• Authors:
    • Sun, Y.
    • Dowd, S.
    • Acosta-Martinez, V.
    • Wester, D.
    • Allen, V.
  • Source: Applied Soil Ecology
  • Volume: 45
  • Issue: 1
  • Year: 2010
  • Summary: Bacterial tag-encoded FLX amplicon pyrosequencing of the 16S rDNA gene was used to evaluate bacterial diversity of a clay loam soil (fine, mixed, thermic Torrertic Paleustolls) after 10 years under an integrated livestock (beef)-cotton ( Gossypium hirsutum L.) production system compared to continuous cotton in a semiarid region. In the integrated system, cattle alternatively grazed a perennial warm-season grass [ Bothriochloa bladhii (Retz) S.T. Blake] paddock and small grains grown in two paddocks of a wheat ( Triticum aestivum L.)-fallow-rye ( Secale cereal L.)-cotton rotation. Areas excluded from grazing in the integrated system were also evaluated. Maximum observed number of unique sequences operational taxonomic units (OTU) at 3% dissimilarity level (roughly corresponding to the species level) corresponded to 1200 and 1100 at 0-5 and 5-15 cm depths, respectively. Predominant phyla (up to 65% of abundance) at 0-5 and 5-15 cm in this soil were Proteobacteria, Actinobacteria and Gemmatimonadetes. Proteobacteria were predominant in soil under all components of the integrated livestock-cotton system compared to continuous cotton whereas Bacteroidetes were predominant under continuous cotton. Firmicutes (i.e., Clostridia) and Chlorofexi (i.e., Thermomicrobia) were more abundant in soil under fallow periods of the rotation compared to under cotton (Rye- Cotton-Wheat-Fallow or continuous cotton) or grass (i.e., pasture). The lowest OTUs were detected in soil under fallow periods of the rotation (Wheat- Fallow-Rye-Cotton) compared to the other treatments. Grazing effects were significant for Actinobacteria, Proteobacteria and Chlorofexi. Compared to the continuous cotton system, this study revealed significant changes in bacterial phyla distribution under integrated livestock-cotton systems for a semiarid soil after 10 years. Positive correlations were found between certain bacteria ( Proteobacteria, Firmicutes, Chloroflexi, Verrucomicrobiae and Fibrobacteres) and the activities of alkaline phosphatase and beta-glucosidase or beta-glucosaminidase.
  • Authors:
    • Evansf, R.
    • Lartey, R.
    • Caesar, T.
    • Sainju, U.
    • Lenssen ,A.
    • Allen, B.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Division Symposium 3.2 Nutrient best management practices
  • Year: 2010
  • Summary: Available water and N fertility are primary constraints to crop production in the northern Great Plains of the USA. A field trial was initiated in 2004 to compare four crop rotations in a complete factorial of two tillage and two management systems. Rotations were continuous spring wheat (SW), pea-SW, barley hay-pea-SW, and barley hay-corn-pea-SW. Tillage systems were no till and field cultivator tillage, while management systems were conventional and ecological. Conventional management included broadcast nitrogen fertilizer, standard seeding rates, and short stubble height. Ecological management practices varied by crop, and included banded nitrogen fertilizer for cereals, increased seeding rate, delayed planting date for SW, and taller stubble height. Continuous SW grain yield was 26% lower than SW in more diverse rotations. Pea grain yield was 18% lower in 2-yr rotations than in more diverse rotations. Ecologically managed SW yielded 29% less than conventionally managed SW, presumably due to the delayed planting date. Ecological management of pea resulted in 12% greater yield compared to conventional management. Tillage system rarely impacted crop yield. Yield increases in SW were related to increased N use efficiency.
  • Authors:
    • Pire, E.
    • Boccanelli, S.
    • Lewis, J.
  • Source: CIENCIA E INVESTIGACION AGRARIA
  • Volume: 37
  • Issue: 2
  • Year: 2010
  • Summary: Agriculture has been practised in the Argentine Pampa Region for more than a century. This long history of disturbance has strongly modified the native vegetation of the region. Some original species have disappeared or its area has been remarkably reduced. The objective was to evaluate vegetation changes over time after the abandonment of agriculture practice. Our hypothesis was that over time vegetation in this region will evolve towards a "flechillar" ( Stipa spp. community) similar to the original vegetation. The experiment was conducted at Zavalla (Santa Fe) Argentina (33degrees01′S, 60degrees53′W and 50 m.a.s.l.). Vegetation evolution was studied during 15 years (1982-1997) after abandonment, considering four initial crop situations (i.e. wheat, soybean, pasture and tillage). Periodically, we measured species cover and abundance in 60 subplots. Data was analyzed using multivariate methods. We identified several groups corresponding to two very well defined successional stages. The first group was very small, and showed predominance of annual species; the second group showed a reduction or almost disappearance of annuals and an increase in perennials such as Baccharis salicifolia (Ruiz & Pav.) Pers. and Sorghum halepense (L.) Pers. accompanied by Carduus acanthoides L. Therefore, a secondary succession was developed, with a first stage of annual species dominance followed by long life cycle species. However, even after 15 years there was no reversion of the vegetation to the original community.
