(In tons of 2,000 lbs.—Season 1961-62)
Damall Amatikulu Felixton Zululand Tongaat Melville Natal Estates Sezela Renishaw..
Pongola Gledhow
Chaka's Kraal ..
Umzimkulu Illovo Umfolozi..
Doornkop Entumeni Glendale ..
White .
— __
—
— 370.500 57,436.400 64,362.000 . 14,169.250
4,003.000 . 71,651.200
—
— . 27,556.006 . 60,223.8055
16,600.000 7,383.950 6,189.700 329,945.8115
Cargo Refining 81,054. 905 19,266.040 41,557.
58,162.
67,670.
9,576.
—
—
—
—
—
—
—
—
—
—
— __
510 100 104 780
277,287.439
Cargo Export 34,764.530 44,640.035 41,844.600 6,793.500 55,556.063 17,687.925 23,554.440 8,980.650 7,213.845 35,854.350 3,578.400 17,262.945 22,544.025 17,831.941 39,166.305 9,867.100 4,499.040 4,042.605 395,682.299
Golden Brown 328.000 344.500 180.000 29,415.850 285.950 3,270.000 9,729.500 168.350 2,642.500 14,034.000
— 3,919.300 8,028.450 5,449.384 12,032.554 3,260.000 1,466.550 1,310.700 95,865.588
TOTAL 116,147.435
64,250.575 83,582.110 94,371.450 123,512.117 30,905.205 90,720.340 73,511.000 24,025.595 53,891.350 75,229.600 21,182.245 30,572.475 50,837.331 111,422.6645
29,727.100 13,349.540 11,543.005 1,098,781.1375
Table 2.—CANE CRUSHED, SUGAR MADE, VARIETIES AND THROUGHPUT
Table 4.-MASSECUITES AND MOLASSES: LIME, SULPHUR AND PHOSPHORIC PASTE CONSUMPTIONS
Proceedings of The South African Sugar Technologists'" Association—April 1962
Table 5.—FINAL DATA OF MHLUME, UBOMBO RANCHES, LUABO AND MARROMEU
31
FACTORY Mhlume Ubombo Ranches Luabo Marromeu
TONS C A N E C R U S H E D TONS S U G A R M A D E Tons Cane per hour Percentage of White Sugar SUCROSE PER CENT C A N E FIBRE PER C E N T C A N E Tons Cane/Ton Sugar Java Ratio
Brix of 1st Expressed Juice Purity of 1 st Expressed Juice Tons fibre per hour
Imbibition per cent Fibre
LOST ABSOLUTE J U I C E per cent Fibre Imbibition per cent Cane
SUCROSE EXTRACTION Sucrose of Bagasse
Moisture of Bagasse
BOILING H O U S E P E R F O R M A N C E Boiling House Recovery
Overall Recovery
PURITY O F MIXED JUICE Red. Sugars/Sucrose Ratios:
—of Mixed Juice
—of Clarified Juice
—of Syrup
Filter Cake per cent Cane Sucrose of Filter Cake BRIX P E R C E N T S Y R U P P U R I T Y O F F I N A L MOLASSES Brix of Final Molasses ..
Molasses of 85° Brix per cent Cane
357,536 42,502 84 44 14.20 12.67 8.41 79.55 20.28 87.98 10.63 209
42.7 26.60 94.20 2.73 54.43 95.9 88.2 83.1 85.5 4.40 4.03 3.88 3.88 2.42 50.5 4 1 . 8 91.6 3.35
215,647 24,624 76 47 14.18 13.83 8.76 79.94 20.04 88.51 10.58 218
44.3 30.10 93.90 2.84 50.59 92.8 85.1 79.9 85.2 5.11 5.53 4.04 5.00 1.91 63.0 34.4*
91.5 4.35
452,903 47,827 121 70 12.56 16.18 9.77 77.92 18.9 85.3 19.54 187
40.8 30.23 92.88 2.59 49.40 98.9 89.8 83.4 83.1 4.27 3.92 3.86 4.08 1.72 58.8 36.8 92.3 3.25
471,914 46,430 131 28 12.65 16.07 10.16 76.36 19.6 84.5 21.11 168
55.9 26.91 90.21 3.40 51.28 94.0 85.3 77.0 82.5 3.42 3.45 2.64 4.00 2.95 64.6 43.8 91.8 3.81 SUCROSE BALANCE
Lost in Bagasse Lost in Filter Cake ..
Lost in Final Molasses Undetermined Losses Total of All Losses . .
5.80 0.66 8.89 1.56 16.91
6.09 0.69 8.98 4.33 20.09
7.07 0.60 8.51 0.39 16.57
9.79 0.93 11.22 1.12 23.05
TOTAL RAINFALL (1961) 23.64" 55.42" 48.52"
Percentage N:Co.310 95 90 66.4 67.8
Affiliated Members of the S.M.R.I.
