‘Escalating fertiliser prices and need for judicious use’ – a response

Dr Parakrama Waidyanatha wrote an interesting and informative article to The Island under the headline, “Escalating fertilizer prices and need for judicious use”, last Monday.

I have the highest regard for views expressed by PD, from time to time. Having been an agriculturist for many years, I hope I will be permitted to make some observations on the said article.

As PD rightly points out fertiliser is no more a cheap commodity, and freely available, as before. One cannot overstate its judicious application today. It perhaps is the most expensive input in crop production.

When it comes to fertiliser usage, there are three major concerns,

How much to apply is determined by soil chemists, depending on the availability in the soil, and plant requirement.

When to apply is determined by the physiologists and agronomists. In both these cases the farmers do not have a say. Where the farmer exercises his discretion is when it comes to how to apply. The usual preferred method, the farmer is most comfortable with, is the soil application, by broadcasting, like in paddy, and sometimes band application in highland crops. There is little or no attempt to incorporate the applied fert into the soil. Equally, little or no attention is paid to whether the soil is moist enough to take in the fert or bone dry. The placement of fert, as PD says, is vital to ensure that it gets into the root zone. In Indonesian cane fields, a hole is dug, close to the sugar cane clump, with a pole, with a metal cap at the end, into which the fert is poured. Excellent!

Indiscriminate broadcasting, not caring where it lands, is a wasteful practice, at most times. I used to call it “yakkunta dummala gahanawa.” 

Split application of topdressings is a good way to use fert for best results. With the escalating labour costs, how feasible is it? Does the increase in yield offset the extra cost of labour? Sometimes one has to compromise best practices for economic reasons. Agriculture is a business and therefore profit is an important factor. There were situations, under extreme conditions, where I did not fertilize fields at all.

Now a few thoughts on foliar applications.

Nature expected the roots to be used for the uptake of water and nutrients. Leaves have a different function to perform.

Stomata, through which plants can absorb, are mostly located on the under surface, Besides, during the day they are more or less closed, thus limiting penetration, Some leaves have pubescence on the leaves. Others have a waxy layer on top. All these are devices to minimize excessive water loss. Therefore, these same devices prevent entry into the inside of the leaf.

PD, being a scientist, has calculated the right strength of the foliar spray. An increase can cause serious damage to the canopy. 60% of the tea is produced by small holders. How competent will they be?

Whatever the method of application, one chooses, there should be an effective extension service to advise the farmers. Have you got one?

There is another very efficient method to ensure maximum benefit of the fert usage, where possible. It is fertigation. Fertiliser in the irrigation water. There is a substantial initial capital cost but it is worth the try. I am aware that it is being used on coconut, in the Mahaweli area, with encouraging results.

As PD says, nano technology sounds promising but very little is known about it.

I wish to thank PD for opening the floodgates

Gamini Peiris

Panadura