• Authors:
    • Turkington, T.
    • Gill, K.
    • Arshad, M.
    • Woods, D.
  • Source: Agronomy Journal
  • Volume: 89
  • Issue: 1
  • Year: 1997
  • Summary: In a field trial near Beaverlodge, Alberta, a Hythe clay loam (fine, montmorillonitic, frigid Mollic Cryoboralf) with initial pH in CaCl 2 ~5 was limed (7.5 t ha -1) in May 1991. Liming increased soil pH to 6.6 in the autumn of 1991. During 1993 to 1995, the pH of limed soil at the 0- to 10-cm depth ranged from 6.2 to 6.3 when conventionally tilled and from 5.6 to 6.2 under no-till. A slight increase at the 10- to 20-cm depth and no change below 20 cm occurred in soil pH due to liming. Liming increased NO 3-N in the 0- to 20-cm depth significantly, but no change was detected in exchangeable Al, NH 4-N and extractable P. Weed populations were not affected by liming in 1993 and 1994, but were suppressed markedly in 1995. Liming reduced brown girdling root rot (BGRR) (caused by Rhizoctonia solani) and increased seed yield of canola [rape]. Three-year mean BGRR ratings (a scale of 0 to 5 scale, from disease-free to disease-impaired) under no lime and lime, respectively, were 2.96 and 2.59 in tilled and 2.76 and 2.63 in no-till soil. The increase in canola seed yield by liming was 0.39 (37%) t ha -1 year -1 in tilled and 0.22 (17%) t ha -1 year -1 in no-till soil. Liming increased dry matter by 1.77 t ha -1 year -1 (31%). No-till plots had higher soil water and canola yields but slightly lower soil pH (0- to 20-cm depth), and lesser BGRR, compared with the tilled system. Increased soil NO 3-N and pH, fewer weeds, and reduced BGRR-all responded to liming and contributed to increased canola yields under both tilled and no-till systems.
  • Authors:
    • Harapiak, J.
    • Lafond, G.
    • Johnston, A.
    • Head, W.
  • Source: Journal of Production Agriculture
  • Volume: 10
  • Issue: 3
  • Year: 1997
  • Summary: A research study was conducted in Saskatchewan and Alberta to determine the potential for precision side band application of partially liquified anhydrous ammonia (AA) at sowing. While AA reduced plant stand over that observed with urea for both wheat and canola [rape], no effect on grain yields of wheat were observed from seven field trials. The use of AA did not adversely affect the rate of wheat establishment as measured by main stem Haun stage or plant development as measured by number of root axes and frequency of tillers produced. With canola, a reduction in seed yield was observed at only one of the five trial sites. The lower canola yield reflects the N loss when AA is applied on clay soils. Loss of AA on clay and silty clay soils, which were wet at application, resulted in reduced crop N uptake and lowered N use efficiency relative to urea at one wheat and two of the canola trial locations. It is suggested that given adequate seed-fertilizer separation, partially liquified AA can be safely applied at sowing in a precision side band application. Soil conditions that are known to cause N loss on application of AA, in particular wet clay and silty clay soils, may benefit more from an alternative N source such as granular urea or solution N.
  • Authors:
    • Franzluebbers, A. J.
    • Arshad, M. A.
  • Source: Soil Science Society of America Journal
  • Volume: 60
  • Issue: 5
  • Year: 1996
  • Summary: Changes in soil organic matter (SOM) pools during adoption of reduced (RT) or zero tillage (ZT) can influence soil physical properties, nutrient cycling, and CO2 flux between soil and atmosphere. We determined soil organic C (SOC), soil microbial biomass C (SMBC), basal soil respiration (BSR), and mineralizable N to a depth of 200 mm at the end of 3, 5, and 6 yr after implementation of tillage management on a Falher clay (fine, montmorillonitic, frigid Typic Natriboralf) near Rycroft, Alberta, in a canola (Brassica campestris L.)-wheat (Triticum Aestivum L.)-barley (Hordeum vulgare L.)-fallow cropping system. At the end of 6 yr, SOC was not different among tillage regimes and averaged 8.6 kg m−2. At the end of 3 and 5 yr, SMBC was not significantly different among tillage regimes, but at the end of 6 yr SMBC was 7% greater in RT and 9% greater in ZT than in conventional tillage (CT). Basal soil respiration and mineralizable N at the end of 6 yr were not different among tillage regimes following barley and averaged 2.7 g CO2-C m−2 d−1 and 5.0 g inorganic N m−2 24 d−1, respectively. However, BSR following fallow was 2.2, 2.5, and 2.6 g CO2-C m−2 d−1 in CT, RT, and ZT, respectively. Mineralizable N following fallow was 5.8 g inorganic N m−2 (24 d)−1 in RT and ZT and 7.3 g inorganic N m−2 (24 d)−1 in CT. At 0 to 50 mm, there was no significant increase in SOC at the end of 6 yr, a 17 to 36% increase in SMBC, and a 12 to 69% increase in BSR with ZT compared with CT, depending on rotation phase. Relatively small changes in SOM pools with adoption of conservation tillage may be attributable to the large amount of SOM initially present and the cold, semiarid climate that limits SOM turnover.
