Table 2 shows the meansfor individual soil properties from different cropping systems in different regions. In general, pH was significantly higher in Kiboga region compared to Luwero. But the soil pH of Ntungamo region was not significantly different from that of Kiboga and Luwero region. Kiboga region had the highest organic matter content compared to the rest of the regions. This was significantly different from that of Ntungamo but not Luwero region. Nitrogen content was also highest in Kiboga region compared to the other two regions. But this was only significantly different from that of Ntungamo region. Amongst the exchangeable cations, potassium levels were significantly high in Ntungamo compared to the rest of the regions. Calcium content was highest in soils from Kiboga region compared to the other two regions. But this was significantly different from that of Luwero only. On the other hand, magnesium content was highest in Luwero region compared to those in Kiboga and Ntungamo regions. It was significantly different from those in other two regions. Available phosphorus was significantly high in Ntungamo region when compared to the rest of the regions. Manganese content was significantly high in Luwero compared to the other regions of Kiboga and Ntungamo. Luwero region had the highest clay content; this was significantly different from that of Kiboga but not for Ntungamo region.
Different cropping systems also generally exhibited significant difference in potassium, calcium, magnesium, available Phosphorus and manganese contents in the soil (Table 2). Potassium levels were significantly highest in cropping systems where bananas susceptible to race 1 strains of Fusarium wilt disease were intercropped with annual crops, perennial crops or integrated with livestock when compared to mono crop of bananas susceptible to race 1 strains of Fusarium wilt disease. But potassium content in monocrop of bananas susceptible to race 1 strains of Fusarium wilt disease was also not significantly different from that where bananas susceptible to race 1 strains of Fusarium wilt disease were mixed with other bananas varieties.
Calcium content was highest in soils from cropping systems where bananas susceptible to race 1 strains of Fusarium wilt disease were intercropped with perennial crops. This was only significantly different in soils from cropping systems where bananas susceptible to race 1 strains of Fusarium wilt disease were intercropped with annual crops. But the calcium content in soils from cropping systems where susceptible bananas intercropped with annual crops wasalsonot significantly different from soils from the rest of the cropping systems.
Magnesium contents were highest in soils from cropping systems where bananas susceptible to race 1 strains of Fusarium wilt disease were integrated with livestock. This was only significantly different from soils from cropping systems where bananas susceptible to race 1 strains of Fusarium wilt disease were intercropped with annual crops. But the magnesium content in soil from these two cropping systems were not significantly different from soils from the rest of the cropping systems.
Available phosphorus was significantly lowest in soils obtained from cropping systems where bananas susceptible were grown as a mono crop. This was different from all cropping systems except in cropping systems where bananas susceptible to race 1 strains of Fusarium wilt disease were intercropped with annual crops.
Manganese contents in soil obtained from cropping systems where bananas susceptible to race 1 stains of Fusarium wilt disease were intercropped with annual crops were significantly different from that in soils obtained from all the cropping systems except from that where bananas susceptible to race 1 strains of Fusarium wilt disease were grown as a mono crop.
Table 3 shows the relationship between the individual soil properties with each other and severity of race 1 strains of Fusarium wilt disease on susceptible bananas. All the soil properties were correlated to each other. For instance, the soil pH was positively correlated to potassium, calcium and phosphorus, but it was negatively correlated to manganese and clay. Organic matter content was positively correlated to all the other soil properties except for available phosphorus, but it was strongly correlated to nitrogen. Similarly, nitrogen was also positively correlated to all the other soil properties except phosphorus and manganese. Potassium was positively correlated to calcium, magnesium and phosphorus, while it was negatively correlated to manganese and clay. Calcium was negatively correlated to manganese and clay, while it was positively correlated to magnesium and phosphorus. Magnesium was negatively correlated to manganese and clay but positively correlated to phosphorus. On the other hand, phosphorus was negatively correlated to both clay and manganese. While clay was positively correlated to manganese.
The severity of race 1 strains of Fusarium wilt disease on susceptible bananas showed a relatively weak positive correlation with organic matter content, nitrogen, magnesium, manganese and clay. But on the other hand, it showed a relatively weak negative correlation with the pH, potassium, calcium and phosphorus.
