THE EXPERIMENT

Abstract

As it result of a relatively short active growing season and cold dry winters the sugarcane crop, in South Africa.remains a predominantly two-year crop. Fertiliser applications normally take place at planting and soon afterv.orat-harvesting and soon after, and very seldom in the second year of growth or even at the endof the first year's growth. It was, therefore , decided to test out experimentally the nutrient absorption by the sugarcane plant at successive stages of growth, under our conditions, and at the same time to assess its growth rate, sucrose accumulation , purity and fibre fluctuations and do such other analyses as may be of interest. The experiment was situated on a black doleritic soil on the Experiment Station, Mount Edgecombe, and consisted of three fertiliser treatments each replicated six times. The fertiliser treatments were:-(a) control; (b) 100 lbs. per acre each of N, P20S and K 2 0 ; and (c) 2001bs. per acre each of N, P 2 0 S and K 2 0. All the phosphate was applied in the furrow as super-phosphate. A quarter of the nitrogen and potash as ammonium sulphate and muriate of potash respectively were applied at planting on the 30th of September, 1953, to the heat-treated N:Co.310 setts, and the rest in two equal top dressings on 21st De-cember, 1953, and 18th November, 1954. The four rows of cane to be harvested in each plot were subdivided by four-foot breaks to give a total of twenty-four lines. One of these short lines per plot was harvested each month for twenty-four months. For the first three months when the cane was very small the setts were dug up and the total shoots removed for weighing and analysis and thereafter the above-ground cane was cut off and used. These short lines were only seven and a half feet long and there was considerable variation between lines with the response to fertiliser small to moderate. The results reported will therefore be, unless otherwise stated, the average of all eighteen lines harvested per month irrespective of treatment. Growth It is known that under dry land conditions the growth made by sugarcane is at a minimum during :1.