AVERAGE OF THREE TONS OF CANE PER ACRE
Proceedings of The South African Sugur Technologists' Association — April 1968 than the cane. It will be said that it is easy to keep
only 95 acres clean, but what about 2,000 acres? The answer is that 2,000 acres is 20 farms of 100 acres.
The author is convinced that if a grower cannot, keep his whole farm clean, it would be belter for him to farm only half of it, and make double the net profit per acre. It. is no use saying, and how often it is said: "Isn't it marvellous? The drought has broken at last, but now the weeds have caught up on me."
It is not the object of this paper to discuss the best method of weed control. Enough has been written on this subject in the past. Whether a grower chooses weedkiller, mechanical or hand-weeding, or a combination of these, one aspect must be stressed, and that is early control. Because of the steep terrain and lack of grazing for mules only hand-hoeing could be done at Hillcrest. By starling to weed before any weeds appeared, or, in other words, by merely dragging the hoe over the ground, tasks ranging from 1,000 yards to 2,000 yards per day were possible. A distance of 1,000 yards at 3 ft. 9 in.
spacing, means four units an acre. At 35c per unit, this means R.1.40 an acre per weeding. At the peak period of weeding, only 30 acres needed to be weeded. On the rest of the farm the cane had already canopied, or had not yet been cut. There- fore, the maximum number of units needed at the peak period in order to be able to weed the fields every fortnight was ten.
Only ten units per 100 acres for weeding and.
despite the drought, the results became obvious.
The cane grew very fast and soon canopied, resulting in no further weeding being necessary.
If weeding is delayed, the task gets smaller and smaller as the weeds grow until a weeder can do no more than 100 yards per day. The problems to be faced may be outlined as follows:
1. Labour will become scarce. Although the energy used to weed 100 yards of tall grass may be the same as that for 1,000 yards of very- small weeds, an African will not consider it to be so. His heart will sink at the sight of the tall grass, and he will immediately say
"Ngihluleka". The Swazi will say "Gute". which stands for anything from "I don't know where it is" to "This task is ridiculous''.
2. The weeds may use up to 60 per cent of the fertiliser. (800 lb. of 1.0.1 mixture is worth R28.
60 per cent of R28 =R17 per acre.)
3. The weeds may use up to 60 per cent of the rainfall. Instead of 40 inches, the cane will get only 24 inches.
4. The number of weeders needed per acre for a task of 100 yards is 40, which will cost R14 per acre.
5. The number of weedings needed increases as the cane takes longer to canopy. The snow- balling effect goes right through to the extra harvesting cost for shorter cane and discontented labour. The profits disappear.
Before a grower starts thinking of fungicides, hot- water treatment, trace elements or cutting machines he should firsL of all give his attention to the most significant factor in the economics of growing sugar- cane—weed control.
Discussion
Dr. Dick (in the chair): It is rather remarkable that a farmer in an area that we consider marginal should have been able to produce cane at one and a half times the average return for the industry. I do not believe this was entirely due to weed control but that Mr. Dymond's overall management must have been excellent.
I think he was rather lucky in getting away with not treating his plant material with fungicide.
Mr. Morrow: Why was the cane cut at the ages shown in Table I?
Mr. Dymoncl: As a new grower there was no point in my cutting at eighteen months or so. The cane was left over to the following year so I could achieve a farm mean peak and that is why the cane is so old. The cane was cut in the order planted.
Mr. du Toit: In an earlier paper I referred to average yield per acre per annum. Pongola, which is considered a peak producing area, gave 31.4 tons cane per acre per annum under cultivation against
Mr. Dymond's figure of 36 tons, without irrigation, on T.M.S. soil, on a hilly site. This is an outstanding result and although I agree with you. Mr. Chairman, that this cannot only be attributed to weeding 1 think Mr. Dymond has stressed the most important factor, weeds. Although bad fields may suffer through
lack of fertilizer or for some other reason the worst fields will undoubtedly be suffering from weeds. If you have weeds you are wasting your time with both fertilizer and irrigation.
