• Authors:
    • Franti, T.
    • Drijber, R.
    • Wortmann, C.
  • 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:
    • Ferguson, R. B.
    • Liska, A. J.
    • Wortmann, C. S.
    • Lyon, D. J.
    • Klein, R. N.
    • Dweikat, I.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 1
  • Year: 2010
  • Summary: Sweet sorghum [SS; Sorghum bicolor (L.) Moench] is a potential biofuel crop for the Great Plains. Sweet sorghum was compared with corn [ Zea mays (L.)] and grain sorghum for potential ethanol yield, energy use efficiency, and greenhouse gas (GHG) emissions at seven dryland site-years in Nebraska. Seasonal rainfall ranged from approximately 340 to 660 mm. Soils were deep with medium texture at all site-years. The effects of seeding rate, N rate, and cultivar on SS performance were evaluated. Sweet sorghum sugar yield was not affected by seeding rate and N application at six of seven site-years, but yield was increased by 19% at one site-year. Calculated ethanol yield and net energy yield were 33 and 21% more, respectively, with the grain crops compared with SS, but mean net energy yield of an earlier-maturing SS cultivar was comparable with the grain crops. The mean ratio of energy produced in ethanol per total energy invested was 23% less for grain crops compared with SS. Mean life cycle GHG emissions were 53% and 66 to 69% less compared with gasoline for SS and grain crops, respectively. Very efficient use of the ethanol coproducts was assumed for the grain crops while SS bagasse was assumed to be returned to the field. At least one SS cultivar is competitive with grain crops for some biofuel criteria, but SS is not competitive with grain crops for total or net liquid transportation fuel produced per hectare.
  • Authors:
    • Boykin, D.
    • Balkcom, K.
    • Arriaga, F.
    • Balkcom, K.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 2
  • Year: 2010
  • Summary: Increased production costs and potential benefits of maintaining surface residue has renewed interest in conservation tillage systems for peanut ( Arachis hypogaea L.) production. We determined surface residue cover from rye ( Secale cereale L.) or oat ( Avena sativa L.) cover crops after two strip tillage systems (narrow vs. wide) and planting operations with different row configurations (single vs. twin). We also compared plant populations, yields, and total sound mature kernels for three peanut cultivars ('ANorden', 'AP-3', and 'Georgia-02C') across each treatment combination. Seven site-years were examined across similar soil types in Alabama and northern Florida during the 2004 to 2006 growing seasons. The highest surface residue counts were for the narrow tillage system planted in single rows. Final plant stands were influenced by an interaction between cultivar and row configuration, with 'ANorden' planted in single rows below recommended rates. Peanut yields were affected by strip tillage system and row configuration, but differences among cultivars were also observed. Twin-row peanut yields were 5% greater than single-row peanut yields in the narrow strip tillage system but were similar across strip tillage systems. Cultivars 'AP-3' and 'Georgia-02C' yielded 20% higher than 'ANorden'. Total sound mature kernels were only affected by peanut cultivar, with the cultivar 'Georgia-02C' producing the highest-quality peanut, followed by 'ANorden' and 'AP-3'. These results indicate that growers interested in using twin rows for peanut production can also take advantage of a narrow strip tillage system that maximizes surface residue coverage and subsequent benefits.
  • Authors:
    • Singer, J.
    • Moorman, T.
