• Authors:
    • Rhinhart, K.
    • Kling, J.
    • Hayes, P.
    • Corey, A.
    • Budde, A.
    • Petrie, S.
    • Castro, A.
  • Source: Crop Management
  • Issue: November
  • Year: 2008
  • Summary: Winter malting barley ( Hordeum vulgare L.) is a potential alternative crop for the dryland region of the Pacific Northwest. Nitrogen fertilization can increase grain yield but may also increase lodging and grain protein and reduce test weight. The objectives of this research were to determine the effect of N application rate and timing on grain yield and quality of winter feed and malting barley varieties. Field trials were conducted at Pendleton, OR (17 inches annual precipitation) and Moro, OR (12 inches annual precipitation). Nitrogen was applied at 0, 50, 100, or 150 lb N per acre in the fall and at 0 or 50 lb N per acre in the spring at Pendleton and at 0, 30, 60, or 90 lb N per acre in the fall and at 0 or 30 lb N per acre in the spring at Moro. Nitrogen fertilization increased grain yields at Pendleton to a maximum of 5,800 lb/acre in 2001 and 5,200 lb/acre in 2002 and at Moro to a maximum of 3,000 lb/acre. Nitrogen fertilization increased grain protein and reduced test weights. Yields of the advanced lines of malting barley were about 90% of the yields of feed type barley varieties. Spring N applications did not increase grain yield or protein more than fall N applications.
  • Authors:
    • Chamorro, L.
    • Romero, A.
    • Xavier Sans, F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 124
  • Issue: 1/2
  • Year: 2008
  • Summary: A comparative survey of weed vegetation in organic and conventional dryland winter cereal fields was performed in central Catalonia (NE Spain) in order to assess the effects of agricultural intensification on the diversity, structure and composition of weed communities. A total of 36 cereal fields were surveyed in nine agricultural sites, where a pair of one long-established organic and one conventional farms were selected. Weed surveys were carried out before harvest in 2003 and 2004, taking into account the spatial pattern. Organic practices produced an increase in weed cover, species richness and Hill's first order diversity (but not in equitability), as well as a shift in weed vegetation composition, which favoured potentially rare arable, broad-leaved, insect-pollinated and legume weeds. Weed diversity was concentrated in the crop edges, especially in the weed communities of conventional cereal fields, which were found to be more spatially heterogeneous than the organic ones.
  • Authors:
    • Stevens, W.
    • Jabro, J.
    • Sainju, U.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 1
  • Year: 2008
  • Summary: Management practices can influence soil CO 2 emission and C content in cropland, which can effect global warming. We examined the effects of combinations of irrigation, tillage, cropping systems, and N fertilization on soil CO 2 flux, temperature, water, and C content at the 0- to 20-cm depth from May to November 2005 at two sites in the northern Great Plains. Treatments were two irrigation systems (irrigated vs. non-irrigated) and six management practices that contained tilled and no-tilled malt barley ( Hordeum vulgaris L.) with 0 to 134 kg N ha -1, no-tilled pea ( Pisum sativum L.), and a conservation reserve program (CRP) planting applied in Lihen sandy loam (sandy, mixed, frigid, Entic Haplustolls) in western North Dakota. In eastern Montana, treatments were no-tilled malt barley with 78 kg N ha -1, no-tilled rye ( Secale cereale L.), no-tilled Austrian winter pea, no-tilled fallow, and tilled fallow applied in dryland Williams loam (fine-loamy, mixed Typic Argiborolls). Irrigation increased CO 2 flux by 13% compared with non-irrigation by increasing soil water content in North Dakota. Tillage increased CO 2 flux by 62 to 118% compared with no-tillage at both places. The flux was 1.5- to 2.5-fold greater with tilled than with non-tilled treatments following heavy rain or irrigation in North Dakota and 1.5- to 2.0-fold greater with crops than with fallow following substantial rain in Montana. Nitrogen fertilization increased CO 2 flux by 14% compared with no N fertilization in North Dakota and cropping increased the flux by 79% compared with fallow in no-till and 0 kg N ha -1 in Montana. The CO 2 flux in undisturbed CRP was similar to that in no-tilled crops. Although soil C content was not altered, management practices influenced CO 2 flux within a short period due to changes in soil temperature, water, and nutrient contents. Regardless of irrigation, CO 2 flux can be reduced from croplands to a level similar to that in CRP planting using no-tilled crops with or without N fertilization compared with other management practices.
  • Authors:
    • Easley, S.
    • Sheedy, J.
    • Smiley, R.
