Swaziland's First National Communication to the United Nations Framework Convention on Climate Change

United Nations Framework Convention on Climate Change National Report on Climate Change National Report on Climate Change

Chapter 4 Vulnerability and Adaptation

4.4 AGRICULTURE

4.4.1 Introduction

The agriculture sector plays a very important role in national development in Swaziland, and is one of the leading sectors contributing to the GDP. The important crops grown in Swazi Nation Land (SNL) are maize and cotton, while in Title Deed Land (TDL) they are sugarcane, cotton and citrus. Crops grown in TDL are mainly for export, while those in SNL are mainly for subsistence purposes, with the exception of cotton, which is a primary source of income.

The agriculture sector is very prone to weather effects and climatic fluctuations. It was hit hard by the drought of 1992. Climatic modelling has shown that on the whole there will be chances in the weather and climatic pattern. Most models show that there will be progressing changes in both precipitation and temperatures in Swaziland in the next 75 years The months of March/April/May (autumn) are projected to have highest increases in precipitation. On average all the months will become warmer. Climatic change will have an implication on crop performance and hence on the yield.

Diseases also become prevalent under high temperatures and moisture content. Atmospheric carbon dioxide content is also expected to double by the year 2075 unless there are interventions to reduce its emission. This chapter attempts to assess the performance of maize, beans, sorghum and other crops under climate change conditions in Swaziland.

4.4.2 Baseline Information

4.4.2.1 Crop production in Swaziland

In 1990/90, the agricultural sector accounted for E135 million or 13.5% of GDP. Of this total, 22% was accounted for by maize and cotton production on Swazi Nation Land, 60% by sugar, citrus and pineapple production on Title Deed Land, and the rest by livestock (Swaziland Government, 1994a).

Agriculture and forestry establishments remain the largest employers offering about 35% of the formal private employment. The figure is even higher when considering the informal sector employment that includes family workers, small-scale traders and private homesteads.

About 11% of the land in both SNL and TDL are used for cropping and this area is gradually increasing. As an example in 1981, 142,426 ha was under cultivation while in 1991 the area under cultivation had increased to 195,000 ha (Swaziland Government, 1992). The practice of fallowing in croplands has been decreasing due to the increase in population leading to higher demands for cropped land.

Table 4.13: Area under major crops in the 1994 - 95 cropping season

Source: Swaziland Government

Subsistence farmers generally carry out agricultural activities on SNL. They tend to diversify their production of crops by growing a mixture of maize and other crops such as jugo beans, groundnuts, and Irish potatoes in the same field. These farmers often sell their produce only when financial needs dictate and most yields are consumed by residents of the adjacent homesteads. A large part of the SNL is under maize production, which is the staple food of Swaziland.

Sugarcane is the leading crop in TDL and it is the main source of foreign exchange for the country. The value of export of sugar was 25% of the total national export in 1992 (Swaziland Government 1994b). Maize remains the most important crop on Swazi Nation Land (Table 4.13).

The country has however never been self-sufficient in maize production, and consumption needs have always been satisfied by imports. The total national cereal national cereal requirements for 1991/92 were estimated at 223,000 tonnes of which 127,000 tonnes were maize. The self-sufficiency rose from 42% in 1991/92 to 59% in 1992/93 (Swaziland Government, 1994a).

A higher maize output of 153,000 tonnes was achieved in 1991 while the lowest, at 30,000 tonnes was achieved in 1983. The 1992 harvest of 46,000 tonnes was the second lowest of all years.

4.4.2.2 Sensitivity to climate

Agricultural production in Swaziland is very sensitive to climate and climate variation. The fluctuations in yearly crop and livestock production are mostly due to inter-annual variations in weather (Table 4.14).

The different crops are sensitive to climatic-related elements. As for example when temperatures fall below 21°C sugarcane growth fails. If the temperatures are too low the sucrose content for the sugarcane is also low. Crops like cotton will not tolerate heavy rainfall. The rainfall in Swaziland is sporadic and there are often prolonged periods of drought. This leads to the dying of cattle in the lowveld, which is most prone to drought.

Table 4.14: Climatic thresholds of Swaziland crops

4.4.2.3 Maize

Maize forms the stable diet, and it is the most common crop grown in Swaziland. The present area under maize production stands at 58,787 ha with 93% of the area (54,757 ha) under Swazi Nation Land (SNL). However maize production in the country does not meet the demand and this leads to importation of large proportion of the required maize and maize products.

