventional and conventional rotations, respectively. The above-ground weed biomass was generally greatest in the organic rotations. The broadleaf weed biomass in sorghum and wheat did not differ between organic and conventional rotations (CRs), but grass weed biomass was greater in organic compared to CRs for all crops. The above-ground weed biomass did not differ within CRs, and within organic rotations the grass weed biomass was generally greatest in the organic green manure rotation. The weed seedbank and above-ground weed communities that have accumulated in these rotations throughout the experiment suggest a need for greater management in long-term organic rotations that primarily include annual crops. However, results suggest that including a perennial forage crop in organic rotations may reduce broadleaf weed seedbank populations and increase weed diversity.
  • Authors:
    • Hao, M.
    • Fan, J.
    • Malhi, S.
  • Source: Canadian Journal of Soil Science
  • Volume: 90
  • Issue: 3
  • Year: 2010
  • Summary: Nitrate (NO 3-) leaching and water contamination have become a worldwide concern. In this review, some examples are presented to show the extent and magnitude of NO 3- accumulation in the soil profiles and its potential effects on contamination of ground water and surface water under dryland farming in northern China. Climatic and management factors affecting NO 3- leaching are also discussed. In northern China, rainfall is relatively sparse, but the high intensity of precipitation and porous soils play an important role in the accumulation of NO 3N in soil and its subsequent leaching in the soil profile. There is a risk of nitrate accumulation and leaching when high rates of fertilizer N are applied to improve crop yields, and it becomes even worse when conventional land use is changed from cereal crops to vegetable crops and fruit orchards. Under such conditions, shallow ground water might be polluted by NO 3-. This suggests that more attention should be paid to prevent this problem by using best management practices, especially by controlling the amount of N fertilizer input, balanced fertilization, split N application, inclusion of crops with deep taproots in the rotation and minimizing summer fallow (especially tilled) frequency.
  • Authors:
    • Franti, T. G.
    • Drijber, R. A.
    • Wortmann, C. S.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 4
  • Year: 2010
  • Summary: Continuous no-till (NT) can be beneficial relative to tillage with fewer field operations, reduced erosion, and surface soil improvement. Field research was conducted at two locations for 5 yr in eastern Nebraska to test the hypotheses that one-time tillage of NT can result in increased grain yield, reduced stratification of soil properties persisting for at least 5 yr, a net gain in soil organic carbon (SOC), and a restoration of the soil microbial community to NT composition. Stratification of soil test P, SOC, and bulk density was similar for all tillage treatments at 5 yr after tillage. Water stable soil aggregates (WSA) were not affected by tillage treatments except that there was more soil as macroaggregates at one location in the 5- to 10-cm depth with moldboard plow tillage (MP) compared with NT. Tillage treatments had no effect on SOC mass in the 0- to 30-cm depth. Soil microbial biomass was greater at the 0- to 5-cm compared with the 5- to 10-cm depth. Biomass of bacteria, actinomycetes, and arbuscular mycorrhizal fungi was greater with NT compared with one-time MP at one location but not affected by the one-time tillage at the other location. Microbial community structure differed among tillage treatments at the 0- to 5-cm depth at one location but not at the other location. Grain yield generally was not affected by tillage treatment. One-time tillage of NT can be done without measureable effects on yield or soil properties.
  • Authors:
    • Robertson, G. P.
    • Grace, P. R.
    • Bohm, S.
    • McSwiney, C. P.
  • Source: Journal of Natural Resources & Life Sciences Education
  • Volume: 39
  • Year: 2010
  • Summary: Opportunities for farmers to participate in greenhouse gas (GHG) credit markets require that growers, students, extension educators, offset aggregators, and other stakeholders understand the impact of agricultural practices on GHG emissions. The Farming Systems Greenhouse Gas Emissions Calculator, a web-based tool linked to the SOCRATES soil carbon process model, provides a simple introduction to the concepts and magnitudes of gas emissions associated with crop management. Users choose a county of interest on an introductory screen and are taken to the input/output window, where they choose crops, yields, tillage practices, or nitrogen fertilizer rates. Default values are provided based on convention and county averages. Outputs include major contributors of greenhouse gases in field crops: soil carbon change, nitrous oxide (N2O) emission, fuel use, and fertilizer. We contrast conventional tillage and no-till in a corn-soybean-wheat (Zea mays L. Glycine max (L.) Merr. Triticum aestivum L.) rotation and compare continuous corn fertilized at 101 and 134 kg N ha -1 yr -1. In corn years, N2O was the dominant GHG, due to high fertilizer requirements for corn. No-till management reduced greenhouse gas emissions by 50% due to net soil carbon storage. Continuous corn fertilized at 101 kg N ha-1 yr-1 emitted 1.25 Mg CO2 equivalents ha-1 yr-1 compared with 1.42 Mg CO2 equivalents ha-1 yr-1 at 134 kg N ha-1 yr-1, providing a 12% GHG savings. The calculator demonstrates how cropping systems and management choices affect greenhouse gas emissions in field crops.