    • Cambardella, C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 87
  • Issue: 3
  • Year: 2010
  • Summary: Coupling winter small grain cover crops (CC) with manure (M) application may increase retention of manure nitrogen (N) in corn ( Zea mays L.), -soybean [ Glycine max (L.) Merr], cropping systems. The objective of this research was to quantify soil N changes after application of liquid swine M ( Sus scrofa L.) at target N rates of 112, 224, and 336 kg N ha -1 with and without a CC. A winter rye ( Secale cereale L.)-oat ( Avena sativa L.) CC was established prior to fall M injection. Surface soil (0-20 cm) inorganic N concentrations were quantified every week for up to 6 weeks after M application in 2005 and 2006. Soil profile (0-120 cm in 5, 20-cm depth increments) inorganic N, total N, total organic carbon and bulk density were quantified for each depth increment in the fall before M application and before the CC was killed the following spring. Surface soil inorganic N on the day of application averaged 318 mg N kg -1soil in 2005 and 186 mg N kg -1soil in 2006 and stabilized at 150 mg N kg -1soil in both years by mid-November. Surface soil NO 3-N concentrations in the M band were more than 30 times higher in the fall of 2005 than in 2006. The CC reduced surface soil NO 3-N concentrations after manure application by 32% and 67% in mid- November 2005 and 2006, respectively. Manure applied at 224 kg N ha -1 without a CC had significantly more soil profile inorganic-N (480 kg N ha -1) in the spring after M application than manured soils with a CC for the 112 (298 kg N ha -1) and 224 (281 kg N ha -1) N rates, and equivalent inorganic N to the 336 (433 kg N ha -1) N rate. These results quantify the potential for cover crops to enhance manure N retention and reduce N leaching potential in farming systems utilizing manure.
  • Authors:
    • Lambrecht, S. C.
    • D'Amore, A.
  • Source: Ecological Restoration
  • Volume: 28
  • Issue: 4
  • Year: 2010
  • Summary: A study was conducted to gauge the relative efficacy of mowing twice, discing, and solarization in controlling invasive weeds. The two specific objectives were to test whether solarization could be used effectively for weed control in a cool, coastal region, and to compare this approach with other methods of weed control in terms of effectiveness, cost, and time required for implementation. The study was conducted in an area within a 1-ha fallow field in California, USA that had not been cultivated for ten years. Non-native annual grasses dominated the vegetation, primarily ryegrass ( Lolium perenne subsp. multiflorum), but also soft brome ( Bromus hordeaceus), oats ( Avena spp.), and foxtail barley ( Hordeum murinum). Mustard ( Brassica rapa) and radish ( Raphanus sativus) were also common non-native weeds. The site is about 7 km from the ocean, so it experiences a strong maritime influence. The solarization treatment was the most effective method for controlling weed cover at Triple M. All treatment areas had similar weed cover beforehand, and treatments differed in their effectiveness. Although all treatments were equally effective in reducing non-native annual grass cover, both the disking and mowing treatment areas were invaded by the annual/biennial bristly oxtongue ( Picris echioides) during the study. This species comprised 85% of the posttreatment weedy forb cover in the disked area and 98% in the mowed area, but was not found in the solar-treated area. This is the first study to demonstrate effective weed control using solarization in a cool coastal region.
  • 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:
    • Elliott, N.
    • Giles, K.
    • Phoofolo, M.
  • Source: Environmental Entolomology
  • Volume: 39
  • Issue: 3
  • Year: 2010
  • Summary: Creating conditions that enhance the abundance of resident populations of natural enemies in agroecosystems is considered critical to the efficiency of biological control of insect pests. We conducted a study to determine the potential of relay-intercropping for enhancing the abundance of aphidophagous lady beetles in sorghum. A relay-intercropping system consisting of alfalfa, winter wheat, and cotton as intercrops and sorghum as a main crop was compared with sorghum monoculture plots at two study sites in OK from 2003 to 2006. Lady beetles and aphids were sampled throughout the season using sticky traps and field counts on individual sorghum plants. Results from sticky traps and field counts show that differences in abundance and species composition of lady beetles between intercropped and monoculture sorghum were not statistically different during each year of study. Also, the lady beetle-greenbug ratios in relay-intercropped and monoculture plots were not significantly different. Lack of significant effects of relay-intercropping in our study may have been attributable to the confounding effects of spatial and temporal scale and the low number of aphids and other alternative prey in the intercrops compared with high incidence of corn leaf aphids in sorghum early in the season.
  • Authors:
    • Brenneman, T.
    • Sorensen, R.
    • Lamb, M.
