How to improve potato yields
Potatoes are a rich source of nutrition and energy because of their high content of vitamins, minerals and essential organic compounds and are both a staple food and a cash crop. Kenya’s expanding population, increased urbanisation and the popularity of fast foods are driving an escalating demand for potatoes to supplement maize and rice as basic foods.
At present the average potato yield in Kenya is only three to six tonnes per acre. Contributing factors for this dismal performance include mono cropping, poor land preparation methods, planting the seed in a furrow rather than in a bed, substandard potato seeds, poor application of fertilizers and insufficient control of disease with substantial harvest and post harvest losses. In potato producing countries like Holland and Ireland outputs of between 60 and 70 tonnes per acre are the norm.
The yield in Kenya can be increased to between to 20 to 30 tonnes per acre by addressing the weaknesses starting with the selection of the seed potato. Currently as certified seed is scarce, Potato farmers are forced to use poor quality seed that continues to limit yield. Many farmers sell the largest potatoes for cash, eat the medium sized ones at home and still use the smallest for future planting material. Inevitably this practice is poor and contributes to low returns from the crop.
Explaining the benefits of mechanisation Fergus Robley, the General Manager of FMD East Africa, said, “ Instead of following the present practice of land preparation it is important that potatoes are planted in rotation with other crops, and that potatoes are planted in beds with the correct tilth to allow for good and even multiplication of the tubers and easy lifting at the point of harvest. We offer the world renowned Grimme range of potato farming implements that include seed bed formers, planters, seed bed maintainers and harvesters to allow Kenyan farmers to enjoy higher yields and profitable potato farming.”
“Potatoes grow well in loose loamy soils and some areas of sandy loam soils where rainfall is higher. The soil needs to be ploughed and free of weeds before using the seed bed former which is also known as the rotary ridger and prepares the soil to give a bed with consistent tilth with good aeration. As a result, the tubers are encouraged to multiply sideways and on a level.”
“The planter then plants the seed at an even and set depth of 12cm at the center of the bed with an even distance between plants of around 30cm to achieve the correct plant population to maximise the harvest potential. Accurate planting in the correct tilth, with the soil structure allowing for an even aggregation of 3mm paves the way for good multiplication and uniform potatoes.”
“During the growing period to achieve good multiplication a bed maintainer is necessary to ensure that the tubers always have soil cover and never see daylight. Once the potato sees light multiplication stops. This has to be done two to three times during the growth cycle.”
“Potato blight must be controlled by spraying, and unfortunately if not kept in check through preventative spraying, leads to very poor yields of rotten potatoes. The monitoring of this by the farmer is very important as the reaction time to spray does not allow for days before disaster sets in!”
Turning to the cause of the greatest loss suffered by the majority of potato growers, Fergus Robley said, “Up to 50 per cent of the crop can suffer harvest losses caused by cuts from manual harvesting. This can be reduced to nearly zero by using a potato harvester.”
“This machine lifts the soil with potatoes just below the crop and the soil is sieved from the potatoes as it passes over the specially coated lifter chains that prevent potato skin damage. The whole undamaged potatoes are then dropped back on the soil surface ready to be weather hardened and bagged.
Using this method also has the added advantage for the farmer as the land is left with a flat and level seed bed to plant another crop directly after the potato crop has been removed leaving no need for any further mechanical land preparation.”
To be fully successful with mechanized potato farming, it is important that quality and proven equipment is used with the necessary training for farmers on the correct handling and maintenance of equipment, so the return on investment is achieved. Fergus Robley stated, “FMD East Africa does this by delivering each piece of equipment to the farmer and training the operator. We also hold clinics every month in various parts of the country where we carry out free inspection of Massey Ferguson tractors and hold demonstrations and guide farmers about embracing good farming practices so the correct and economical land preparation is done for healthy crops.”
To avoid post harvest losses potatoes can be kept in a cool dry place for up to two weeks. Subsequently they need be put in cold storage which can extend the shelf life for a further two months.
As with any crop potatoes should be grown in rotation with others to maintain and preserve our soils for now and for future generations. Potatoes should be alternated with crops such as maize and beans. It is also important to avoid crops that have the same pathogens that cause disease, for example tomatoes.