ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

ENERGY BALANCE OF A CORN RESIDUE-COVERED FIELD DURING SNOWMELT (1998)

Sauer, T J. ; Hatfield, J. L. ; Prueger, J. H. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Journal of the American Water Resources Association 34 (1998), S. 0

add to mindlist on the mindlist

Details

ISSN: 1752-1688

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Architecture, Civil Engineering, Surveying , Geography

Notes: : Transport of agricultural chemicals in runoff and recharge waters from snowmelt and soil thawing may represent a significant event in terms of annual contaminant loadings in temperate regions. Improved understanding of the melt dynamics of shallow snowpacks is necessary to fully assess the implications for water quality. The objective of this study was to measure the energy balance components of a corn (Zea mays L.) stubble field during the melting of its snowcover. Net radiation (Rn), soil (G), sensible (H), and latent (Q) heat fluxes were measured in a field near Ames, Iowa, during the winter of 1994–1995. Energy consumed by melting including change in energy storage of the snowpack was determined as the residual of the measured energy balance. There was continuous snowcover at the field site for 71 days (maximum depth = 222 mm) followed by an open period of 11 days before additional snowfall and a second melt period. The net radiation and snow melt/energy storage change (5) terms dominated the energy balance during both measurement intervals. Peak daily sensible and latent heat fluxes were below 100 W m−2 on all days except the last day of the second melt period. There was good agreement between predicted and measured values of H and Q during the melting of an aged snow layer but poorer agreement during the melt of fresh snow. Both snowpacks melted rapidly and coincident changes in soil moisture storage were observed. Improved estimates of Q and H, especially for partially open surfaces, will require better characterization of the surface aerodynamic properties and spatially-representative surface temperature measurements.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1752-1688.1998.tb05440.x

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Influence of storage methods on corn root length measurements (1988)

Logsdon, S. D. ; Reneau, R. B.

Springer

Plant and soil 111 (1988), S. 155-157

add to mindlist on the mindlist

Details

ISSN: 1573-5036

Keywords: root diameter ; root length ; root mass ; root storage

Source: Springer Online Journal Archives 1860-2000

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

Notes: Abstract This study evaluated the changes in root length, mass, and diameter after air drying and rehydration of corn (Zea mays L.) root samples. For corn roots washed from soil, rehydrated root length was not reduced when compared with fresh root length, but rehydrated root mass was reduced to about half of fresh root mass, and rehydrated root diameter was approximately 75% of fresh diameter. Three storage methods (air dried, 70% ethanol, and 5% formaldehyde solution) were also compared for corn roots grown in moist paper towels. Although root mass and diameter were significantly reduced by air drying, root length was not altered by any of the treatments.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02182051

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Maize and soybean root clustering as indicated by root mapping (1991)

Logsdon, S. D. ; Allmaras, R. R.

Springer

Plant and soil 131 (1991), S. 169-176

add to mindlist on the mindlist

Details

ISSN: 1573-5036

Keywords: root clustering ; root number ; trench profile method

Source: Springer Online Journal Archives 1860-2000

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

Notes: Abstract Horizontal and vertical root mapping was used to relate rooting to a structured soil environment. Selected horizontal planes and associated vertical walls were exposed, and root locations were marked on polyethylene sheets. Separate sheets were used to indicate pores and cracks. Image analysis of the marked sheets indicated location of each root and root number per unit area (N). Number of roots growing in pores and cracks was determined by alignment of the marked sheets. Sixteen undisturbed cores (118 cm3) were taken in a grid pattern from each Ap horizon and adjacent subsoil for determination of root length density (D). Root clustering was associated with high coefficients of variation (ranging from 27 to 102%) for D. D/N (number−1) ratios were 16 (much greater than the theoretical value of 2 for a random root system). Both root branching and location of plant rows caused root clustering. Most of the root mappings were considered clustered by distributional statistics methods. Only a small percentage of roots were growing in preexisting pores and cracks, but many roots were located on ped faces.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00009446

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

Root growth as influenced by aggregate size (1987)

Logsdon, S. D. ; Parker, J. C. ; Reneau, R. B.

Springer

Plant and soil 99 (1987), S. 267-275

add to mindlist on the mindlist

Details

ISSN: 1573-5036

Keywords: Root deflection ; Root impedance ; Soil aggregates

Source: Springer Online Journal Archives 1860-2000

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

Notes: Summary This study examined the effects of aggregate size on root impedance and developed an equation to describe the root pressure necessary to avoid deflection around an aggregate. This critical root pressure was predicted to increase with increasing aggregate size, decreasing root diameter, and decreasing deflection angle. In growth chamber experiments, maize (Zea mays L.) seedlings were grown in A horizon material of Groseclose silt loam (Clayey, mixed, mesic, Typic Hapludult). The soil had been moist sieved into different aggregate sizes (0–1, 1–2, 2–3, and 3–6 mm diameter). The larger aggregates did constitute a slight root impedance as roots were deflected around them. Diameters of roots grown in 3–6 mm aggregates increased significantly, whereas root lengths were not always signficantly decreased. The smaller aggregates did not impede root growth and were readily displaced by roots. Large aggregates were more of an impedance to lateral roots than to main axes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02370873

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Comparing Field Methods that Estimate Mobile-Immobile Model Parameters (1999)

Casey, F. X. M. ; Jaynes, D. B. ; Horton, R. ; [et al.]

Springer

Soil Science Society of America journal 63 (1999), S. 800-806

add to mindlist on the mindlist

Details

ISSN: 1435-0661

Source: Springer Online Journal Archives 1860-2000

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

Notes: im ) and mass exchange coefficient (α) of the mobile-immobile solute transport model. The objective of this study was to compare two single tracer methods (basic and variance) with one multiple tracer method for estimating θim and α from data obtained on the same field soil locations. Hydraulic conductivity (K(h0)) was also estimated using these methods. Research was done at five interrow sites in a ridge-tilled corn (Zea mays L.) field, and the soil was mapped as a Nicollet series (fine-loamy, mixed, superactive, mesic, Aquic Hapludoll). The values of θim and α estimated by the multiple tracer method compared well with previously measured values using the same technique on the same field. The θim values for the multiple tracer technique were larger than values derived from the basic single tracer technique. The basic single tracer technique did not take into consideration a mass exchange between θim and the mobile water domain (θm). The α values were less variable for the multiple tracer method than for the single tracer-variance method. Values of immobile water fraction (θim/θ) for the multiple and basic single tracer techniques ranged from 0.30 to 0.52 and from 0.24 to 0.35, respectively. The values of α for the multiple and singe tracer-variance techniques ranged from 0.06 to 0.9 d-1 and from 0.03 to 60 d-1, respectively. The volumetric water content (θ) changed considerably over the course of the experiment for the estimation of α using the single tracer-variance method; thus, the assumptions of this technique were compromised. The measured values of K(h0) at the five sites ranged from 0.47 to 1.66 μm s-1. There was evidence that the basic single tracer method underestimated θim and overestimated θm, because this method considers α = 0 during the tracer application.

Type of Medium: Electronic Resource

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

Permalink