• Authors:
    • Parton, W. J.
    • Mueller, T.
    • Molina, J. A. E.
    • Li, C.
    • Komarov, A. S.
    • Klein-Gunnewiek, H.
    • Kelly, R. H.
    • Jensen, L. S.
    • Jenkinson, D. S.
    • Frolking, S.
    • Franko, U.
    • Coleman, K.
    • Chertov, O. G.
    • Arah, J. R. M.
    • McGill, W. B.
    • Powlson, D. S.
    • Smith, J. U.
    • Smith, P.
    • Thornley, J. H. M.
    • Whitmore, A. P.
  • Source: Geoderma
  • Volume: 81
  • Issue: 1-2
  • Year: 1997
  • Summary: Nine soil organic models were evaluated using twelve datasets from seven long-term experiments. Datasets represented three different land-uses (grassland, arable cropping and woodland) and a range of climatic conditions within the temperate region. Different treatments (inorganic fertilizer, organic manures and different rotations) at the same site allowed the effects of differing land management to be explored. Model simulations were evaluated against the measured data and the performance of the models was compared both qualitatively and quantitatively. Not all models were able to simulate all datasets; only four attempted all. No one model performed better than all others across all datasets. The performance of each model in simulating each dataset is discussed. A comparison of the overall performance of models across all datasets reveals that the model errors of one group of models (RothC, CANDY, DNDC, CENTURY, DAISY and NCSOIL) did not differ significantly from each other. Another group (SOMM, ITE and Verberne) did not differ significantly from each other but showed significantly larger model errors than did models in the first group. Possible reasons for differences in model performance are discussed in detail.
  • Authors:
    • Bauer, P. J.
    • Hunt, P. G.
    • Matheny, T. A.
  • Source: Journal of Production Agriculture
  • Volume: 10
  • Issue: 3
  • Year: 1997
  • Summary: Cotton (Gossypium hirsutum L.) production has dramatically increased in the Southeast, but the role of conservation tillage in doublecropped cotton systems has not been clearly defined. Therefore, from 1988 to 1994, we investigated doublecropped wheat (Triticum aestivum L.) and cotton on plots that had been in continuous conservation vs. conventional tillage since 1979. The experimental site wits located near Florence, SC, on a Norfolk loamy sand (fine-loamy, siliceous, thermic Typic Kandiudult). Conventional tillage consisted of multiple diskings and cultivations; surface tillage was eliminated for conservation tillage. Wheat yields were not significantly affected by tillage, but cotton yields were significantly higher for conservation tillage (P less than or equal to 0.01). Cotton planting dates ranged from 7 to 18 June, and 5 of the 7 yr had more than 145 frost-free days. Two years had crop failure because of early freezes, and a June drought prevented the planting of cotton in 1 yr. In the 4 yr with harvestable yields, seed cotton yields among the eight cultivars ranged from about 500 to 2200 and 300 to 1850 lb/acre for conservation and conventional tillage, respectively. The early maturing cultivar, 'Deltapine (DP) 20,' had the highest seed cotton yields with means of 1442 and 1123 lb/acre for conservation and conventional tillage, respectively Development of earlier maturing cotton and wheat cultivars will be important for this cropping system in the northern Coastal Plain portion of the Cotton Belt.
  • Authors:
    • Madramootoo, C. A.
    • Mehuys, G. R.
    • Burgess, M. S.
