Why canola is becoming the rotational crop of choice for large-scale farmers

Mau Narok is a scenic agricultural town characterised by rolling hills and large tracts of land.

A cloud of dust reaches unbearable level as one traverses the region, passing Mwisho wa Lami trading centre towards Ole Tipis, about 70km from Narok town.

Until recently, the expansive farms of the region hosted maize, potatoes, barley and wheat exclusively but winds of change are sweeping across the agriculturally rich region as farmers seek better returns.

The farms are now dotted with canola plant, with the crop creating a distinctive, beautiful sea of green and yellow that stretches to as far as the eyes can see.

The crop has come as a relief to large-scale farmers whose harvest from barley and wheat has been declining.

"Canola has become the ideal crop to grow our profits as we seek to break the cycle of barley and wheat," says Boniface Kinyua, a manager of Sansora farm and pioneer growers of canola in Mau Narok.

Canola as a rotation crop

"We started using canola as a rotational crop on our 350-acre farm in 2016 and it has a positive impact on production as it has controlled the notorious ryegrass boosting wheat production from 10 bags per acre to 15 bags," adds Kinyua.

They have been planting the crop on 350 acres, but he says the farm would raise the acreage to 700 acres next season.

"When the cereal crop is grown, fungicides have a chance to perform better and improve disease control compared to if one practices mono-cropping."

Government institutions have also embraced canola farming for its attendant benefits.

William Ruto, the manager at Agricultural Development Corporation (ADC) Inchili Farm, says using canola as a rotation crop reduces the cost of inputs on potato seeds production and controls the notorious ryegrass.

Ruto says before they started growing the crop, they had a  big challenge in weed management.

Improve disease control

The government firm owns 1,632 acres and about 72 acres are under canola.

"We expect to harvest two tonnes per acre of canola, what translates to 144 tonnes and with the market price of Sh40 per kilo, it means this farm will generate Sh5.7 million," says Ruto, noting the sell their harvest to a private company that processes it for oil.

Canola can be planted as a main crop. However, it is recommended as a rotational crop where one grows wheat, canola, beans and barley –  in that order.

Jason Kamunya, a project manager at the Center of Excellence for Crop Rotation at Agventure, says introduction of canola has helped farmers to grow their crops more sustainably by reducing erosion and improving soil moisture.

Previously, farmers grew wheat or barley and then let the land fallow, which means they did not earn anything.
"But with canola, when the next cereal crop is grown, the fungicides will have a chance to perform better and improve disease control," says Kamunya.

Natural weed suppressant

According to him, the crop that matures in five months also boosts soil health, thanks to its deep roots.

"Canola consumes nitrogen which is not wanted by the barley crop. It also add sulphur and boron in the soil,” he says.

When one farms canola and follows it with wheat, the wheat yield goes up to 22  bags per acre. When you farm an acre that has not been crop rotated with canola, one harvests 14 bags, says Jackson Yenko, an agronomist. He notes canola is grown for its highly nutritious oil, which is extracted from the seeds.

"The crop contains chemical compounds, which repel cereal pests and it works well for rotational purposes," says Yenko.

He adds that the deep rooting structure of canola crop makes cereals more resilient to dry periods and has helped farmers to grow their crops more sustainably.

"Farmers can grow wheat-canola-barley rotation which helps to manage soil erosion better. The crop is also a natural weed suppressant.”

Canola suppresses ryegrass and brome grass, which have become stubborn weeds and are very difficult to control.

Improves soil fertility

Brome grass seeds can lie dormant in the soil for up to three years or more, explains Yenko.

He observes that canola's deep roots help open cracks in the soil and it extracts nutrients from the lower level of the soil and bring them to the upper level.

"Wheat and barley are shallow-rooted crops and canola brings the nutrients on the upper soil helping them to access nutrient bank and improve soil structure and drainage."

Yenko says when the canola leaves dry and fall on the surface and rot, this improves soil fertility.

"They have a higher nitrogen and phosphorus content than wheat and barley straw, and this leads to increased production and reduced cost of operations per acre."

Prof Miriam Gaceri Kinyua of the University of Eldoret says canola rotation improves yield per acre and reduces soil acidity.

"Canola rotation breaks disease cycle, improves nutrients, drainage, water retention capacity, and stimulates a wider range of beneficial soil bacteria and fungi, " says Prof Kinyua, noting small farmers can also grow the crop.

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Planting

1. Canola does well in same weather conditions that favour maize, barley and wheat, but is well-suited for soils that do not crack.
2. An acre requires 4 kilos of seeds and the plant can be planted manually, but use of a planter is recommended.
3. The seeds are planted from a half to three quarters inches in the soil. 
4. They should not be planted any deeper than one inch because they will not germinate. 
5. They should be spaced six to nine inches apart.