• Authors:
    • Garcia, P. A.
    • Benitez, E.
    • Ramos, M. E.
    • Robles, A. B.
  • Source: Applied Soil Ecology
  • Volume: 44
  • Issue: 1
  • Year: 2010
  • Summary: Frequent tillage has been widely used in rainfed orchards in SE Spain in order to impede weed establishment and to increase water reposition in the soil profile. However, this practice may lead to soil degradation by decreasing structural stability, organic carbon content and microbial activity. This work examines the effect of different cover crop managements and frequent tillage on soil physical, chemical and biological properties in almond orchards in SE Spain. Two cover crops (oat - Avena sativa L. and oat-vetch - Vicia sativa L.) with two fertilization managements (mineral and organic) and three harvesting regimes (grazing in mid May, hay in early June, and grain-straw in mid July) were compared to a frequently tilled orchard system (three or four tillages per year). Most parameters were sensitive to soil management. Wet aggregate stability, total organic carbon, total nitrogen, carbon:nitrogen ratio, phosphatase, and beta-glucosidase activities increased with cover crops, whereas the soil-water content declined, especially for the grain-straw treatment. The kind of fertilizer affected the available P content, which was higher for mineral fertilizer, and influenced the beta-glucosidase activity, which augmented for the organic fertilizer. Livestock dejections depressed phosphatase activity, and increased WSC and available P. This study suggests that cover crops in semiarid environments improve soil quality compared to frequently tilled management, by increasing the organic matter content, improving the chemical and physical fertility of the soil, and enhancing the soil biological activity. Only higher water extraction by the plants could affect the orchard development and/or productivity; however, early cover crop removal would minimize possible yield losses.
  • Authors:
    • Silva, R.
    • Rosolem, C.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 41
  • Issue: 1
  • Year: 2010
  • Summary: Cation mobility in acidic soils with low organic-matter contents depends not only on sorption intensity but also on the solubility of the species present in soil solution. In general, the following leaching gradient is observed: potassium (K +) > magnesium (Mg 2+) > calcium (Ca 2+) > aluminum (Al 3+). To minimize nutrient losses and ameliorate the subsoil, soil solution must be changed, favoring higher mobility of M 2+ (metal ions) forms. This would be theoretically possible if plant residues were kept on the soil surface. An experiment was conducted in pots containing a Distroferric Red Latosol, with soil solution extractors installed at two depths. Pearl millet, black oat, and oilseed radish residues were laid on the soil surface, and nitrogen (as ammonium nitrate) was applied at rates ranging from 0 to 150 mg kg -1. Corn was grown for 52 days. Except for K + and ammonium (NH 4+), nitrogen rates and plant residues had little effect upon the concentrations and forms of the elements in the soil solution. Presence of cover crop residues on soil surface decreased the effect of nitrogen fertilizer on Ca leaching. More than 90% of the Ca 2+, Mg 2+, and K + were found as free ions. The Al 3+ was almost totally complexed as Al(OH 3) 0. Nitrogen application increased the concentrations of almost all the ions in soil solution, including Al 3+, although there was no modification in the leaching gradient.
  • Authors:
    • Garcia, R.
    • Werle, R.
    • Rosolem, C.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 34
  • Issue: 6
  • Year: 2010
  • Summary: Crop species with the C 4 photosynthetic pathway are more efficient in assimilating N than C 3 plants, which results in different N amounts prone to be washed from its straw by rain water. Such differences may affect N recycling in agricultural systems where these species are grown as cover crops. In this experiment, phytomass production and N leaching from the straw of grasses with different photosynthetic pathways were studied in response to N application. Pearl millet ( Pennisetum glaucum) and congo grass ( Brachiaria ruziziensis) with the C 4 photosynthetic pathway, and black oat ( Avena Strigosa) and triticale (* Triticosecale), with the C 3 photosynthetic pathway, were grown for 47 days. After determining dry matter yields and N and C contents, a 30 mm rainfall was simulated over 8 t ha -1 of dry matter of each plant residue and the leached amounts of ammonium and nitrate were determined. C 4 grasses responded to higher fertilizer rates, whereas N contents in plant tissue were lower. The amount of N leached from C 4 grass residues was lower, probably because the C/N ratio is higher and N is more tightly bound to organic compounds. When planning a crop rotation system it is important to take into account the difference in N release of different plant residues which may affect N nutrition of the subsequent crop.
