Potassium Research and Agricultural Production - The International ...

are easier to use than three separate single nutrient materials. Recommendations
should be easy to understand and should take account of the kind of fertilisers farmers
will use.
These problems were not discussed in Abidjan. In the paper to the Fourth Session the
Ministry of Agriculture for Ivory Coast said that of the 82000 tonnes used in 1972
about 60% were simple fertilisers. Over 80% of the total was used on a few export
crops (named as bananas, pineapples, oil palm, coconuts and cacao). This leaves little
for other industrial crops (e.g. cotton, rubber) and local food crops. In visiting other
developing countries I have been struck by the difficulties that local farmers have in understanding
the nature of different fertiliser materials and in dealing with materials in
bad physical condition. '
4.5.1. Mixedfertilisers. Where more than one plant nutrient is needed there is much to
be said for manufacturing mixed fertilisers. The nutrients needed for particular crops
and soils can be provided in the correct proportions in a well-granulated form that is
easy to transport and spread. Where fertiliser use is being newly developed, mixed fertilisers
are particularly helpful. The fanner does not have to learn the special properties
and purposes of three separate materials supplying N, P and K, nor does he have to
mix together the right proportions of each, or go over his field three times to apply N,
P and K separately. Mixed fertilisers can be labelled for crop, soil and district; if more
than one type is sold in a district, the mixtures should be colour-coded. It is much easier
for the farmer to accept advice on the lines of 'apply 200 kg/ha from the blue bags'
than it is to understand recommendations in terms of three single-nutrient straight fertilisers,
or more difficult still, in terms of kilogrammes of N, P 20 5 and K 20 per hectare.
The compositions of mixed fertilisers should be adjusted to suit particular crops and
soils, or to supply nutrients in the ratios needed by the whole system. Packaging and
advice must help farmers to use products efficiently.
4.5.2 .• Safe' fertilisers. If farmers are to acquire confidence in fertilisers, the materials
offered must be easy to use and wholly beneficial, causing no damage to crops. The requirements
of a,suitable fertiliser are formidable. To suit the farmer they must be a)
cheap, b) highly concentrated, c) cause least damage to soil (e.g. by not acidifying it),
d) cause no damage to crops when placed with seeds or plants. Lime may have to be
applied at the same time as other fertilisers. All dressings may be placed too close to
seeds or plants by unskilled workers. For such purposes fertiliser materials are needed
where i) solubility of P is not lessened by lime (polyphosphates may serve), ii) useless
ions that raise salt concentrations are eliminated (e.g. the CI- in KCI) and iii) the form
of nitrogen used will not damage roots and is not easily lost from soil. There is great
scope for new technological developments to meet such needs with materials in good
physical condition; [ think the developed world has to supply this technology, the developing
countries cannot.
5. Potassium Research and Agricultural Production
I must now summarise some of the questions and problems raised in the last three Colloquia
which will be discussed here in Budapest. As we have a much wider gathering of
agricultural scientists from many more countries, I hope that we can make progress by
46