Charcoal Hearth Soils: Remnants of the Iron …...Charcoal Hearth Soils: Remnants of the Iron Industry in the Northeastern U. S. Kevin Hesson* abstract Over the past years there has

Natural Sciences Education bull Volume 45 bull 2016 1 of 5

StudENt ESSayS

Charcoal Hearth Soils Remnants of the Iron Industry in the Northeastern U S

Kevin Hesson

abstractOver the past years there has been an increasing interest in biochar Research involving charcoal hearths may help to further illustrate the differences found among soils with charcoal amendments and also provide information regarding the changes that occur with the presence of charcoal in the soil thus contributing to the growing body of research surrounding biochar This research focused on the historic charcoal sites in the Northeastern United States Forested areas in the Northeast region of the United States were once heavily affected by the iron industry In iron producing areas charcoal was necessary to provide a fuel source for refining Charcoal was itself produced in order to meet this demand Charcoaling spurs various changes within the soil Our results showed that in charcoal hearths there was an increase in cation exchange capacity (CEC) as well as higher pH and higher levels of soil respiration than non- hearth soils Soil color was also examined and differences were found in relation to soil organic matter (SOM) and soil color

This study was a continuation of research on char-coal hearth soils and their relation to soil organic carbon and bulk density (Turk and Kiska 2015) The

process by which charcoal was made involved a simple process consisting of the thermochemical decomposition of wood at high temperatures while being deprived of oxygen (Miranda 2013) Wood fuel was stacked on a hearth lit on fire and covered with soil to prevent the burning wood from oxidizing (Powell 2012) The result yielded charcoal which was then raked and collected to be used in the local iron furnaces The continuous production of charcoal had a significant impact on the hearth soils over the course of multiple decades

The iron industry in the Northeast spanned from the mid 1700s and declined during the very early 1900s (Muntz 1960) In regions where the iron industry was present charcoal hearths were often constructed on soils that were deemed poor for farming (Muntz 1960) By designating poor soils for charcoal production alterations made during charcoaling over the span of decades resulted in soil more suitable for farming Ironworks required massive amounts of fuel to process ore and therefore the hearths produced quantities to match The iron industry was prevalent in the Northeast for more than a hundred years during a period of prevalent economic opportunity (Muntz 1960) Large tracts of forests were used as fuel for charcoal production (Hart et al 2008) This intensive management contributed to the decimation of forest resources that was common during the era These kinds of hearths are found all over the East coast of the United States where charcoal production developed alongside iron production The objective of this study was to examine the differences in properties between these charcoal hearth soils and their non-hearth counterparts

MEthodSThis study examined charcoal hearths located in

Sterling Forest State Park The State Park is located within the Ramapo Mountain Range which is part of the Appalachian Mountain Range Hearth soils at two different sites were examined and compared to nearby non-hearth soils The first site examined was located in unsorted till

co Judith Turk School of Natural Sciences and Mathematics 101 Vera King Farris Drive Stockton University Galloway NJ 08205-9441 Corresponding author (judithturkstocktonedu kevinmhessongmailcom)

Published in Nat Sci Educ 45 (2016) doi104195nse2016020771 Received 29 Feb 2016 Accepted 29 Feb 2016

Copyright copy 2016 by the American Society of Agronomy 5585 Guilford Road Madison WI 53711 USA All rights reserved

F i r S t P l a c EThis was written as a scientific paper with an audience of researchers The research reported

in this paper was part of a larger project and data may be used again in reporting the results of that paper Soil organic matter data was obtained from Ryan Kiska

Published December 20 2016

2 of 5 Natural Sciences Education bull Volume 45 bull 2016

(Fig 1 and 2) and the second site was located in a boulder field (Fig 3 and 4) The locations in which the hearths were once present were not obvious to the untrained eye but could be identified by a circular clearing and relative flatness of the hearth They are typically found in this condition although sometimes they are indistinguishable from surrounding forest vegetation (Young et al 1996)

Measurements were taken during the summer for ease of data collection and to allow for the measurement of respiration Slope at the sites varied although slopes measured at the charcoal hearths were low due to the need for hearths to be relatively flat for ease of production In order to use the space for charcoal production the area was

cleared and flattened thus yielding a relatively low slope Aspects at all sites were SSE or SEE Pits were dug at each site and the soil profiles were analyzed according to official NRCS techniques (Schoeneberger et al 2012)