Table 2
Means and standard deviations of chemical and physical status for soils from different cropping systems in the different regions of Uganda
Region
|
Cropping system
|
pH
|
OM
|
Nitrogen
|
K
|
Ca
|
Mg
|
Available P
|
Mn
|
Clay
|
Sample size (N)
|
|
%
|
Cmoles/kg
|
ppm
|
%
|
Luwero
|
Mono crop of susceptible bananas
|
5.7 ± 0.33
|
2.97 ± 1.001
|
0.154 ± 0.045
|
0.544 ± 0.130
|
5.66 ± 1.569
|
2.19 ± 0.553
|
9.93 ± 16.019
|
44.2 ± 9.46
|
17.37 ± 2.973
|
8
|
Mixed banana species
|
5.7 ± 0.47
|
2.71 ± 0.726
|
0.150 ± 0.033
|
0.515 ± 0.139
|
5.13 ± 1.893
|
2.07 ± 0.769
|
13.36 ± 17.126
|
43.5 ± 11.72
|
19.50 ± 7.071
|
8
|
Intercropped with annual crops
|
5.4 ± 0.25
|
3.62 ± 1.002
|
0.185 ± 0.056
|
0.611 ± 0.175
|
4.04 ± 0.913
|
1.94 ± 0.463
|
6.89 ± 9.450
|
53.0 ± 9.93
|
19.12 ± 7.772
|
8
|
Intercropped with perennial crop
|
5.8 ± 0.51
|
4.05 ± 0.913
|
0.209 ± 0.052
|
0.614 ± 0.097
|
6.21 ± 2.123
|
2.22 ± 0.666
|
10.84 ± 9.822
|
39.2 ± 14.41
|
19.57 ± 5.533
|
7
|
Integrated with animals
|
6.0 ± 0.69
|
2.96 ± 1.032
|
0.163 ± 0.039
|
0.574 ± 0.152
|
6.14 ± 2.089
|
2.78 ± 0.915
|
19.28 ± 21.273
|
37.1 ± 14.59
|
17.75 ± 5.007
|
8
|
Total
|
5.7 ± 0.48b
|
3.24 ± 1.018a
|
0.171 ± 0.048a
|
0.571 ± 0.140b
|
5.42 ± 1.855b
|
2.24 ± 0.718a
|
12.09 ± 15.314b
|
43.5 ± 12.77a
|
18.64 ± 5.682a
|
39
|
Kiboga
|
Mono crop of susceptible bananas
|
6.3 ± 0.77
|
3.39 ± 1.144
|
0.198 ± 0.054
|
0.453 ± 0.116
|
6.08 ± 1.061
|
1.89 ± 0.476
|
8.51 ± 8.188
|
28.5 ± 12.17
|
12.50 ± 5.071
|
8
|
Mixed banana species
|
5.9 ± 0.27
|
3.60 ± 0.826
|
0.180 ± 0.050
|
0.436 ± 0.076
|
5.86 ± 0.832
|
1.71 ± 0.585
|
16.70 ± 10.574
|
22.3 ± 6.01
|
15.20 ± 5.070
|
5
|
Intercropped with annual crops
|
5.9 ± 0.61
|
2.88 ± 0.857
|
0.174 ± 0.047
|
0.530 ± 0.218
|
5.66 ± 0.949
|
1.58 ± 0.475
|
23.88 ± 42.892
|
32.5 ± 7.34
|
16.00 ± 6.000
|
8
|
Intercropped with perennial crop
|
6.3 ± 0.47
|
3.11 ± 1.003
|
0.170 ± 0.037
|
0.590 ± 0.297
|
7.39 ± 1.243
|
2.13 ± 0.729
|
41.64 ± 53.535
|
22.5 ± 7.46
|
12.50 ± 7.521
|
8
|
Integrated with animals
|
6.3 ± 0.22
|
3.85 ± 0.617
|
0.203 ± 0.011
|
0.717 ± 0.291
|
6.53 ± 0.304
|
2.30 ± 0.585
|
60.14 ± 67.561
|
26.9 ± 8.36
|
14.14 ± 1.773
|
7
|
Total
|
6.2 ± 0.54a
|
3.33 ± 0.935a
|
0.185 ± 0.042a
|
0.549 ± 0.2347b
|
6.33 ± 1.105a
|
1.93 ± 0.605b
|
30.46 ± 45.844b
|
26.9 ± 9.10b
|
13.97 ± 5.412b
|
36
|
Ntungamo
|
Mono crop of susceptible bananas
|
5.7 ± 0.70
|
2.24 ± 0.356
|
0.126 ± 0.020
|
0.460 ± 0.1347
|
5.28 ± 0.915
|
1.54 ± 0.473
|
19.92 ± 19.511
|
26.5 ± 7.06
|
20.40 ± 4.506
|
5
|
Mixed banana species
|
6.5 ± 0.46
|
2.35 ± 0.603
|
0.122 ± 0.016
|
1.086 ± 0.5070
|
7.44 ± 1.452
|
1.90 ± 0.571
|
141.72 ± 91.381
|
22.5 ± 1.55
|
13.20 ± 4.919
|
5
|
Intercropped with annual crops
|
6.0 ± 0.57
|
2.82 ± 0.329
|
0.148 ± 0.026
|
0.994 ± 0.5483
|
5.82 ± 0.798
|
1.71 ± 0.470