  • Authors:
    • Sun, Y.
    • Zhao, Y.
    • Wu, P.
    • Cui, H.
    • Chen, Z.
  • Source: Soil & Tillage Research
  • Volume: 110
  • Issue: 2
  • Year: 2010
  • Summary: Wind erosion near soil surface is one of the major causes of farmland degradation and desertification in arid and semiarid areas. Intercropping wheat and potato can effectively reduce wind erosion, soil desertification and degradation. In this paper, a quantitative research on effective resistance width to wind erosion for the wheat and potato intercropping farmland was performed using several 8-channel wind speed samplers and a movable wind tunnel. As can be seen from the test results, the effective width to control wind erosion for conventional tillage strips on wheat and potato intercropping farmland was lower than or equal to 5 m as the wind speed at 2 m height was 6-7 m.s -1. Moreover, the effective width to control wind erosion of conservation tillage strips on wheat and potato intercropping farmland should be greater than or equal to 5.5 m. Therefore, wheat and potato intercropping with suitable strip width is a cropping mode that not only protects farmland soil from wind erosion to the utmost but also satisfies the requirements of regional planting structure.
  • Authors:
    • Eslami, S.
    • Ebranimi ,E.
    • Mahmoodi, S.
  • Source: Proceedings of 3rd Iranian Weed Science Congress, Volume 1: Weed biology and ecophysiology, Babolsar, Iran, 17-18 February 2010
  • Year: 2010
  • Summary: Ceratocarpus arenarius is one of the problematic and noxious weeds in dryland farming of wheat, barley, lentil and peas in North Khorasan. Laboratory experiments were conducted on germination and seedling emergence of ceratocarpus. Germination ability of this weed species was similar in light/dark and continuous dark conditions, therefore seeds of this weed species are non-photoblastic. Seeds germinated over 80% in the range of alternating day/night temperatures (20/10, 25/15 and 30/20C) and the maximum germinability (96%) was observed at 25/15C. Seed of this weed species retained their germination ability until high salinity levels and even at 800 mM NaCl 20% of seeds germinated. Seeds of this weed species could tolerate high level of drought stress, so that 25% of seeds germinated at osmotic potential of -1 MPa. Seedlings could emerge from a range of burial depths from 0 (without covering with filter paper) to 8 cm and maximum emergence (94%) was observed in seeds planted on the soil surface covered with 3 layers of filter paper.
  • Authors:
    • Rubio, S.
    • Ballesteros-Gomez, A.
    • Garcia-Fonseca, S.
    • Perez-Bendito, D.
  • Source: Journal of Chromatography
  • Volume: 1217
  • Issue: 16
  • Year: 2010
  • Summary: A supramolecular solvent made up of reverse micelles of decanoic acid, dispersed in a continuous phase of THF: water, was proposed for the simple, fast and efficient microextraction of OTA in wheat prior to liquid chromatography-fluorescence determination. The method involved the stirring of 300 mg-wheat subsamples (particle size 50 m) and 350 L of supramolecular solvent for 15 min, subsequent centrifugation for 15 min and the direct quantitation of OTA in the extract, previous 5.7-fold dilution with ethanol/water/acetic acid (49.5/49.5/1), against solvent-based calibration curves. No clean-up of the extracts or solvent evaporation was needed. Interactions between the supramolecular solvent and major matrix components in the wheat (i.e. carbohydrates, lipids and proteins) were investigated. The reverse micelles in the extractant induced gluten flocculation but only in the coacervation region of lower analytical interest (i.e. at percentages of THF above 11%). The quantitation of OTA was interference-free. Representativity of the 300 mg-wheat subsamples was proved by analysing a reference material. OTA recoveries in wheat ranged between 84% and 95% and the precision of the method, expressed as relative standard deviation, was 2%. The quantitation limit of the method was 1.5 g kg -1 and was below the threshold limit established for OTA in raw cereals by EU directives (5.0 g kg -1). The method developed was validated by using a certified reference material and it was successfully applied to the determination of OTA in different wheat varieties from crops harvested in the South of Spain. OTA was not detected in any of the analysed samples. This method allows quick and simple microextraction of OTA with minimal solvent consumption, while delivering accurate and precise data.
  • Authors:
    • Andrew, J.
    • Gazey, C.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Symposium 4.1.2 Management and protection of receiving environments
  • Year: 2010
  • Summary: Surface application of agricultural lime to treat acidity in the soil profile delivers multiple benefits to the broadcare dryland farming systems in Western Australia. Soil pH measured in 2009 to a depth of 40-50 cm was increased by applications of lime applied in 1991 and 2000. The ameliorated soil pH profile, which meets the Wheatbelt Natural Resource Management 2025 resource targets (Avon Catchment Council 2005) (designed to remove acidity as a constraint to productive agriculture), has provided multiple benefits in terms of increased productivity, increased crop competitiveness, reduced weed burden, reduced risk of soil erosion by wind due to increased biomass cover and potentially reduced off-site effects which result from decreased water use efficiency on profiles with low pH. Current annual losses due to soil acidity for the WA wheatbelt are estimated at between $300-400 million or around 9% of the total crop. The treated soil profile in this trial returned $175/ha benefit from increased wheat yield in 2008 and $225/ha benefit from increased barley grain yield in 2009.
