Mean Square

Source of Variation

df

Cu-Carbonate

Cu-Oxide

Cu-Organic

Cu-Residual

Replication (RE)

2

0.018

0.12

0.019

3

Crop residues (P)

2

0.12^*

1.17^***

5.72^***

3.77

Error

6

0.53

0.039

1.094

1.81