Tillage Effects on Spatiotemporal Variability of Particulate Organic Matter

Table 4

Effect of standard tillage and no-till on particulate organic matter (POM)-N (BACI^† analysis). All the POM-N fractions were log transformed.

Fraction	Source	DF	Sum of squares	Mean square	𝐹 value	Pr > 𝐹
>1000 𝜇m	Field	1	3.978	3.978	39.33	<0.0001
	Time	2	1.284	0.642	12.56	<0.0001
	Field × time	2	1.510	0.755	14.77	<0.0001
	Location (field)	70	7.087	0.101	1.98	0.000
	Residual	140	7.106	0.051
	Contrast^‡
	𝑇0−𝑇1	1			29.17	<0.0001
	𝑇0−𝑇2	1			11.08	0.001
	Overall means	1			25.41	<0.0001
250–1000 𝜇m	Field	1	0.920	0.920	40.65	<0.0001
	Time	2	0.834	0.417	25.22	<0.0001
	Field × time	2	1.144	0.572	34.61	<0.0001
	Location (field)	70	1.584	0.023	1.37	0.060
	Residual	140	2.314	0.017
	Contrast
	𝑇0−𝑇1	1			59.75	<0.0001
	𝑇0−𝑇2	1			42.63	<0.0001
	Overall means	1			67.77	<0.0001
53–250 𝜇m	Field	1	0.115	0.115	9.43	0.003
	Time	2	0.604	0.302	47.87	<0.0001
	Field × time	2	0.245	0.123	19.44	<0.0001
	Location (field)	70	0.854	0.012	1.93	0.0005
	Residual	140	0.882	0.006
	Contrast
	𝑇0−𝑇1	1			38.16	<0.0001
	𝑇0−𝑇2	1			14.64	0.000
	Overall means	1			33.35	<0.0001

^†BACI: Before-After and Control-Impact model.
^‡Difference in the interaction of field and time between August 2003 (𝑇₀), April (𝑇₁), and October 2004 (𝑇₂).