* Apparent Purity.
Table 6.-AVERAGE MANUFACTURING RETURNS BY MONTHLY PERIODS FOR SOUTH AFRICAN SUGAR FACTORIES
(SEASON 1961 - 1962)
Table 7.—COMPARISON OF FINAL RESULTS FOR S.A. SUGAR FACTORIES (Season 1952 to Season 1961 inclusive)
Table 8—COMPARATIVE DATA OF REPORTING S.A. FACTORIES FROM 1925 TO 1961 INCLUSIVE
1
1925 1926..
1927..
1928..
1929..
1930..
1931..
1932..
1933..
1934..
Average
1935 1936..
1937..
1938..
1939..
1940..
1 9 4 1 . . 1942..
1943..
1944..
Average 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 Average
1955
Per cer Sucrose
12.55 12.23 13.66 13.75 12.95 13.66 13.84 13.48 13.88 11.88 13.19
13.65 13.30 13.92 13.64 13.41 13.19 14.00 13.40 13.14 13.67 13.53 14.28 14.21 13.32 13.89 13.52 14.19 13.33 13.87 13.93 13.34 13.79 13.87
1956 13.35 1957
1958 1959 1960
1961
13.11 13.12 13.66 13.69
13.75
t Cane Fibre
15.88 16.01 16.27 15.88 16.52 15.82 15.75 15.65 15.78 15.24 15.78
15.92 15.01 15.14 14.51 14.85 15.56 15.66 15.24 15.26 15.83 15.30 15.99 16.21 15.80 15.90 16.19 15.80 16.29 16.10 16.31 16.03 16.06 15.74 15.81 15.38 15.92 15.92 15.22
14.52
Tons of Cane per I Sugar
10.77 9.92 9.69 9.49 10.06 9.59 9.53 9.61 9.28 10.67 9.86
9.19 9.29 8.80 8.89 8.95 9.26 8.62 8.93 8.98 8.67 8.96 8.29 8.36 8.84 8.55 8.76 8.32 8.98 8.50 8.55 8.87 8.60 8.51 8.87 8.93 9.09 8.74 8.70
8.51
on of 96° Sugar
10.46 9.74 9.48 9.30 9.87 9.40 9.33 9.40 9.03 10.40 9.64
8.96 9.06 8.58 8.66 8.73 9.03 8.39 8.69 8.74 8.44 8.73 8.08 8.14 8.60 8.31 8.52 8.09 8.73 8.27 8.24 8.65 8.36 8.28 8.62 8.67 8.82
8.44
8.41
8.26
Extrac- tion
89.30 90.86 89.30 89.47 89.02 89.78 89.40 89.86 90.28 91.07 89.83
90.64 91.08 91.53 91.90 92.24 91.91 92.37 92.69 92.97 93.13 92.05 93.28 93.07 93.44 93.32 92.24 93.33 92.98 93.00 92.67 92.40 93.04 92.32 92.93 93.36 92.87 92.86 93.35
94.21
Boiling House
81.98 81.97 83.01 83.90 84.39 83.80 83.27 84.27 84.88 85.20 83.67
86.52 87.44 87.85 88.48 88.88 87.98 88.40 88.98 88.84 89.27 88.36 89.29 89.12 89.61 89.14 89.68 89.63 88.72 89.96 89.36 90.04 89.46 90.51 89.79 90.43 89.49 89.42 89.40
89.72
Overall Recovery
72.38 74.48 74.13 75.06 75.13 74.77 74.39 74.73 76.63 77.59 75.12
78.40 79.64 80.41 81.31 81.98 80.86 81.66 82.48 83.52 83.14 81.34 83.30 82.94 83.73 83.19 83.35 83.65 82.50 83.66 82.81 83.20 83.23 83.56 83.44 84.42 83.11 83.04 83.45
84.53
Per cent Cane
— —
26.3 25.5 26.6 27.9 29.7 30.4 30.2 27.6
33.0 32.4 31.8 31.7 31.3 32.6 34.8 32.8 31.6 33.7 32.6 35.0 35.2 34.4 34.1 33.7 32.8 35.0 34.9 32.7 30.7 33.8 32.1 35.2 34.5 32.9 34.6 36.2
36.7
Per cent Fibre
_
— —
166 164 168 177 190 193 198 175
208 216 210 218 211 209 222 215 207 213 213 219 217 218 214 208 206 215 217 200 191 210 204 222 224 207 218 238
253
Per cent Sucrose
4.03 3.53 4 . 0 6 4.10 4.07 4.20 4.22 3.83 3.71 3.05 3.88
3.48 3.40 3.40 3.30 3.11 3.02 3.03 2.88 2.76 2.73 3.11 2.77 2.79 2.54 2.67 2.66 2.72 2.57 2.65 2.75
Per cent Moisture
49.38 49.33 49.49 50.01 50.69 50.66 50.09 51.89 51.32 52.11 50.57
51.93 52.76 52.01 52.17 51.79 51.60 51.50 51.24 50.80 50.23 51.60
LOST Absolute
JUICE per cent
FIBRE
60.7 52.8 58.3 59.8 63.2 57.4 60.0 58.4 55.9 57.7 58.4
