• Authors:
    • Holm, F. A.
    • Sapsford, K. L.
    • Cathcart, J.
    • Hall, L. M.
    • Clayton, G. W.
    • Harker, K. N.
    • O'Donovan, J. T.
    • Hacault, K.
  • Source: Weed Science
  • Volume: 55
  • Issue: 1
  • Year: 2007
  • Summary: There is no published information on the impact of volunteer barley on wheat yield loss or on the economics of controlling barley with a herbicide. With the registration of imazamox-resistant wheat, it is now possible to control volunteer barley in wheat. Thus, the likelihood of growing wheat in rotation with barley may increase. Field experiments were conducted in 2003 and 2004 at Beaverlodge, Lacombe, and Edmonton, AB, Canada, and Saskatoon, SK, Canada, to determine the impact of volunteer barley on yield of imazamox-resistant spring wheat seeded at relatively low (100 kg ha(-1)) and high (175 kg ha(-1)) rates. Barley was seeded at different densities to simulate volunteer barley infestations. Regression analysis indicated that wheat-plant density influenced the effects of volunteer barley interference on wheat yield loss, economic threshold values, and volunteer barley fecundity among locations and years. Econornic thresholds varied from as few volunteer barley plants as 3 m(-2) at Beaverlodge in 2003 and 2004 to 48 m(-2) at Lacombe in 2003. In most cases, wheat yield loss and volunteer barley fecundity were lower and economic thresholds were higher when wheat was seeded at the higher rate. For example, averaged over both years at Beaverlodge initial slope values (percentage of wheat yield loss at low barley density) were 4.5 and 1.7%, and economic threshold values of volunteer barley plants were 3 m(-2) and 8 m(-2) at low and high wheat seeding rates, respectively. Results indicate that volunteer barley can be highly competitive in wheat, but yield losses and wheat seed contamination due to volunteer barley can be alleviated by seeding wheat at a relatively high rate.
  • Authors:
    • Labreuche, J.
    • Thiébeau, P.
    • Mary, B.
    • Laurent, F.
    • Oorts, K.
    • Nicolardot, B.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Soil N mineralization was quantified in two long-term experiments in northern France, in which no-till (NT) and conventional tillage (CT) had been differentiated for 33 years (Site 1) and 12 years (Site 2). Both sites had the same soil type but differed in crop rotation. N mineralization kinetics were assessed in situ in bare soil in both systems for 254 days (Site 1) and 555 days (Site 2) by taking frequent measurements of water and nitrate contents from soil layers and using the LIXIM calculation model. The N mineralization potential was also determined in soil samples incubated under controlled laboratory conditions. Small or non-significant differences in water and nitrate contents between NT and CT were apparent within the soil profiles on both sites. Net mineralization did not differ significantly between sites or tillage treatments. The amount of N mineralized from August 2003 to April 2004 was 6710 kg N ha -1 on Site 1 and 745 kg N ha -1 on Site 2, and 1616 kg N ha -1 from August 2003 to February 2005 on Site 2. The kinetics of N mineralization versus normalized time (equivalent time at constant temperature of 15degreesC and water content at field capacity) were linear during the shorter period (254 days corresponding to 120 normalized days). The slope (N mineralization rate) did not differ significantly between treatments and sites, and the average rate was 0.570.05 kg N ha -1 nd -1. The kinetics were non-linear on Site 2 over the longer period (555 days corresponding to 350 normalized days). They could be fitted to an exponential model with a slope at the origin of 0.62 kg N ha -1 nd -1. The N mineralization kinetics obtained in laboratory incubations for 120-150 normalized days were also almost linear with no significant differences between treatments. Assuming that mineralization took place in the ploughed layer (in CT) or over the same soil mass (in NT) they were in good agreement with the kinetics determined in situ on both sites. The calculated water drainage below the sampled profile was slightly greater in NT due to lower evaporation. The calculated leached N was slightly higher in NT than CT on Site 1, but did not differ between treatments on Site 2. It is concluded that N mineralization and leaching in NT and CT were similar, despite large differences in N distribution within the soil profile and a slight difference in organic N stock.
  • Authors:
    • Labreuche, J.
    • Gréhan, E.
    • Merckx, R.