|
70.34 ± 64.531
|
27.7 ± 6.71
|
14.00 ± 2.550
|
5
|
Intercropped with perennial crop
|
6.0 ± 0.74
|
2.89 ± 0.900
|
0.138 ± 0.032
|
0.850 ± 0.3976
|
5.69 ± 1.393
|
2.00 ± 0.742
|
87.50 ± 89.181
|
32.0 ± 11.80
|
17.00 ± 4.036
|
8
|
Integrated with animals
|
5.7 ± 0.50
|
2.85 ± 0.874
|
0.140 ± 0.037
|
0.876 ± 0.4383
|
5.23 ± 1.080
|
1.70 ± 0.440
|
95.63 ± 90.462
|
28.7 ± 4.99
|
17.14 ± 3.388
|
7
|
Total
|
6.0 ± 0.64ab
|
2.67 ± 0.714b
|
0.135 ± 0.028b
|
0.854 ± 0.4437a
|
5.83 ± 1.340ab
|
1.79 ± 0.554b
|
84.31 ± 82.110a
|
28.0 ± 7.89b
|
16.47 ± 4.369ab
|
30
|
|
Mono crop of susceptible bananas
|
5.9 ± 0.65
|
2.96 ± 1.018
|
0.164 ± 0.052
|
0.489 ± 0.1272b
|
5.73 ± 1.234ab
|
1.92 ± .544ab
|
11.77 ± 14.547b
|
34.0 ± 12.69ab
|
16.24 ± 5.157
|
21
|
Mixed banana species
|
6.0 ± 0.53
|
2.86 ± 0.843
|
0.151 ± 0.040
|
0.652 ± 0.3844ab
|
5.97 ± 1.763ab
|
1.93 ± 0.652ab
|
49.94 ± 74.458a
|
31.8 ± 13.48b
|
16.56 ± 6.345
|
18
|
Intercropped with annual crops
|
5.8 ± 0.53
|
3.15 ± 0.879
|
0.172 ± 0.047
|
0.671 ± 0.3505a
|
5.08 ± 1.201b
|
1.75 ± 0.474b
|
28.47 ± 46.272ab
|
39.1 ± 13.78a
|
16.71 ± 6.278
|
21
|
Intercropped with perennial crop
|
6.0 ± 0.61
|
3.32 ± 1.028
|
0.170 ± 0.049
|
0.688 ± 0.3093a
|
6.44 ± 1.699a
|
2.11 ± 0.689ab
|
48.22 ± 67.009a
|
30.9 ± 12.90b
|
16.22 ± 6.353
|
23
|
Integrated with animals
|
6.0 ± 0.56
|
3.21 ± 0.9412
|
0.168 ± 0.040
|
0.715 ± 0.3210a
|
5.97 ± 1.453ab
|
2.29 ± 0.799a
|
56.57 ± 69.539a
|
31.2 ± 10.93b
|
16.41 ± 3.887
|
22
|
Total
|
5.9 ± 0.58
|
3.11 ± 0.9457
|
0.166 ± 0.046
|
0.644 ± 0.3138
|
5.85 ± 1.523
|
2.01 ± 0.659
|
39.02 ± 59.682
|
33.4 ± 12.89
|
16.42 ± 5.559
|
105
|
The severity of race 1 strains of Fusarium wilt disease varied at different levels of soil properties (Table 4). At low levels of either pH or phosphorus, the severity of race 1 strains of Fusarium wilt disease on susceptible bananas in farmer’s fields was highest compared to when either of the individual soil properties (pH or P) were low, but the severity of the disease was not significantly different from each other when either of the individual soil properties was at a higher or lower levels. On the other hand at high levels of either potassium or clay content in the soil, the severity of race 1 strains of Fusarium wilt disease on susceptible bananas was high compared to when any of the individual soil property was at low levels.But these differences were not significantly different from each other.
Table 5 shows individual soil properties for different soil typologies. Soil type 1 exhibited a significantly higher pH level compared to soil type 2. Furthermore, it exhibited significantly higher potassium, calcium and available phosphorus contents compare to soil type 2. While it showed significantly lower manganese and clay contents compared to soil type 2.