  • Source: Plant Disease
  • Volume: 92
  • Issue: 12
  • Year: 2008
  • Summary: Dryland field crops in the Pacific Northwest United States are commonly produced in silt loams infested by the root-lesion nematodes Pratylenchus neglectus and P. thornei. Soils at 30 sites in Oregon were sampled from 0 to 120 cm depth to examine the vertical distribution of these Pratylenchus spp. Both species were distributed through entire soil profiles of all cropping systems. Populations were generally greatest in the surface 30 cm, but sometimes high populations were detected at depths greater than 45 cm. Sampling to 30 cm depth allowed detection of more than 50% of the population in most sites, while sampling to 45 cm depth yielded more than 75% of the population in over 75% of the sites evaluated. Therefore, soil samples should be collected to 30 to 45 cm depth to accurately estimate populations of Pratylenchus spp. in dryland crops produced on silt loams in the Pacific Northwest. Populations of Pratylenchus spp. were found to be related to the most recently planted crop, with populations after barley, after wheat, and during summer fallow being detected in ascending order.
  • Authors:
    • Blackshaw, R. E.
    • Johnson, E. N.
    • Beckie, H. J.
    • Gan, Y.
  • Source: Canadian Journal of Plant Science
  • Volume: 88
  • Issue: 2
  • Year: 2008
  • Summary: Competitive crops or cultivars can be an important component of integrated weed management systems. A study was conducted from 2003 to 2006 at four sites across semiarid prairie ecoregions in Saskatchewan and Alberta to investigate the productivity and quality of canola (Brassica napus L.) and mustard cultivars under weed competition. Four open-pollinated canola cultivars, four hybrid canola cultivars, two canola-quality mustard and two oriental mustard cultivars [Brassica juncea (L.) Czern. & Coss.], and two yellow mustard (Sinapis alba L.) cultivars were grown under weedy and weed-free conditions. When combined across site-years, crop aboveground biomass at maturity and seed yield were reduced by weed interference, except for yellow and oriental mustard. However, seed oil and protein content of cultivars were not affected by weed competition. Among crop types, yellow and oriental mustard were best able to maintain biomass and seed yield under weed interference, followed in decreasing order of competitiveness by hybrid and open-pollinated canola, then canola-quality mustard.
  • Authors:
    • Brenzil, C. A.
    • Hall, L. M.
    • Thomas, A. G.
    • Leeson,J. Y.
    • Beckie, H. J.
  • Source: Weed Technology
  • Volume: 22
  • Issue: 4
  • Year: 2008
  • Summary: Agricultural practices, other than herbicide use, can affect the rate of evolution of herbicide resistance in weeds. This study examined associations of farm management practices with the occurrence of herbicide (acetyl-CoA carboxylase or acetolactate synthase inhibitor)-resistant weeds, based upon a multi-year (2001 to 2003) random Survey of 370 fields/growers from the Canadian Prairies. Herbicide-resistant weeds Occurred in one-quarter of the surveyed fields. The primary herbicide-resistant weed species was wild oat, with lesser occurrence of green foxtail, kochia, common chickweed, spiny sowthistle, and redroot pigweed. The risk of weed resistance was greatest in fields with cereal-based rotations and least in fields with forage crops, fallow, or where three or more crop types were grown. Weed resistance risk also was greatest in conservation-tillage systems and particularly low soil disturbance no-tillage, possibly due to greater herbicide use or weed seed bank turnover. Large farms (> 400 ha) had a greater risk of weed resistance than smaller farms, although the reason for this association Was unclear. The results of this study identify cropping system diversity as the foundation of proactive weed resistance management.
  • Authors:
    • Buschiazzo, D. E.
    • Alvarez, R.
    • Bono, A.
    • Cantet, R. J. C.
  • Source: Soil Science Society of America Journal
  • Volume: 72
  • Issue: 4
  • Year: 2008
  • Summary: Tillage systems may affect soil C sequestration, with a potential impact on crop productivity or organic matter mineralization. We evaluated crop yield, C inputs to the soil, and in situ CO 2-C fluxes under no-till and conventional tillage (disc tillage) during the 3- to 6-year period from the installation of an experiment in an Entic Haplustoll of the Semiarid Pampean Region of Argentina to elucidate the mechanisms responsible for possible management-induced soil organic matter changes. Yield and biomass production were greater under no-till than disc tillage for all the crops included in the rotation (oat + hairy vetch ( Vicia villosa ssp. villosa), maize, wheat and oat). This result was attributed to the higher soil water content under no-till. Carbon inputs to the soil averaged 4 Mg C ha -1 year -1 under no-till and 3 Mg C ha -1 year -1 under disc tillage. Soil temperature was similar between tillage systems and CO 2-C emission was approximately 4 Mg C ha -1 year -1, with significant but small differences between treatments (~0.2 Mg C ha -1 year -1). Carbon balance of the soil was nearly equilibrated under no-till; meanwhile, greater C losses as CO 2 than inputs in crop residues were measured under conventional tillage. Organic C in the soil was 5.4 Mg ha -1 higher under no-till than the disc tillage treatment 6 years after initiation of the experiment. Results showed that in our semiarid environment, C sequestration occurred under no-till but not conventional tillage. The sequestration process was attributed to the effect of the tillage system on crop productivity rather than on the mineralization intensity of soil organic pools.
