Tillage Effects on Spatiotemporal Variability of Particulate Organic Matter
Table 6
Significance of effects of soil physical properties on particulate organic matter (POM) C and N fractions, accounting for effects of field and time. All POM fraction values were log-transformed.
Effect
1000 m POM
250–1000 m POM
53–250 m POM
POM-C
-value
Field
0.0001
.0001
0.0001
Time
0.0001
.0001
0.0001
Sand
0.0416
.5101
0.0801
Clay
0.1504
.3504
0.0010
Bulk density
0.0010
.0001
0.0001
Field time
0.0001
.0001
0.0001
Time clay
0.0043
.0155
0.7712
Time bulk density
0.0196
.0016
0.0399
Std. Dev. location
NA†
.0969
0.0935
Std. Dev. residual
0.5762
.2717
0.1499
POM-N
-value
Field
0.0001
.0001
0.0001
Time
0.0001
.0001
0.0001
Sand
0.0001
.015
0.8818
Clay
0.1786
.0912
0.0004
Bulk density
0.1767
.0011
0.0001
Field time
0.0001
.0001
0.0001
Field clay
–‡
–
0.2774
Time clay
–
–
0.7443
Fieldtimeclay
–
–
0.0017
Std. Dev. location
0.1858
.0932
0.0814
Std. Dev. residual
0.5061
.2749
0.1631
: not applicable. The likelihood ratio test indicated that the random effect for location was not necessary and thus it was removed from the model according to Pinheiro and Bates (2000). effect was removed from the model because it was not significant at the level of 2%.