But on the other hand, field results show that soil type 2 exhibited significantly higher severity of race 1 strains of Fusarium wilt disease compared to soil type 1 (Table 5). Results of the pot experiment for soil type 2 also showed that all the treatments i.e. where soils were not sterilised, sterilised only and sterilized and inoculated with race 1 strains of Fusarium wilt had higher severity of disease on susceptible bananas compared to their respective treatments under soil type 1. However, the respective treatments under soil type 1 and 2 were not significantly different from each other.
Table 3
Relationship between individual soil properties and severity of race 1 strains of Fusarium wilt disease on susceptible bananas in Uganda
| pH | OM | N | K | Ca | Mg | P | Mn | Clay | SI |
pH | 1.00 | | | | | | | | | |
OM | 0.11 | 1.00 | | | | | | | | |
N | 0.15 | 0.85 | 1.00 | | | | | | | |
K | 0.40 | 0.09 | 0.01 | 1.00 | | | | | | |
Ca | 0.78 | 0.07 | 0.12 | 0.32 | 1.00 | | | | | |
Mg | 0.29 | 0.09 | 0.08 | 0.03 | 0.48 | 1.00 | | | | |
P | 0.52 | -0.03 | -0.12 | 0.87 | 0.41 | 0.01 | 1.00 | | | |
Mn | -0.57 | 0.01 | -0.01 | -0.14 | -0.63 | -0.15 | -0.32 | 1.00 | | |
Clay | -0.38 | 0.05 | 0.01 | -0.27 | -0.32 | -0.06 | -0.33 | 0.27 | 1.00 | |
SI | -0.08 | 0.18 | 0.15 | -0.08 | -0.03 | 0.15 | -0.22 | 0.33 | 0.11 | 1.00 |
SI = severity of race 1 strains of Fusarium wilt disease
Table 4
Means and standard deviations in parenthesis of severity of race 1 strains of Fusarium wilt disease at low and high levels of individual soil properties from different plots in Uganda
Nutrients
|
SI
|
Low
|
High
|
pH
|
19.05(12.34)
|
14.80(12.81)
|
K
|
16.23(9.32)
|
17.24(14.14)
|
P
|
15.23(11.24)
|
13.65(11.69)
|
Clay
|
16.21(9.29)
|
18.42(11.61)
|
Sample size (N)
|
25
|
25
|
SI = Severity of race 1 strains of Fusarium wilt disease
Table 5
Means and standard deviations ofindividual soil properties and disease severity in the field and pot experiment for different soil types in Uganda
Soil type
|
pH
|
OM
|
N
|
K
|
Ca
|
Mg
|
Available P
|
Mn
|
Clay
|
Field
|
CDIfor pot experiment
|
N
|
SI
|
Not ST
|
ST only
|
ST + FOC
|
|
%
|
Cmoles/kg
|
Ppm
|
%
|
|
|
|
|
1
|
6.5a
(0.43)
|
2.92
( 0.80)
|
0.15
( 0.04)
|
1.24 a
(0.29)
|
6.88 a
(1.19)
|
1.93
(0.45)
|
162.96a
(43.39)
|
25.4 b
(5.21)
|
12.53 b
( 4.14)
|
10.9b
(7.79)
|
1.06
(0.24)
|
1.00
(0.00)
|
3.72
(1.49)
|
17
|
2
|
5.8 b
(0.55)
|
3.15
( 0.97)
|
0.17
( 0.05)
|
0.53 b
(0.14)
|
5.65 b
( 1.51)
|
2.02
(0.69)
|
15.08b
( 18.17)
|
34.9 a
(13.37)
|
17.17 a
(5.50)
|
17.17a
(11.51)
|
1.48
(1.16)
|
1.02
(0.15)
|
4.40
(1.65)
|
88
|
Overall
|
5.9
(0.58)
|
3.11
( 0.95)
|
0.17
( 0.05)
|
0.64
(0.31)
|
5.85
(1.52)
|
2.01
( 0.66)
|
39.02
(59.68)
|
33.37
(12.89)
|
16.42
(5.56)
|
16.16
(11.20)
|
1.41
(1.067)
|
1.02
(0.14)
|
4.26
(1.65)
|
105
|
Note: figures in parenthesis = Standard deviations of the variables, Variable with different letters in the same column were significantly different from each other using a t-test, while those with no letters were not significantly different from each other, Field = direct observation from the field surveys, CDI = Corm Discolouration Index, Not ST = Not sterilized soil, ST soil only = Sterilized only, ST + FOC = Sterilized soil + race 1strains of Fusarium wilt |