    • Oorts, K.
    • Nicolardot, B.
  • Source: Soil & Tillage Research
  • Volume: 95
  • Issue: 1/2
  • Year: 2007
  • Summary: The greenhouse gases CO 2 and N 2O emissions were quantified in a long-term experiment in northern France, in which no-till (NT) and conventional tillage (CT) had been differentiated during 32 years in plots under a maize-wheat rotation. Continuous CO 2 and periodical N 2O soil emission measurements were performed during two periods: under maize cultivation (April 2003-July 2003) and during the fallow period after wheat harvest (August 2003-March 2004). In order to document the dynamics and importance of these emissions, soil organic C and mineral N, residue decomposition, soil potential for CO 2 emission and climatic data were measured. CO 2 emissions were significantly larger in NT on 53% and in CT on 6% of the days. From April to July 2003 and from November 2003 to March 2004, the cumulated CO 2 emissions did not differ significantly between CT and NT. However, the cumulated CO 2 emissions from August to November 2003 were considerably larger for NT than for CT. Over the entire 331 days of measurement, CT and NT emitted 3160269 and 4064138 kg CO 2-C ha -1, respectively. The differences in CO 2 emissions in the two tillage systems resulted from the soil climatic conditions and the amounts and location of crop residues and SOM. A large proportion of the CO 2 emissions in NT over the entire measurement period was probably due to the decomposition of old weathered residues. NT tended to emit more N 2O than CT over the entire measurement period. However differences were statistically significant in only half of the cases due to important variability. N 2O emissions were generally less than 5 g N ha -1 day -1, except for a few dates where emission increased up to 21 g N ha -1 day -1. These N 2O fluxes represented 0.800.15 and 1.320.52 kg N 2O-N ha -1 year -1 for CT and NT, respectively. Depending on the periods, a large part of the N 2O emissions occurred was probably induced by nitrification, since soil conditions were not favorable for denitrification. Finally, for the period of measurement after 32 years of tillage treatments, the NT system emitted more greenhouses gases (CO 2 and N 2O) to the atmosphere on an annual basis than the CT system.
  • Authors:
    • Osborne, S. L.
    • Riedell, W. E.
    • Pikul, J. L. Jr.
  • Source: Recent Research Developments in Soil Science
  • Volume: 2
  • Year: 2007
  • Summary: Maize (Zea mays L.) grown in rotation with high residue crops generally has lower grain yield under no-till than under tilled soil management in the northern US maize belt. Hence, the research objectives were to further characterize soil physical properties, maize grain yield, and seed composition under tilled and no-till soil management following soybean ( Glycine max L.) or winter wheat ( Triticum aestivum L). The two year field study was conducted on a Barnes sandy clay loam soil (fine-loamy, mixed, superactive, frigid Calcic Hapludoll) in eastern South Dakota USA. Research plots were managed under no-till starting in 1996. Tillage treatments (fall chisel plow prior to winter wheat, fall chisel plow plus spring disk-harrow prior to maize and soybean, or no-till) were started in 2001. Tillage and previous crop treatments were arranged in a completely randomized block design with 4 replications. Soil temperatures (30 cm depth) in tilled plots after winter wheat were warmer than no-till plots in June and again in August of the 2004 growing season. In 2003, soil temperatures were very similar across tillage treatments. Soil bulk density (0 to 10 cm depth) and soil penetration resistance (0 to 7 cm depth) were much greater under no-till soil management than under tilled conditions when measured in mid-June (V6 leaf development stage). While tillage treatment affected maize seed oil concentration (4.0% in tilled, 4.3% in no-till), there were no significant previous crop or interaction effects on seed oil or protein concentration. In the warmer and drier year (2003), maize grain yield under tilled conditions was 8.2 Mg ha -1 compared with 8.7 Mg ha -1 under no-till. In the cooler and wetter year (2004), yields were 9.4 Mg ha -1 under tilled soil management and 7.4 Mg ha -1 under no-till. The no-till soil management treatment following winter wheat had 27% lower maize grain yield than the tilled treatments and the no-till following soybeans. We conclude that greater bulk density and penetration resistance levels under no-till soil management, along with cool soil conditions that typically occur in the spring in the northern US maize belt, reduced maize yield under no-till management in soils with moderately low to low internal drainage.