A variety of tests were conducted at our sites On site testing of respiration was conducted using Draeger tubes Measurements were taken during the month of August on site Techniques consistent with the USDA guide for measuring soil quality were used (USDA 1999) Tests that were conducted in the lab were soil color pH and CEC Soil color was measured using a Konica Minolta Chroma Meter Samples were separated by horizon and measured individually filling the Chroma Meter sample dish A pH

Fig 1 Soil profile of control at unsorted till site Fig 2 Soil profile of charcoal at unsorted till site

Fig 3 Soil profile of control at boulder field site Fig 4 Soil profile of charcoal at boulder field site


meter was used to measure pH values for the samples Samples of 20 g were taken and mixed with 20 mL of water and subsequent measurements were recorded CEC was measured through the use of a spectrophotometer using the calcium precipitation method (Weil 1998) In measuring CEC 2 g of soil was used for each sample Samples were saturated in Ca in order to occupy all exchange sites on the colloids The Ca was then precipitated by adding ammonium oxalate The resulting supernatant solution was measured for Ca concentrations and a standard curve was constructed From here CEC was determined using absorption values from the spectrophotometer and measured Ca concentrations

rESultS aNd diScuSSioN

differences in Physical PropertiesWhen comparing the soils at the control sites to the

charcoal hearths there was a difference in color In the control areas the soils yielded color values from 9YR 388 to 81YR 3707 for the A horizons In observing the whole profile for the control areas the colors are generally consistent with the individual site characteristics As for the charcoal hearths the color values measured for the A horizon were more consistent with one another The A horizon of the charcoal hearth at the unsorted till site yielded 86YR 376 and the charcoal soil at the boulder field yielded 86YR 3707 Furthermore as depth increased consistency between the colors of the samples decreased This is not surprising as it is expected that charcoaling only affects the top horizons of a soil profile

Color was also measured using the Lab method in which L measures the degree of lightness (0 being black and 100 being white) a represents how red or green the color is (the higher the value the more red the color) and finally b represents how blue or yellow the color is (the higher the value the more yellow the color) (Turk et al 2008) When examining the Lab color values the charcoal hearth soil was darker (lower L) at the surface at the unsorted till site The soil organic matter at the boulder field was already higher than the unsorted till site As a result charcoaling had less of an effect on the boulder field soils in terms of color It may be concluded that soil color is not particularly affected by charcoaling below a certain depth Soils in the hearths were also slightly greener and bluer (lower a and lower b) Within the A horizon charcoaling produced a similar color within the hearths More study sites should be examined in order to observe and confirm a trend

The trend between charcoal inputs and changes in color was further illustrated by the comparison of L to soil organic matter (SOM) In comparing these values for the boulder field and unsorted till sites it is evident that the charcoal hearths are darker in all instances for all levels of SOM (Fig 5 and 6) The degree of difference in L between charcoal hearth soils and non-hearth soils becomes smaller as SOM increases (Fig 5 and 6)

differences in chemical PropertiesSoils found at historic charcoal hearths have been

shown to exhibit higher pH values than their non-hearth counterparts (Mikan and Abrams 1995) This suggests that long-term charcoal production has the ability to change the pH of the hearth soil The most desirable level of pH for most agricultural crops falls between 65 and 7 on the pH scale Many of the charcoal sites were located away from farming activity and where there were plenty of trees present (Muntz 1960) The land used for charcoaling had not been previously selected for farmland due to its low fertility It is interesting to note that charcoaling has increased the pH values at charcoal hearths contributing to the development of soil more desirable for crop growth pH values were measured and the weighted averages were calculated Analysis of soil pH at the unsorted till control site showed a pH of 469 and the soils found at the respective charcoal hearth yielded a pH of 483 The boulder field control site had a pH of 442 and the respective charcoal site yielded a pH of 504 Not only were the weighted averages higher at the charcoal hearth sites but there was a greater increase in pH relative to depth for the charcoal sites (Fig 7)

The soils found at the charcoal hearth sites were closer to the desirable fertility threshold of 65 to 7 pH than the non-charcoal hearth sites This indicates that the production of charcoal altered the soil and contributed to the formation of a more basic soil Charcoal production generated a lasting impact on the hearth soils leaving them with higher pH over the course of decades This presents a new possibility for agricultural pH management A common practice for agricultural pH management is the application of lime to raise soil pH Since the conventional liming technique requires that lime be applied in large quantities and in frequent intervals it can become a cumbersome process (Brady and Weil 2010) As an alternative to traditional lime charcoal amendments could be used to raise soil pH and would not need to be reapplied nearly as frequently