54.2 55.6 52.4 53.1 49.6 48.9 45.1 45.1 43.8 41.1 48.9 50.19 j 39.3 50.32 j 40.5 50.46 39.8 50.53
50.84 51.22 51.71 52.53 52.47 2.75 52.92
39.8 41.0 39.3 4 0 . 2 40.8 41.7 44.1 2.69 i 51.32 1 40.6 2.91 ! 53.18 ! 45.5 2.60
2.47 2.55 2.66 2.60
53.12 ! 42.1 53.06 j 40.9 52.38 j 42.3 53.26 i 43.0 53.01 i 42.0
2.43 52.54 : 39.0
M I X E D JUICE
Purity
84.47 84.65 85.47 84.90 86.04 85.88 85.27 85.30 84.92 84.02 85.09
86.49 85.43 85.60 86.36 86.46 85.34 85.67 85.96 86.56 86.19 86.01 86.23 85.86 86.24 85.92 86.22 86.40 84.92 86.25 85.61 85.86 85.95 85.96 85.49 85.10 84.46 85.52 85.63
86.04
Reducing Sugar R A T I O
— —
3.86 3.35 3.35 3.55 3.09 4.01 4.21 3.65
2.65 3.04
Purity Final Molasses
44.5 4 5 . 3 46.1 45.3 45.1 45.9 45.0 4 5 . 1 44.9 45.6 45.3
46.6 43.9 3.23 i 4 3 . 7 3.08 ! 43.1 3.27 3.81 3.35
42.7 42.9 43.4 3.07 j 43.2 3.18 ; 41.8 3.49 i 42.4 3.22 I 4 3 . 3 3.38 ! 42.0 3.30 ! 41.8 2.95 3.67 3.11 3.12 3.52 2.92 3.66 3.28 3.29 3.40 3.32 3.69 4.30 3.51 3.31
3.31
41.1 41.5 41.4 40.5 4 0 . 3 39.3 39.5 39.3 4 0 . 7 39.6 39.9 38.5 39.1 40.3 40.3
39.5
BOILING H O U S E PERFOR- MANCE
89.4 88.8 89.6 90.8 90.7 90.2 90.0 91.1 92.2 92.9 90.6
93.0 94.6 95.0 95.4 95.7 95.3 95.6 96.2 96.7 96.4 95.4 96.4 96.7 96.8 96.5 96.9 96.9 96.7 97.2 96.9 97.4 96.8 97.9 97.4 98.5 97.8 97.1 96.8 97.1
N u m b e r of reporting of factories
11 of 25 13 of 23 14 of 21 14 of 25 16 of 25 17 of 23 15 of 22 16 of 23 15 of 23 17 of 23 15 of 23
17 of 23 17 of 23 17 of 23 17 of 23 19 of 22 19 of 22 19 of 22 19 of 22 19 of 22 19 of 22 18 of 22 19 of 21 19 of 21 18 of 20 18 of 20 18 of 20 17 of 19 17 of 19 17 of 19 16 of 18 17 of 19 18 of 20 17 of 19 17 of 18 17 of 18 18 of 18 18 of 18 18 of 18 18 of 18
Percent- crop covered
60.4 73.3 81.0 83.3 91.0 94.9 94.5 94.4 90.0 96.5 85.9
97.1 96.2 96.4 96.6 98.5 99.0 98.5 98.4 98.6 98.4 97.8 99.0 99.2 99.8 99.1 99.2 99.2 99.5 99.3 99.3 99.2 99.3 99.1 99.2 99.2 100.0 100.0 100.0 100.0
Table 9.—COMPARATIVE RESULTS FROM OTHER COUNTRIES FOR RECENT YEARS
COUNTRIES
CANE
Per cent Sucrose Per cent Fibre
FIRST EXPRESSED JUICE
:Brix Purity
MILLING
Imbibition per cent Fibre Lost Abs. Juice per cent Fibre Imbibition per cent cane Sucrose Extraction Sucrose per cent Bagasse Moisture per cent Bagasse Lower Calorific Value
BOILING HOUSE PERFORMANCE
South Africa
1960-61 1961-62
13.69 15.22
19.88 87.8
238 42 36.2 93.4 2.60 53.01 3023
96.9
13.75 14.52
19.55 88.0
253 39 36.7 94.2 2.43 52.54 3069
97.1
J 1958
12.15 14.21
18.51 83.0
128 35 18.1 94.2 2.60 48.17 3442
98.7 imaica
1959
11.76 14.20
18.01 82.1
131 37 18.6 93.8 2.48 48.31 3431
97.2
British Guiana
1959 1960
10.93 15.06
17.35 81.1
187 49 28.2 91.4 2.91 49.61 3311
96.0
10.99 15.08
17.36 81.4
196 49 29.5 91.2 3.05 49.61 3309
97.7
Philippines 1958-1959
13.14 11.72
19.52 85.10
98 55 11.5 92.4 3.86 49.60 3295
98.9
Mauritius 1960
11.83 14.38
17.51 85.90
210 40 30.2 94.4 2.21 49.79 3308
95.6
1960
11.71 13.22
18.26 80.80
159 53 21.1 92.5 3.03 50.32 3248
98.1 Trinidad
1961
11.97 13.68
18.99 80.64
140 57 19.1 91.6 3.28 50.61 3218
97.4
India 1957-58
12.55 15.57
19.34 83.60
131 66 20.4 91.5 3.25 48.46 3405
97.0
