• Authors:
    • Halloran, J. M.
    • Olanya, O. M.
    • Griffin, T. S.
    • Honeycutt, C. W.
    • Larkin, R. P.
    • He, Z.
  • Source: Phytopathology
  • Volume: 101
  • Issue: 1
  • Year: 2011
  • Summary: Four different potato cropping systems, designed to address specific management goals of soil conservation, soil improvement, disease suppression, and a status quo standard rotation control, were evaluated for their effects on soilborne diseases of potato and soil microbial community characteristics. The status quo system (SQ) consisted of barley under-seeded with red clover followed by potato (2-year). The soil-conserving system (SC) featured an additional year of forage grass and reduced tillage (3-year, barley/timothy-timothy-potato). The soil-improving system (SI) added yearly compost amendments to the SC rotation, and the disease-suppressive system (DS) featured diverse crops with known disease-suppressive capability (3-year, mustard/rapeseed-sudangrass/rye-potato). Each system was also compared with a continuous potato control (PP) and evaluated under both irrigated and nonirrigated conditions. Data collected over three potato seasons following full rotation cycles demonstrated that all rotations reduced stem canker (10 to 50%) relative to PP. The SQ, SC, and DS systems reduced black scurf (18 to 58%) relative to PP; ST reduced scurf under nonirri2ated but not irrigated conditions; and scurf was lower in DS than all other systems. The SQ. SC, and DS systems also reduced common scab (15 to 45%), and scab was lower in DS than all other systems. Irrigation increased black scurf and common scab but also resulted in higher yields for most rotations. SI produced the highest yields under nonirrigated conditions, and DS produced high yields and low disease under both irrigation regimes. Each cropping system resulted in distinctive changes in soil microbial community characteristics as represented by microbial populations, substrate utilization, and fatty acid methyl-ester (FAME) profiles. SI tended to increase soil moisture, microbial populations, and activity, as well result in higher proportions of monounsaturated FAMEs and the FAME biomarker for mycorrhizae (16:1 omega 6c) relative to most other rotations. DS resulted in moderate microbial populations and activity but higher substrate richness and diversity in substrate utilization profiles. DS also resulted in relatively higher proportions of FAME biomarkers for fungi (18:2 omega 6c), actinomycetes, and gram-positive bacteria than most other systems, whereas PP resulted in the lowest microbial populations and activity; substrate richness and diversity; proportions of monounsaturated and polyunsaturated FAME classes; and fungal, mycorrhizae, and actinomycete FAME biomarkers of all cropping systems. Overall, soil water, soil quality, and soilborne diseases were all important factors affecting productivity, and cropping systems addressing these constraints improved production. Cropping system approaches will need to balance these factors to achieve sustainable production and disease management.
  • Authors:
    • Moreno, F.
    • Muñoz-Romero, V.
    • López-Bellido, L.
    • López-Bellido, R. J.
    • Melero,S.
    • Murillo, J. M.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 2
  • Year: 2011
  • Summary: Studies of the impacts of the interactions of soil agricultural practices on soil quality could assist with assessment of better management to establish sustainable crop production system. The main objective was to determine the long-term effects of tillage system, crop rotation and N fertilisation on soil total N and organic C (SOC), labile fractions of organic matter (water soluble carbon, WSC, and active carbon, AC), nitrate content, and soil enzymatic activities (dehydrogenase (DHA), beta-glucosidase (Glu) and alkaline phosphatase (AP)) at four different soil depths (0-5, 5-10, 10-30 and 30-50 cm), in a Mediterranean dryland Vertisol in SW Spain. Tillage systems were conventional tillage (CT) and no tillage (NT). Crop rotations were wheat-sunflower (WS), wheat-chickpea (WC), wheat-faba bean (WFb), wheat-fallow (WF) and continuous wheat (WW). Nitrogen fertiliser rates were 0, 50 and 150 kg N ha(-1). The different crop rotation systems had a great influence in soil C and N fractions and enzymatic activities. In general, the SOC. total N. WSC, and beta-glucosidase contents were higher in the no tillage system than in conventional tillage system in the wheat-wheat and in the wheat-faba bean rotations at upper layer (0-5 cm), while the lowest ones were obtained in the wheat-fallow rotation in both tillage systems. Carbon and N fractions, calculated by volumetric soil, showed an increase with depth in both tillage systems and in all crop rotations, which could be related to the increase of soil bulk density and soil mass with depth. The highest N fertiliser rate increased most of soil variables, especially nitrate content at deeper layers, thereby precautions should be taken with long-term N fertilisation to avoid leaching of nitrates below the tillage layer. With the exception of wheat-fallow rotation, slightly greater grain and above-ground biomass yields were obtained for wheat in NT, especially at 150 kg N ha(-1). Combination of NT with any biannual rotation except fallow could be an adequate sustainable management in order to improve soil quality of Vertisols, under our conditions. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Nichols, K. A.
