Harmattan Stresses on the Farm

Rainfed, non-irrigated agriculture is a prime reason for Africa's poor agricultural performance, according to all the authorities. How much water do West African citrus trees need during the dry season? Particularly in the harmattan? Have our local varieties (whatever they might be) adapted to the climatic conditions here such that irrigation makes little difference to them? Or would watering not only improve yield but perhaps even bring a second harvest? I wish I knew.

3 yr old citrus in West African harmattan

My young citrus trees though are a long way from bearing fruit and are showing very definite signs of water stress in the dry West African harmattan. Leaves have curled and a few weeks ago I noticed one or two had started browning. In past dry seasons some did not survive. A few weeks ago I began bringing in water, 20 gallons a day, weekdays, for approximately 40 saplings, about half a gallon per day per plant. It seems like quite a lot to me, but I'm not sure the plants agree. The browning has been reversed, but the leaf curl doesn't seem to be going away. The youngest citrus, 1 yr old, 1 foot high approx, respond more readily to watering than the older plants. At about 4 yrs old, 2" trunk base diameter, the signs of water stress are less obvious; these citrus seem able to survive the dry season without being watered. Their root systems must be deep enough to be getting some ground water. I can find nothing definitive on the internet. One source from the University of Arizona in the USA estimates that mature citrus trees need, depending on the season, between 17 and 135 gallons of water per day. This has to be a joke, right? Forget all the citrus trees and all the rest of agriculture, in Freetown right now and for most of the dry season we have people queuing at public standpipes to get water to drink. My minifarm has long been abandoned by the public water utility, so the best I can do is lug in limited amounts of water to placate my young plants.

Mature citrus, along with all our other fruit, mango, pawpaw, pear, guava etc do tolerate our five- or six-month dry season pretty well, so some sort of adaptation must have occurred: presumably these trees all have deep roots going down to the water table. The fascinating question though is how much improvement in output would be gained by watering during the dry season? And how much water would be enough to trigger that elusive second harvest, when fruit would not be in season and prices would be much higher? I wish I knew...

I search the internet without much joy. An article on mango exports from Africa to Europe grabs my attention. Lo and behold, there is a somewhat thriving mango export business in parts of West Africa. The mango, two-a-penny in Sierra Leone in season, is quite big business elsewhere. According to the experts it originally made its way to Africa over the decades from Asia, via Florida if you please, evolving numerous varieties along the way. The European market has settled on a few of these varieties, one call Kent in particular which I had never heard of, and some West African countries have invested heavily in plantations to meet this demand. But it's a tough business, with exacting European standards for quality - color, freshness, freedom from blemish, taste and perhaps most important of all now phytosanitary certification including details of treatment for fruit fly infestations. The list of diseases that affect mangos is thoroughly depressing; no doubt many of these same diseases and others could affect my citrus. Perhaps, I think, West Africa is the wrong place for the fruit business. Our climate makes fruit susceptible to such a huge variety of bugs. Perhaps again the plantation monoculture of Western growers is the wrong thing to emulate, as it presents a huge single target for the bugs to attack. In 2018 though West African exports of mango to Europe were some 103 million euros, with the French, through their tropical agricultural research centre, CIRAD, providing much needed technical support. Major West African mango exporters were Ivory Coast, Senegal, Mali, Burkina Faso, Ghana, Guinea and Gambia.

Another internet source reports that some citrus need 15 years before they begin to bear fruit. 15 years! This is no easy business! I had 5 yr old citrus

been counting on five years, but my first citrus plantings are now five years old and they look a long way from bearing fruit. They are about 8 ft high, but branch canopy diameter is only about 5 ft and trunk diameter base 2.5 to 3 inches. Should I trim the tops to encourage branch spread? Does regular watering increase growth and reduce the years to first fruit? More unknowns. The difficulties of farming in West Africa become more and more apparent, even though I am attempting it in the cosy confines of a capital city. I haven't been to the agriculture ministry this harmattan to seek advice, but my last visit there was far from encouraging. This is no easy business oh! Fifteen years is a long time to wait on an empty stomach. Would any sensible businessman undertake an investment where the first returns did not come in for fifteen years? More and more, the time to first harvest seems to me to be a crucial determinant of agricultural success, particularly with traditional West African communal land tenure practices, where longterm ownership or occupation is not guaranteed.

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