Mr. Main: Were the cane yields on Mr. Dymond's farm different in the three areas that had been respec- tively under wattle, under gums and virgin veld? In the Midlands we have been getting tremendous yields from old wattle lands.
Mr. Dymond: No difference at all. Wattle being a legume will supply sufficient nitrogen for at least the plant crop. When grass land is ploughed in, sufficient nitrogen is needed to assist not only in the rotting down of the organic material but also for the cane crop. If this is not done then there will be a difference in yield between ex grass and ex wattle land.
Mr. Wise: Why does Mr. Dymond contemplate cutting at 15 months when his cane at 23 months gave him 36 tons per acre per year, as did his 18- month cane and as he now expects to get at 15 months. What is the point? You will merely weed more often and fertilize more often to get the same end result.
Mr. Dymond: This is a very important question.
Perhaps the answer is young cane is easily handled, 40 tons per acre being the ideal tonnage to cut.
There is also a slight saving in insurance cost under 181
eighteen months and there is greater tons per aere over a period.
Against it of course is the fact of more weeding.
Mr. du Toit: This question of Mr. Wise's as to the point of culling early for the same yields is intriguing.
I think Mr. Dymond is right, that we should dis- regard age and aim at cutting a certain tonnage — say 40 to 45 tons per acre.
Mr. Wise: In the Umhlali area the bulk of ihe growth is in the first twelve months whereas in the Midlands it is in the second twelve months. Mr.
Dymond's figures do not show that the main growth is in the first twelve months. Even if cutting early makes for easy culling at 40 or 45 tons per acre I do not think it compensates for the extra labour and extra weeding required, if the end result is the same.
Mr. Wilson: The experiment station would recom- mend culting at 40 to 45 tons cane per acre as the advantages outweigh the disadvantages.
Fertilizer use should not be affected as it should be based on crop requirement.
Mr. Bartlett: I am a neighbour of Mr. Dymond's and in my first year f averaged 2.03 tons per acre per month but with poor weed control. With my ratoons 1 followed Mr. Dymond's example and raised the figure to 2.58 tons cane per acre. [ do not think (hat his figure of 3 tons of cane per acre per month can be attributed to growLh on old wattle land as one of my fields was old mealie land and gave 3.2 tons cane per acre per month, a 16-month old ratoon crop.
Mr. Pearson: Mr. Dymond's figures are particularly creditable as they include in the second year the harvesting of some ratoon cane where one might
expect a decrease in yield, but the tons cane per acre per annum are in the region of 36 tons for both years of harvesting.
Mr. Aucock: You can cut at 12 months depending on what time of the year the previous harvest was.
If you cut in May you can do so again next May but if you cut in December then you should not cut in the following December.
Mr. Morrow: If 4' 6" row spacing on a slope is equivalent to 3' 9" on ihe Hal then it might be more economic to farm on sloping land.
Mr. Dymond: The ground slope is seldom more than 25° and therefore makes very little difference lo the average. In fact my aerial photograph shows only 0.4 acres difference from the ground survey.
Mr. Boyce: Mr. Dymond says that no weeds were allowed to grow at all and I would like Dr. Thomp- son's comments on this.
Dr. Thompson: I certainly agree thai if possible you should prevent weeds appearing, but in estate practice we made the limit three man days per acre which agrees fairly well with Mr. Dymond's figure.
I think Mr. Dymond's rainfall efficiency of 88%.
is very good and if it was as a result of following experiment station advice it is very gratifying.
Mr. Stewart: If one. by cutting at younger cycles, is trying to get more tons sucrose per acre, the opposite effect can be induced if this is taken to extremes.
Mr. Morrow: I think this question of when to cut could be dealt with as a problem in programming, by the experiment station with the co-operation of an estate, and the results reported at our next congress.
FARM PLANNING AS THE BASiS FOR PEAK PRODUCTIVITY
Crop production efficiency is determined very largely by a range of management practices, many of which are interdependent and in some cases synergistic in effect. Thus, taken separately, factors such as fertilizer use, irrigation, trashing, and time of harvesting, are each capable of producing limited increases in yields. Taken together, however, and modified as appropriate, they can produce tremend- ous yield increases, some possibly in excess of a mere additive response.
