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ORGANIC SUGAR PRODUCTION –

THE MAURITIAN EXPERIENCE

J Deville

Mauritius Sugar Industry Research Institute, Reduit, Mauritius

 

 

ABSTRACT

Organic sugar production started in Mauritius in 1992 after it was realised that a demand existed in Europe. Production followed the standards laid down by the Organic Farmers & Growers Ltd (UK). These have to be strictly adhered to if the produce is to be certified as being organic by a registered inspector. The use of organic fertilizers, because of their variable and heterogeneous composition, may lead to over or under fertilization. Manual weeding was found to be expensive and ineffective. On the processing side, juice clarification was a major problem as clarifying aids are not permitted. Sucrose recoveries were consistently low. Owing to these constraints, producers gradually lost interest in organic sugar and only one estate, out of the three originally, is still involved.

Keywords: organic farming, organic sugar, clarifying aids, sucrose recovery, sustainable agriculture, by-products.

Introduction

Over the last two decades more and more attention has been given to the production of organic foods in Europe and North America. There are probably two reasons that explain the evolution of organic farming: the increasing public awareness of the need for environment protection, and the benefits to be derived from the utilization of renewable resources instead of non-renewable ones. In some European countries, government encourages organic production by providing financial incentives or by giving support for marketing, research and extension. Such official encouragements have led to a rapid development of organic farming in Europe.

In Mauritius sugar is the only food produced and exported according to established organic norms.

Following the visit, in 1991, of the representative of a British firm involved in the marketing of organic foods, it was realised that there was a market for organic sugar in Europe. Furthermore the price was attractive. Three sugar estates out of the 19 operating at the time, showed an interest in producing organic sugar. Sugar cane fields were identified for the purpose in 1991 and processing started in 1992.

 

Requirements for the production of organic food

For a produce to be certified by a registered inspector as organic, it has to have been produced according to certain norms. These are set by organizations whose role is to ensure that the organic nature of a produce is maintained.

The production of organic sugar in Mauritius follows the standards laid down by the Organic Farmers & Growers Ltd (OF&G) of UK which operates an independent certification scheme for organic food production (Anon 1993).

The system of organic production, according to OF&G is geared towards the production of optimum quantities of food of high quality by using management practices which avoid the use of agrochemical inputs and which minimize damage to the environment and wildlife. The principles of organic production are given below:

The above principles have to be strictly followed as any deviation may lead to the removal of the organic status. Visits are carried out by a registered inspector to ensure that the norms are being complied with. The fields are normally visited at harvest time, two to three months later, and a few weeks before harvest. The factory is visited before processing starts, and when sugar is being bagged. Every year a comprehensive certification report has to be forwarded to OF&G after sugar has been produced.

 

Some main considerations

For an operation to be certified as organic, it is required that when switching from conventional to organic production, a ‘transition’ period be respected. A product may only be sold under an organic label if it has been produced after a period of transition of at least two years. This means that there must be 24 months from the last use of any non-permitted material before planting of the organic crop. For a produce to be considered as ‘in transition’ that period will be of 12 months instead. For a sugar cane crop which is harvested 12 months after planting, the first consignment of organic sugar would be available 36 months after the field had last been under conventional production. Thus, if organic sugar production is to be started, a decision has to be taken well in advance. It is only under circumstances where new land is being cultivated that organic cane production can start straightaway.

As far as sugar production is concerned, the aspects requiring more attention are: fertilizer use and pest control for the agronomic side, and clarifying aids for the processing side.

 

Pesticide use

Mauritius is fortunate in that no insecticide is used in its sugar industry. Insects are controlled by biological control methods which have been in use in the country for more than two centuries.

For disease control, preventive measures are taken by the use of tolerant or resistant varieties, and by hot water treatment of cuttings prior to planting.

However for weed control, the use of herbicides has to be resorted to if optimum production is to be achieved. In fact it has been reported that certain weeds, such as Cyperus rotundus, if allowed to proliferate, may have an adverse effect on the sugar cane yield (MSIRI 1980, MSIRI 1981). As the use of herbicides is not permitted in fields under organic crop production, manual weeding had to be resorted to. In view of the acute labour shortage and the increasing cost of labour, this item was a major contributor to the costs of production and one of the main sources of discouragement for producers who generally do not like to see their fields infested by weeds. Manual weeding is also known to be ineffective.

Although alternative methods of weed control exist, they could not be envisaged in the Mauritian context. Using a flame applicator would represent a fire hazard because of the presence of dry trash in the field, and weeding by mechanical means is not convenient because of the rocky nature of the soil. Weed control in the fields under organic cane was therefore not carried out to the same extent as it is in conventionally grown cane.

 

Nutrition and fertilizer use

Cane produced according to organic specifications should not in theory yield less than under conventional production methods as long as the amount of nutrients supplied is the same in the two cases. Indeed studies carried out in Mauritius comparing the use of organic with that of inorganic fertilizers have shown that similar yields were obtained (MSIRI 1989, Ng Kee Kwong et al 1997).