The study spurred further questions that would be best addressed in future research on charcoal hearths Issues

Fig 5 Comparison of soil L in relation to SOM for the boulder field site

Fig 6 Comparison of soil L in relation to SOM for the unsorted till site


of pH and its relationship between the presence of charcoal inputs and depth should be investigated with the addition of more study sites The study should focus on the degree of impact that charcoaling has on the pH profile at lower depths

The presence of charcoal remains in the hearth soils help generate additional exchange sites which results in a higher CEC (Heitkoumltter and Marschne 2015) The hearth sites within both the boulder field and the unsorted till yielded CEC that was higher than their non-hearth counterparts The boulder field charcoal hearth soils exhibited a weighted average for CEC of 76 cmolckg while the control site had a weighted average for CEC of 67 cmolckg (Fig 8) The control in the unsorted till had a weighted average for CEC of 43 cmolckg and its respective charcoal hearth

had a weighted average for CEC of 51 cmolckg (Fig 8) Higher CEC at the surface may also have the ability to extend to deeper horizons with materials carried through the movement of water over time Results from this study resemble those from a study conducted in Germany (Borchard et al 2014) In the German study their results showed that charcoal hearths had higher CEC but by small margins At the Siegerland acidic rock site the charcoal hearth soils had a CEC of 1136 cmolckg while the non-hearth soils had a CEC of 1072 cmolckg (Borchard et al 2014) They also studied charcoal hearth soils and their non-hearth counterparts at an Eifiel calcareous rock site The charcoal hearth soils had a CEC of 1672 cmolckg while the non-hearth soils had a CEC of 1402 cmolckg (Borchard et al 2014) In their study they attribute the small degree of change to the already high fertility of the soils they studied

There was a clear difference in soil respiration between the charcoal hearth and non-hearth soils Soils in the charcoal hearths respired at higher rates than the control soils In the unsorted till the charcoal soil had a respiration of 4753 CO2 poundsacreday compared to the 2535 CO2 poundsacreday found for the control soil (Fig 9) The same trend was found at the boulder field where the charcoal soilrsquos rate of respiration was 6336 CO2 poundsacreday while the control soilrsquos rate of respiration was 3407 CO2 poundsacreday (Fig 9) The higher levels of respiration found in the soils within the charcoal hearths suggest increased levels of biological activity Net ecosystem production is also affected by rates of respiration A large portion of gross primary productivity (80) is respired back into the atmosphere and of that soil respiration accounts for 70 (Ryan and Law 2005) Therefore soil respiration has a significant impact on the balance of gross primary productivity and as a result net ecosystem production

coNcluSioNHistoric charcoal production in the 18th 19th and early

20th centuries in the Northeastern United States changed the fertility of the soil Charcoal hearths located in Sterling Forest State Park exhibited higher levels of CEC than the samples taken from outside the hearths pH was also found to be higher at the charcoal sites Higher pH does not necessarily relate to higher fertility however the pH levels found in the soils at the charcoal soils (483 and 504 ) are more basic than the non-hearth soils (469 and 442)

Fig 7 pH depth analysis for each site

Fig 8 Weighted averages of CEC for each site

Fig 9 Soil respiration rates at each site


Application of charcoal may be a way of creating a more alkaline environment in the soil to combat the acidification of soil by rain and plant activity over long periods of time pH also increased with depth in the profile It is unclear whether this is due to charcoaling and the long-term effects of illuvial action leaching cations derived from organic material through the soil profile or if it may be attributed to the natural variation in the soil

The relationship between charcoal production and soil color was less strong Color varied with respect to hearth and non-hearth soils but the degree of variation suggests that the changes could be heavily influenced by initial differences in organic matter between the boulder field and the unsorted till sites Soils in the hearths were slightly blacker greener and bluer (lower L lower a and lower b) Perhaps the strongest trend was found with respect to respiration Soil respiration rates were noticeably higher in the charcoal hearth soils than in the non-hearth soils This higher rate of biological activity is a result of charcoal inputs and this fact supports the movement to use charcoal as an amendment in soils in an effort to make them more productive As with the effects on pH color should be further analyzed by establishing more study sites at other charcoal hearths