  • Authors:
    • Gregova, E.
    • Polisenska, I.
    • Sudyova, V.
    • Srobarova, A.
    • Slikova, S.
    • Mihalik, D.
  • Source: Biologia
  • Volume: 65
  • Issue: 4
  • Year: 2010
  • Summary: Oats as a source of antioxidants and complex polysaccharides are currently an important component in human nutrition. Producing healthy, safe and high-quality grain for this purpose depends upon growing oat cultivars with improved resistance to diseases caused by Fusarium spp. producing mycotoxins. Thirteen cultivars of naked (Abel, Detvan, Izak and Avenuda) and covered (Zvolen, Auron, Atego, Flamingsstern, Kanton, Viktor, Zlat'ak, Euro and Ardo) oats were inoculated with conidial suspensions of F. culmorum isolate in the field at flowering in 2006 and 2007. After harvest, reduction in thousand-kernel weight (R-TKW), reduction in panicle-kernel weight (R-PKW), and deoxynivalenol (DON) content in grain and hulls were determined. The ELISA immunochemical method was employed for the quantitative analyses of DON. Values of yield components (R-TKW; R-PKW) were 35.4% and 31.1% lower in dehulled covered oats than in naked oat cultivars. The DON accumulation was highest in hulls as compared with DON content in kernels of naked and covered oat cultivars. Accumulation of DON in dehulled covered cultivars was 34.4% lower than the average contamination in naked cultivars. When the cultivars were compared, there were positive correlations between R-TKW and R-PKW and also between DON content and R-PKW. With a view to growing oat cultivars for production of cereal foods, it was shown that dehulling of covered oat grain resulted in substantially reduced DON content.
  • 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.
  • Authors:
    • Galizio, R.
    • Moreno, M. V.
    • Dinolfo, M. I.
    • Stenglein, S. A.
    • Salerno, G.
  • Source: PLANT DISEASE
  • Volume: 94
  • Issue: 6
  • Year: 2010
  • Summary: In December 2008, a study of oat (cv. Graciela INTA) seeds from Trenque Lauquen, Buenos Aires, Argentina, was conducted. Seeds were surface sterilized by dipping successively into 70% ethanol for 2 minutes, 5% sodium hypochlorite for 2 minutes, rinsed twice in fresh sterilized distilled water, plated on 2% potato dextrose agar (PDA; pH 6) and incubated at 242°C with 12 h photoperiods. Six isolates morphologically similar to Fusarium spp. were observed after 6 days of incubation. For identification, monosporic isolates were transferred onto 2% PDA and carnation leaf agar (CLA) to grow with the conditions described above. Two isolates produced abundant, white, aerial mycelium and violet-to-dark (with age) pigments in the PDA. On CLA, macroconidia were abundant, slender, almost straight, thin walled and usually 3-5 septate. Microconidia were abundant, usually single celled, oval or club-shaped in chains (less commonly in false heads) on monophialides and polyphialides. Chlamydospores were absent. The fungus was identified as F. proliferatum based on fungal morphology. The pathogenicity of the fungus was tested by spraying 5 healthy inflorescences of oat with a 5 ml suspension (2 * 10 5 conidia/ml). Another 2 healthy inflorescences were sprayed with sterile distilled water. Plants were placed in a growth chamber with a 12 h photoperiod at 222°C and covered with polyethylene bags that were removed after 3 days and plants were moved to a glasshouse. Inoculated inflorescences showed bleaching glumes that sometimes became necrotic with some grains that presented pale brown discoloration and necrotic areas. The fungus was reisolated from glumes and grains of inoculated plants and not from controls. To confirm the morphological diagnosis, the genomic DNA of the isolates was extracted and a PCR reaction with specific primers was chosen. Successful amplifications were confirmed by gel electrophoresis. The size of the DNA fragment was estimated using a 100 bp DNA ladder. The expected size product (585 bp) was obtained, confirming the identification. This is thought to be the first report of F. proliferatum on oat in Argentina.
  • Authors:
    • Trawczynski, C.