    • Toro, M.
  • Source: Soil & Tillage Research
  • Volume: 111
  • Issue: 2
  • Year: 2011
  • Summary: Soil aggregate stability is a frequently used indicator of soil quality, but there is no standard methodology for assessing this indicator. Current methods generally measure only a portion of the soil or use either dry-sieved or wet-sieved aggregates. Our objective was to develop a whole soil stability index (WSSI) by combining data from dry aggregate size distribution and water-stable aggregation along with a 'quality' constant for each aggregate size class. The quality constant was based on the impact of aggregate size on soil quality indicators. Soil quality indicators can be loosely defined as those soil properties and processes that have the greatest sensitivity to changes in soil function. The WSSI was hypothesized to have a better relationship to the impacts of aboveground management than other soil aggregation indices such as a mean weight diameter (MWD), geometric mean diameter (GIVID), and the normalized stability index (NSI). Soil samples used in this study were collected from sites established on the same or similar soil types at the Northern Great Plains Research Laboratory in Mandan, ND. By utilizing dry aggregate size distribution, water-stable aggregation, and the quality constant, the WSSI detected differences in soil quality due to management (such as amount of disturbance, plant cover, and crop rotation) with the highest values occurring for the undisturbed, native range and the lowest values for conventional tillage, fallow treatments. The WSSI had the best relationship with management and is recommended as a standard measurement for soil aggregation. Published by Elsevier B.V.
  • Authors:
    • Strickland, T. C.
    • Bosch, D. D.
    • Webster, T. M.
    • Truman, C. C.
    • Potter, T. L.
  • Source: Journal of Agricultural and Food Chemistry
  • Volume: 59
  • Issue: 14
  • Year: 2011
  • Summary: Intensive glyphosate use has contributed to the evolution and occurrence of glyphosate-resistant weeds that threaten production of many crops. Sustained use of this highly valued herbicide requires rotation and/or substitution of herbicides with different modes of action. Cotton growers have shown considerable interest in the protoporphyrinogen oxidase inhibitor, fomesafen. Following registration for cotton in 2008, use has increased rapidly. Environmental fate data in major use areas are needed to appropriately evaluate risks. Field-based rainfall simulation was used to evaluate fomesafen runoff potential with and without irrigation incorporation in a conventional tillage system (CT) and when conservation tillage (CsT) was practiced with and without cover crop residue rolling. Without irrigation incorporation, relatively high runoff, about 5% of applied, was measured from the CT system, indicating that this compound may present a runoff risk. Runoff was reduced by >50% when the herbicide was irrigation incorporated after application or when used with a CsT system. Data indicate that these practices should be implemented whenever possible to reduce fomesafen runoff risk. Results also raised concerns about leaching and potential groundwater contamination and crop injury due to rapid washoff from cover crop residues in CsT systems. Further work is needed to address these concerns.
  • Authors:
    • Nichols, R. L.
    • Kelton, J. A.
    • Culpepper, S. A.
    • Balkcom, K. S.
    • Price, A. J.
    • Schomberg, H.
  • Source: Journal of Soil and Water Conservation
  • Volume: 66
  • Issue: 4
  • Year: 2011
  • Summary: Conservation tillage reduces the physical movement of soil to the minimum required for crop establishment and production. When consistently practiced as a soil and crop management system, it greatly reduces soil erosion and is recognized for the potential to improve soil quality and water conservation and plant available water. Adoption of conservation tillage increased dramatically with the advent of transgenic, glyphosate-resistant crops that permitted in-season, over-the-top use of glyphosate (N-[phosphonomethyl] glycine), a broad-spectrum herbicide with very low mammalian toxicity and minimal potential for off-site movement in soil or water. Glyphosate-resistant crops are currently grown on approximately 70 million ha (173 million ac) worldwide. The United States has the most hectares (45 million ha [99 million ac]) of transgenic, glyphosate-resistant cultivars and the greatest number of hectares (46 million ha [114 million ac]) in conservation tillage. The practice of conservation tillage is now threatened by the emergence and rapid spread of glyphosate-resistant Palmer amaranth (Amaranthus palmeri [S.]Wats.), one of several amaranths commonly called pigweeds. First identified in Georgia, it now has been reported in Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee. Another closely related dioecious amaranth, or pigweed, common waterhemp (Amaranthus rudis Sauer), has also developed resistance to glyphosate in Illinois, Iowa, Minnesota, and. Missouri. Hundreds of thousands of conservation tillage hectares, some currently under USDA Natural Resources Conservation Service conservation program contracts, are at risk of being converted to higher-intensity tillage systems due to the inability to control these glyphosate-resistant Amaranthus species in conservation tillage systems using traditional technologies. The decline of conservation tillage is inevitable without the development and rapid adoption of integrated, effective weed control strategies. Traditional and alternative weed control strategies, such as the utilization of crop and herbicide rotation and integration of high residue cereal cover crops, are necessary in order to sustain conservation tillage practices.
