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Least Limiting Water Range: Traffic and Long-term Tillage Influences in a Webster Soil (1998)

Betz, C.L. ; Allmaras, R.R. ; Copeland, S.M. ; [et al.]

Springer

Soil Science Society of America journal 62 (1998), S. 1384-1393

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ISSN: 1435-0661

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: b ). The LLWR concept and associated measurements were used to evaluate the impact of tillage on root and hydrologic environment at two depths in a poorly drained clay loam: (i) the 5- to 10-cm depth in nontracked and tracked interrows of three long-term tillage treatments (chisel plow, CH; moldboard plow, MB; and no tillage, NT); and (ii) a plow pan at 25- to 30-cm depth. Soil shrinkage, ρb, saturated hydraulic conductivity, water retention, characteristic (WRC), and penetration resistance characteristic (PRC) were all measured in undisturbed soil cores (5 cm long by 5 cm in diameter). Both the WRC and PRC included ρb as an independent variable. Linearized fits of the WRC and PRC, with R2 〉 0.70, were sensitive to tracking and to CH vs. MB tillage; compaction in the plow pan and tracking in the NT reduced by 75% the impact of ρb on the PRC. Tracking reduced the LLWR as much as 0.04 to 0.06 m3 m-3 in CH and NT treatments, but the reduction in the MB treatments was 〈 0.02 m3 m-3 . Penetration resistance was more limiting than the wilting point in the NT treatment and the plow pan, but not in treatments receiving annual tillage. Aeration was more limiting than available water in the NT and plow pan than in the MB and CH. The LLWR portrayed a major soil structural impact on physical control of rooting. Soil hydraulic properties associated with the LLWR explained a compaction and drainage problem with conservation tillage that can be linked to shallow penetration of tillage tools in this poorly drained soil.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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Green manures of oat, rape and sweet corn for reducing common root rot in pea (Pisum sativum) caused by Aphanomyces euteiches (1997)

Williams-Woodward, Jean L. ; Pfleger, F.L. ; Fritz, Vincent A. ; [et al.]

Springer

Plant and soil 188 (1997), S. 43-48

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ISSN: 1573-5036

Keywords: alfalfa ; amendments ; crop residue ; rolled towel bioassy ; root rot ; snap bean ; soybean

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Green manure crops of sweet corn, soybean, alfalfa, snap bean, rape, pea and of the two oat cultivars ‘Dane’ and ‘Troy’ were incorporated into the same soil and containers in which the crop had grown for five weeks. The soil was then evaluated for suppression of common root rot (Aphanomyces euteiches) of pea grown in infested pasteurized and non-pasteurized soils in the greenhouse. Pea biomass reduction and a plant bioassay for A. euteiches were used to measure the green manure suppression of disease. Green manures of sweet corn cv.‘Jubilee’, oat cv.‘Troy’, and rape cv.‘Humus’ significantly reduced pea biomass losses over the non-amended control soil treatments. Oat cv.‘Troy’and sweet corn cv.‘Jubilee’ green manures significantly reduced inoculum density of A. euteiches over the corresponding fallow controls in inoculated pasteurized soil by 87% and 76%, respectively, and in inoculated non-pasteurized soil by 67% and 66%, respectively. Only the green manure of oat cv. ‘Troy’ reduced inoculum density significantly below fallow.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004260214107

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Soil strength and water content influences on corn root distribution in a sandy soil (1998)

Laboski, C.A.M. ; Dowdy, R.H. ; Allmaras, R.R. ; [et al.]

Springer

Plant and soil 203 (1998), S. 239-247

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ISSN: 1573-5036

Keywords: compaction ; cone penetrometer ; corn (Zea mays L.) ; soil strength ; soil water content

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Initial field observations revealed a shallow corn (Zea mays L.) root system on a Zimmerman fine sand in a corn/soybean (Glycine max L.) rotation. Since root distribution influences crop water and nutrient absorption, it is essential to identify factors limiting root growth. The objective of this study was to determine the factor(s) limiting corn rooting depth on an irrigated fine sand soil. Bulk density, saturated hydraulic conductivity, and soil water retention were measured on undisturbed soil cores. Corn root distribution assessed at tasseling over a 3-yr period showed an average of 94% of total root length within the upper 0.60 m of soil with 85% in the upper 0.30 m of soil. Mechanical impedance was estimated with a cone penetrometer on two dates with differing water contents. Cone penetrometer measurements greater than 3 MPa indicated mechanical impedance in soil layers extending from 0.15 to 0.35 m deep. Penetration resistance decreased as soil water content increased. However, soil water contents greater than field capacity were required to decrease penetration resistance below the 3 MPa threshold. Such water saturated conditions only occurred for short periods immediately after precipitation or irrigation events, thus roots usually encountered restrictive soil strengths. The soil layer from 0.15 to 0.60 m had high bulk density, 1.57 Mg m-3. This compacted soil layer, with slower saturated hydraulic conductivities (121 to 138 mm hr-1), held more water than the soil above or below it and reduced water movement through the soil profile. Crop water use occurred to a depth of approximately 0.75 m. In conclusion, a compacted soil layer confined roots almost entirely to the top 0.60 m of soil because it had high soil strength and bulk density. The compacted layer, in turn, retained more water for crop use.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004391104778

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Influence of cultural practices on edaphic factors related to root disease in Pinus nursery seedlings (1998)

Juzwik, J. ; Gust, K.M. ; Allmaras, R.R.