  • Source: Journal of Research and Applications in Agricultural Engineering
  • Volume: 55
  • Issue: 4
  • Year: 2010
  • Summary: The aim of this investigation was to determine balance of nitrogen, phosphorus and potassium in organic crop rotation system on light soil. The crop rotation comprised following agricultural plant species: potato, oat, yellow lupine, rye, phacelia. Apart from these main species 3 plants were cultivated as intercrop: field pea, white mustard, serradella. Before potato cultivation the manure in dose of 25 t.ha -1 was applied. The calculations were based on real data of obtained yields and nutrients content in the yields. The "on surface of field" method was used in this investigation. In the crop rotation positive balance of nitrogen (+20,4 kg N.ha -1 per year -1) and slightly negative one for phosphorus (-3,1 kg P.ha -1 per year -1) and potassium (-4,5 kg K.ha -1 per year -1) were noted.
  • Authors:
    • Zekaite, V.
  • Source: Vagos
  • Issue: 88
  • Year: 2010
  • Summary: Field experiments, designed to study weed incidence in Poaceae and Fabaceae monocrops and their mixtures as influenced by an organic cropping system, were carried out during 2007-2009 at the Experimental station of the Lithuanian Research Centre for Agriculture and Forest in Perloja on a Hapli-Albic Luvisol. Short-lived weeds prevailed in the crops. They accounted for 93-95% of the total weeds. The highest counts of weeds were recorded at the beginning of the growing season when the conditions for their emergence were the most conducive ones. In 2007 and 2009 the weather conditions during cereal tillering stage were wet and warm, which created optimal conditions for weed emergence and the weed count per m -2 was 257-264. In the third ten-day period of April 2008, re-current night frosts inhibited cereal and weed emergence, which resulted in 43.6-51.7% lower emergence. With increasing crop competitive power (milk maturity stage), weed emergence tended to decline and was by 17.9-9.8% lower compared with the weed count at tillering stage. Weed air dry weight decreased proportionally, however, only at crop hard maturity stage, with the reduction in crop competitive power, weed air dry weight increased by 31.6%. Due to the weather conditions, weed air dry weight in the wet year 2007 was by 35-55% higher than that in 2008 and 2009. Lupines, oats and wheat and its mixture with peas performed best in suppressing weeds. A strong linear correlation was established between weed number and precipitation and weigh (r=0.901, r=0.758); between plant density and precipitation amount (r=0.745).
  • Authors:
    • Ristolainen, A.
    • Sarikka, I.
    • Hurme, T.
    • Alakukku, L.
  • Source: Agricultural and Food Science
  • Volume: 19
  • Issue: 4
  • Year: 2010
  • Summary: Surface water ponding and crop hampering due to soil wetness was monitored in order to evaluate the effects of conservation tillage practices and perennial grass cover on soil infiltrability for five years in situ in gently sloping clayey fields. Thirteen experimental areas, each having three experimental fields, were established in southern Finland. The fields belonged to: autumn mouldboard ploughing (AP), conservation tillage (CT) and perennial grass in the crop rotation (PG). In the third year, direct drilled (DD) fields were established in five areas. Excluding PG, mainly spring cereals were grown in the fields. Location and surface area of ponded water (in the spring and autumn) as well as hampered crop growth (during June-July) were determined in each field by using GPS devices and GIS programs. Surface water ponding or crop hampering occurred when the amount of rainfall was clearly greater than the long-term average. The mean of the relative area of the ponded surface water, indicating the risk of surface runoff, and hampered crop growth was larger in the CT fields than in the AP fields. The differences between means were, however, not statistically significant. Complementary soil physical measurements are required to investigate the reasons for the repeated surface water ponding.
  • Authors:
    • Kohei, U.
    • Ebel, R.
    • Horowitz, J.
  • Source: Economic Information Bulletin
  • Volume: 70
  • Year: 2010
  • Summary: Most U.S. farmers prepare their soil for seeding and weed and pest control through tillage-plowing operations that disturb the soil. Tillage practices affect soil carbon, water pollution, and farmers' energy and pesticide use, and therefore data on tillage can be valuable for understanding the practice's role in reaching climate and other environmental goals. In order to help policymakers and other interested parties better understand U.S. tillage practices and, especially, those practices' potential contribution to climate-change efforts, ERS researchers compiled data from the Agricultural Resource Management Survey and the National Resources Inventory-Conservation Effects Assessment Project's Cropland Survey. The data show that approximately 35.5 percent of U.S. cropland planted to eight major crops, or 88 million acres, had no tillage operations in 2009.