  • Authors:
    • Jat, M.
    • Sharma, S.
    • Balyan, J.
    • Sharma, R.
    • Jain, L.
  • Source: Current Agriculture
  • Volume: 31
  • Issue: 1/2
  • Year: 2007
  • Summary: A study was conducted at Dryland Farming Research Station, Arjia, Bhilwara during 1996 and 1997, to find out the tillage requirement for the maize, Seven tillage systems were evaluated for production of maize in kharif season. The tillage systems included were: A. Summer (T1 - Disc plough followed by cultivator, T2 - Cultivator followed by cultivator, T3 - Deshi plough followed by cultivator and T4 - Deshi plough followed by deshi plough), B. After pre monsoon (T5 - Disc plough followed by cultivator and T6 - Cultivator followed by cultivator) and C. At sowing (T7 - Cultivator followed by cultivator). The tillage system comprising of summer disc ploughing followed by cultivator was more beneficial as of this resulted in higher yield and net return supported by effective reduction in runoff, soil loss and increase water use efficiency for crops in the region. However, during good and low rainfall, for higher net return, there is a need of shift in tillage practices.
  • Authors:
    • Jia, H.
    • Ma, C.
    • Yang, Q.
    • Liu, Z.
    • Li, G.
    • Liu, H.
  • Source: Nongye Jixie Xuebao = Transactions of the Chinese Society for Agricultural Machinery
  • Volume: 38
  • Issue: 12
  • Year: 2007
  • Summary: The present status of dry farming in northern China was analyzed and a three-year rotation tillage method suitable for the ridged cultivation region of northeastern China and the techniques for efficient utilization of natural rainfall in the Loess Plateau region of northwestern China was put forward. The tests conducted in the northeast showed that stalk mulching increased the percentage of soil moisture content by 10% and the content of soil organic matter by 0.06 percentage point after three years, decreased the volume density of soil by 0.09 g/cm 3, chiseling increased the percentage of soil moisture content by 26.2%, and less tillage increased the percentage of soil moisture content by 3 percentage point. The tests conducted in the northwest showed that for winter wheat, the percentage of water storage increased by 18-5%; for spring corn, the percentage of soil moisture content increased by 30%. The stalk mulching tests for two years showed that the content of soil organic matter increased by 0.05%-0.1% and the content of total nitrogen increased by about 0.1 g/kg.
  • Authors:
    • Ahuja, L. R.
    • Green, T. R.
    • Ma, L. W.
    • Kozak, J. A.
  • Source: Hydrological Processes
  • Volume: 21
  • Issue: 2
  • Year: 2007
  • Summary: Crop canopies and residues have been shown to intercept a significant amount of rainfall. However, rainfall or irrigation interception by crops and residues has often been overlooked in hydrologic modelling. Crop canopy interception is controlled by canopy density and rainfall intensity and duration. Crop residue interception is a function of crop residue type, residue density and cover, and rainfall intensity and duration. We account for these controlling factors and present a model for both interception components based on Merriam's approach. The modified Merriam model and the current modelling approaches were examined and compared with two field studies and one laboratory study. The Merriam model is shown to agree well with measurements and was implemented within the Agricultural Research Service's Root Zone Water Quality Model (RZWQM). Using this enhanced version of RZWQM, three simulation studies were performed to examine the quantitative effects of rainfall interception by corn and wheat canopies and residues on soil hydrological components. Study I consisted of 10 separate hypothetical growing seasons (1991-2000) for canopy effects and 10 separate non-growing seasons (1991-2000) for residue effects for eastern Colorado conditions. For actual management practices in a no-till wheat-corn-fallow cropping sequence at Akron, Colorado (study II), a continuous 10-year RZWQM simulation was performed to examine the cumulative changes on water balance components and crop growth caused by canopy and residue rainfall interception. Finally, to examine a higher precipitation environment, a hypothetical, no-till wheat-corn-fallow rotation scenario at Corvallis, Oregon, was simulated (study III). For all studies, interception was shown to decrease infiltration, runoff, evapotranspiration from soil, deep seepage of water and chemical transport, macropore flow, leaf area index, and crop/grain yield. Because interception decreased both infiltration and soil evapotranspiration, no significant change in soil water storage was simulated. Nonetheless, these findings and the new interception models are significant new contributions for hydrologists.