• Authors:
    • Cote, D.
    • Voroney, R. P.
    • Angers, D. A.
  • Source: Soil Science Society of America Journal
  • Volume: 59
  • Issue: 5
  • Year: 1995
  • Summary: This study was conducted to determine the influence of tillage practices on the decomposition of corn (Zea mays L.) residues and turnover of soil organic matter (SOM). Measurements of {delta}13C were made of the whole soil, the microbial biomass, and two particle-size fractions (50 {micro}m) in soils that had been under corn production for 11 yr and from an adjacent meadow. Meadow-derived C in total SOM (0-24 cm) decreased under corn cropping at the same rate under all tillage treatments. Corn-derived C was evenly distributed with depth in the moldboard plow treatment and accumulated at the surface in the shallow, reduced-tillage treatments. The incorporation of corn residue C into SOM in the 0- to 24-cm layer was not significantly affected by tillage and was estimated to be {approx}41 g C m-2 yr-1, which represents {approx}30% of the corn residue inputs. Both the macroorganic matter (>50 {micro}m) and microbial biomass had a greater enrichment (up to 35%) in corn-derived C than either the whole soil or the microorganic matter (<50 {micro}m), indicating that these pools are important recipients of plant residue inputs. Nevertheless, the microorganic matter was also a significant sink for C input, acounting for {approx}50% of the total corn-derived C remaining in the surface (0-8 cm) soil. Under the conditions of this study, tillage practices influenced the vertical distribution of SOM and corn residues but had no detectable effect on SOM turnover and on the fate of corn residues when the whole Ap horizon was considered.
  • Authors:
    • Ghaffarzadeh, M.
    • Cruse, R. M.
    • Robinson, C. A.
  • Source: Soil Science Society of America Journal
  • Volume: 60
  • Issue: 1
  • Year: 1994
  • Summary: Time, fertilizer, tillage, and cropping systems may alter soil organic carbon (SOC) levels. Our objective was to determine the effect of long-term cropping systems and fertility treatments on SOC. Five rotations and two N fertility levels at three Iowa sites (Kanawha, Nashua, and Sutherland) maintained for 12 to 36 yr were evaluated. A 75-yr continuous corn (Zea mays L.) site (Ames) with a 40-yr N-P-K rate study also was evaluated. Soils were Typic and Aquic Hapludolls and Typic Haplaquolls. Four-year rotations consisting of corn, oat (Avena sativa L.), and meadow (alfalfa [Medicago sativa L.], or alfalfa and red clover [Trifolium pratense L.]) had the highest SOC (Kanawha, 32.1 g/kg; Nashua, 21.9 g/kg; Sutherland, 27.9 g/kg). Corn silage treatments (Nashua, [≤] 18.9 g/kg; Sutherland, [≤]23.2 g/kg) and no-fertilizer treatments (Kanawha, 25.3 g/kg; Nashua, [≤]20.9 g/kg; Sutherland, [≤]23.5 g/kg) had the lowest SOC. A corn-oat-meadow-meadow rotation maintained initial SOC (27.9 g/kg) after 34 yr at Sutherland. Continuous corn resulted in loss of 30% of SOC during 35 yr of manure and lime treatments. SOC increased 22% when N-P-K treatments were imposed. Fertilizer N, initial SOC levels, and previous management affected current SOC levels. Residue additions were linearly related to SOC (Ames, r2 = 0.40; Nashua, r2 = 0.82; Sutherland, r2 = 0.89). All systems had 22 to 49% less SOC than adjacent fence rows. Changing cropping systems to those that conserve SOC could sequester as much as 30% of C released since cropping began, thereby increasing SOC.
  • Authors:
    • Copeland, S. M.
    • Tanaka, D. L.
    • Power, J. F.
    • Allmaras, R. R.
  • Source: Conservation Tillage in Temperate Agroecosystems
  • Year: 1994
  • Authors:
    • Black, A. L.
    • Bauer, A.
  • Source: Soil Science Society of America Journal
  • Volume: 58
  • Issue: 1
  • Year: 1994
  • Summary: The positive effects of soil organic matter (OM) on soil properties that influence crop performance are well documented. But definitive and quantitative information of differential effects of soil OM contents is lacking for the northern Great Plains. The objective of this study was to quantify the contribution of a unit quantity of soil OM to productivity. Experiments were conducted on Williams loam (fine-loamy, mixed, Typic Argiboroll) for 4 yr in the same field. The variables were soil OM content of the upper 30.5 cm together with all combinations of three postplanting soil available N levels (55, 90, and 125 kg N ha-1 as NO3-N to 1.2 m) and three water levels. Water levels were uniformly maintained with a trickle system that independently metered water to each plot for each soil available N level. Pretillering spring wheat (Triticum aestivum L.) plant population decreased as soil OM content decreased in 3 of 4 yr. On an annual basis, highest total aerial dry matter and grain yields were associated with highest OM contents. The contribution of 1 Mg OM ha-1 to soil productivity, across the range of 64 to 142 Mg OM ha-1, was calculated as equivalent to 35.2 kg ha-1 for spring wheat total aerial dry matter and 15.6 kg ha-1 for grain yield. Loss of productivity associated with a depletion of soil OM in the northern Great Plains is primarily a consequence of a concomitant loss of fertility.
