UMBS DIRT Organic Matter of Oea/A Soils from 2004 to 2009
Written by Jim LeMoine (12/18/2009)
Updated by John Den Uyl (2/22/2018)
The "UMBS_DIRT_OeaA_Soil_Organic_Matter_2004_2009.csv" file contains data for calculating organic matter pool sizes for the organic rich surface layer (Oea/A) in the UMBS DIRT plots for 2004, 2005, and 2009. Included in the "Oea/A_Organic_Matter" sheet are calculations for percent organic matter in oven dry (105ºC) soil derived from the ash weight. Soils were ashed in a muffle furnace for 14 hours (430ºC) in each sampling year.
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.
Processing Methods
Personnel involved: Jim LeMoine
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 #
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