RECOVERIES AND AFFECTING QUALITATIVE DATA Purity of Mixed Juice Purity of Final Molasses Average Pol. of Sugars Undetermined Losses Boiling House Recovery Overall Recovery Tons Cane/Ton 96° Sugar
FILTER CAKE Per cent sucrose Weight per cent cane
85.6 40.3 98.88
0.97 89.4 83.4 8.41
1.66 6.10
86.0 39.5 80.90
1.32 89.7 84.5 8.26
1.63 5.43
81.8 32.8 97.2 1.82 89.5 82.7 9.50
2.27 2.49
80.5 32.4 97.0 2.05 87.7 82.3 9.89
2.01 2.60
78.8 32.5 97.3 1.51 86.6 79.2 11.10
1.21 3.14
79.1 31.4 97.7 1.26 87.6 80.0 10.91
1.35 3.14
84.6 37.7 97.95
0.44 90.9 84.0 8.77
2.41 2.00
83.5 37.2 98.73
2.81 87.1 82.2 10.16
3.00 2.70
78.9 31.5*
96.67 0.74 87.9 81.3 9.85
1.86 2.91
78.9 32.0*
96.91 0.64 87.6 80.2 9.99
1.64 2.64
81.7 35.8*
99.8 0.87 87.1 79.7 9.70
2.66 4.17
•Apparent Purity.
36 Proceedings of The South African Sugar Technologists' Association—April 1962 Mr. J. L. du Toit, in the chair, said that last year
Mr. Perk was awarded the Talbot Crosbie Prize for his Annual Summary, but this year his contribution contained even more information.
Dr. Dodds pointed out that on page 34 was shown the progress that had taken place since these reports were first published in 1925. When he was first made Director of the Experiment Station he considered adopting the idea of publishing reports of this kind, as he had just come from Cuba, where they published a very good report, but he did not see how one could publish at that time one to compare with that standard here, for he found at first a certain amount of oppo- sition to the publication of factory results.
He noticed from the report that N:Co.310 was still planted extensively in Taiwan and in Somalia. In America the only foreign variety now grown was also N:Co.310 and in Australia in many districts it was the most popular variety.
Mr. Fourmond, in connection with the final molasses brix figures shown in Table 4, said he had determined and noted the brix of the final molasses on a 50 per cent dilution, but then he had found other factories were using a 20 per cent dilution, thus recording a lower purity.
Mr. Perk answered that the Recommended Methods dilution should be followed.
Mr. Rault considered the new chapter on the fuel position at the various factories to be a wonderful new innovation.
On the purity of final molasses, the differences found between the various factories, which ranged from 34 to 40 degrees was upsetting, for this was unusual in South Africa. He asked if this was due to the differ- ence in reducing sugar content of the molasses. He did not think we found a big difference in this country when processing ripe, as against unripe, cane.
Mr. Perk remarked in reply to Mr. Rault's question, that it was a pity that not all factories recorded the reducing sugars and the sulfated ash contents of their molasses, nor did they always give both purities of their molasses. However, most high molasses are
not a result of unfavourable composition, but lack of centrifugal capacities and other technical short- comings. Too much C-massecuites have to be boiled too coarse, because of insufficient capacity of the C-m.c. centrifugals.