  • Authors:
    • Fernandez-Quintanilla, C.
    • Izquierdo, J.
  • Source: Agrociencia
  • Volume: 44
  • Issue: 1
  • Year: 2010
  • Summary: Lolium rigidum is a major grass weed of winter cereals in the Mediterranean area, in spite of the continuous use of herbicides in these crops. New management approaches focus on the reduction of the seed banks by enhancing crop competitiveness and, consequently, minimizing weed seed rain. However, the spatial heterogeneity that exists within fields results in differences in the growth and the competitiveness of crops and weeds. In order to determine if the competitive interactions between barley and L. rigidum are site-specific biomass and seed production of this weed, growing in monoculture (plots with L. rigidum) and in mixed culture (plots with L. rigidum+barley), were studied at three sites (in upland, mid-slope and lowland positions) within barley fields. In each site were determined weed populations, and in soil separates, nutrient content, organic matter, slope and orientation were determined for each site. Crop presence significantly reduced weed biomass between 5 and 79% and seeds per spike between 10 and 48%, depending on the site. The competitive effect of the crop was greater in the more fertile sites (with higher N, P and organic matter content). In these sites, differences in plant biomass accumulation between the weed in monoculture and the weed in mixed culture started to be significant after stem elongation. Regardless the reduction in the number of seeds per spike observed in the most fertile sites, seed rain (measured as seeds m -2) could still be very important if weed density of the site is high. The differences in the competitive interactions between barley and L. rigidum observed within the fields suggest that adequate crop husbandry practices addressed site-specifically to enhance crop competitiveness can play an important role as a mechanism to reduce L. rigidum populations over the long term.
  • Authors:
    • Gao, M.
    • Zhou, T.
    • Zhu, S.
    • Jin, X.
  • Source: Journal of Northwest A & F University - Natural Science Edition
  • Volume: 38
  • Issue: 4
  • Year: 2010
  • Summary: A comparative analysis of the structure and function characteristics and ecological and economic benefits of different agroforestry models in a purple soil area in China was conducted. An agroforestry ecosystem composed of a pear forest and different crops planted under the local forest was taken as the research objective. The emergy analysis method was used to compare the emergy input and output of pear-rapeseed-maize system (model 1), pear-rapeseed-groundnut system (model 2), pear-wheat-maize system (model 3) and pear-wheat-sweet potato system (model 4). Results showed that the energy input structure in the four agroforestry models was similar. The investment of non-renewable emergy took a main proportion in the systems. The human labour emergy and the fertilizer emergy played dominant roles. Model 1 had the highest production efficiency, the most advantageous in price-competition, and the most powerful self-development. Model 4 had the lowest renewable resource utilization, the smallest environment load ratio and the biggest emergy sustainable indices. The net emergy yield ratio and emergy self-support ratio of model 2 were close to that of model 3. However, model 2 had a higher development potential because of its lower environment pressure. The science and technology level of the agroforestry ecosystem in the purple soil area was lower. The input of organic manure should be increased. Model 1 was the best model at present and model 4 was the most potential model for development.
  • Authors:
    • Adamczewski, K.
    • Kaczmarek, S.
    • Matysiak, K.
  • Source: Acta Scientiarum Polonorum - Agricultura
  • Volume: 9
  • Issue: 4
  • Year: 2010
  • Summary: The aim of this study was to compare the herbicidal efficiency of mixture florasulam+2,4-D (Mustang 306 SE) in spring wheat cultivar Bryza, spring barley cultivar Antek and oat cultivar Cwa sown in monocrops and two-species mixtures. Field experiments were carried out in 2005-2007 at the Experimental Station in Winna Gora (5212′N; 1727′E), owned by the Institute of Plant Protection - National Research Institute in Poznan. Herbicyd Mustang 306 SE was applied in a dose of 0.5 dm 3.ha -1 at 3-5 leaf stage of cereals using the knapsack sprayer Gloria. The analysis of weed infestation of cereal stand was made with the quantitative-weighing method twice in the growing period (3-4 weeks after the application and 7-8 weeks after the application). Efficiency of herbicide action in mixtures was compared with its effectiveness in monocrops of individual species. From the analyses made it follows that of the cereal mixtures, the barley-oat mixture was infested in the least degree, and the wheat-oat mixture in the most degree. Strongest effect of cultivation in mixtures on reduction of weed infestation was noticeable on the control treatments, where the herbicide was not applied, whereas the cereal cultivation system (pure or mixed sowing) not always differentiated the herbicide efficiency. Cereal grain yields in mixtures after the application of mixture florasulam+2,4-D were significantly higher than yields of at least one of the component, and yields of mixtures harvested from the control treatments exceeded grain yields of both cereal species in monocrops.