CAB129-37 — Page 373

Page 373.

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196

Although the festfit

'aré

somewhat variable, theregs omstendency for

responses to be lower at the lower rates than would be expected from the response to the top rate. It is noteworthy that the response at top rate is similar to that obtained in the exploratory experiments at the comparable rate of placement of N and P.

Results for groundnuts of Urambo and fiwi bean weights at Namanga show similar trends:-

Crop

Table 14.-Results of Experiments on Rate of Application of Standard

Fertiliser at Urambo and Namanga, 1947-48

Centre

Soil type

· Unit

Plant No: C00/acre Yield, no fertiliser

***

...

Urambo Red

Urambo Grey Groundnuts

Groundnuts

lbs, kernels/acre lbs. kernels/acre

22.4

106

21.4

334

Namanga Red Loam

Fiwi bean

lbs. fresh wt./acre-

526

I. Responses

46 lb. fertiliser

93 lb. fertiliser

186 lb. fertiliser

...

...

S.E. of responses ±

II. Soil data

pH...

Extracted P mgm./100gm.

Extracted Ca mgm./100gm.

22

1

121

86

66

393

63

107

569

38.1

70.1

6.0

7.4

5.1

...

0.23 38

0.80 42

0.10

22

Experiments on calcium nutrition of groundnuts

For the reasons set out in Section 4, p. 108, a series of experiments was set out to examine the effect on the crop of ground limestone and gypsum at three rates of application-applied broadcast before sowing, placed 2 inches either side of the row, and spread on the plants at first flowering, 6 to 8 weeks after sowing. The limestone and gypsum were placed using standard equipment with a modification to make the application of the middle rate possible. To place the highest rate it was necessary to run over the plots twice, delivering half the application on each run, and sowing seed on the second run. These experiments. also served to give further information on the lime requirements of the soils.

The limestone used was a lacustrine magnesian limestone from Sagara, Kongwa. district (CaO 40 per cent. MgO 3.2 per cent.), and it was applied at 2, 4 and 8 cwt. per acre. Gypsum, from Mkomazi, Korogwe district, was applied at rates calculated to give equivalent CaO. The design used was a 3x3x3 design in three blocks. plot size being 0.014 acre. The results at Kongwa are shown in. Table 15.

Table 15.-Experiments on Calcium Nutrition of Groundnuts, Kongwa, 1947-48

(Lbs. kernels per acre)

Experiment No.

13

23

3

6

8

19

25 Mean

Variety

Val.

Val.

Sp.

Sp.

Sp.

Sp.

N.C.

Plant number (CC0/acre)

27.0 22.9

16.5

8.2

10.4

8-2

12.0 15.0

Yield, no added Ca

895

634

794

588

569

471

335

612

1. Response to—

Limestone

6

-82

23

-53

-10

63

8

Gypsum

-16

-53

21

-39

22

40

32

S.E. of response +

57.6

52.0

47.0

29.3 29.6

41.6

42.6

11. Soil data

Red-

Upland

Upland Upland

Upland brown

Type

pallid

Red

pallid pallid

Red

pallid valley

pH

6.1

6.2

6.9

5.5

6.7

5.6

7.5

Extracted P mgm./

100gm. 0.15

0.12

0.05 0-10

0.10

0.15 0.24

Extracted Ca mgm./

100gm. 40

60

40

40

40

50

232