It has been shown that by weeding cane at the right time and in the right way, yields, compared with an unweeded crop, can be increased by by much as 50 per cent. Earlier harvesting has been shown to increase yields by as much as 33 per cent, and fertilizer responses can be of the order of 10 to 20 per cent. The careful selection of varieties, the pro- duction of disease free seed, and proper attention to a range of cultural recommendations, all add to the potential yield which can be obtained economi- ally on a cane farm. Water, it is appreciated by most growers, is a major factor limiting cane yields in many parts of Natal. Yet only on a limited num- ber of farms have serious attempts been made to make full use of rain.
There is substantial evidence to show that for each one inch of rain effectively used by the crop, one ton of cane per acre can finally be harvested.
Despite this, yields per acre on many farms are much lower than the rainfall measured on the farm suggests it should be. This apparent loss of effective water can, in many cases, be substantially and economically reduced by conservation practices. The average yield throughout the cane belt is 16.8 tons of cane per acre per annum.
This average is derived from a range of farms where yields vary from 45 tons of cane per acre per annum, down to some which produce as little as six tons per acre per annum. Rainfall, however, varies from a low level of 20 to 25 inches per annum north of Mkuzi, through 25 to 30 inches in the Heaionville area and 35 to 40 inches in the main coastal belt, to 50 to 55 inches in isolated areas extending from Miunzini, to north of Empangeni.
Some farms in these areas admittedly have specific problems, but relatively few enjoy yields related to rainfall-inferred potential.
Farm Planning
If we accept, as we should, that potential yield for rain grown cane is governed by rainfall, then farm planning can be divided into two main groups.
One of these is associated with the coastal region
where rainfall exceeds 40 inches per annum, while the other relates to areas where rain is less than 40 inches.
In the higher rainfall region, planning involves the provision of facilities for the safe disposal of surplus water. This entails installation of grass guarded waterways and, on steep slopes, suitable conservation structures. Proper fertilizer use and the careful selection of varieties will offer the greatest possible benefit in these areas. Furthermore, valley bottoms, demarcated by cut-off roads, should be used for crops cut on a twelve month rotation. Slopes will carry longer term crops but even relatively steep slopes or hilltops need never carry crops which have to be cut at intervals exceeding 18 months.
Where rainfall is less than 40 inches, cane farms need to be organised with water conservation as the major issue to be borne in mind. Provision should be made to carry water slowly across the slope in deep or wide structures capable of taking up to 8 to 10 cusecs at any one time. Such structures need to be built with careful appreciation of the limits imposed by soil type and the water acceptance capacity of the sub soil. They need to be capable of absorbing rain water from flash storms and ensur- ing its seepage into the soil and interstices in the rock below. Provision may be made, if necessary, for excessive water to be caught and held in a reservoir. But it is usually far better and more efficient to store water in the profile than in a reservoir, as it has to be removed from the latter and applied to the land, all of which entails recur- rent expense.
Critical studies on the value of storing rain water in the soil profile have not been undertaken in the South African cane belt. There is, therefore, only an inference which can be drawn from work with other crops, and reference to the casual impressions of individual cane growers. Debatable as these may be, they do serve to support claims of economic benefits from water conservation. Thus, one farm in the cane belt with 465 acres under sugarcane, harvested 4,776 tons of cane in 1954. In 1966, it produced 9,902 tons and in 1967. 11,500 tons, both of these yields being from 405 acres. This increase from 10.3 and 28.4 tons per acre per annum is due in part to conservation practices adopted in the interim, a conservative estimate of the response being rive tons of cane per acre per annum. The outlay on conservation works and on constructing a farm dam was R10 per acre. The yield increases in excess of five tons per acre were obtained as a result of improvements in farming practices made possible by the reorganisation of the farm.
Proceedings of The South African Sugur Technologists' Association — April 1968 183
by C. H. O. PEARSON
South African Sugar Experiment Station, Mount Edgecombe
Aids to planning
The Experiment Station provides growers, on request, with various forms of assistance in planning their farms. Firstly, they provide stereoscopic inter- pretations of aerial photographs of the farm itself, showing crest and drainage lines. They will advise on the location of dams, on placement of conserva- tion structures, on the use of varieties, and on agronomic practices. The grower, however, has to implement and extend these recommendations, for he alone is aware of the vagaries of his fields, and the location of features such as seasonal spring lines.