Mr. Covas said he had found a 4 degree difference in the final molasses from ripe as compared with unripe canes, but a further point was the difference between apparent and Clerget purity, the former being 33 degrees when the latter was 36.8. That amount of difference was found whether purities were high as in 1960 or low as in 1961. He explained that he used a dilution of 50 per cent for the determination of brix in all his analyses of molasses.
Mr. Phipson asked if there was any quick method of ascertaining the sufficiency of crystal in a massecuite.
Dr. Graham replied that there was a quick method which consisted in placing the sample of massecuite in a cylinder fitted with a plunger on top and a sup- ported wire gauge on the bottom and applying pres- sure on the plunger which forces the "lubricating fraction" of the molasses through the wire gauge.
The crystals together with adhering molasses remain in the cylinder. The contraction in volume is measured and may be related to the crystal content.
Mr. Rault remarked on the Darnall figure for imbi- bition per cent fibre which was the highest in the Industry. This was accompanied by the highest effici- ency. It had always been considered in the past that application of over a certain amount of water did not lead to better extraction, but this seemed now to be disproved.
Dr. Douwes Dekker said that the figure quoted did not prove that the application of such a large quantity of water would lead to higher efficiency. If the amount of water had been reduced the efficiency might have remained the same.
Mr. van Hengel related that during a period when the imbibition at Darnall had been reduced from 380 to 280 per cent on fibre the lost absolute juice per cent fibre was hardly altered and still remained very low.
Proceedings of The South African Sugar Technologists' Association—April 1962
WEATHER REPORT FOR THE YEAR 1st JUNE 1961, TO 31st MAY, 1962
By J. L. DU TOIT
37
General Scope of Report
As in previous years this weather report deals with the rainfall data from 54 well scattered centres throughout the sugar belt, but other meteorological data such as temperatures, evaporation and hours of sunshine refer to the South African Sugar Association Experiment Station at Mount Edgecombe which is however reasonably centrally situated and reflect the conditions prevailing within the Industry fairly well.
The rainfall recorded during the year June, 1961 to May, 1962 will be discussed in some detail but reference will also be made to the rainfall of the previous year, for it too will have some effect on the crop to be harvested during the 1962-63 season.
In Table 1 the annual rainfall data for the past five years are given for each of the 54 recording stations.
Table 2 gives the rainfall by magisterial districts, and also for the three main divisions for each month of the year from June, 1961 to May, 1962.
Table 3 gives the calculated mean rainfall for the past 38 years and the monthly percentage distribution.
The actual rainfall for the year now under review is also given as are the evaporation data taken at the Experiment Station, Mount Edgecombe.
Table 4 gives the rainfall distribution according to growing periods for the past two years for all magis- terial districts and the three main sub-divisions of the Industry.
Table 5 gives the monthly rainfall for 54 centres for the past 4 years, the evaporation from an open water tank at the Experiment Station for the same period and the amount by which evaporation exceeded rainfall for each month.
TABLE 1 Rainfall for 54 Centres
38 Proceedings of I he South Ajrican Sugar Technologists' Association—April 1962 TABLE 2
Rainfall in Inches by Districts for Months of June, 1961, to May, 1962 inclusive
District
Port Shepstone . Umzinto
Durban, Pinetown
e t c . - - •
Mean: S. Coast . lnanda
Lower Tugela Mean: N. Coast M e a n : S . of Tugel Mtunzini
Eshowe .. • Lower Umfolozi.
Hlabisa .. . Ubombo .. • Piet Retief .. .
No. or
Centres
1 6 3 . 10 . 9 . 13
22 a 32 . 5 . 3 . 8 . 4 . 1 . 1
June
1.43 1.34 1.56 1.42 3.54 3.65 3.61 2.92 5.09 2.04 5.21 7.96 2.36 2.33
July
2.03 1.74 0.72 1.46 1.02 0.50 0.71 0.94
1.09 0.30 1.75 1.98 0.06 0.02
Aug.
0.16 0.33 0.22 0.28 0.78 0.93 0.87 0.68 1.13 0.47 1.15 0.96 0.93 0.15
9 6 1 Sept.
3.56 2.95 2.90 3.00 3.04 3.43 3 . 2 7 3 . 1 8 3.40 3.87 3.08 2.69 3.12 2.78
Oct.
2.36 2.16 2.30 2.22 3.28 3.97 3.69 3.23 4.79 3.59 4.34 4.04 3.10 2.07
N o v .
4 . 8 5 4 . 2 4 2.90 3 . 9 0 3.70 3.81 3 . 7 6 3.81 4 . 7 5 5.61 5.30 3.15 3.98 2.26
D e c .
1.86 2.19 2.70 2.3T 2.21 3.07 2.72 2.59 3.54 4.41 2.60 2.45 0.83 1.48
J a n .
