Nitrogen Immobilization in Plant Growth Substrates: Clean Chip Residual, Pine Bark, and Peatmoss

Table 1

Physical properties of clean chip residual, pine bark, and peatmoss substrates.^z

Substrates^y	Air space^x	Container capacity^w (% Vol)	Total porosity^v	Bulk density (g·cm^−3)^u
0.48 cm CCR	28 b^t	57 b	85 b	0.22 a
0.95 cm CCR	48 a	42 d	90 b	0.19 b
PB	31 b	48 c	79 c	0.18 b
PM	11 c	87 a	98 a	0.11 c

^zAnalysis performed using the North Carolina State University porometer.
^yCCR: clean chip residual, PB:  pine bark, and PM:  sphagnum peatmoss.
^xAir space is the volume of water drained from the sample/volume of the sample.
^wContainer capacity is (wet weight−oven dry weight)/volume of the sample.
^vTotal porosity is container capacity  +  air space.
^uBulk density after forced-air drying at 105°C (221.0°F) for 48 h.
^tMeans within column followed by the same letter are not significantly different based on Waller-Duncan 𝑘 ratio t-tests at 𝛼  =  0.05 (𝑛  =  3).