  • Authors:
    • Yang, C. H.
    • Han, S. M.
    • Zhu, R. X.
    • Xue, S. P.
    • Yang, Q.
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 23
  • Issue: 1
  • Year: 2007
  • Summary: The objective of this study was to determine conservation tillage techniques suitable for semiarid regions in North China. Ten different mechanized patterns of no-till or reduced-tillage for two crops (winter wheat and summer maize) within one year were set up at the Experiment and Demonstration Site for Mechanized New Techniques and Machinery at Yangling, Shaanxi Province, China, and these conservation tillage patterns were compared with conventional tillage. Results showed that wheat yield increased by 53% and summer maize yield increased by 25%, average soil water storage increased from 1% to 1.2% at different depths, and average organic matter increased by 1.03 g/kg relatively for the conservation tillage system with wheat residue cover and no-till seeding of maize immediately after wheat harvest, compared with conventional bare soil ploughing. Moreover, the efficiency of yield increase and water storage for deep soil loosening was higher than that for deep ploughing. No-till seeding of maize on high stubble mulching was better than seeding on low stubble. Finally, cost-benefit analysis results showed that conservation tillage resulted in great economic returns than convention tillage due to greater yields and lower production costs resulting from reduced tillage.
  • Authors:
    • Zhang, X. M.
    • Wang, X. Y.
    • Gao, H. W.
    • Li, H. W.
    • Yao, Z, L.
  • Source: Transactions of the Chinese Society for Agricultural Machinery = Nongye Jixie Xuebao
  • Volume: 38
  • Issue: 8
  • Year: 2007
  • Summary: A new no-till wheat planter, named 2BMDF-12 no-till wheat planter, was developed at the China Agricultural University to solve an extremely important problem, including zero-tillage planting of wheat in narrow row spacing (150-200 mm) between rows of very high-levels full length, standing maize stubble in one pass in double cropping area of North China. A combined anti-blocking device that is composed of a power chopping axle and a planting unit of double-disc opener was designed. Field performance test results showed that the machine could accomplish many procedures, such as stubble chopping, furrow opening, seeds and fertilizer placement, etc, in one pass, and operation costs could be decreased by ~50%. The machine worked well for planting wheat into standing maize stubble and maize stubble shattered. The power chopping axle resolved the anti-blockage problem, and the double-disc opener unit reduced the blockage between planting units. Meanwhile, the variations for seed depth reduced to 19.8 and 21.3%. Thus, this machine can be a good solution to no-till wheat planting in double cropping areas.
  • Authors:
    • Schomberg, H. H.
    • Franzluebbers, A. J.
    • Endale, D. M.
  • Source: Soil & Tillage Research
  • Volume: 96
  • Issue: 1/2
  • Year: 2007
  • Summary: The type of conservation-tillage management employed could impact surface-soil properties, which could subsequently affect relationships between soil and water quality, as well as with soil C sequestration and greenhouse gas emissions. We determined soil bulk density, organic C and N fractions, plant-available N, and extractable P on Typic Kanhapludults throughout a 7-year period, in which four long-term (>10 years), no-tillage (NT) water catchments (1.3-2.7 ha each) were divided into two treatments: (1) continuation of NT and (2) paraplowing (PP) in autumn (a form of non-inversion deep ripping) with NT planting. Both summer [cotton ( Gossypium hirsutum L.), maize ( Zea mays L.), sorghum ( Sorghum bicolor L. Moench), soybean ( Glycine max L. Merr.)] and winter [wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.), rye ( Secale cereale L.), crimson clover ( Trifolium incarnatum L.)] crops were NT planted throughout the study under each management system. Soil bulk density was reduced with PP compared with NT by as much as 0.15 Mg m -3, but the extent of reduction was inversely related to the time lag between PP operation and sampling event. Soil organic C became significantly enriched with time during this study under NT (0.49 Mg C ha -1 year -1), but not under PP, in which poultry litter was applied equivalent to 5.7 Mg ha -1 year -1 to all water catchments. Soil maintained a highly stratified depth distribution of organic C and N fractions and extractable P under both NT and PP. Inability to perform the PP operation in the last year of this study resulted in rapid convergence of soil bulk density between tillage systems, suggesting that PP had
  • Authors:
    • Liebig, M. A.
