Conservation agriculture

In his French A-Z, included in the fascinating non-fiction miscellany that makes up Bamboo, William Boyd writes about Xavier Rolland, his neighbour in SW France. Rolland has a small farm, which he works himself and, according to Boyd is "possibly the hardest working person I have ever encountered". For those of us who occasionally witness the daily grind of rural life, this comes as little surprise.

Boyd is usually very incisive and accurate in his observations, but in the following passage about Xavier Rolland, he falls prey to a very common misconception about farmers: namely that they enjoy a loving relationship with mother nature. "He ploughs his fields to the very edge of roads. He obliterates hedgerows..... and cuts down trees..... to gain a few extra square metres..... He is close to the land, but his relationship with nature seems more like that of a tenant with a rapacious and demanding landlord. There seems no love of the countryside..." No indeed: in many ways, conventional agriculture is little more than a ceaseless battle against the forces of nature.

Last Sunday evening, I travelled to Northern Tanzania and stayed the night in a small hotel in the town of Boma N'gombe, close to Kilimanjaro. The following morning, I flew about 100km to the south in a tiny single-engine Cessna. It was a bright clear morning. For once, Kilimanjaro was fully visible, resplendent in the sunshine, with a fresh coating of snow and frost. We flew over the semi-arid scrub that makes up such a large proportion of Tanzanian and Kenyan Maasailand. There was little or no sign of agriculture, at least on any scale: indeed, the only signs of human activity were red-clad Maasai herdsmen, their flocks and their manyattas, overnight homesteads for family and flock alike. From the air, the landscape is dotted with trees, except for a few large expanses of grassland. It is a fragile environment: the sandy red soil is prone to rapid erosion, especially if the trees are cleared for cultivation. Rainfall is low and unpredictable. The large expanses of grassland are usually evidence of areas of black cotton soil, where the heavy clay content of the soil prevents drainage, making the land prone to waterlogging and, in turn, unsuitable for most trees.

African farmers have traditionally avoided farming black cotton soil. It is heavy and hard to work using hand tools. But, in comparison to the red soils which are preferred, it is nutrient-rich. In some parts of the world (Queensland and Southern Brazil, for example), commercial farmers using conservation agriculture techniques have managed to unlock the potential of these soils to great effect.

Conservation agriculture is yet to be widely adopted in Africa, perhaps because so little of the continent is commercially farmed. Often called zero-tillage farming, it has three fundamental principles: to minimise soil disturbance, thereby preventing erosion, water loss and the oxidisation of organic material; to increase organic matter in the soil, creating a living rather than an inert soil environment; and regular crop rotation, reducing the build-up of pests and pathogens in the soil.

Later that same day, I returned to Sanya Juu, a small town on the lower slopes of Kilimanjaro. We invested in the development of a Hass avocado plantation there about four years ago. The young trees are already laden with fruit (as shown in the picture above). The environment there is very different. Annual rainfall is higher. Soils are fertile and deep. The altitude is higher and the ambient temperature cooler. European farmers (like Xavier Rolland) feel at home in this more temperate environment, where conventional farming methods yield excellent results.

But across Tanzania, (and elsewhere in East Africa), these areas are already farmed very intensively. To unlock Tanzania's agricultural potential, farmers will need to venture further into lower altitudes and semi-arid conditions, and will need to adopt new farming methods suitable for different soil types, in the forefront of which is conservation agriculture.