  • Authors:
    • Maule, C.
    • Reed, W.
  • Source: Canadian Agricultural Engineering
  • Volume: 35
  • Issue: 3
  • Year: 1993
  • Summary: The effects of no-till and conventional tillage systems on water infiltration and related soil parameters were investigated in five fields under dryland farming in southern Saskatchewan. A rainfall simulator was used for the infiltration measurements. Three fields were under a no-till system for different lengths of time ranging from 5 years to 13 years. A heavy duty cultivator was used in both fields under conventional tillage; one field was under continuous cropping, and the other under a traditional wheat-fallow rotation. Fields under the no-till system had higher organic matter contents, higher macroporosities, and higher saturated hydraulic conductivities than the fields with the conventional tillage. Organic matter in the no-till and conventional continuously cropped fields increased approximately 0.2% for every year since the last conventional fallow-crop rotation. The field in conventional fallow had the lowest infiltration rates, while the conventional continuously cropped field had the highest infiltration rates, although not significantly different than those from the 13 year old no-till field. Cumulative infiltration at 60 minutes was most highly correlated with organic matter content; for every 1 percentage point increase in organic matter, cumulative infiltration increased by 9 mm.
  • Authors:
    • Raimbult, B. A.
    • Vyn, T. J.
  • Source: Agronomy Journal
  • Volume: 85
  • Issue: 5
  • Year: 1993
  • Summary: Tillage systems need to be compared over an extended period of time to determine their transitional and long-term impacts on crop growth and soil properties. A 15-yr experiment established in 1976 compared reduced tillage systems with conventional fall moldboard plowing for production of continuous corn (Zea mays L.) on a Maryhill silt loam soil (Typic Hapludalf). Corn plant growth and yield and soil properties were compared for five tillage systems: fall plow (fall mold-board plow + spring secondary tillage), fall chisel plow (fall chisel plow + spring secondary), spring plow, spring plow/secondary (spring plow + secondary), and no-till. No-till consistently resulted in slower plant growth than most or all of the other tillage systems. The fall plow and spring plow/secondary treatments resulted in grain yields averaging 5% more than fall chisel plow, 9% more than spring plow, and 16% more than no-till yields. From 1976 to 1983, no-till yields tended to increase relative to fall plow; from 1988 to 1990, however, no-till yields were much less than fall plow. No-till resulted in the lowest proportion of aggregates < 5 mm in diameter, highest bulk density, and greatest penetrometer resistance. Penetrometer resistance of the spring plow plots increased at a slower rate with depth than the fall chisel plow system. Among soil properties measured, the proportion of aggregates < 5 mm in diameter was most often significantly correlated with yield.
  • Authors:
    • Lindstrom, M. J.
    • Reicosky, D. C.
  • Source: Agronomy Journal
  • Volume: 85
  • Issue: 6
  • Year: 1993
  • Summary: The increasing concern for rising CO2 concentrations from agricultural activities has prompted the need to better understand the flux of greenhouse gases to the atmosphere. This work determines the effect of four fall tillage methods on short-term CO2 flux from a Hamerly clay loam (fine-loamy, frigid Aerie Calciaquoll) in the northern Corn Belt. Moldboard plow only, moldboard plow plus disk harrow twice, disk harrow once, and chisel plow once using standard tillage equipment following a wheat (Triticum aestivum L.) crop were compared with no-tillage. The CO2 flux was measured with a large portable system commonly used to measure canopy gas exchange of field crops. Measurements of CO2 flux were initiated within 5 min after tillage completion for each tillage treatment and continued intermittently for 19 d. Moldboard plow had the roughest soil surface and the highest initial CO, flux (29 g m-2 h-1) and maintained the highest flux throughout the study. Moldboard plow plus disking twice and chisel plow had similar initial rates (7 and 6 g m-2 h-1, respectively) that were greater than disk harrow and no-tillage. The high initial CO2 fluxes were more related to depth of soil disturbance that resulted in a rougher surface and larger voids than to residue incorporation. The differences in CO2 flux between tillage treatments were small but consistent 19 d after initial tillage and 64 mm rain. Lower CO2 flux rates caused by tillage were associated with low soil disturbance and/or small voids. Tillage methods affected the initial CO2 flux differently and suggest improved soil management can minimize agriculture's impact on global CO2 increase.
