Potassium Research and Agricultural Production - The International ...

Such a heavy production per hectare was possible with a heavy use of N, P and K for
every crop. In India, under the AI/India Coordinated Agronomic Trial Scheme, numerous
multiple crop rotations are being tried for the last five years at 44 centres. Generally
the results indicate that with two crops more than 10 tons and with 3 crops 15 tons
grain per hectare can be produced. Rice-Rice-Ragi rotation at Mangalore on lateritic
soil produced 14.756 tons/ha while Rice-Wheat-Moong (greengram)gave 13.813 tons/ha
at Pura farm in Madhya Pradesh (India). In hundreds of national demonstrations
conducted on the cultivators' fields in India very high yield potentional of multiple
cropping has been shown. Even as high as 23.4 tons/ha from a three crops of rice in a
year has been produced. But this was possible only because of very heavy use offertilisers
containing N, P, K and micronutrients. The data in Table 15 give an analysis ofa
few cases of high yields and the fertiliser used (KanH'ar [I3J). From this data it is evident
that with the application of heavy doses of balanced fertilisers and using high
yielding varieties the production per unit area is many times higher than normally possible.
But this also implies many times more depletion of nutrients. For instance, a
farmer producing six tons of rice and six tons of wheat per hectare per annum is annually
removing 276 kg N, 125 kg P,O" and 396 kg K,Ojha. In addition he is also removing
3.97 kg Fe, 6.69 kg Mn, 1.03 kg Zn, 0.57 kg Cu in available forms. This shows
that in this region no doubt there are tremendous potentialities of increasing many
times more food per unit area per unit time by using multiple cropping but the rate of
depletion of nutrients is also very high and these high yields cannot be attained without
heavy use of balanced fertilisers. The world strategy for agricultural production is
based on use of high yielding varieties and multiple cropping and for the realisation of
goals with this strategy, potassium is as indispensible as nitrogen or phosphorus.
16. Conclusions
The Question arises that inspite of such overwhelming evidence for the need for potassium
in the tropical and sub-tropical countries of the region, why is it that the consumption
of potassium is very low. There are numerous factors responsible for the situalion
and one of them is the fact that in soils particularly the alluvial soils in this region
which are very heavily cropped with rice, the responses to potassium have been
Iow. It may be due to cultivation of varieties with low fertiliser responsiveness and the
greater degree of release of K from non-exchangeable forms of potassium. But with the
high yielding varieties of rice higher yield levels and multiple cropping, this situation is
changing fast. The investment on potash which is a low cost fertiliser seems to be an investment
for enhancing the returns particularly in dry season paddy from NPK with
HYV. The chemistry of potassium availability has not received much attention in the
paddy soils of Asia and the experience of temperate zone countries is not applicable
to the tropical paddy lands. In depth studies are needed in this region to appreciate the
problem of potassium. There is no doubt that for feeding the large populace of Asia
and keeping in view the crops and cropping patterns, the use of potassium in this region
cannot be ignored. It may be appreciated that so far as the plantation crops such
as Coconut, Sugarcane, Rubber, Tea, etc., are concerned it is unthinkable to obtain
satisfactory yields without potassium. It can hardly be overemphasised that in all such
crops often wrong conclusions are drawn on short duration studies and the plantations
suffer in yield and Quality due to deficiency of K.
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