Impact of Forage Fertilization with Urea and Composted Cattle Manure on Soil Fertility in Sandy Soils of South-Central Vietnam
Table 1
Preexperiment soil fertility levels at 15 to 25 cm depth on six farms in Cát Trinh Commune.
Parameter
Overall mean
Overall SD
Farm means ()
()
Farm 1
Farm 2
Farm 3
Farm 4
Farm 5
Farm 6
CEC (cmol+/kg)
1.3
0.60
2.4
1.4
1.3
0.9
0.9
1.0
pH (1 : 1 soil : water)
5.67
0.658
5.98
5.53
6.23
5.76
4.63
5.88
OM (g/kg)
3.5
2.1
5.2
4.5
2.1
1.6
5.1
2.5
S (mg/kg)
9.1
4.47
10.1
9.9
6.3
5.6
17.0
5.6
P (mg/kg)
37
27.3
67
41
68
22
14
12
Ca (mg/kg)
176
68.3
269
204
190
126
116
151
Mg (mg/kg)
29
23.3
71
19
28
17
21
16
K (mg/kg)
36
36.2
91
41
32
11
31
12
Na (mg/kg)
23
13.1
43
20
19
19
21
17
B (mg/kg)
0.18
0.19
0.25
0.38
0.24
0.01
0.15
0.04
Fe (mg/kg)
116
75.2
180
142
153
28
169
27
Mn (mg/kg)
7
7.5
14
7
16
1
2
5
Cu (mg/kg)
1.6
1.29
3.3
2.3
1.6
0.6
1.1
0.6
Zn (mg/kg)
2.7
5.43
4.4
7.1
1.5
0.4
1.0
1.6
Al (mg/kg)
280
179.7
375
346
235
116
540
72
NO3-N (mg/kg)
3
2.6
5
5
1
1
5
2
NH4-N (mg/kg)
8
4.1
5
15
7
6
8
7
Ca : Mg
7.8
3.79
4.2
12.5
7.2
7.7
5.6
9.4
CEC: cation exchange capacity determined by summation of cations Ca, Mg, K, Na, and H, according to Ross [15]. Soil organic matter (OM) was determined by loss-on-ignition at 360°C [16]. Elements are Mehlich-3 extractable nutrients [17]. Aluminum toxicity might be an issue due to low pH (<5) on farm 5.
