Table 3.

Treatment effects (p values) for the nitrogen uptake by different maize organs at silking and physiological maturity for four fixed factors (year, mulch, nitrogen fertilizer application rate, and planting density)

Sources	Nitrogen uptake at the silking				Nitrogen uptake at physiological maturity
	Leaf	Stem	Cob	Grain	Leaf	Stem	Cob	Grain
Year (Y)	0.003	0.001	<  0.001	<  0.001	0.002	ns	<  0.001	<  0.001
Mulch (M)	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001
Nitrogen (N)	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001
Density (D)	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001
Y * M	ns	ns	ns	ns	ns	ns	ns	ns
Y * N	ns	ns	ns	ns	ns	ns	ns	ns
Y * D	ns	ns	ns	ns	ns	ns	ns	ns
M * N	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001	<  0.001
M * D	0.034	ns	ns	<  0.001	0.006	0.002	ns	0.001
N * D	ns	ns	<  0.001	0.007	ns	ns	<  0.001	0.012
Y * M * N	ns	ns	ns	ns	ns	ns	ns	ns
Y * M * D	ns	ns	ns	ns	ns	ns	ns	ns
Y * N * D	ns	ns	ns	ns	ns	ns	ns	ns
M * N * D	ns	0.05	0.005	<  0.001	0.01	0.008	0.007	0.028
Y * M * N * D	ns	ns	ns	ns	ns	ns	ns	ns

Note: ns Not significant (p > 0.05)