  • Source: Agronomy Journal
  • Volume: 88
  • Issue: 5
  • Year: 1996
  • Summary: Reduced tillage is often recommended to decrease soil degradation and erosion associated with intensive row cropping. This study assessed the effects of different tillage and crop residue levels on corn (Zea mays L.) yields and related factors on a 2.4-ha site in southwestern Quebec over a 3-yr period. The soil, a Typic Endoaquent, consisted of sandy loam or loamy sand (mean depth, 46 cm) overlying clay, with subsurface drains at the 1.2-m depth. Treatments, begun in fall 1991, consisted of no-till (NT), reduced tillage (RT; dished in fall and spring), and conventional tillage (CT; moldboard-plowed in fall, dished in spring), in combination with two crop residue levels: no residue (-R; grain and stover removed at harvest, as for silage corn) and with residue (+R; stover left on site at harvest, as for grain corn). High crop-residue mulches resulted from NT+R (77-97% of soil surface covered), RT+R (45-92%), and at times NT-R (8-35%), potentially protecting the soil from erosive forces. Seedling emergence was delayed (1992, 1993) or partly suppressed (1994) in NT+R, and was also delayed in CT+R in 1992 and 1993, and in CT-R and RT+R in 1993. Final populations were affected only in 1993. In -R (silage) plots, yields with NT and RT were either greater (1992) or the same as their CT counterparts. On +R (grain) plots, grain, stover, and total yields were lower with NT in 1992 and 1994, due in part to difficulties in planting through the residue mulch, while RT reduced grain, stover, and total yields in 1992 and stover and total yields in 1993. Thus, for silage-corn production, NT and RT may offer economically viable alternatives to CT, although the use of dishing for a RT system provides almost no protective residue cover. In continuous grain corn, high residue buildup with NT and RT requires special attention to seeding technique or yield losses may result.
  • Authors:
    • McIntosh, M. S.
    • Mulford, F. R.
    • Meisinger, J. J.
    • Decker, A. M.
    • Clark, A. J.
  • Source: Agronomy Journal
  • Volume: 87
  • Issue: 3
  • Year: 1995
  • Summary: Hairy vetch (Vicia villosa Roth) can fix N-2 for subsequent release to a corn (Zea mays L.) crop, but kill date effects on vetch N accumulation, soil water, and subsequent corn production have not been studied. A hairy vetch cover crop can deplete soil water through transpiration, but cover crop mulches can conserve soil water for no-till corn. In order to determine optimum spring kill date and corn fertilizer N (FN) rates, hairy vetch was killed early April, late April, or mid-May, followed by three corn planting dates and four FN rates (0, 45, 135, and 202 kg N ha(-1)). From early April to mid-May, hairy vetch aerial phytomass and N content increased significantly, from 2800 to 4630 and 96 to 149 kg ha(-1), respectively. Corn grain yields ranged from 5.2 to 10.1 Mg ha(-1) and were significantly greater following mid or late kill, compared with early kill of vetch, regardless of corn planting date or FN rate. Gravimetric soil water under mid- or late-kill vetch was often significantly greater than after early-kill vetch. We conclude that soil water conservation by late-killed vetch mulches had a greater influence on corn production than vetch spring water use. Optimum N production and water conservation occurred when vetch was killed the last week of April. Early-kill vetch sacrificed N production and minimized soil water conservation, resulting in reduced corn grain yield. Late kill did not add significant N benefits, but could deplete soil water or interfere with timely corn planting.
  • Authors:
    • Fausey, N. R.
    • Mahboubi, A. A.
    • Lal, R.
  • Source: Soil Science Society of America Journal
  • Volume: 58
  • Issue: 2
  • Year: 1994
  • Summary: Sustainable use of soil resources can be assessed from management-induced changes in soil properties from long-term experiments. Such data are scanty, especially with regard to changes in soil physical properties. Therefore, soil physical and chemical analyses were performed 28 yr after initiating a crop rotation-tillage experiment on a well-drained Wooster silt loam soil (fine-loamy, mixed, mesic Typic Fragiudalf) at Wooster, OH. All combinations of three rotations (continuous corn [CC; Zea mays L.]; corn and soybean [Glycine mar (L.) Merr.] in a 2-yr rotation [CS]; and corn, oat [Avena sativa L.], and meadow in a 3-yr rotation [COM]) and of three tillage treatments (no-tillage [NT]; chisel plow [CP]; and moldboard plow [MP]) were maintained on the same plots for the entire length of study. All crops were grown every year. Soil properties studied for the 0- to 15-cm layer were: structural stability of aggregates, bulk density, total porosity, penetration resistance, organic C, pH, cation-exchange capacity (CEC), and exchangeable K, Ca and Mg. Mean bulk densities measured prior to tillage treatments and planting were 1.18, 1.24, and 1.28 Mg m-3 for CC, CS, and COM rotations, respectively. The lowest bulk density was observed for the CC-NT combination. Total aggregation in CS was 26.9% greater than CC and 111.2% greater than COM. With tillage treatments, aggregation was in the order of NT>CP>MP. Rotation treatments had no effect on aggregate size. In accord with bulk density, the relative magnitude of organic C content was 100, 85, and 63 for CC, CS, and COM rotations, respectively.
