Impact of Forage Fertilization with Urea and Composted Cattle Manure on Soil Fertility in Sandy Soils of South-Central Vietnam

Table 10

P values for treatment effects on soil chemical properties in 0 to 15 cm and 15 to 25 cm strata for models containing fixed effects of compost (C), urea (U), compost × urea (C × U), and preexperiment soil fertility measurement for each parameter sampled at 15 to 25 cm depth (PSF), with block as a random effect. Each row represents a single model for each soil depth. Significant values at P ≤ 0.05 are in bold.

Parameter	C	U	C × U	PSF	C	U	C × U	PSF
	0 to 15 cm depth				15 to 25 cm depth
CEC (cmol+/kg)	0.2145	0.6271	0.3142	0.0797	0.6827	0.5997	0.4332	0.0363
pH (1 : 1 soil : water)	0.0071	0.1196	0.0705	<0.0001	0.0460	0.1071	0.0856	<0.0001
OM (g/kg)	0.0087	0.6440	0.0505	<0.0001	0.2699	0.0035	0.7938	<0.0001
S (mg/kg)	0.2249	0.9163	0.0720	0.2507	0.8146	0.7345	0.1171	0.0547
P (mg/kg)	0.6723	0.5556	0.3621	0.0157	0.6537	0.3633	0.4554	0.0001
Ca (mg/kg)	<0.0001	0.4688	0.0147	0.0718	0.1873	0.9323	0.6124	0.2071
Mg (mg/kg)	0.0015	0.2469	0.2219	0.0540	0.0542	0.4886	0.4991	0.0006
K (mg/kg)	0.1703	0.3593	0.7202	0.0301	0.2833	0.1041	0.3959	0.3572
Na (mg/kg)	0.0788	0.6333	0.8865	0.0446	0.1636	0.0246	0.0201	0.3319
B (mg/kg)	0.0954	0.4529	0.4883	0.9517	0.0788	0.2146	0.8916	0.5975
Fe (mg/kg)	0.9956	0.4733	0.2342	0.0020	0.4978	0.9109	0.1584	<0.0001
Mn (mg/kg)	0.0002	0.4951	0.6742	0.9859	0.5170	0.2015	0.3686	0.0002
Cu (mg/kg)	0.5569	0.3744	0.5829	0.0343	0.3963	0.8292	0.4546	0.0003
Zn (mg/kg)	0.8383	0.6481	0.2006	0.1849	0.9202	0.5418	0.0771	0.0046
Al (mg/kg)	0.6086	0.4611	0.6980	<0.0001	0.1240	0.2865	0.1456	<0.0001
NO3-N (mg/kg)	0.5608	0.2398	0.2026	0.1510	0.1936	0.4103	0.2641	0.0885
NH4-N (mg/kg)	0.1017	0.6409	0.1306	0.0155	0.9530	0.5630	0.0386	0.0068