Maize grows well on a wide range of soil types throughout Swaziland provided the pH of the soil is around 5.0, but prefers deep, well-drained soils. Rainfall in excess of 760 mm during the growing season is necessary for full development. The maize crop is very sensitive to water shortages, particularly at tasselling and silking and does not yield well if distribution is irregular.

The Lowveld areas are considered marginal for maize production, unless irrigation is available. Maize is also sensitive to extreme temperatures. Too cold (highveld winters) inhibit growth while too hot (Lowveld summers) shorten the life of the plant and interfere with pollination.

The optimum period for maize plantation is after the first spring rains in October through mid November. Early planted (August-September) maize is liable to maize streak. Late planted (December-January) is also susceptible to streak, drought and witchweed. Out of the harvest of about 3000 kg /ha a farmer can lose 50 kg/ha/day by planting after the end of October. Maize planted at the end of December rarely yields more than 250 kg/ha. Hybrids will always out yield open pollinated varieties by as much as 750 kg to 1500 kg/ha, but new seed, which is expensive, must be brought each year.

A farmer who rarely exceeds 500 to 1000 kg/ha will gain no advantage from planting expensive hybrid seeds because other husbandry input require improvement as a priority. Open pollinated (local selections) may mature in 130 to 200 days, while some hybrids may mature in as little as 100 to 110 days.

4.4.2.4 Sugarcane

There has been an increase in sugarcane production in the country with farmers in SNL growing it. All the cane cultivated in the country is under irrigation, and the sugar industry is therefore able to better cope with drought situations. The sugarcane is planted mainly in the Lowveld and Lower Middleveld where temperatures are optimal. Export represents about 82% of the total sugar. For the current base period the country produces an average of about 3,807,000 tonnes of sugarcane per annum.

4.4.2.5 Citrus

The citrus industry produces grapefruits, oranges, soft citrus and lime. Seven estates whose activities fall under the auspices of the Swaziland Citrus Board produce the fruit. About 60% of the fruit are exported.

4.4.2.6 Cotton

Cotton is grown on about 27,000 ha in the whole of Swaziland, with 11,000 ha being in the SNL. High yields for cotton can only be obtained where seasonal temperatures are high and with plenty of sunshine. Growth is poor above 800 m altitude. Cotton tolerates drought but is particularly susceptible to waterlogging. Only hybrid cottonseeds are grown in the country (Albacala 72 and Deltapine). Cotton can only be planted after the legal planting date (October), which has been set to control diseases and pests.

4.4.2.7 Beans

Beans are adapted to a wide range of climate conditions but do not yield well under extremes of temperature. Hot, dry wind during flowering can cause severe blossom drop and may shrivel mature pods. Beans are often killed by frost. Similarly cool, wet-seasons are highly unfavourable because beans are easily injured by excessive moisture, and are subject to attack by diseases which thrive under such conditions.

The optimum amount of rainfall is 400 to 500 mm of rain, well distributed over the growing season. Beans are very susceptible to drought, particularly during flowering and pod set which normally takes place 6 to 9 weeks after planting. Irrigation is required where plantings are recommended outside the seasonal rain (October to March). The following are recommended planting seasons:

Highveld: October - February
Middleveld: August - September: January - March
Lubombo: September - October: February - March Dry
Middleveld: January - March
Lowveld: February - August

There are several bean varieties with varying length of maturity. Contender has a short growing season of 110 days, while Speckled Sugar, which is the most popular type matures unevenly in 120 - 140 days. Brown Haricot is a long season variety that matures in about 150 days. About 2000 tones of beans are produced annually in the current base period.

4.4.2.8 Pineapples

Pineapples are grown in the middleveld by the company Swazican on its own land and on leased land, and to a lesser extent, by farmers on Swazi settlement scheme. In addition, Swazican imports some pineapples from the Republic of South Africa.

4.4.2.9 Sorghum

Sorghum grows best with rainfall of 650-900 mm. It is more drought resistant than maize. Sorghum is very sensitivity to soil acidity and no crop will be obtained if the pH is less than about 4.0. There are hybrid sorghum varieties (e.g. NK 300 and D036) as well as open pollinated varies (Red Swazi and Ntuli Red).

Hybrid varies tend to require better fertility and more rain than open pollinated varieties which will do moderately well in marginal rainfall areas. Most varieties are expected to flower within 60 to 75 days of planting with maturing in a further 50 to 60 days thereafter.