  • Source: Peanut Science
  • Volume: 37
  • Issue: 1
  • Year: 2010
  • Summary: Strip tillage with various crop covers in peanut ( Arachis hypogaea, L.) production has not shown a clear yield advantage over conventional tillage, but has been found to reduce yield losses from some diseases. This study was conducted to determine pod yield and disease incidence between two tillage practices, five winter cover crops, three peanut cultivars, and three fungicide programs. Conventional and strip tillage treatments were implemented on a Greenville sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults) near Shellman, GA. Five winter cereal grain cover crops (strip tillage) and a no-cover crop treatment were sprayed at recommended (1R), half recommended (0.5R) or untreated (0R) fungicide programs. Within peanut cultivars, leaf spot ( Cercospora arachidicola Hori) intensity decreased as the number of fungicide applications increased; however, stem rot ( Sclerotium rolfsii) incidence was the same for the 1R and 0.5R fungicide programs but increased 0R program. Conventional tilled peanuts developed more leaf spot compared with strip tillage. There was no difference in leaf spot ratings among winter crop covers. There was no difference in stem rot incidence with tillage or winter cover crop. There was no yield difference with peanut cultivar. Pod yield was the same for the 1R and 0.5R fungicide program (3867 kg/ha) but decreased at the 0R fungicide program (2740 kg/ha). Pod yield was greater with conventional tillage and strip tillage with black oats ( Avena sativa L.) (3706 kg/ha) compared with strip tillage of other winter crop cover treatments (3358 kg/ha). Conventional tillage had more leaf spot, equal incidence of stem rot, and higher yield compared with strip tillage. The 0.5R fungicide program had the same yield compared with the 1R fungicide program implying a possible 50% savings on fungicide applications on well rotated fields with lower disease risk.
  • Authors:
    • Mitchell, J. P.
    • Summers, C. G.
    • Stapleton, J. J.
    • Prather, T. S.
  • Source: PHYTOPARASITICA
  • Volume: 38
  • Issue: 1
  • Year: 2010
  • Summary: Experiments were conducted in laboratory bioreactors and in field plots to test effects of certain cultivated members of the grass family (Poaceae=Gramineae), including wheat ( Triticum aestivum cv. Yolo), barley ( Hordeum vulgare cv. UC337), oats ( Avena sativa cv. Montezuma), triticale ( X Triticosecale), and a sorghum-sudangrass hybrid ( Sorghum bicolor * S. sudanense="sudex", cv. Green Grazer V) for soil disinfestation potential. Soilborne pest organisms tested for effects on survival and activity included the phytopathogens Sclerotium rolfsii, Pythium ultimum and Meloidogyne incognita, and a variety of weed taxa. Following soil amendment, bioreactors were incubated for 7 days at ambient (23°C) or elevated, but sublethal (38°C day/27°C night), soil heating regimens. Addition of each of the poaceous amendments to soil at 23°C resulted in inconsistently reduced tomato root galling (49-97%) by M. incognita, or reduced recovery of S. rolfsii and P. ultimum (0-100%) fungi in soil, after 7 days' incubation ( P≤0.05). When the organisms were exposed to the poaceous soil amendments at the 38°/27° temperature regimen, nematode galling and recovery of active fungi were consistently and significantly reduced by 98-100%. These results demonstrated feasibility of soil disinfestation ("biofumigation") by activity of poaceous amendments, further aided by combining plant residues with soil heating (e.g. solarization). Results from three field experiments with sudex cover crops, conducted throughout the growing season, demonstrated biocidal activity on a range of weedy plants, including Amaranthus retroflexus, Calandrinia ciliata, Cerastium arvense, Digitaria sanguinalis, Echinochloa crus-galli and Poa annua. Both shoots and roots of sudex provided allelopathic weed biomass reductions of 35-100%, and for at least 106 days after shredding. Deleterious activity of shredded residues incorporated in soil was less persistent. These properties in poaceous crops can be useful for soil disinfestation; however, harmful phytotoxicity to subsequent crops may also result. In order to take full advantage of these low-input measures for controlling soilborne diseases and pests, further understanding of their properties must be gained, and user guidelines developed.