Browsing by Author "Kroll, U."
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Item The Effect of Fertilizers, Manures, Irrigation and Ridging on the Yield of Pyrethrum.(1963) Kroll, U.The results of experiments with fertilizers, irrigation and ridge planting on pyrethrum are discussed.Phosphorus appears to be in short supply on many soils in the Kenya Highlands as well as in Southern Tanganyika. Applications of 150 to 200 lb. Triple Super-phosphate at planting time either placed into the planting holes or below the ridges are recommended. The effect of these treatments usually lasts over two to three seasons. Basic phosphates have shown no advantage .over super-phosphates. Nitrogen and potash have so far produced no yield increases. Calcium (lime) has on occasions and on highly leached acid soils given positive responses. Results are not conclusive. Applications of the minor elements Zinc, Molybdenum and Copper have had no results. Farmyard manure, except in nurseries to stimulate the initial growth of seedlings, is not recommended. Mulch between the rows of plants has produced yield increases especially in drier seasons and at the warmer altitudes.Green manures have, on the whole, been disappointing. One year of a green crop between two pyrethrum plantings, does not constitute a means to keep up yields. A grass lye should be included in a balanced rotation.Satisfactory yields on land which is repeatedly planted with pyrethrum can only be maintained by phosphorus application, even if a reasonable rotation is followed.The pyrethrum content cannot be influenced by any fertilizer or manure. Irrigation at the rate of 4 ins. per month can increase the flower yield as well as the pyrethrins content during dry spells within the growing season but does not prolong flowering into the dry season. Ridge planting has in most cases given increased yields and is recommended.Item Notes on Kenya Agriculture V-Plantation Crops(1959) Hanger, B.F.; Savile, A.H.; Bennison, R.H.; Wright, W.A.; Kroll, U.; Lerche, K.; Gill, S.S.; Gamble, G.; East African Tobacco Company Limited; Empire Cotton Growing Corporation; Department of Agriculture, KenyaPROPAGATION AND ESTABLISHMENT The Seed.—Only seed from selected mother trees (ie clonal trees raised by vegetative propagation) should be used. Clonal seed supplies are available from Coffee Research Station, Ruiru. Seed taken from seedling trees produces sizeable minority of inferior plants. Sow seed immediately it is available to avoid decline in viability. Seed should have moisture content of 15-18 per cent.
