1. Chemical Properties of Forest Soils in the Catskills Region
Chris E. Johnson & Charles T. Driscoll
Dept. of Civil & Environmental Engineering
Syracuse University

2. Catskills Soils Predominantly Inceptisols Work of Michael Kudish
Derived largely from glacial till. High stone content.
Minimal horizonation evident. Sandy loam texture. Various classifications: Dystrochrepts, Haplaquepts, Fragiochrepts, Fragiaquepts.
Work of Michael Kudish
Forest species distribution related to soil/till depth. No relation to chemistry (pH), due to minimal variation within region.
Recent work
Lawrence, Semion, Murdoch – 200 sites across region. O horizons and top 10 cm. Some deeper sampling. Related to stream chemistry – “base cation surplus”
Lovett, Goodale – largely O and A horizons. Addressing N cycling and forest ecology questions.

3. 2011 Soil Sampling Campaign
Goals:
Establish a baseline for future monitoring.
Examine relationships between soil chemistry and stream chemistry
Provide data for biogeochemical modeling.

4. Sampling Sites Twenty-five headwater catchments:
Selected from sites studied by Lovett et al. (2000)

5. Site Selection In each watershed:
One site near stream sampling location.
One site at elevation approximately half-way between stream sampling site and watershed divide.
Total = 50 pits [25 watersheds x 2 pits]
Sample sites that actually have soil
Sample range of forest types
State land – low probability of land-use change

6. Catskills Study Watersheds

7. Sampling Method
“Quantitative” soil pits

8. Sampling Method “Quantitative” soil pits:
Direct measurement of soil mass (kg m-2)
Calculate soil chemical pools
Layers sampled:
Oi+Oe
Oa/A
Mineral soil by depth increment: 0-10 cm, 10-20, 20-C

9. Processing and Storage
Air-drying to constant mass
Dry sieving
5-mm – Oi+Oe and Oa/A samples
2-mm – Mineral soil layers
Subsamples oven-dried (80 oC) and combusted (500 oC)
Stored in glass jars
Archiving
Currently at Syracuse University
Hoping to archive at NY State Museum

10. Chemical Analysis Analytes: Loss-on-Ignition ≈ Organic matter content
Total C, N (Combustion/GC)
Soil pH (DI water, 0.01 M CaCl2)
Exchangeable Ca, Mg, K, Na (NH4Cl extraction)
Exchangeable Acidity, Al, H (KCl extraction)
“Effective” Cation Exchange Capacity (by summation)
Total Acidity (BaCl2 extraction)
Organically Bound Al (CuCl2 extraction)

11. Soil Depth Distribution

12. Soil Mass and Physical Properties
Horizon/Layer
Soil Mass
(kg m-2)
Coarse Fragments (% of Volume)
Bulk Density
(Mg m-3)
Oi+Oe
1.4
---
Oa/A
0.4
0-10 cm
32.3
25.8
0.44
10-20 cm
43.1
27.3
0.65
20 cm – C Horizon
123
24.9
0.60
Total
210

13. Organic Horizons Average Thickness: 2.96 cm (± 1.48 cm)
Oi+Oe Horizons:
50/50 Sites
Average Mass: 1.4 kg m-2
Average LOI: 89.1%
Average Carbon: 46.8%
C:N Ratio: 19.8
Oa/A Horizons:
22/50 Sites
Average Mass: 0.4 kg m-2
Average LOI: 63.9%
Average Carbon: 31.9%
C:N Ratio: 17.0

14. Soil Carbon and Nitrogen
Horizon/Layer
Soil Carbon
(Mg ha-1)
Soil Nitrogen
C:N Ratio
Oi+Oe
6.6
0.34
19.8
Oa/A
1.5
0.08
17.0
0-10 cm
17.8
1.16
16.1
10-20 cm
11.1
0.80
13.9
20 cm – C Horizon
21.2
1.53
13.4
Total
58.2
3.91
14.9

15. Soil Acidity

16. Exchange Capacity and Base Saturation

17. Potential Acidity

18. Potential Acidity
Catskills
Data
Woods Lake,
Adirondacks

19. Soil Nutrient Pools Horizon/Layer Soil Nitrogen (kg ha-1) Exch. Ca
Exch. Mg
Exch. K
Oi+Oe
340 63 9 13
Oa/A 80 12 2
0-10 cm
1160
133 21 23
10-20 cm
800 71 15
20 cm – C Horizon
1530
123 19 26
Total
3910
302 79
Hubbard Brook Soil
6890
265 35
107
Hubbard Brook Trees
792
710 69
298

20. Relation to Stream Chemistry

21. Relation to Stream Chemistry

22. Conclusions
Forest soils in the Catskills are predominantly stony, acidic Inceptisols, developed largely in glacial till.
Quantitative sampling of 50 sites in headwater catchments revealed an average depth to C horizon of 50 cm.
Organic horizons average 3 cm in thickness, with true humus layers occurring at fewer than half of our sites.

23. Conclusions
Soil pH ranges from 3.5 to 5.0. Despite the high acidity, exchangeable Ca and cation exchange capacity are moderate, compared to other forest soils in the northeastern US.
Due to low soil masses, pools of mineral nutrients are small compared to vegetation pools, with implications for sustainable forestry.
The exchangeable Ca pool in the soil represents about 20 years of stream Ca flux at current concentrations.