CAB129-37 — Page 375

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1097

Page 375

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In the absence37fbanf ects of either calcium supplyingmahal stile? is no

need to examine the data in further detail. It is clear from results and from those of the general exploratory experiment that calcium need only be supplied. at Kongwa at extracted values below about 20 mgm./100 gm. or 1 m. eq./100 gm. Since such soils are rare in the Kongwa Region, there is no case for a general. policy of liming at Kongwa.

On the red soil at Urambo, no general response was obtained to either lime- stone or gypsum. On the grey soil, however, there was some evidence that benefit was obtained, particularly from limestone. The results were as shown in Table 16,

Table 16.-Results of Experiment on Calcium Nutrition of Groundnuts, Urambo

Grey Soil, 1947-48

(Yield: lbs. kernels per acre)

Variety: Valencia

No added Ca, 781 lbs. per acre

197

Limestone Gypsum

Mean

Limestone Gypsum

Mean

Ro

R1

R2

Mean

842

915

867

874

858

819

806

828

...

850

867

836

851

Το

Ti

T2

929

806

888

.874

712

896

875

828

821

851

881

851

•

Ro-2 cwt. limestone or equal Ca as gypsum. R1-4 cwt. limestone or equal Ca as gypsum.

R2-8 cwt. limestone or equal Ca as gypsum.

To-broadcast before sowing.

Ti-placed near seed.

T2-dusted on plants at early flowering.

Soil data: pH 6.1, extracted P 0-28, extracted Ca 48 mgm./100 gm.

At Namanga fiwi bean fresh weights showed an increase with limestone from 2,221 to 2,712 lbs. per acre, but gypsum seemed less effective.

The soil had pH 4.9, extracted P 0.13, extracted Ca 18 mgm. / 100gm.

Effects of fertiliser on oil content in groundnuts

In a preliminary examination of this question, samples were taken from the produce of Experiment 5 (Table 7). In this experiment the largest response to phosphate in the series, and the only significant response to lime, were recorded.

Oil content was determined on duplicate 10 gm. sub-samples drawn from a main sample of 200 gm. of kernels, reduced for analysis by means of a nutmeg grater. Extraction was carried out with petrol ether (B.P. 40-60°C.) in standard Soxhlet equipment. The extraction was interrupted after some hours and the kernel residues were ground with sand in a pestle and mortar, subsequently being returned to the apparatus and further extracted.