Springer

Plant and soil 207 (1998), S. 195-208

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ISSN: 1573-5036

Keywords: compaction ; cone penetrometer ; Fusarium spp. ; incorporated biomass ; soil organic matter ; tillage

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Conifer seedlings grown in bare-root nurseries are frequently damaged and destroyed by soil-borne pathogenic fungi that cause root rot. Relationships between nursery cultural practices, soil characteristics, and populations of potential pathogens in the soil were examined in three bare-root tree nurseries in the Midwestern USA. Soil-borne populations of Fusarium spp. and Pythium spp. were enumerated as a function of soil depth in the upper 42 cm; red and white pine seedling root systems were assessed visually for signs of root rot. Soil organic carbon and resistance to cone penetration (as a function of depth) were augmented by saturated hydraulic conductivity (Ksat), water retention characteristic, texture and pH at selected depths. Cone index (CI) provided accurate ‘fingerprints’ of cultural practices in each nursery. A tillage pan due to rotary tillage was detected by CI in the Minnesota and Wisconsin nurseries, but no such tillage pan was indicated in the Michigan nursery, which did not use rotary tillage. Curves of CI also indicated differing maximum depth of tillage disturbance between nurseries; maximum rooting depth based on 3 MPa CI were different among nurseries. Vertical distribution of soil-borne Fusarium spp. reflected the vertical incorporation pattern associated with the type of tillage implement used to incorporate cover crop residue prior to Pinus seedling establishment. Peak numbers of Fusarium spp., from 250 to 950 colony-forming units (cfu g-1 dry soil) were recorded between 12 – 24 cm depth in two nurseries using a moldboard plow for incorporation while steadily decreasing populations, from 1800 to 250 cfu g-1 dry soil, were found from 0 to 15 cm in the third nursery using a disc. Vertical distribution of the Fusarium spp. also correlated with organic carbon levels, which suggested that cover-crop incorporation and conifer rooting had determined the location of soil-borne Fusarium spp. propagules. Ksat suggest that tillage pans caused by rotary tillage may impede drainage during nearly daily irrigation enough to cause physiological stress to the seedlings and predispose them to disease. Low levels of mortality (from 〈 1% to 5%) were observed in two-year-old Pinus seedlings while disease severity varied by nursery and seedling species. Tillage should be used to control depth placement of biomass residue and pathogenic fungal propagules, and adjusted to prevent tillage pans within the seedling root zone. More studies are needed to determine the impact of these cultural controls on the need and application depth of fumigation for pathogen control.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1026441014147

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Carbon Dynamics in Corn-Soybean Sequences as Estimated from Natural Carbon-13 Abundance (1998)

Huggins, D.R. ; Clapp, C.E. ; Allmaras, R.R. ; [et al.]

Springer

Soil Science Society of America journal 62 (1998), S. 195-203

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ISSN: 1435-0661

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: 2 . Our objectives were to assess SOC dynamics using natural 13C abundance in corn (Zea mays L., a C4 species)-soybean [Glycine max (L.) Merr., a C3 species] sequences. Fifteen treatments of continuous corn, continuous soybean, various sequences of corn and soybean, and fallow were initiated in 1981 at Lamberton, MN, on a Webster clay loam (fine-loamy, mixed, mesic Typic Haplaquoll). In 1991, soil and aboveground shoot samples from all treatments were analyzed for total organic C and δ13C. Carbon inputs, δ13C, and SOC were integrated into a two-pool model to evaluate C dynamics of corn and soybean. Total SOC was similar across all treatments after 10 yr; however, differences in soil δ13C occurred between continuous corn (δ13C = -17.2‰) and continuous soybean (δ13C = -18.2‰). Modeled C dynamics showed SOC decay rates of 0.011 yr-1 for C4-derived C and 0.007 yr-1 for C3-derived C, and humification rates of 0.16 yr-1 for corn and 0.11 yr-1 for soybean. Decay and humification rates were slightly lower than those found in other Corn Belt studies. Levels of SOC were predicted to decline an additional 7 to 18% with current C inputs from either corn or soybean, respectively. Annual C additions required for SOC maintainance averaged 5.6 Mg C ha-1, 1.4 to 2.1 times greater than previously reported estimates. Controlled variation in natural 13C abundance in corn-soybean rotations during a 10-yr period adequately traced C dynamics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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