  • Authors:
    • Copeland, S. M.
    • Tanaka, D. L.
    • Power, J. F.
    • Allmaras, R. R.
  • Source: Conservation Tillage in Temperate Agroecosystems
  • Year: 1994
  • Authors:
    • Grisso, R. D.
    • Jasa, P. J.
    • Dickey, E. C.
  • Source: Journal of Production Agriculture
  • Volume: 7
  • Issue: 4
  • Year: 1994
  • Summary: In Nebraska, early adopters of conservation tillage, especially those using no-till planting, had some concerns regarding planter performance, early season weed control, and possible yield reductions. Selected tillage and planting systems were used long term to evaluate effects on soybean [Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench] yield, soil properties, and residue cover in a nonirrigated rotation. The six tillage and planting systems selected for evaluation were: no-till, no-till with row-crop cultivation, disk, double disk, chisel, and plow. In 1981, two sets of field plots were established near Lincoln, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) so that both crops could be evaluated each year. Measurements were not taken until completion of one crop rotation cycle. After this cycle, for the first 3 yr of yield measurements, no differences occurred in grain yield among the tillage and planting systems. After five additional years, differences in yield were measured, with no-till tending to have the greatest yield for both crops. Row-crop cultivation of no-till soybean did not result in any measurable yield differences, but for grain sorghum, row-crop cultivation resulted in an average yield decrease of 6 bu/acre. Soil organic matter tended to be greatest for the continuous no-till system and lowest for the plow system. The plow system had slightly less penetration resistance within the 4- to 8-in. depth than the other treatments, whereas, the double-disk system was slightly greater within the 2- to 6-in. depth. Draft and power requirements for planting in the selected tillage and planting systems were not different. The major difference among the tillage and planting systems was residue cover remaining after planting. No-till had the most residue cover, but there was no appreciable accumulation of residue over the 10 yr of continuous use of the tillage and planting systems. For the last 5 yr, no-till tended to have the greatest yield for both crops. Thus, for the soil and conditions evaluated, no-till yields were as good as the other systems during early years, and were better after 5 yr of continuous use. Thus, producers adopting no-till and other residue management practices have the opportunity to enhance profitability because of the same or greater yields and reduced production costs by eliminating tillage operations.
  • Authors:
    • Weise, S. F.
    • Swanton, C. J.
  • Source: Weed Technology
  • Volume: 5
  • Issue: 3
  • Year: 1991
  • Summary: A growing awareness of environmental issues in Canada has had a major influence on government policies. An initiative was launched by the government of Ontario to promote research toward the development of an integrated weed management (IWM) system. Research in IWM must take all aspects of the cropping system into consideration and evolve in a progressive manner. This approach must encompass the role of conservation tillage, knowledge of the critical period of weed interference, alternative methods of weed control, enhancement of crop competitiveness, modeling of crop-weed interference, influence of crop rotation and seed bank dynamics, and education and extension of the findings. The complexity involved in addressing these issues requires a multi-disciplinary approach.
  • Authors:
    • Harman, W.
    • Jones, O.
    • Smith, S.
  • Source: Optimum erosion control at least cost. Proceedings of the National Symposium on Conservation Systems, December 14-15, 1987, Chicago, IL, USA
  • Year: 1987
  • Summary: Graded-terraced field-size watersheds have been cropped in a dryland wheat - fallow - sorghum - fallow (2 crops in 3 years) sequence with no-till and conventional (stubble-mulch) tillage systems at Bushland, Texas since 1982. No-till had little effect on wheat yields but increased sorghum yields 14% due to reduced evaporation, as a result of surface residue. No-till reduced erosion by 66%; however, soil loss with conventional tillage was also low due to terracing and contouring. NPK loss was very low. Economically, no-till performed very well, due mainly to reduced equipment inventories and lower operating costs. No-till gave increased storm runoff due to soil crusting, and there were problems with grass weeds. A system consisting of successive no-tillage and stubble-mulch tillage is proposed.
  • Authors:
    • Miranowski, J.
    • Shortle, J.
  • Source: Applied Agricultural Research
  • Volume: 1
  • Issue: 2
  • Year: 1986