HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Field, D. J. Articles by Minasny, B. Search for Related Content PubMed Articles by Field, D. J. Articles by Minasny, B. Agricola Articles by Field, D. J. Articles by Minasny, B.

COMMENTS AND LETTERS TO THE EDITOR

Comments on "Modeling Energy Inputs to Predict Pedogenic Environments Using Regional Environmental Databases"

Faculty of Agriculture, Food and Natural Resources, The Univ. of Sydney, NSW 2006, Australia

^* Corresponding author (d.field{at}usyd.edu.au).

RASMUSSEN ET AL. (2005) and Rasmussen and Tabor (2007) present a quantitative pedologic energy model for predicting soil properties across the USA. Their model calculated the energy expanded for soil genesis based on energy used in transfer of water, net primary production, and mineral weathering and in doing so have provided a quantitative approach of Runge's energy model. In this letter we would like to bring to the attention of the above authors that a quantitative energy model for soil formation had been proposed earlier by V.R. Volobuyev and detailed in his book, "Ecology of Soils" (Volobuyev, 1964). Volobuyev (1964, p. 174) defined the energy balance for soil formation as follows:

where

Q is the energy involved in soil formation

w₁ is the energy of physical rock weathering

w₂ is the energy for chemical weathering

b₁ is the energy accumulating in soil organic matter

b₂ is the energy for soil organic matter transformation

i₁ is the energy for evaporation from soil surface

i₂ is the energy for transpiration

g is the energy losses in leaching of salts and fine materials

v is the energy expended by the process of heat exchange between the soil and atmosphere (usually negligible).

When identifying data that can be used to populate this model, Volobuyev (1964, p. 172–190) concentrated on energy parameters describing climate (i₁, i₂), production of biological material (b₁, b₂), and the weathering of parent material (w₁, w₂). These parameters share similarities with those identified in Rasmussen's et al. (2005) model. To populate the climate parameter, Volobuyev (1964, p. 174–176) develops a relationship estimating the amount of precipitation (R) relative to evaporation (E_n) and uses this to estimate expenditure of energy of total evaporation represented in Fig. 33 (Volobuyev, 1964, p. 176). The relationship is conditioned by the development of hydro- and thermo-sequences which describe the climatic areas of the main soil types on earth (Volobuyev, 1964, p. 94). Similarly, Rasmussen et al. (2005, p.1268) present an equation taking into account the relationship between precipitation and evaporation, which is conditioned using mean annual temperature (MAT).

Volobuyev (1964, p. 175) continues by developing his production of biological material relationship, which mirrors what Rasmussen et al. (2005, p. 1268–1269) names Net Primary Production (NPP). Similar to Rasmussen et al. (2005) in their use of Lieth's (1975) findings in NPP, Volobuyev (1964, p. 123–125) identifies the amount of organic matter produced in different ecosystem types (Table 22, p. 123–124) and relates this to his defined hydro- and thermo-sequences (Fig. 16, p. 125). Using a chemical equation of photosynthesis, Volobuyev (1964, p. 175) converts the amount of vegetative matter to energy, then relates this to his hydro- and thermo-sequences in Fig. 34 (p. 178), whereas Rasmussen et al. (2005) assign a single average energy value to each gram of dry matter input.

When considering weathering of parent material, Volobuyev (1964, p. 175–179) concentrates his efforts on knowing the energy required to decompose particular minerals and regulating this with the amount of water and range in temperatures, from which was developed the energy relationship expressed in Fig. 35 (p. 179). In the more recent treatment by Rasmussen et al. (2005), a parent material index is used to describe weathering susceptibility of a wide range of rock types.

The total energy for soil formation is calculated by summing energy for evapotranspiration, biomass production, and mineral weathering. We have converted Volobuyev's graph into SI units and present it in Fig. 1 . The soil forming energy is largely allocated to evapotranspiration (95–99.5% of total energy). The energy for biological processes is only 0.5–5% of the total energy. The energy for mineral weathering comprises only 0.01% of the total energy required for soil formation. Volobuyev (1964, p. 181) showed the energy of soil formation is variable for different climatic regions: in humid tropical wet areas, the annual energy is around 2000 MJ/m², as compared with 40–100 MJ/m² for tundras and 500 to 1000 MJ/m² for forests and steppes. We note that the energy calculated by Volobuyev (1964) is one order of magnitude larger than that presented in Fig. 2 of Rasmussen et al. (2005) and Rasmussen and Tabor (2007).

View larger version (54K): [in this window] [in a new window]   Fig. 1. Total energy (Q) for soil formation as a function of mean annual temperature (MAT) and precipitation over index of moistening (potential evaporation) (R/En).

	NOTES

TOP NOTES REFERENCES

 
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.

Received for publication December 11, 2007.

	REFERENCES

TOP NOTES REFERENCES

 

• Leith, H. 1975. Primary production of the major vegetation units of the world. p. 203–215. In H. Lieth and R. H. Whittaker (ed.) Primary productivity of the biosphere. Springer-Verlag, New York.
• Rasmussen, C., and N.J. Tabor. 2007. Applying a quantitative pedogenic energy model across a range of environmental gradients. Soil Sci. Soc. Am. J. 71 :1719–1729.[Abstract/Free Full Text]
• Rasmussen, C., R.J. Southard, and W.R. Horwath. 2005. Modeling energy inputs to predict pedogenic environments using regional environmental databases. Soil Sci. Soc. Am. J. 69 :1266–1274.[Abstract/Free Full Text]
• Volobuyev, V.R. 1964. Ecology of soils. Academy of Sciences of the Azerbaidzan SSR. Institute of Soil Science and Agrochemistry. Israel Program for Scientific Translations, Jerusalem.
• Volobuyev, V.R. 1974. Main concepts of soil ecology. Geoderma 12 :27–33.[CrossRef][Web of Science]
• Volobuyev, V.R. 1983. Thermodynamic basis of soil classification. Soviet Soil Sci. 15 :71–83.
• Volobuyev, V.R. 1984. Two key solutions of the energetics of soil formation. Soviet Soil Sci. 16 :1–8.
• Volobuyev, V.R. 1985. Biological component energetics of the soil formation. Soviet Soil Sci. 17 :1–4.

This Article Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Field, D. J. Articles by Minasny, B. Search for Related Content PubMed Articles by Field, D. J. Articles by Minasny, B. Agricola Articles by Field, D. J. Articles by Minasny, B.