  • Authors:
    • Armengot, L.
    • Berner, A.
    • Sans, F. X.
    • Maeder, P.
  • Source: Weed Research
  • Volume: 51
  • Issue: 4
  • Year: 2011
  • Summary: Conservation tillage could provide environmental benefits to organic farming. However, potential weed problems often tend to discourage farmers from adopting it. The effects of tillage (reduced vs. conventional), fertilisation (slurry vs. manure compost) and the application of biodynamic preparations (with and without) on crop yield and on weed cover, diversity and biological attributes were investigated in a cropping sequence of wheat, sunflower and spelt. Total weed cover and perennial cover in reduced tillage treatments were two to three times greater than in conventional treatments. Monocotyledon cover in reduced tillage was three times that in conventional tillage in spelt, whereas the dicotyledon Stellaria media dominated in sunflower. Weed diversity was similar across treatments, regardless of cereal crop, whereas lower diversity values were observed with reduced tillage in sunflower, because of the dominance of S. media. There was virtually no effect of fertilisation and biodynamic preparations on weed parameters. Although wheat and spelt yield decreased in reduced tillage plots (14% and 8% respectively), the sunflower grain yield was unaffected. Reduced tillage could thus be useful in organic cropping systems but would require proper management of perennial and monocotyledonous weeds, which are often problematic for annual crops.
  • Authors:
    • Smith, J. P.
    • Smith, M. K.
    • Stirling, G. R.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 2
  • Year: 2011
  • Summary: Ginger (Zingiber officinale) production is facing increasing disease and pest pressure and declining yield with continuing intensive cultivation practices. A four year experiment was established in south-eastern Queensland on a red ferrosol that had a long (>60 years) history of ginger farming. Minimal tillage and organic amendments were compared with conventional practice that involved frequent tillage and soil fumigation using 1,3-dichloropropene (Telone (R)). Ginger crops were grown in the second and fourth year of the experiment, following an annual rotation with different cover crops including oats (Avena sativa), Brassica spp., soybean (Glycine max) and forage sorghum (Sorghum bicolour X S. sudanese). A pasture ley of Pangola grass (Digitaria eriantha subsp. pentzii) provided a treatment continuum from major to minor disruption in the soil's physical fertility and biological communities, and was therefore only planted to ginger in the fourth year of the experiment. Ginger seed-pieces (sections of the rhizome used for planting) were planted into both tilled and untilled beds using a double disc opener on a specially designed ginger planter. Rhizome yield in the final year was greatest (74.2 t/ha) and losses to pathogens (Pythium myriotylum and Fusarium oxysporum f. sp. zingiberi) minimal (7.0%) in the pasture ley that had been cultivated prior to planting ginger. Furthermore, the minimum-tilled cover cropped treatment, which likewise had been cultivated prior to planting ginger, yielded well (62.0 t/ha), with few losses (5.0%) from rhizome rots. Conversely the fumigated treatment had the highest losses (35.9%) due to Pythium Soft Rot and lowest yields (20.2 t/ha). Minimum-tilled plantings of ginger, however, resulted in poor yields (30.9-43.1 t/ha) but had acceptable levels of disease. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Hyde, J.
    • Mortensen, D. A.
    • Barbercheck, M. E.
    • Smith, R. G.