4.4.2.10 Potatoes

Potatoes produce heaviest yields in areas with cool days and adequate moisture. Frost can kill potatoes. Summer production in the Lowveld is unsatisfactory because of too high temperatures. Summer production in the Middleveld is difficult because of pest and disease problems associated with temperature and moisture. Potatoes can be grown in the highveld during summer; again disease problems reduce yields.

4.4.3 Methods of estimating effects of climatic changes on crop yield

4.4.3.1 Simulation of crop yields

The Decision Support System for Agrotechnical Transfer (DSSAT3) comprehensive software system was used to simulate the yield of three crops under present climatic conditions and under projected climatic and atmospheric conditions. The three crops for which simulations were run are maize, sorghum and dry beans. The simulations were done for three sites; Big Bend, Malkerns and Mbabane, representing the lowveld, middleveld and highveld respectively.

The simulations were done with all other conditions such as fertilisation, weeding and pest and disease control being optimised. Simulations were done to project yields for the year 2025 since reliable historical climatic data available for the weather stations dated back to 30 years.

The output of the modelling includes not only the harvest yield, but also parameters such as biomass yield, stalk yield and nitrogen content of the crop. For this project only the harvest yield was considered. Simulations were done using climatic patterns based on three climate simulation models; CCEQ, GFDL and UKTR under three conditions for each; low change (low), medium change (medium), and high change (high) in environmental conditions. For maize the simulations were further done to determine sensitivity of yield to changes in planting dates and changes in atmospheric carbon dioxide.

4.4.3.2 Effect of climatic change on other crops

Expert judgement was used to suggest likely effects of climatic changes to other crops that could not be supported by the DSSAT3 software. These judgments were based on the known climatic requirements and threshold conditions for the crops. For example, cotton will not tolerate heavy rains and will need temperatures of between 24-29°C for growth.

4.4.3.3 Comparison of model output with actual yields

Reliable experimental data on yields for the crops in Swaziland was lacking for all the stations. In an attempt to compare the outputs of the projections with actual yields average yields under SNL, which were obtained during a census (1992-1993) were used (Central Statistical Office, 1993). The actual yield will depend to a large extent on the management standard. The management standard under SNL conditions tends to be lower on average, even though there are always those individual farmers who have high standards. Table 4.15 shows average yield from Swazi Nation Land for selected crops.

Table 4.15: Average yield (kg/ha) under present situation for different crops

Source: Central Statistics Office, 1993

4.4.4 Results

4.4.4.1 Maize

The projected yields for maize for Big Bend and Malkerns are shown in Table 4.16. A decrease in the projected yields was observed for most of the models for both Big Bend and Malkerns when the maize was planted during the recommended period, which is the second week of October. (Tables 4.16 and 4.17)

The change in projected yield for Big Bend ranged from -59% (CCEQ low) to -30% (UKTR medium). This was an indication that a decrease in maize yield is expected in Swaziland under the expected climatic change conditions. This could have a negative impact on the country’s status of food security.

The projected doubling of the population in 25 years will further increase the demand for food. The area under maize production is currently decreasing due to a number of farmers in both Swazi Nation Land and Title Deed Land shifting from growing traditional crops such as maize to sugarcane which is considered more profitable.

In the event of doubling atmospheric carbon dioxide concentrations, the change in projected yield would not be significant. The predicted change in maize yield for Big Bend (CCEQ low) would be from -59% to -57%, and for CCEQ high, it would change from -33% to -17%. The projected yields showed great improvement when changing the planting season from the traditional second week of October to the second week of August. There was an increase in the projected yield of up to 9% under Big Bend conditions when using the CCEQ medium prediction model (Table 4.16). The projected yield increase was even greater under Malkerns conditions, recording an increase of as much as 28% (CCEQ low) prediction model. With planting done earlier than August the projected yield was reduced at all sites and for all the models. The recorded reduction in yield was as much as 85% at Big Bend with CCEQ low.

Table 4.16: Projected maize yield (kg/ha) under different crop and model conditions

4.4.4.2 Sorghum

The simulations indicate a decrease in the yield of sorghum for all the other weather stations except at Mbabane. For Big Bend the decrease in yield is projected to range from 78% (UKTR: low) to 59% (GFDL: medium). The yield for Malkerns is projected to fall by between 25% and 8%. The yield for Mbabane is expected to increase by a margin of between 60% and 8%. This can be attributed to the fact that the temperature for Mbabane is expected to increase, as well as the rainfall.