  • 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:
    • Mineau, P.
    • McLaughlin, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 55
  • Issue: 3
  • Year: 1995
  • Summary: Agricultural activities such as tillage, drainage, intercropping, rotation, grazing and extensive usage of pesticides and fertilizers have significant implications for wild species of flora and fauna. Species capable of adapting to the agricultural landscape may be limited directly by the disturbance regimes of grazing, planting and harvesting, and indirectly by the abundance of plant and insect foods available. Some management techniques, such as drainage, create such fundamental habitat changes that there are significant shifts in species composition. This paper considers the relative merits of conventional tillage versus reduced, or no-till farming, and reviews the benefits of rest-rotation grazing, crop rotation and intercropping in terms of maintaining wild species populations. There are a number of undesirable environmental impacts associated with fertilizer and pesticide usage, and in this paper we attempt to provide an account of the ways in which these inputs impact on biodiversity at various levels including plant, invertebrate, and vertebrate groups. Factors which are considered include the mobility, trophic interactions, persistence, and spectrum of toxicity for various pesticides. The ecological virtues of organic and inorganic fertilizers are compared, and the problems arising from excessive use of fertilizer are discussed. The findings in this review indicate that chemical fertilizer loadings must be better budgeted to not exceed local needs, and that pesticide inputs should be reduced to a minimum. The types and regimes of disturbance due to mechanical operations associated with agricultural activity may also be modified to help reduce negative impacts on particular groups of species, such as birds. For those plant and insect species which need to be controlled for agronomic reasons, the population decreases brought about by disturbance regimes may be desirable as a form of pest management. The prevalence of agriculture over such a large portion of the Canadian landscape means that it is important that we find solutions to conflicts that arise between agriculture and wild species. It is important to realize that the impact of agricultural inputs varies greatly among regions and species, and actual effects have generally not been investigated for many species in any one locality; while the focus of this review is on Canada, much Canadian-specific research is lacking, thus, this review also draws from relevant research done elsewhere.
  • 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:
    • 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:
    • Milchunas, D.
    • Vose, J.
    • Rice, C. W.
    • Fisher,Frederick M.
    • Parmenter, R. R.
    • Tilman, D.
    • Zak, D. R.
    • Martin, C. W.
  • Source: Ecology
  • Volume: 75
  • Issue: 8
  • Year: 1994
  • Summary: Annual C inputs from plant production in terrestrial ecosystems only meet the maintenance energy requirements of soil microorganisms, allowing for little or no net annual increase in their biomass. Because microbial growth within soil is limited by C availability, we reasoned that plant production should, in part, control the biomass of soil microorganisms. We also reasoned that soil texture should further modify the influence of plant production on soil C availability because fine-textured soils typically support more microbial biomass than coarse-textured soils. To test these ideas, we quantified the relationship between aboveground net primary production (ANPP) and soil microbial biomass in late-successional ecosystems distributed along a continent-wide gradient in North America. We also measured labile pools of C and N within the soil because they represent potential substrate for microbial activity. Ecosystems ranged from a Douglas-fir forest in the western United States to the grasslands of the mid-continent to the hardwood forests in the eastern U.S. Estimates of ANPP obtained from the literature ranged from 82 to 1460 g cntdot m-2 cntdot yr-1. Microbial biomass C and N were estimated by the fumigation-incubation technique. Labile soil pools of C and N and first-order rate constants for microbial respiration and net N mineralization were estimated using a long-term (32 wk) laboratory incubation. Regression analyses were used to relate ANPP and soil texture with microbial biomass and labile soil C and N pools. Microbial biomass carbon ranged from 2 g/m-2 in the desert grassland to 134 g/m-2 in the tallgrass prairie; microbial N displayed a similar trend among ecosystems. Labile C pools, derived from a first-order rate equation, ranged from 115 g/m-2 in the desert grassland to 491 g/m-2 in the southern hardwood forest. First-order rate constants for microbial respiration (k) fell within a narrow range of values (0.180 to 0.357 wk-1), suggesting that labile C pools were chemically similar among this diverse set of ecosystems. Potential net N mineralization rates over the 32-wk incubation were linear in most ecosystems with first-order responses only in the alpine tundra, tallgrass prairie, and forests. Microbial biomass C displayed a positive, linear relationship with ANPP (r-2 = 0.51), but was not significantly related to soil texture. Labile C also was linearly related to ANPP (r-2 = 0.32) and to soil texture (r-2 = 0.33). Results indicate that microbial biomass and labile organic matter pools change predictably across broad gradients of ANPP, supporting the idea that microbial growth in soil is constrained by C availability.
  • 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.