THE MYSTERY THAT IS AERIAL YAMS

Pastor Simon Ngure is a busy man. In addition to tending to his flock at the Almighty God Ministries Church in Kiriaini, Murang’a, he also tends to aerial yams on his small piece of land.

Simon was introduced to aerial yams in 2009 by two friends. At the time he was planting the Medium Altitude Climber MAX 64 bean variety. The first yam he planted produced yams the size of a fist. The difference between the aerial yam and the regular yam is that it produces yams that hang in the air from its climbing vine unlike the regular yam which has tubers underground.

Initially, he would plant the yams for domestic consumption but as they kept reproducing, he started selling. He always visit agricultural shows to exhibit and get people to learn more about the aerial yams. Sometimes he does this on invitation from various agricultural training centers. When we spoke to him, he had just concluded exhibiting at an agricultural show at  Kamweti Agricultural Training Center

The surprising thing is that some agricultural officers at these shows hadn’t come across aerial yams and they would ask him a lot of questions. It is here that he realized that there was a need to start teaching farmers about the yams.

Agricultural officers also visit his farm to see how he is doing. The Divisional Agricultural Officer for Mathioya, Mr. Nyaga is one of the interested government officials.

The aerial yam is scientifically known as Dioscorea bulbifera. Simon is however quick to clarify that there are edible and toxic varieties of aerial yams. The toxicity is nonetheless debatable because it can be made edible by boiling for several hours. The edible aerial yams only need slight boiling like you would with potatoes but the toxic variety needs several hours of boiling to remove the poisonous elements.

To differentiate the edible from the toxic variety, Simon gives a few pointers. The non-poisonous vine goes clock-wise around the supporting pole. The poisonous vine goes anti-clockwise around the supporting pole.

The non-poisonous vine has a round stem like a pen while the poisonous vine has a flat stem like a ruler. In one of his trips, he has ever come across a farmer in Meru County who had planted the poisonous variety and would boil it all day to remove the toxicity but Simon gave him the edible variety and he now just consumes it like regular potatoes. In fact aerial yams taste like potatoes but a bit harder.

Aerial yams can be consumed in four ways. They can be boiled like potatoes but they are eaten without peeling. They are eaten together with their protective skin. They can also be roasted. The roasting is done by placing the unpeeled yam in hot ash. They are not roasted over an open fire like on charcoal grills. This will only remove the water from the yam reducing its size. They are also cooked in a stew just like you would with potatoes. Finally, they can be eaten raw like sweet potatoes.

Aerial yams are popular with Nigerians for whom it is a staple food. They fondly call it fufu. It is rich in potassium, B6 vitamin, manganese and vitamin C. It is also a good source of dietary fibre.

There are two types of the edible variety. There is the Golden Yellow variety and the purple variety. The Golden Yellow variety is suitable for both cold and warm climates and it has big dark green leaves. Its vine is wide and round. The purple variety is suitable for warm climates and has small light green leaves. Its vine is narrower.

Simon specializes in selling yams as seeds to other farmers. A 20kgs container (debe) can fetch  Kshs. 20,000. Aerial yams are planted in holes that are 1.5ft squared. Mix well decomposed manure with black charcoal dust and with soil. Simon doesn’t advocate for the use of ash or fertilizers while planting. The charcoal dust protects against bacterial wilt.

Once planted, the tuber takes 4 weeks to sprout and from there it grows 8 inches per night. When it gets to 2 metres in length, simon advises that you can spray the leaves with milk to protect against blight and black spots. The milk is diluted with water at a ratio of one litre to ten litres of water. It is then sprayed at midday when the sun is hottest. This drys the mixture onto the leaf providing a protective layer.

The milk is sprayed twice at an interval of 21 days. Simon tells farmers to do a small control experiment on the farm with the milk and charcoal dust remedies to test for themselves before implementing it to the entire farm.

The vines will need support from trelling posts. He advices against using wires or strings. Wires get hot in the sun which stresses the vine resting on the wire. Strings sometimes can’t support the weight of the yams when fully developed.

If the farm has moles, Simon has devised a method to protect tubers. He uses buckets or other large plastic containers and plants the tuber inside with soil. He perforates small holes on the sides for roots to get out. He then buries the bucket up to the ground level.

The aerial yam takes 5.5 months to mature in warm climates and 6.5 months in cold climates. The bulbs start appearing at 3 months and take another 3 months to mature. They start out green and turn brownish when mature and can be harvested for 4 months.

Once the four harvesting months are over, the leaves and vine dry up. After 2 months, a new shoot grows from the buried tuber. A buried tuber can go through this cycle for even 50 years. The yam’s shelf-life is 6 months.

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