Table 4.17: Projected change in maize yield (%) under different crop and model conditions

4.4.4.3 Beans

The projected yield for beams is expected to decrease for all the places by the year 2025 except under Big Bend conditions when planted during the usual period of February. The reduction in Mbabane is expected to range from 11% to 23%, while that for Malkerns is expected to range from 30% to 46%. An increase in yield at Big Bend is expected. The expected increase in yield ranges from 38% to 191%.

4.4.5 Expected effect of environmental change to other crops

The effect of environmental change to other major corps in the country could not be simulated due to lack of simulation model to support them. However some possible effects were deduced on the basis of projected weather data and climatic requirements for the crops. For example for cotton the projected increase in rainfall may bring about waterlogging of the crop.

The high rainfall and high temperatures may result in high incidence of pests and diseases especially in the middleveld. This may result in decline in yield. Potatoes, being temperate crops may not do well since temperatures will be high. The may be high incidences of diseases due to high moisture and temperatures. The yields are generally expected to decline. Some areas such as the Middleveld, which are currently suitable for growing potatoes, are expected not to be suitable in the future.

Table 4.18: Projected sorghum yield (kg/ha) under different crop and model conditions (year 2025)

The temperature is expected to be suitable for sugarcane production in most regions in the country. The increase in rainfall and temperature is expected to have a positive impact on pineapple performance.

Yield for citrus is expected to decrease due to high incidences of pests and diseases. The overall expected effect on crop production is a decline in yield for temperate crops and an increase in tropical and subtropical crops.

4.4.6 Adaptation

One of the main adaptation strategies that may be followed is a change of growing the season in the country. The normal planting season for maize middle of October. When maize was planted in the second week of August there was a projected increase in the yield in most areas.

Late planting (mid December) is projected to lead to decline in yield. Another adaptation strategy would be to grow varieties that are tolerant to high temperatures and high rainfall. This would require breeding of crops to suit the conditions. There may be changes in the types of crops grown in the different regions in the future. For example sugar cane may be grown predominantly in the highveld as opposed to the current situation where it is grown predominantly in the lowveld and the middleveld. The type of crops grown in the country may have to change. For example potatoes may not be grown in the country in the future, and crops such as cassava may be the main root crop.

4.4.7 Conclusion

The effects of climatic change in Swaziland will vary with different crops. The effect will however be negative for maize, which is the staple crop in the country. The maize yield is expected to decline by as much as about 60% in other areas of the country unless some measures are taken.

The Highveld may not be suitable at all for growing maize in the next 25 years. The impact may be positive for some crops such as sugarcane. The climatic change will bring about changes in cropping pattern and dates. One of the adaptation measures that may be followed is to change the planting season of the crops. When planted during the first week of August, maize could produce increased yields.

The outlook for the agriculture sector on the whole is not favourable. The predicted decrease in maize yield of as much as 60% would offset the goal of the government for self-sufficiency in maize. The high population growth and demand of land for cash crops such as sugarcane and pineapples may further compound the reduction in yield. More of the maize may have to be imported, draining the limited foreign reserves of the country.

A large percentage of the population could end up on food aid. The government may have to set up strategies to assist the population. The agriculture sector does not only directly provide employment, but also provides raw material for other manufacturing industries. With reduction if yield of major crops such as maize, people may lose their jobs due to lack of raw material.

The combination of food shortage and lack of employment could lead to high crime rates. The government may not be able to fulfill its goals of increasing rural income and improving the nutritional status of the population. As the predictions indicate that maize yield may be increased by early and timely planting, means should be found to have enough tractors in the "Tractor Hire Scheme" of the government. Finance should be made available to purchase inputs such as fertilizers and hybrid seeds. The use of land should be controlled to minimise the conversion of land used to grow food crops to growing cash crops such as sugarcane.

4.4.7.1 Limitations of project

i. The lack of experimental data made it not possible to calibrate and statistically test the effectiveness of the modelling under Swaziland conditions. Average yields for the different crops were used to demonstrate the relationship between projected yield and actual yield. There is need to carry out experiments in the four agro-ecological zones and to further calibrate the model.

ii The DSSAT3 Model used was fully developed for a limited number of crops. Modules for important crops such as sugarcane, potatoes and cotton are still lacking. There is need to fully develop the missing modules for it to be more comprehensive in its usage.

Table 4.19: Projected dry beans yield (kg/ha) under different crop and model conditions ( year 2025)

This page was last updated on 11 October 2004