Tithonia species: Their use and abuse By Tim Pagella

1. Tithonia species: Their use and abuseBy Tim Pagella

2. Also known as the ‘Mexican sunflower’ or ‘sunhemp’, Tithonia diversifolia actually originated in Mexico, but is now widely distributed throughout the humid and sub-humid tropics in Central and South America, South East Asia and tropical Africa • It is typically found in hedges, or as small areas of pure stands in an on-farm context, although it may also extend for large areas in pure stands on common land in less populated areas

3. Current uses Biomass Transfer Improved Fallow species Pest and weed control Medicinal shrub Fodder, poultry feed Soil erosion control Land demarcation Building materials & fuel

4. Biomass transfer with Tithonia • Transferring of biomass involves using the foliage of selected trees, shrubs and other plants as organic fertilizers -or green manure - on agricultural fields. • Tithonia diversifolia has aroused research interest because of the relatively high nutrient concentrations that are found in its biomass, and because of its ability to extract relatively high amounts of phosphorus from the soil

5. Although it is not a legume, tithonia accumulates large amounts of nitrogen and phosphorus from the soil (nutrient scavenging). When it is cut and incorporated into the soil, it rots quickly, releasing nearly all its nitrogen into the soil within just 2 weeks • In 1997, ICRAF researchers and their national partners, working in seriously degraded soils in western Kenya found that in research trials where tithonia had been applied (at rates of 5, 10, and 20 tonnes per hectare), maize yields were more than 1000 kilogramme per hectare higher than the control plots, and actually outperformed commercial fertilisers.

6. Advantages for biomass transfer • It can produce up to 275 tonnes of green material (about 55 tonnes of dry material) per hectare per year in favourable conditions • It is very hardy and can withstand being pruned to soil level and being burned. • It is inexpensive and readily available alternative to purchased fertilizers • The plant is easy to establish through cuttings • When combined with indigenous rock phosphate can double or triple maize yields • Its scavenging ability means that it can arrest the nutrients seeping out of the farming system

7. Disadvantages for tithonia biomass transfer • Jama et al., (2000) found that to increase maize yields from 1.3 t ha-1 to 4.2 t ha-1 required 50 kg ha-1 of mineral fertiliser. To supply the equivalent P (56 kg ha-1) with Tithonia biomass alone would require a DM application of about 15 t ha-1. Assuming that dry Tithonia biomass is about 15% of the Fresh Weight, the amount of FW biomass that would have to be cut and transported to supply the equivalent of 56 kg P ha-1 would be about 100 t ha-1 • Assuming that a pure Tithonia hedge produces about 8 kg fresh biomass m-1 (about 1 kg DM m-1) (Drechsel & Reck, 1998), the length of the hedge required to supply 56 kg P would be about 15 km • It is suggested that this would require approximately 450 man days to harvest this amount

8. It suggests that farmers either need to have a lot of land and/or a lot of labour to be able to utilise it therefore putting it beyond the reach of subsistence farmers. This land use practice would exclude other species that farmers may wish also to include in their hedges • It is more efficient when used in combination with a phosphate rock, but again this is usually to expensive for subsistence farmers • Tithonia is efficient at extracting nutrients but does not add to the net quantity in the soil. Tithonia will eventually mine the soil of nutrients and in an on-farm situation this is unsustainable

9. In situations where the farmer does not have sufficient labour to manage it, Tithonia may become a pest and invade farmland, thereby increasing labour of the farmer, who has to find ways of controlling it (It is considered a pest species in S.Africa) • Data from ICRAF showed that under farmers managed conditions, investing in Tithonia fertilisation was viable for high value Kale but uneconomical when used with a low value crop, in this case maize.

10. Socio economics, especially gender, has important implications • Biomass transfer is generally widespread where there is access to large quantities of organic matter from common resources that already exist. It is unlikely that most resource poor farmers will be willing to develop biomass banks off farm on common land, although they may be willing to invest in their management. Development of biomass transfer from common resources may be possible in Nepal, where it is already a major technique, however in Bolivia and Brazil, the high availability of land and the low availability of labour makes transfer of off-farm perennial biomass relatively unattractive

11. However • There is often conflicting evidence presented • Optimising management options and economic aspects are both under researched • Farmers are using it on their fields in Kenya, actual utility decision making criteria is not fully understood or documented • If it is judged on it’s phosphorous ‘supplying’ merits alone it is not as attractive as was first thought, but it does provide a number of other benefits, not least in supplying readily available nitrogen. The value of these multiple effects on fertility is often greater than the value of any single effect, especially when combined with other aspects such as erosion control, etc

12. Additional uses:Pest and weed control • Tithonia acts as a natural pesticide: it is effective against nematodes and may be effective in controlling striga • It has been used as an effective termite control agent in Kenya • Described as the ‘weed that kills weeds’ in S.America • In Asia it has been used as a biological tool to eradicate Imperata

13. Improved fallow species • ICRAF work carried out in the Philippines has shown that through rapid growth, efficient scavenging of soil nutrients, copious leaf litter, and rapid decomposition, tithonia appears to accelerate nutrient cycling and enable soil rehabilitation during an abbreviated fallow period • The large leaf area of sunflower intercepts most light and hard-to-control grasses are quickly choked out • Sunflower hedgerows maintained around the swidden perimeter provide the seed source to facilitate rapid colonisation during the fallow

14. A two year fallow appears to be the normal, after which the sunflower biomass is easily slashed and mulched or burned. Some farmers interviewed claim that soil physical properties improve so dramatically during this period that ploughing is unnecessary and seeds can be dibbled directly - an advantage in erosion-prone sloping uplands.

15. Medicinal and Fodder properties • Tithonia is believed to kill intestinal worms in cattle • It is also given as fodder to goats, sheep and cattle in the dry season (not very palatable) . • As a medicinal shrub people use it to deworm young children. It is used to prevent malaria and to cure fevers and stomach upsets

16. Conclusions • The main reason for using a plant such as tithonia in biomass transfer is that it has all the necessary attributes to rapidly store 'lost nutrients' in its biomass, thus it is able to arrest the nutrients seeping out of the farming system. This means a lot of free fertiliser if farmers and labourers can be mobilised