  • Authors:
    • Liu, R.
    • Phillips, D. L.
    • Lee, J. J.
  • Source: Water, Air, & Soil Pollution
  • Volume: 70
  • Issue: 1
  • Year: 1993
  • Summary: The EPIC model was used to simulate soil erosion and soil C content at 100 randomly selected sites in the US corn belt. Four management scenarios were run for 100 years: (1) current mix of tillage practices maintained; (2) current trend of conversion to mulch-till and no-till maintained; (3) trend to increased no-till; (4) trend to increased no-till with addition of winter wheat cover crop. As expected, the three alternative scenarios resulted in substantial decreases in soil erosion compared to the current mix of tillage practices. C content of the top 15 cm of soil increased for the alternative scenarios, while remaining approximately constant for the current tillage mix. However, total soil C to a depth of 1 m from the original surface decreased for all scenarios except for the no-till plus winter wheat cover crop scenario. Extrapolated to the entire US corn belt, the model results suggest that, under the current mix of tillage practices, soils used for corn and/or soybean production will lose 3.2 x 10^6 tons of C per year for the next 100 years. About 21% of this loss will be C transported off-site by soil erosion; an unknown fraction of this C will be released to the atmosphere. For the base trend and increased no-till trend, these soils are projected to lose 2.2 x 10^6 t-C yr-1 and 1.0 x 10^6 t-C yr-1, respectively. Under the increased no-till plus cover crop scenario, these soils become a small sink of 0.1 x 10^6 t-C yr-1. Thus, a shift from current tillage practices to widespread use of no-till plus winter cover could conserve and sequester a total of 3.3 x 10^6 t-C yr-1 in the soil for the next 100 years.
  • Authors:
    • Zentner, R. P.
    • Campbell, C. A.
  • Source: Soil Science Society of America Journal
  • Volume: 57
  • Issue: 4
  • Year: 1993
  • Summary: Few studies conducted in western Canada have assessed how crop rotations and fertilization influence soil organic matter content on land that has been cropped for many years. We monitored soil organic matter in the 0- to 0.15- and 0.15- to 0.3-m depths of a 24-yr crop rotation experiment conducted on a medium-textured Aridic Haploboroll in southwestern Saskatchewan. Prior to the study, the land had been in a hard red spring wheat (Triticum aestivum L.)-fallow rotation for {approx}50 yr. Only the 0- to 0.15-m segment showed significant treatment effects. Due to good weather and crop yields in the first 15 yr, soil organic matter had increased under well-fertilized annually cropped rotations, and it remained constant under fallow-containing rotations and under continuous wheat receiving inadequate N fertilizer. Because of several dry years in the final 9 yr of the study, all rotations except a well-fertilized, fallow-winter cereal-wheat system lost organic matter. Changes in organic matter were directly related to the amount of crop residues produced by these systems and their ease of eroding. Soil organic matter was inversely related to apparent N deficit (i.e., N exported in grain minus N applied as fertilizer). The fallow-flax (Linum usitatissimum L.)-wheat rotation receiving N and P fertilizer had the lowest soil organic matter, partly due to low production of crop residues by flax, partly to greater leaching of NO3, and partly due to some loss of flax residues blown from the plots. Soil organic matter in the well-fertilized fallow-winter cereal-wheat rotation remained constant because its shorter fallow period reduced soil erosion, and due to its more efficient use of N, as evidenced by minimal leached NO3-N.
  • Authors:
    • Anderson, G. W.
    • Shaw, J. E.
    • Swanton, C. J.
    • Eadie, A. G.
  • Source: Weed Technology
  • Volume: 6
  • Issue: 3
  • Year: 1992
  • Summary: The acceptance of no-till crop production systems has been limited due to expected problems with weed management. Field experiments were established at two locations in Ontario in 1988 and one location in 1989. Band or broadcast applications of preemergence (PRE) combinations of high or low label rates of atrazine with or without metolachlor or inter-row cultivation, were evaluated for their effectiveness in controlling annual weeds in no-till corn. At each location, different herbicide and cultivation combinations were required to achieve adequate weed control. Corn grain yield was equivalent regardless of whether herbicides were applied as a band or broadcast treatment at all three sites. At two of the three sites, one cultivation combined with herbicides applied as a band was adequate to maintain weed control and corn grain yields. Selective application of herbicides in bands represented an approximate 60% reduction in total herbicide applied into the environment. The integration of a shallow post-plant inter-row cultivation combined with the soil conservation attributes of no-till, would enhance the sustainability of a modified no-till corn production system.