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

Table 8

Soil fertility means before and after the experiment at the 15 to 25 cm depth for compost × urea treatment combinations. Elements are Mehlich-3 extractable nutrients. Data from before the experiment are included as a treatment baseline. Means calculated in each cell are an average of 6 farms. The only pair that differed significantly based on a paired one-tailed -test, using the Bonferroni-adjusted P value cutoff of 0.003, is in bold.

Parameter	Compost treatment (Mg DM/ha per yr) / urea treatment (kg N/ha per yr)
	0	4	8	12	24	0	4	8	12	24	0	4	8	12	24
	0	0	0	0	0	60	60	60	60	60	120	120	120	120	120
Before pH (1 : 1 soil : water)	5.37	5.98	5.63	5.87	5.68	5.52	5.27	5.83	5.83	5.63	5.72	5.50	5.82	5.75	5.45
After pH (1 : 1 soil : water)	5.05	5.30	5.47	5.48	5.67	5.58	5.05	5.48	5.37	5.50	5.18	5.32	5.32	5.10	5.32
Before CEC (cmol+/kg)	1.19	1.16	1.19	1.22	1.53	1.52	1.20	1.40	1.29	1.43	1.33	1.17	1.35	1.28	1.23
After CEC (cmol+/kg)	0.922	1.10	1.13	1.16	1.47	1.69	1.05	1.26	1.26	1.26	1.14	1.04	1.31	1.44	1.25
Before OM (g/kg)	4.07	2.58	2.87	3.05	4.15	4.68	3.28	3.35	3.13	3.87	3.98	3.47	3.15	4.22	3.15
After OM (g/kg)	6.82	5.5	5.97	6.65	7.23	6.62	7.12	6.13	6.1	7.48	4.8	4.98	5.53	6.32	5.58
Before S (mg/kg)	9.67	8.00	9.33	7.50	9.50	9.67	9.33	8.67	8.67	10.30	9.83	9.17	8.17	8.50	9.00
After S (mg/kg)	8.67	6.83	7.17	7.33	7.67	6.67	8.50	7.00	7.67	7.50	8.33	7.33	7.67	7.67	7.33
Before P (mg/kg)	36.5	37.7	36.5	27.2	39.0	50.8	33.2	46.2	34.2	39.7	36.2	37.3	42.8	29.3	37.3
After P (mg/kg)	25.3	18.5	24.2	23.5	36.5	29.0	27.7	26.5	22.0	24.2	23.2	20.7	25.3	17.0	24.2
Before Ca (mg/kg)	165	159	165	178	207	198	170	193	159	201	174	162	179	165	150
After Ca (mg/kg)	119	156	154	163	220	181	141	168	185	174	136	141	187	176	169
Before Mg (mg/kg)	25.8	22.0	23.5	22.0	30.2	31.8	22.8	31.3	33.2	29.2	34.3	23.5	30.7	27.7	34.2
After Mg (mg/kg)	20.8	20.2	23.8	24.8	26.7	24.0	21.7	23.5	21.5	26.5	20.0	19.7	25.8	16.2	30.5
Before K (mg/kg)	24.3	35.5	32.7	23.2	47.3	64.8	25.7	29.5	48.3	32.5	26.5	29.5	38.7	33.5	38.2
After K (mg/kg)	12.3	10.7	10.8	11.8	10.2	16.0	12.2	12.0	11.0	12.5	11.0	11.5	11.8	10.7	12.0
Before Na (mg/kg)	21.3	20.7	20.5	18.8	28.8	21.2	20.3	22.5	21.3	23.7	24.2	20.8	24.5	32.5	22.7
After Na (mg/kg)	28.2	29.7	29.3	25.0	27.5	42.3	30.5	28.2	28.0	32.0	26.3	32.0	28.8	28.3	27.8
Before B (mg/kg)	0.135	0.170	0.228	0.208	0.243	0.203	0.135	0.148	0.100	0.262	0.230	0.075	0.203	0.127	0.138
After B (mg/kg)	0.262	0.115	0.125	0.090	0.170	0.290	0.223	0.100	0.207	0.128	0.300	0.235	0.143	0.183	0.313
Before Fe (mg/kg)	132	123	116	97.8	116	153	106	127	115	132	100	128	107	109	114
After Fe (mg/kg)	138	112	120	132	148	154	125	135	127	125	108	122	152	120	121
Before Mn (mg/kg)	8.50	5.83	5.17	8.17	8.17	10.5	6.17	5.67	8.00	6.00	6.33	6.67	8.83	11.5	5.33
After Mn (mg/kg)	6.50	7.00	10.0	8.00	13.7	8.00	9.67	7.00	11.0	6.17	6.17	5.33	9.33	7.50	6.17
Before Cu (mg/kg)	1.74	1.11	1.19	1.24	1.76	1.45	1.20	1.50	1.69	1.50	2.05	1.94	1.17	2.39	1.56
After Cu (mg/kg)	1.81	1.65	2.02	1.67	1.73	1.73	1.74	1.59	1.44	2.05	1.99	1.69	2.24	2.02	1.68
Before Zn (mg/kg)	2.45	1.45	2.06	3.20	3.14	2.72	1.88	1.64	1.76	2.11	3.69	2.09	2.05	10.60	1.61
After Zn (mg/kg)	1.37	2.12	2.17	5.97	3.53	4.13	1.84	1.59	1.89	2.42	3.57	1.98	3.89	2.25	1.60
Before Al (mg/kg)	293	235	306	244	273	285	289	339	246	267	369	292	249	225	265
After Al (mg/kg)	250	192	245	257	254	221	267	248	230	202	313	210	245	230	242
Before NO3-N (mg/kg)	3.93	2.40	2.40	2.67	5.10	3.87	3.15	1.90	3.32	2.68	1.67	2.78	3.48	4.57	2.45
After NO3-N (mg/kg)	1.37	1.33	0.77	1.25	0.400	0.450	1.87	0.533	1.48	0.650	0.850	0.433	1.98	2.57	1.12
Before NH4-N (mg/kg)	8.90	6.13	8.30	6.73	7.60	8.88	8.57	8.65	8.72	8.17	9.73	8.25	7.72	6.70	7.77
After NH4-N (mg/kg)	13.5	9.52	9.82	10.2	10.1	10.2	12.4	9.92	10.6	10.7	11.0	10.4	13.5	10.8	10.6