The sources of nutrients that have been used in organic cane production in Mauritius are: poultry litter as source of N, filter muds as source of P, and vinasse as source of K. The typical composition of these materials is given in Table 1. Poultry litter and filter muds were available on all estates, while vinasse was available only on Estate B.

 

(TABLE 1)

 

As these materials are quite heterogeneous, an analysis had to be carried out on each batch prior to utilization in order to determine the rates to be applied so as to provide those recommended by MSIRI.

Poultry litter when used in organic agriculture has to be composted before application so as to eliminate pathogenic organisms. This was done by allowing the manure heap to reach a temperature of 55-60 °C and maintaining it for a period of 72 hours. After mixing and allowing the heap to reheat to 55-60 °C it could be used after another three days.

 

Foliar diagnosis of organic cane fields

The diagnosis of the nutrient status of sugar cane fields by leaf analysis has been a recurrent annual exercise in Mauritius since 1962. The aim is to allow agronomists to apply corrective measures to their fertilization programme in relation to the leaf analysis results. When organic cane production started, some fields were identified as Permanent Sampling Units (PSU) for annual leaf sampling and analysis. From the results of foliar analysis in these PSU’s (Table 2), it can be observed that a minor nutrition problem exists only at Estate A. While in Field 1 the nutrient status shows a slight degeneration over the last two years, deficiencies have persisted for some time in Field 2, despite the corrective measures taken.

 

(TABLE 2)

 

It should be noted that one of the problems related to the use of organic fertilizers is that the nutrients (especially N) contained therein are in bound form and are therefore not as readily available as in inorganic fertilizers. Although this may be taken into consideration by using an availability factor, the latter is not a constant one and may even be unknown. The result is that there can be over or under fertilization due to approximate amounts being applied. N applied in rates below the optimum may lead to uneconomical cane yields, while excessive doses may have a detrimental effect on the sucrose content.

As a matter of interest, yields obtained from fields under organic production are compared with those from adjacent fields under conventional production (Table 3) for a typical year, i.e. without drought or cyclonic conditions.

 

(TABLE 3)

 

These differences in yield illustrate the variability which may be expected from the two types of production. It should be noted that although Estate B had better yields with its organic cane compared to conventional cane, much more complaints about production constraints were received from that estate than from the other two.

 

Processing of organic cane

The standards for the processing of organic food require that it is carried out in a unit totally separated from that for conventional food. In the case of sugar, this cannot of course be envisaged as an additional factory would be required. Two alternative arrangements were proposed and accepted. Either the processing of organic cane would be carried out at the beginning of the milling season when the processing line would have already been cleaned and free from conventional cane products, or it could take place at the end of the season, i.e. after all the conventional cane has already been processed. In this second case, the processing line would need to be thoroughly cleaned to eliminate all residues of conventional cane. Such cleaning, using water and steam jets, concerns the whole of the factory, starting from the unloading bay right up to the sugar bin. Two sugar estates chose the second alternative, the main reason for their choice being that the sugar cane variety planted was a late maturing one. Should such a variety be processed early, the sucrose recovery would not be maximized.

However processing at the end of the season was never possible at one of the factories as every year accidental or criminal fires broke out in some of the fields under organic cane in the middle of the season. Thus instead of processing the burnt cane as conventional all the organic fields were harvested. This meant that the factory had to be stopped to enable cleaning before processing of the burnt organic cane could start. Needless to say, this situation causes a lot of inconvenience as it disrupts the routine of the factory. Furthermore cane with a sub-optimal sucrose content had to be processed.

One important step in the processing of sugar cane is the clarification of the juice obtained after milling.

This procedure is essential to remove impurities which would otherwise interfere with the crystallization of sugar. In practice, the juice is limed so as to produce coagulated suspensions. These settle slowly, and will require a fair amount of time to thicken. It is therefore common practice that flocculants (or clarifying aids) are added to the limed juice in order to improve settling and compaction of the coagulates.

However in the production of organic food, these synthetic clarifying aids are not permitted. As only lime can be utilized, the consequence is that settling of the suspended solids takes a considerable time, leading to frequent overflows of juice and mud from the clarifier. On some occasions, it happened that whole batches of juice were lost. Furthermore, with the extended settling time, sucrose losses due to inversion may also happen. Recent trials carried out on the possibility of using seed extracts from a common tropical plant, Moringa oleifera, as clarifying aid have given promising results (Wong Sak Hoi et al 1999).

Apart from the above-mentioned losses that happen during processing of organic cane, another source of loss exists, contributing to the generally observed low recovery of organic sugar. After the A-massecuite has been centrifuged to obtain the sugar crystals, the remaining solution still contains a certain amount of sugar which is normally recovered after being re-circulated in a fresh batch of massecuite. When organic sugar is processed, there will always be the last batch which cannot be further re-circulated (as organic). The volume of this last batch is constant, whatever the tonnage of organic cane being processed. Hence there is an amount of organic sugar which will be mixed with conventional sugar and is unmarketable as organic sugar. The proportion of sugar recovered from organic cane will therefore be less than that from conventional cane. The data given in Table 4 illustrate the low sugar recoveries obtained at the three factories for the period 1993-1997. The recoveries are within a range of 2.7 – 7.3% compared to that of 9.99 – 11.33% obtained throughout the 1998 crushing period. These problems were a constant source of discouragement and frustration to the factory personnel who gradually lost interest in producing organic sugar.