The effects of charcoaling are long lasting and the presence of charcoal at or near the surface of the soil has an impact on the ability of the soil to support plant growth As can be seen by the results from CEC and color analysis of the soil in addition to the respiration and pH measurements anthropologic changes in the soil are still present after multiple decades This can be beneficial to the health of a soil Alterations made to a soil through charcoal amendments will persist and have long lasting impacts on soil fertility The future of advancement in agricultural biochar technology will have long term impacts and it is critical to understand the specific effects of those alterations as well as their degree of intensity

rEFErENcESBorchard N B Ladd S Eschemann D Hegenberg BM Moseler

and W Amelung 2014 Black carbon and soil properties at historical charcoal production sites in Germany Geoderma 232-234236ndash242 doi101016jgeoderma201405007

Brady NC and RR Weil 2010 Elements of the nature and proper-ties of soil 3rd ed Prentice Hall New York

Hart JL SL van de Gevel DF Mann and WK Clatterbuck 2008 Legacy of charcoaling in a Western Highland Rim forest in Tennessee Am Midl Nat 159238ndash250 doi1016740003-0031(2008)159[238LOCIAW]20CO2

Heitkoumltter J and B Marschne 2015 Interactive effects of biochar ageing in soils related to feedstock pyrolysis temperature and historic charcoal production Geoderma 245-24656ndash64 doi101016jgeoderma201501012

Mikan CJ and MD Abrams 1995 Altered forest composition and soil properties of historic charcoal hearths in southeastern Pennsylvania Can J For Res 25687ndash696 doi101139x95-076

Miranda R 2013 Cogenerating electricity from charcoaling A promising new advanced technology Energy Sustain Dev 17171ndash176 doi101016jesd201211003

Muntz AP 1960 Forests and iron The charcoal iron industry of the New Jersey Highlands Geogr Ann 42315ndash323

Powell A 2012 Identifying archaeological wood stack charcoal production sites using geophysical prospection Magnetic characteristics from a modern wood stack charcoal burn site J Archaeol Sci 391197ndash1204 doi101016jjas201111005

Ryan MG and BE Law 2005 Measuring and modelling soil respiration Biogeochemistry 733ndash27 doi101007s10533-004-5167-7

Schoeneberger PJ DA Wysocki and EC Benham and Soil Survey Staff 2012 Field book for describing and sampling soils Version 30 Natural Resources Conservation Service National Soil Survey Center Lincoln NE

Turk JK BR Goforth RC Graham and KJ Kendrick 2008 Soil Morphology of a debris flow chronosequence in a coniferous forest southern California USA Geoderma 146157ndash165 doi101016jgeoderma200805012

Turk JK and R Kiska 2015 The impact of historical charcoal production on soil properties in the Atlantic Highlands 24ndash25 March Stockton Day of Scholarship Galloway NJ

USDA 1999 Soil Quality Test Kit Guide 1-79

Weil R 1998 Laboratory manual for introductory soils 6th edition KendallHunt Publishing Dubuque IA

Young MJ JE Johnson and MD Abrams 1996 Vegetative and edaphic characteristics on relic charcoal hearths in the Appalachian Mountains Vegetatio 12543ndash50 doi101007BF00045203


(Fig 1 and 2) and the second site was located in a boulder field (Fig 3 and 4) The locations in which the hearths were once present were not obvious to the untrained eye but could be identified by a circular clearing and relative flatness of the hearth They are typically found in this condition although sometimes they are indistinguishable from surrounding forest vegetation (Young et al 1996)

Measurements were taken during the summer for ease of data collection and to allow for the measurement of respiration Slope at the sites varied although slopes measured at the charcoal hearths were low due to the need for hearths to be relatively flat for ease of production In order to use the space for charcoal production the area was

cleared and flattened thus yielding a relatively low slope Aspects at all sites were SSE or SEE Pits were dug at each site and the soil profiles were analyzed according to official NRCS techniques (Schoeneberger et al 2012)

A variety of tests were conducted at our sites On site testing of respiration was conducted using Draeger tubes Measurements were taken during the month of August on site Techniques consistent with the USDA guide for measuring soil quality were used (USDA 1999) Tests that were conducted in the lab were soil color pH and CEC Soil color was measured using a Konica Minolta Chroma Meter Samples were separated by horizon and measured individually filling the Chroma Meter sample dish A pH

Fig 1 Soil profile of control at unsorted till site Fig 2 Soil profile of charcoal at unsorted till site

Fig 3 Soil profile of control at boulder field site Fig 4 Soil profile of charcoal at boulder field site









































































































































Documents

Charcoal Hearth Soils: Remnants of the Iron …...Charcoal Hearth Soils: Remnants of the Iron Industry in the Northeastern U. S. Kevin Hesson* abstract Over the past years there has