    • Merrill, S. D.
    • Krupinsky, J. M.
    • Tanaka, D. L.
    • Hanson, J. D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Producers need to know how to sequence crops to develop sustainable dynamic cropping systems that take advantage of inherent internal resources, such as crop synergism, nutrient cycling, and soil water, and capitalize on external resources, such as weather, markets, and government programs. The objective of our research was to determine influences of previous crop and crop residues (crop sequence) on relative seed and residue yield and precipitation-use efficiency (PUE) for the no-till production of buckwheat ( Fagopyrum esculentum Moench), canola ( Brassica napus L.), chickpea ( Cicer arietinum L.), corn ( Zea mays L.), dry pea ( Pisum sativum L.), grain sorghum ( Sorghum bicolor L.), lentil ( Lens culinaris Medik.), proso millet ( Panicum miliaceum L.), sunflower ( Helianthus annus L.), and spring wheat ( Triticum aestivum L.) grown in the northern Great Plains. Relative seed yield in 2003 for eight of the 10 crops resulted in synergistic effects when the previous crop was dry pea or lentil, compared with each crop grown on its own residue. Buckwheat, corn, and sunflower residues were antagonistic to chickpea relative seed yield. In 2004, highest relative seed yield for eight of the 10 crops occurred when dry pea was the previous crop. Relative residue yield followed a pattern similar to relative seed yield. The PUE overall means fluctuated for seven of the 10 crops both years, but those of dry pea, sunflower, and spring wheat remained somewhat constant, suggesting these crops may have mechanisms for consistent PUE and were not as dependent on growing season precipitation distribution as the other seven crops. Sustainable cropping systems in the northern Great Plains will approach an optimal scheme of crop sequencing by taking advantage of synergisms and avoiding antagonisms that occur among crops and previous crop residues.
  • Authors:
    • Anderson, R. L.
  • Source: Weed Technology
  • Volume: 21
  • Issue: 2
  • Year: 2007
  • Summary: Weed management is evolving to include cultural tactics that reduce weed populations. This study near Brookings, SD, evaluated the effect of crop sequence and tillage on seedling emergence of common sunflower across years. In the third and fourth years of the study, seedling density was sevenfold greater after 2 yr of soyabean with tillage compared with a 2-yr sequence of canola and winter wheat with no-till. Apparently, canola and winter wheat enhanced the natural decline of common sunflower seed density in soil, leading to fewer seedlings in following years. In the first year of the study, tillage increased seedling emergence of common sunflower compared with no-till; seedlings rarely emerged in canola or winter wheat. Most seedlings of common sunflower emerged in May, with more than 90% of seedlings emerging between May 7 and June 4. Cool-season crops grown with no-till may affect weed seed survival in soil in the western Corn Belt.
  • Authors:
    • Anderson, R. L.
    • Beck, D. L.
  • Source: Weed Technology
  • Volume: 21
  • Issue: 1
  • Year: 2007
  • Summary: Producers in the Great Plains are exploring alternative crop rotations with the goal of reducing the use of fallow. In 1990, a study was established with no-till practices to compare 8 rotations comprising various combinations of winter wheat (W), spring wheat (SW), maize (C), chickpea (CP), dry pea (Pea), soyabean (SB), or fallow (F). After 12 years, we characterized weed communities by recording seedling emergence in each rotation. Downy brome ( Bromus tectorum), cheat ( Bromus secalinus), redroot pigweed ( Amaranthus retroflexus), and green foxtail ( Setaria viridis) were the most common weeds observed. Weed community density was highest for W-CP, being 13-fold greater than with Pea-W-C-SB. Downy brome and cheat were rarely observed in rotations where winter wheat was grown only once every 3 or 4 years; in contrast, density of the brome species was 75-fold greater in W-CP. Warm-season weeds were also affected by rotation design; density of redroot pigweed and green foxtail was 6-fold greater in W-C-CP compared with Pea-W-C-SB or W-F. One rotation design that was especially favourable for low weed density was arranging crops in a cycle of 4, with 2 cool-season crops followed by 2 warm-season crops.