(table 4)

Thus, by 1998, two of the initially three estates had discontinued production. The exports which had reached a peak of 557 tonnes in 1995, from a modest start in 1992, dropped to 116 tonnes (Table 5).

(TABLE 5)

Conclusion

There are a few constraints to the production of organic sugar. Some may be overcome, e.g. fertilization and weed control, but some may prove difficult to surmount, e.g. that of low sucrose recovery during processing. Should the problem of clarifying aid be solved, an increase in sugar recovery may be obtained by processing a much larger tonnage of cane. The processing of all the organic cane produced in only one factory could be considered.

Nevertheless organic cane production is a practical way of utilizing by-products and renewable resources, which is in accordance with the concept of sustainable agriculture and environment protection.

 

References

 

Anon (1993). Organic Production Standard. Organic Farmers & Growers Ltd.

MSIRI (1980). Ann. Rep. Maurit. Sug. Ind. Res. Inst. 18, 27-46.

MSIRI (1981). Ann. Rep. Maurit. Sug. Ind. Res. Inst. 19, 48-49.

MSIRI (1989). Ann. Rep. Maurit. Sug. Ind. Res. Inst. p. 34.

Ng Kee Kwong, K. F. and Paul, J. P. (1997). Vinasse as a potassium fertilizer for sugar cane. Revue agric. sucr. Ile Maurice. 76:34-37.

Wong Sak Hoi, Y. L. and Tse Chi Shum, S. (1999). Plant materials as natural flocculant in cane juice clarification. Presented at XXIII Congress ISSCT, February 1999, New Delhi.

 

 

 

 

 

 

 

 

 

 

 

LIST OF TABLES

Table 1 Average composition of organic fertilizers

Table 2 Results of leaf analysis of organic sugar cane

Table 3 Comparative yields of organic and conventional cane (TC/ha)

Table 4 Sugar recovered % cane

Table 5 Export of organic sugar (tonnes)

 

 

 

 

Table 1. Average composition of organic fertilizers

 

N

P

K

% DM

Filter muds

1.64

0.81

0.21

94.4

Poultry litter

3.91

0.86

1.35

82.9

Vinasse (g h-1)

1.50

-

21.2

-

 

 

 

Table 2. Results of leaf analysis of organic sugar cane

Estate A

 

Field 1

Field 2

 

N

P

K

N

P

K

1993

1994

1995

1996

1997

-

1.98

1.94

1.86

1.77

-

0.194

0.190

0.191

0.181

-

1.29

1.25

1.18

1.14

1.80

1.80

1.84

1.79

1.78

0.211

0.201

0.199

0.188

0.183

1.12

1.13

1.15

1.10

1.16

Threshold

1.85

0.19

1.2

1.85

0.19

1.2

Estate B

 

Field 1

Field 2

 

N

P

K

N

P

K

1993

1994

1995

1996

2.14

2.13

2.09

2.00

0.225

0.241

0.245

0.241

1.21

1.30

1.34

1.32

1.95

1.89

1.91

1.91

0.217

0.232

0.237

0.239

1.31

1.27

1.28

1.27

Threshold

1.85

0.19

1.2

1.85

0.19

1.2

Estate C

 

Field 1

Field 2

Field 3

 

N

P

K

N

P

K

N

P

K

1993

1994

1995

1996

2.21

2.17

-

1.93

0.208

0.213

-

0.216

1.14

1.23

-

1.23

2.35

2.09

2.03

1.85

0.225

0.204

0.201

0.181

1.16

1.13

1.09

1.04

2.33

2.12

2.03

1.88

0.236

0.218

0.217

0.199

1.08

1.10

1.10

1.12

Threshold

1.85

0.19

1.20

1.85

0.19

1.05

1.85

0.19

1.05

 

 

 

Table 3. Comparative yields of organic and conventional cane (TC/ha)

 

Estate A

Estate B

Estate C

Organic

70.5 ± 4.4

58.5 ± 9.1

80.3 ± 1.8

Conventional

77.4 ± 4.6

49.1 ± 4.6

109.4 ± 5.7

 

 

 

Table 4. Sugar recovered % cane

Estate

1993

1994

1995

1996

1997

1998

A

2.7

5.2

5.2

5.1

5.3

4.6

B

5.77

3.57

6.97

7.1

NP

NP

C

6.0

3.68

6.5

4.3

4.7

NP

NP : No production.

 

 

Table 5. Export of organic sugar (tonnes)

Crop year

Export of organic sugar (tonnes)

In transition

Organic

1992

1993

1994

1995

1996

1997

1998

61.7

-

11.89

-

-

-

-

72.4

159.5

219.7

557.8

271.9

206.8

115.8