4 . 6 0 5.14 6.68 5 . 5 5 3.96 3.95 3 . 9 5 4 . 4 5 3.25 3.78 4 . 3 0 3.07 1.68 1.69
F e b .
2.15 5.04 3.82 4.39 2.45 3.10 2.84 3.32 3.13 1.92 1.64 0.62 2.24 0.35
1 9 6 2 M a r .
11.14 5.83 5.70 6.32 4.38 4.70 4.57 5.12 4.33 4.08 5.69 7.88 3.72 2.25
A p r .
0.91 1.26 1.71 1.36 1.82 1.74 1.77 1.64 1.65 1.61 3.37 2.68 1.34 2.83
May
1.20 0.66 0.68 0.72 0.83 0.77 0.79 0.77 1.13 0.54 1.43 0.62 Nil 0.03
T o t a l J u n e 1961
t o May 1962
36.25 32.88 31.89 3 2 . 9 3 31.01 33.62 3 2 . 5 5 3 2 . 6 5 37.28 3 2 . 2 2 3 9 . 8 6 38.20 2 3 . 3 6 18.24 Mean: Zululand
and Piet Retief 22 4.99 1.29 0.96 3.18 4.13 4.63 2.90 3.53 1.80 5.31 2.50 0.96 36.18 General Mean 54 3.76 1.08 0.80 3.18 3.60 4.14 2.72 4.08 2.70 5.20 1.99 0.85 34.10
TABLE 3
Rainfall and Evaporation Data
Month
June ..
July ..
August September October November December . January February . March April May ..
Mean Percentage Rainfall Distribution
1924-1961
Computed Mean Rainfall for
54 Centres 1924-1961
Actual Rainfall for 54 Centres June, 1961, to May, 1962
Evaporation at Experiment Station Mean
1936-1961 June, 1961, to May, 1962 3.88
2.76 3.57 6.78 9.17 11.21 12.43 11.21 12.41 13.68 7.58 5.32
1.49 1.06 1.37 2 . 6 0 3 . 5 2 4 . 3 0 4 . 7 7 4 . 3 0 4 . 7 6 5 . 2 5 2 . 9 1 2 . 0 4
3.76 1.08 0.80 3.18 3.60 4 . 1 4 2.72 4 . 0 8 2.70 5.20 1.99 0.85
2.34 2.52 2.93 3.62 4.19 4.75 5.32 5.62 4.76 4.48 3.36 2.80
2.15 2.51 3.60 4 . 1 4 4.97 5.13 6.07 5.80 5.07 5.28 4.30 3.34
100.00 38.37 34.10 46.69 52.36
Proceedings of The South African Sugar Technologists Association—April 1962 T A B L E 4
Rainfall in Inches by Districts for the Two-year Period June, 1960 to May, 1962 inclusive
39
Port Shepstone .. . Umzinto
Durban, Pinetown, etc.
Mean: South Coast Inanda
Lower Tugela Mean: North Coast
No. of Centres
1 6 3 10 9 13 22
I960 Winter Growth June to August
1.38 1.76 0.78 1.42 1.84 2.29 2.12
I960 Early Growth Sept. and
October 7.13 6.33 6.32 6 40 5.31 5.81 5.60
1960-1961 Optimum
Growth Nov. to March 27.11 27.70 26.57 27.30 26.19 27.63 27.05
1961 Late Growth April and
May 12.59 11.44 9.22 10.88 11.27 9.27 10.08
1961 Winter Growth June to August 3.62 3.41 2.50 3.16 5.34 5.08 5.19
1961 Early Growth Sept. and
October 5.92 5.11 5.20 5.22 6.32 7.40 6.96
1961-1962 Optimum Growth Nov. to March 24.60 22.44 21.80 22.47 16.70 18.63 17.84
1962 Late Growth April and
May 2.11 1.92 2.39 2.08 2.65 2.51 2.56
Total for Two Years June,1960
to May, 1962
84.46 80.11 74.78 78.93 75.62 78.62 77.40 Mean: South of Tugela 32
Mtunzini 5 Eshowe 3 Lower Umfollzi 8 Hlabisa 4 Ubombo 1 Piet Retief 1 Mean: Zululand and Piet
Retief 22 General Average 54 Computed Mean for 38 years
1.90
2.45 2.12 3.92
5.86 27.11 10.34 4.54 6.41 19.29
4.84 33.34 7.62 7.24 7.38 18.17 5.44 29.65 9.22 5.64 6.78 18.84
2.41
6.12 23.38 4.95 3.92 6.12 23.38 3.46 2.84 4.95
77.86 1.47
1.93 2.64 1.35 0.55 0.91