  • Authors:
    • Anderson, R. L.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 25
  • Issue: 3
  • Year: 2010
  • Summary: Weeds are a major obstacle to successful crop production in organic farming. Producers may be able to reduce inputs for weed management by designing rotations to disrupt population dynamics of weeds. Population-based management in conventional farming has reduced herbicide use by 50% because weed density declines in cropland across time. In this paper, we suggest a 9-year rotation comprised of perennial forages and annual crops that will disrupt weed population growth and reduce weed density in organic systems. Lower weed density will also improve effectiveness of weed control tactics used for an individual crop. The rotation includes 3-year intervals of no-till, which will improve both weed population management and soil health. Even though this rotation has not been field tested, it provides an example of designing rotations to disrupt population dynamics of weeds. Also, producers may gain additional benefits of higher crop yield and increased nitrogen supply with this rotation design.
  • Authors:
    • Piccolo, M. de C.
    • Feigl, B. J.
    • Cerri, C. C.
    • Cerri, C. E. P.
    • Frazao, L. A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 135
  • Issue: 3
  • Year: 2010
  • Summary: The Brazilian Cerrado soils were incorporated into the agricultural production process in the 1970s. The introduction of pastures and/or annual crops utilizing different management systems produced changes in the dynamics of soil organic matter. This study evaluated the microbial attributes of a Typic Quartzipsamment (Arenosols in FAO classification) in native vegetation, pastures, and soybean cultivation under conventional (CT) and no-till (NT) systems. The soil samples (0-5, 5-10 and 10-20 cm layers) were collected in July 2005 and February 2006 from different systems: native Cerrado (CE), CT for 4 years with soybean (CT4 S), CT for 4 years with soybean in rotation with millet (CT4 S/M), an area that has been under pasture for 22 years (PA22), and an area that remained under pasture for 13 years, followed by NT with soybean in rotation with millet for 5 years (NT5). Soil inorganic N (nitrate and ammonium), microbial C and N and basal respiration were determined. The soil metabolic quotient (qCO 2) and the C mic:C org ratios were calculated. The predominant form of inorganic N in the native Cerrado (CE) and in the pasture area (PA22) was ammonium, while the conventional system (CT4 S/M) and no-till system (NT5) areas presented higher nitrogen availability for crops in the form of nitrate. The microbial C and N concentrations increased in the wet season, and the highest values were found in the Cerrado (CE) and in pasture (PA22) areas, where the permanent soil cover and the lack of soil disturbance by agricultural practices allowed more favorable conditions for microbial development. The CT4 S area presented the highest qCO 2 index and the lowest C mic:C total ratio, indicating that the conversion of total carbon into microbial carbon is less efficient in this system. Since sandy soils are more susceptible to degradation, the use of more conservationist management systems promotes more favorable conditions to microbial development and maintenance.
  • Authors:
    • Snapp, S. S.
    • Robertson, G. P.
    • Gelfand, I.
  • Source: Environmental Science & Technology
  • Volume: 44
  • Issue: 10
  • Year: 2010
  • Summary: The prospect of biofuel production on a large scale has focused attention on energy efficiencies associated with different agricultural systems and production goals. We used 17 years of detailed data on agricultural practices and yields to calculate an energy balance for different cropping systems under both food and fuel scenarios. We compared four grain and one forage systems in the U.S. Midwest: corn ( Zea mays) - soybean ( Glycine max) - wheat ( Triticum aestivum) rotations managed with (1) conventional tillage, (2) no till, (3) low chemical input, and (4) biologically based (organic) practices, and (5) continuous alfalfa ( Medicago sativa). We compared energy balances under two scenarios: all harvestable biomass used for food versus all harvestable biomass used for biofuel production. Among the annual grain crops, average energy costs of farming for the different systems ranged from 4.8 GJ ha -1 y -1 for the organic system to 7.1 GJ ha -1 y -1 for the conventional; the no-till system was also low at 4.9 GJ ha -1 y -1 and the low-chemical input system intermediate (5.2 GJ ha -1 y -1). For each system, the average energy output for food was always greater than that for fuel. Overall energy efficiencies ranged from output:input ratios of 10 to 16 for conventional and no-till food production and from 7 to 11 for conventional and no-till fuel production, respectively. Alfalfa for fuel production had an efficiency similar to that of no-till grain production for fuel. Our analysis points to a more energetically efficient use of cropland for food than for fuel production and large differences in efficiencies attributable to management, which suggests multiple opportunities for improvement.