UMBS DIRT Soil C:N from 2004 to 2014
Written by John Den Uyl (2/27/2018)
This file contains percent (%) Carbon and Nitrogen, C:N ratios, and Carbon and Nitrogen content per square meter for soils sampled from 3 depths (Oea/A, 0-10 cm, 10-20 cm) for each of the 9 DIRT treatments.
The "UMBS_DIRT_C_N_by_Treatment_2004_2014.csv" file includes C:N, C Content and N Content means calculated on the treatment level (3 samples per plot, 3 plots per treatment) for each year and depth.
All %C and %N measurements were obtained using a Perkin Elmer 2400 Series II Elemental Analyzer.
Sampling Methods
Written by Jim LeMoine (November 2004)
Personnel involved: Jim LeMoine, Pat Micks
Samples were collected directly beneath 3 soil respiration collars in each plot. We collected 3 Oea/A ‘brownies’ per plot.
Oea/A: Soil respiration collars were carefully removed and recent litter and still-recognizable Oe material were brushed away. Using a sharp knife, a spatula, and a 14 cm x 14 cm we cut and collected a ‘brownie’ consisting of the remainder of the Oe material, the Oa material, and the A horizon soil. We tried to keep the brownie intact but in many cases the circular cut from the respiration collar caused the brownie to fall apart. For most samples the uppermost mineral soil was a mixture of grey and dark brown material, grading to all grey with depth. In order to capture the A horizon we collected all of the grey-brown mixture in locations where this layer was thin. In other cases where this layer was very deep, changing color gradually to all gray, we did not collect all of it but rather kept the brownie to no more than about 6 cm depth. If we sampled too deeply we scraped the gray soil off of the bottom of the brownie and let it fall back into the sample hole. After the brownie was removed and placed in a ziploc bag, we patted the mineral soil evenly over the bottom of the hole and recorded the depth of the hole on each of 4 sides (1 measurement per side) to the nearest half-centimeter. We have removed all recognizable fragments from the O layer but are still calling it Oea.
Mineral: We used a 30 cm AMS stainless steel split corer with a slide hammer to collect the mineral samples from the same locations as the brownies were taken. Three 10 cm long clear plastic sleeves (7.62cm diameter) were placed in the core body. The corer was driven 20 cm into the soil, starting at the exposed mineral soil surface at the bottom of the brownie hole. The soil was moderately moist and held together well in the sampler. After the corer was opened, the 0-10 and 10-20 cm sections were separated slightly and the boundary between them cut with a knife. The two samples were bagged separately in ziploc bags. This procedure was followed for each of the three sampling locations in each plot.
Processing Methods
Personnel involved: Jim LeMoine
Oea/A:
1. Recorded fresh weight of brownie + bag.
2. Dumped brownie onto sieve and weighed empty ziploc bag.
3. Sieved brownie through 5.6 mm sieve.
4. Weighed sieved material in pan (wt. of pan previously recorded) and recorded pan #
<
p>Mineral:
Mineral soils were run through a 2mm sieve, and all material <2mm was bagged, weighed, and dried in a drying oven at 105C.
Other Terms:
Oea/A Organic matter rich surface layer of the soil (includes, Oe, Oa, and A layers)
SOM Soil Organic Matter
-9999.99 Indicates no directly observed measurement