ANNUAL SUMMARY OF AGRICULTURAL DATA FOR THE
and March was deficient but fortunately good late rains were experienced during April and May, 1952.
The following table gives the monthly rainfall for the period June, 1951 to May, .1952 for fifty-four centres as well as their computed mean rainfall for the past twenty-five years.
yield per acre would have been some 29.4 tons cane per acre. As stated, Co.281 is now rapidly being eliminated and N:Co.310 and Co.331 are being increased, as is shown in the following tables:
The total rainfall for the year under review for these fifty-four representative stations was, therefore, 36.34 inches, compared with a computed average of 37.42 and distribution of rainfall left a lot to be desired. Taking these facts into consideration, the average yield of 26.29 tons cane per acre can bo regarded as satisfactory. The average rainfall for 1952-53 was again low and badly distributed, but the rainfall for the period June, 1953 to May, 1954 was above normal and well-distributed, with the result that much better yields can be expected for the 1953-54 season.
Effect of Varieties on Average Yield
For some years now, it has been realised t h a t Co.281 has lost it's original vigour and has been depressing average cane yields. This variety is now rapidly being eliminated and the following table shows clearly what disastrous results would have been obtained had this variety not been replaced by new varieties:
It is, of course, true that the yields of Co.281 and also Co.301 suffer from the fact that they are now predominantly older ratoons, but the above com- parison is nevertheless regarded as fair, because to start with, N:Co.310 was mainly represented as plant cane and further more a varietal decline can, as a rule not be so readily detected in these, industrial averages, because the poorer fields are continually being eliminated, leaving only the better fields for future records.
And yet, 21.5 per cent, of the total area harvested, during the year now under review, was occupied by Co.281. If that had not been the case the average
For a considerable time the area under Co.301 remained fairly constant and Co.331 and N:Co.310 increased as a result in the fall in area under Co.281, but the area under cane on the 30th April, 1953, shows a decided decrease in Co.301 and the table giving the area under plant cane shows that Co.301 has from 1951 been replaced by N:Co.310 and Co.331 and that in 1953 only 17.5 per cent, of the land under plant, cane was planted to Co.301 while N:Co.310 and Co.331 occupied about 80 per cent, of the total area under plant cane.
Yields from Different Areas
The average yield of tons cane per acre obtained for the industry during the season 1952-53 was 26.29.
The South Coast averaged only 20.03 tons cane per acre and Zululand 27.27 tons per acre while the North Coast had the best average yield of 28.67 tons per acre.
The following table gives some of the past yields recorded for the industry and its main sub-divisions:
It will be seen that the average yields for 1952-53, with the possible exception of the South Coast, compare reasonably favourably with that of averages for recent years.
The lowest average yield recorded was that for Port Shepstone, which only averaged 16.33 tons per acre. This low yield is, however, largely due to the very high percentage and low yield of Co.281. This district, still harvested Co.281 to the extent of 69.0 per cent, of the total area and this variety only averaged 11.75 tons cane per acre. All the other varieties harvested in this area averaged. 26.52 tons cane per acre. The best yields obtained, as was the case last year, were from the Hlabisa area., which averaged 36.70 tons cane per acre. Inuanda district averaged 29.92 tons cane per acre.
Average Age of Cane and Percentages of Plant and Ratoon
The average age of cane, at ploughing out, was 5.99 years.
For the season under review the "Special Census"
indicates that 50,606 acres were long fallowed, 30,041 acres were short fallowed and 10,594 acres of virgin land were planted to cane.
Of the 391,930 acres under cane on the 30th April, 1953, as given in the "Special Census," the following areas were under plant and ratoons:
Fertilizers Used
The yield of cane per acre is affected by climatic conditions, variety and fertilizers, as well as some other factors. Rainfall has been given in. the past and is now recorded in more detail. Arrangements have been made with the Fertilizer Traders' Associ- ation to supply certain data that will enable us to review the fertilizer usage in the industry annually.
During 1953, or rather for the year ending Febru- ary, 1954, the sugar industry used 19,817 tons of mixtures containing the following amounts of plant foods:
Tons N Tons P2O5 Tons K2O
832 2,418 476 The average composition of this "mixture" was, therefore, about 4-12-2.5. In addition the industry used the following quantities of straight fertilizers:
11,882 tons nitrogenous fertilizers containing 2,495 tons N;
17,883 tons phosphatic fertilizers containing 3,307 tons P2O5;
2,060.5 tons potassic fertilizers containing 1,236 tons K2O.
Filter cake added to the cane plantations during the year may account for a further 650 tons N, 2,000 tons P2O5 and 150 tons K2O. There are, of course, small quantities of manures and other fertilizer materials being used, but the main items enumerated above amount to the following totals:
Tons N Tons P2O5 Tons K2O
3,977 7,725 1,862 Now assuming the area harvested and therefore area to be fertilized, was 224,000 acres then the average application of plant foods per acre would have been:
Nitrogen 30 lbs. as N Phosphate 09 lbs. as P2O5
Potash 17 lbs. as K2O
The application of phosphates appear adequate to high, nitrogen low and potash very low, but com- pared with a similar survey made for the 1951.
season there has been a most encouraging increase in the usage of nitrogenous and potassic fertilizers and a fall in the case of phosphates.
Ignoring the amounts of plant foods in filter cake, manures and low-grade fertilizer materials the following table gives a comparison of the quantities of straight and mixed fertilizers used during the 1951 and 1953 seasons:
1951 1953
Tons mixed fertilizers ... 25,277 19,817 Tons nitrogenous fertilizers 5,280 11,882 Tons phosphatic fertilizers 15,297 17,883 Tons potassic fertilizers ... 125 2,060 The tons N2, P50 and K20 contained in these straight and mixed fertilizers were as follows:
1951 1953
Tons nitrogen as N 2,135 3,327 Tons phosphate as P205 ... 6,526 5,725
Tons potassium as K20 ... 842 1,712
This table, therefore, reflects over 50 per cent, increase in nitrogen, a 12 per cent, decrease in phosphates and an increase of more than 100 per cent, in potassic fertilizers. The use of straight potassic. fertilizers has increased by more than sixteen-fold since 1951.
Experiment Station,
South African Sugar Association, Mount Edgecombe.
26th July, 1954.
( E U R O P E A N PLANTERS O N L Y ) 1952-1953
Compiled f r o m U n i o n Department of Census Returns
Compiled from Union Department of Census Returns
Compiled from Union Department of Census Returns
Compiled from Union Department of Census Returns