5.87 5.34 4.38 4.55 3.35 4.57
31.81 31.26 40.33 26.91 29.77 20.54
10.77 6.13 8.83 4.17 5.34 2.65
7.31 2.81 8.11 10.90 3.35 2.50
8.19 7.46 7.42 6.73 6.22 4.85
19.00 19.80 19.53 17.17 12.45 8.03
2.78 2.15 4.80 3.30 1.34 2.86
87.20 76.88 96.04 75.08 62.37 46.91 84.43 80.53 76.74
TABLE 5
Rainfall and Evaporation in Inches for the Past Four Years
Month June July
August . . September October . . November December January February March April May
Evapora- tion . . 2.22 . . 2.11 . . 2.65 . . 2.92 . . 4.95 . . 4 . 5 9 . . 5.03 . . 5.13 . . 4.15 . . 4 . 6 2 . . 3.68 . . 2.42
1958 - 1959 Rainfall
0.78 0.55 0.37 4.28 2.71 4.95 3.90 4.15 3.29 1.15 1.01 6.20
Rainfall Deficiency
1.45 1.56 2.28 0.00 2.24 0.00 1.03 0.98 0.86 3.47 2.67 0.00
Evapora- tion 2.34 2.51 3.33 4.06 4.74 4.62 5.40 5.46 4.87 5.21 3.35 2.74
1959 - 1960 Rainfall
0.07 0.66 2.35 2.63 4.58 3.03 3.99 2.10 5.05 4.68 5.12 1.40
Rainfall Deficiency
2 . 2 7 1.85 0 . 9 8 1.43 0 . 1 6 1.59 1.41 3.36 0 . 0 0 0 . 5 3 0 . 0 0 1.34
Evapora- tion 2.38 2.65 2.27 3.51 4.07 5.08 4.85 5.68 5.48 4.88 3.70 2.94
I960 - 1961 Rainfall
0.43 0.63 1.06 2.30 3.14 7.24 9.59 4.76 3.70 4 . 3 6 8.24 0.98
Rainfall Deficiency
1.95 2.02 1.21 1.21 0.93 0.00 0.00 0.92 1.78 0.52 0.00 1.96
Evapora- tion 2.15 2.51 3.60 4.14 4.97 5.13 6.07 5.80 5.07 5.28 4.30 3.34
1961 - 1962 Rainfall
3.76 1.08 0.80 3.18 3.60 4.14 2.72 4.08 2.70 5.20 1.99 0.85
Rainrall Deficiency
0.00 1.43 2.80 0.96 1.37 0.99 3.35 1.72 2.37 0.08 2.31 2.49 Total 44.47 33.34 16.54 48.63 35.66 14.92 47.49 46.43 12.50 52.36 34.10 19.87
40 Proceedings of The South African Sugar Technologists' Association—April 1962
TABLE 6
The following are the Screen Temperatures by Months in Degrees Fahrenheit at the Experiment Station for the Year June, 1961 to May, 1962, compared with the Means for the Period 1928 to 1961
THIS PERIOD AVERAGE 1928 TO 1961 INCLUSIVE
Month Maximum Minimum
June 73.6 56.7 July 72.3 55.4 August 72.3 53.1 September 74.1 59.5 October 73.2 58.3 November 76.6 63.3 December 77.5 64.0 January 79.3 66.9 February 81.1 68.4 March 81.3 66.2 April 78.1 62.6 May 74.3 55.8 Mean 76.1 60.9
Mean
65.1 63.9 63.5 66.9 65.8 70.0 70.9 73.2 74.8 73.8 70.3 65.1
Plus or Minus Average
+ 2.3 + 1.7 - 0 . 1 + 1.1 - 2 . 5 - 0 . 6 - 1 . 9 - 1 . 0 + 0.1
f0.5 0.0 - 1 . 4
Daily Range
16.9 16.9 19.2 14.6 14.9 13.3 13.5 12.4 12.7 15.1 15.5 18.5
Maximum Minimum
72.9 72.4 73.2 74.2 75.8 77.7 79.8 81.1 81.6 80.4 78.2 75.9
52.7 52.0 53.9 57.3 60.8 63.4 65.7 67.2 67.7 66.2 62.3 57.1
Mean
62.8 62.2 63.6 65.8 68.3 70.6 72.8 74.2 74.7 73.3 70.3 66.5
Daily Range
20.2 20.4 19.3 16.9 15.0 14.3 14.1 13.9 13.9 14.2 15.9 18.8
68.5 - 0 . 2 15.2 76.9 60.5 68.7 16.4
TABLE 7
The following table gives the mean monthly earth temperatures
Month
June July August..
September October November December January February March April ..
