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Table 9.--Results of General Exploratory Experiments, Urambo
and Namanga
I. Urambo Red Soil; groundnut kernels, Ibs. per acre assuming shelling 66.7 per cent. Mean yield 134 lbs. per acre
Standard errors
Effect N
Effect P
...
Interaction NP
Effect K
Mean
Broadcast
Placed
Effect of Placement
+9.4
13.2
+18.7
...
11 43+ - 14
14
8
6
27*
58t
29
-8
19
-11
...
Scil data: pH 6.90, extractable P 0·14, Ca 58 mgm/100 gm.
Standard errors
Effect N Effect P
...
Interaction NP
Effect K
440
II. Urambo Grey Soil, Groundnuts, Kernels, lbs. per acre Mean yield 398 lbs. per acre
...
...
...
Mean
Broadcast
Placed
Effect of Placement
21.1
29.9
+42.3
47*
58
36
-22
45
83*
8
-75
- 16
-38
+6
+44
45
Soil data: pH 7.25, extractable P 1·34, Ca 68 mgm/100 gm.
III. Namanga Red Loam: Fiwi Beans, Green Matter, lbs. per acre Mean yield lbs. per acre
Effect N Effect P
•
...
Interaction NP Effect K
...
Mean
Broadcast
Placed
Effect of Placement
4
20
...
418
378
12 458
·
-32
19
-10
48
40
2888881
80
58
Soil data: pH 5.10, extractable P 0.04, Ca 34 mgm/100 gm.
Effects of this size are not likely to arise by chance in more than 1 in 20 cases.
t
95
""
""
1 in 100 cases.
On the Urambo and Namanga red soils, the dominating effect is that of PO, still further intensified at Urambo by placement. The Urambo grey soil has provided no response to P2O spread immediately above the seed, and there is a nearly significant effect of potash.
Experiments on types of phosphate
The response of the groundnut crop to a range of different types of phosphate may be expected to throw light on several different problems. From the practical point of view, materials cheaper per unit of PO. than processed phosphates may be found. Secondly, information may be obtained on the types of Potpound whichAnder the given soil conditiongean field to the groundnut crop. Thirdly, reactions between phosphates and the soil, leading to immobilisation of soluble P2O, may be indicated.
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