He also has to decide on issues such as the location of loading points. The grower will have to peg and arrange for construction of conservation works, although the Experiment Station does, and will, arrange training courses to explain the principles of planning, and to demonstrate pegging out and the use of dumpy and Abney levels.
Replanning a farm is less difficult than most growers anticipate. Planning must necessarily be flexible, and the grower once he has made a start will find that it becomes easier with time. Experience will also teach him to adapt the detail of his plan to suit his peculiar circumstances. The important factor is to ensure that changes are tied to a basic plan framed from an aerial photograph. The scale of this plan should be 1 : 6000, which corresponds to the scale at which farm maps have been drawn.
Redesigning one farm
The aerial photograph of Brandon Hill Farm (Pty) Ltd., taken during the S.A.S.A. aerial survey in May 1966, is shown in Fig. 1. Extending eastward from the homestead, a narrow valley bottom has been demarcated as suitable for frequent cutting. This area can undoubtedly be enlarged and the valley adjoining it, running across the farm from N.E. to S.W., can be treated in the same way.
The first overlay shows that there are four main soil types on the farm. Granites occupy the high land in the west and along the northern boundary, the rolling area in the west of the centre is occupied by schists, while to the east of the centre and on the eastern boundary there are recent red and grey sands. The top overlay shows the crest and drainage pattern. As the farm lies in the high rainfall zone receiving 50 to 55 inches of rain, the main problem will be to dispose of surplus water, and to guard the waterway with permanent grasses.
The proposed layout for this farm is shown in Fig. 2, on the adjacent page. In this, the main haulage roads are marked in red, and many of them lead To the loading zone in the south-east corner, via the district road which is marked in black.
Waterways are shown as a double blue line enclosed in a dotted line. Proposed contour structures are depicted in green, and each of these is sloped gently from the ridge to the waterway at a gradient of
1 : 150. Fields, once the plan is implemented, would consist of long narrow areas suitable for strip crop- ping. Each of these fields would need to be planted on the master line principle to give long lines of cane ending either on a road or a waterway. Each line would be self draining and, because of the turn- ing space available at the structure, road or water- way, they would be quite suitable for the operation of mechanical equipment.
To redesign a farm
Designs similar to those prepared for Brandon Hill farm, can be secured by any cane grower for his own farm. All he has to do is lo a.\k the Experi- ment Station to secure, at his expense, an enlarged photograph of his farm. When ordering, he should provide the name and address of the farm and his Central Board, Schedule A number. The photograph will cost the grower about R10 for a 400-acre hold- ing, and for this he will be provided with a set of photographs mounted on stiff board, together with suitable overlays. A third overlay is provided so that planning details can be added.
A grower who has ordered his map in this way will, once he has received it, be visited by his Regional Representative and a planning officer.
When priorities for work and the location of essential roads have been agreed upon, the grower will, if he wishes, be assisted in his initial field work by Experiment Station personnel. The same staff will be able to advise him by telephone if he should run into any difficulty. In addition to recommendations on planning and field work, the grower will be able to ask for advice on changes in his techniques of cane growing. Eventually, he will be able to assess the productive capacity of the farm by comparison with accepted standards. By keeping simple records of labour and tractor use, he will Then be able to determine not only his overall management efficiency, but the relative returns obtained from different areas of the farm.
Summary
Crop production efficiency is a measure of the effectiveness of a complex set of agricultural prac- tices which, if properly organised, can be expected to produce tremendous yield increases on the majority of farms in the cane belt. With rain grown crops, conservation of water for use by the crop is of primary importance. Indeed conservation prac- tices arc the basic requirement for farm planning.
The Experiment Station provides extensive assist- ance in the replanning of farms. It assists, within limits, in the execution of such plans. Advice is provided on reorganisation, cultural practices and management efficiency, and their integration to ensure achievement of maximum potential yield.