May
Experiment Station 1935-61 Experiment Station June 1961 to May 1962 1 foot
64.1 62.7 64.5 67.6 70.7 73.5 76.3 78.7 79.5 78.2 74.7 69.3
2 feet
66.6 64.6 65.6 68.1 70.8 73.3 76.1 78.9 79.5 78.9 76.1 71.5
4 feet
69.5 66.9 66.7 68.2 70.2 72.6 74.5 76.7 78.0 78.2 76.6 73.5
1 foot
65.7 64.8 64.0 68.0 68.9 72.1 74.5 77.2 78.4 77.5 74.7 68.4
2 feet
66.9 65.7 64.9 68.4 69.3 71.8 74.1 76.8 78.1 77.7 75.7 70.0
4 feet
69.6 67.8 66.7 68.2 69.4 70.7 72.7 75.2 76.6 76.8 76.3 72.5
Mean 71.7 72.5 72.6 72.0 71.6 71.9
Proceedings of The South African Sugar Technologists' Association—.
Comments on Rainfall
Although the crop now to be cut benefited from the excellent rains during the year June, 1960 to May,
1961, it was adversely affected by the deficient rainfall of the year June, 1961 to May, 1962, when only 34.10 inches of rain fell compared with our 38 years' mean of 38.37 inches. The distribution of rainfall was also relatively poor with the important growing months of December and February being very dry.
The Industry experienced unusually heavy rains during June, 1961 when an average fall of 3.76 inches was recorded. Uloa had no less than 13.33 inches for the month of which 8.12 inches fell within 30 hours causing considerable damage on the Umfolozi fiats.
Mtunzini had 10.25 inches and drainage became a real problem. The condition of the cane was excellent, temperatures were high but there was excessive flower- ing of cane in many areas. The rainfall during July was 1.08 inches and it was not until August with a rainfall of 0.80 inches that the Industry started suffer- ing from a drought. It was therefore on the whole a very favourable winter and the rainfall from Septem- ber to November averaging respectively 3.18 inches, 3.60 inches and 4.14 inches was quite satisfactory.
December was very dry with only 2.72 inches of rain or more than 2 inches below our 38 years' mean for the month. January, 1962 had a rainfall of 4.08 inches which is not much lower than the mean for January, but February with only 2.70 inches of rain was again very dry and more than 2 inches below our mean for the month. The drought was particularly bad in Zululand with an average rainfall of only 1.80 inches for the month. The rainfall for March was 5.20 inches which although nearly equal to the mean of the month did not make up for the deficient rainfall of December and February. The last two months i.e.
April and May were both very dry with 1.99 inches and 0.85 inches of rain respectively. Since December, 1961 to May, 1962 the total rainfall was therefore only 17.54 inches compared to our mean rainfall of 24.03 inches for the 6 months. The Industry at the end of May was therefore suffering from a bad drought and the indications are that conditions may become quite serious during winter.
Summarising the rainfall over the past two years, it can be stated that the crop went through a normal winter drought in 1960. Fairly good rains fell towards the end of September and during October and excep- tionally heavy rains fell during November and Decem-
i—April 1962 41 ber. Satisfactory rainfall and growing conditions
continued and during April the rainfall was again very high. Although May was relatively dry excellent rains fell in June and the crop experienced its first real set-back with the low rainfall of December. The important growing month of February was similarly deficient in rainfall. Although the rainfall during March was satisfactory, April and May were decidedly dry and at the end of May the Industry was in a drought with the crop prospects well below best.
Temperatures
The mean screen temperature for the year under review was 68.5°F at the Experiment Station. The mean screen temperature was thus 0.2° F below our 34 years' mean. June and July had mean screen tem- peratures well above the average for these months but October and May were relatively cool months.
Evaporation
Evaporation from an open water surface totalled 52.36 inches compared with our 26 years' mean of 46.69 inches. This exceptionally high total evapora- tion makes the rainfall deficiency even greater. There was only one month, June, 1961, when the average rainfall in the Industry exceeded the evaporation at the Experiment Station. The accumulated rainfall deficiency for the year i.e. the monthly total evapora- tion in excess of rainfall amounted to 19.87 inches.
This is the highest rainfall deficiency we have had for many years and more than 60 per cent of this deficiency occurred during the last six months of the year under review.
Hours of Sunshine
The hours of sunshine for the year were 103.9 per cent of the 34 years' mean. The hours of sun- shine for the period March to June, 1962 were 109.7 per cent of the mean. The year under review was therefore dry and sunny.
Conclusions
Although the first half of the year was on the whole favourable for sugarcane growth, the last six months were dry and excessive evaporation further desiccated the soil.
By the end of May the Industry was suffering from a bad drought which must affect cane yields adversely.
S.A.S.A. Experiment Station, MOUNT EDGECOMBE.
27th July, 1962.
42 Proceedings of The South African Sugar Technologists' Association- April 1962