    • Hulting, A. G.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 1
  • Year: 2011
  • Summary: In the mid-Atlantic region, the demand for organic dairy has provided incentives for farmers to transition their land to organic feed grain production. At the same time, interest in minimum-tillage organic production is growing. Two field experiments were conducted to assess the effects of a first year cover crop and tillage system on weed populations, cash crop yield, and net returns over the 3-yr transition period in a cover crop-soybean (Glycine max (L.) Merr.)-corn (Zea mays L.) feed grain rotation. The cover crop treatments were rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth) (hereaft er RYE) and timothy (Phleum pratense L.)-red clover (Trifolium pratense L.) (hereaft er TIM). Tillage system treatments were moldboard plow (full tillage, FT) and chisel plow (minimum tillage, MT). Across both experiments, soybean yields ranged from 1190 to 3721 kg ha(-1). Corn grain yields were affected by tillage in the first experiment only, and were 59% higher in FT (9370 kg ha(-1)) compared to MT (5906 kg ha(-1)). Weed abundance was primarily affected by tillage, with densities in corn being 244% higher in MT compared to FT. Cumulative net returns in the first experiment were profit-generating in systems where TIM was the initial cover crop (mean = U.S. $ 317 ha(-1)). Mean cumulative net returns were positive in three of the four treatment combinations in the second experiment (U.S. $ 74-299 ha(-1)). Improved strategies for minimizing the costs associated with fertilization and management of weeds in minimal tillage will be necessary to improve the profitability and sustainability of reduced-tillage organic systems.
  • Authors:
    • Schultz, R. C.
    • Zaimes, G. N.
  • Source: Ecological Engineering
  • Volume: 37
  • Issue: 11
  • Year: 2011
  • Summary: Extensive land-use changes in Iowa have increased erosional processes and the amount of fines deposited on stream beds. Large amounts of fines cover the other bed substrate that are essential habitat for invertebrates and fish. In Iowa and other agricultural Midwestern states, riparian conservation land-uses are being established to minimize sediment inputs to streams. This study compared stream bed substrate composition in reaches adjacent to: riparian forest buffers, grass filters, row-cropped fields, pastures with cattle fenced out of the stream and continuous, rotational and intensively grazed rotational pastures, in three regions of Iowa. The objective was to examine the impacts of the adjacent riparian land-uses on stream bed substrate composition. The percentages of fines in this study ranged from: 36 to 63% in the central region; 10 to 31% in the northeast region; and 22 to 85% in the southeast region. The high percentage of fines in most stream bed reaches indicates high embeddedness. The high embeddedness resulted in the few significant differences in substrate percentages among riparian land-uses. Decades of agricultural land-uses have heavily impacted stream beds and only significant reductions in surface and bank erosion at the watershed scale can begin to reverse this trend. There were indications that riparian forest buffers and to a lesser degree, pastures with cattle fenced out of the stream, could decrease fines resulting in a more diverse substrate composition. Overall, more targeted approaches for the establishment of conservation land-uses in combination with other restoration practices (e.g. in-stream enhancements) are required to successfully decrease fines on stream beds. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Gomez-Macpherson, H.
    • Mateos, L.
    • Boulal, H.
  • Source: Irrigation Science
  • Volume: 29
  • Issue: 5
  • Year: 2011
  • Summary: Zero tillage and controlled traffic have been proposed as means for more productive and sustainable irrigated farming. Both practices affect soil infiltration characteristics and, therefore, should have effects on sprinkler irrigation performance. This study compared water infiltration and runoff in three sprinkler irrigation tests performed on an alluvial loam soil at different times during a maize (Zea mays L.)-cotton (Gossypium hirstium L.) rotation under two soil managements: permanent beds with crop residue retention (PB: planting beds maintained unaltered from year to year) and conventional beds with residues incorporated with tillage (CB: disc and chisel ploughing followed by rotavator pass and bed forming every year). Traffic was controlled and two types of furrows were distinguished in both tillage systems: with (+T) and without (-T) wheel traffic. The irrigation tests were performed on maize at full cover, on bare soil just before cotton sowing and on cotton with 50% ground cover. Infiltration and runoff were affected notably by both traffic and soil management. The soil under PB infiltrated more water than under CB, and -T furrows more than +T furrows. Considering the combined treatments, -T furrows in the CB system infiltrated more water than +T furrows in the PB system. A sprinkler irrigation model for simulating water application and soil infiltration and runoff was formulated. The model was used to analyse irrigation performance under infiltration characteristic of the CB and PB systems in trafficked and non-trafficked furrows. Five irrigation performance indicators were used to assess the various combinations of tillage and traffic: Wilkox-Swailes coefficient of uniformity; application efficiency; deep percolation ratio; tail water ratio; and adequacy. The model was used to develop operation diagrams and provided guidelines for making irrigation decisions in the new controlled traffic/permanent bed system and in a standard conventional system.