Tuesday, January 9, 2018

Unearthing Underground Crops Back to the Roots

Yields for underground crops remain a mystery until harvest, along with the pests and diseases that could lurk just under the surface. The challenge of caring for these crops is tremendous – and much is at stake in cultivating these prized plants that mean nutrition and sustenance for millions.
Craig MacFarlane became a farmer unexpectedly. At age 20, he inherited Loch Buighe, the family farm in Ixopo, South Africa. Established in 1868, Loch Buighe sits on a misty landscape about 200 meters above sea level, an hour west of South Africa’s southeastern shore. Among the farm’s holdings is a 70-hectare stretch for potato crops.

Craig MacFarlane is the fifth generation at Loch Buighe, the family farmland founded in 1868, and an expert in potato farming.  Master farmers like MacFarlane provide markets with a range of potatoes seen below.

Over the last three decades, MacFarlane has grown in confidence and farming knowledge. By 2015, he was named South Africa’s Seed Potato Grower of the Year. Walking between long green rows of burgeoning potato plants at Loch Buighe, he explains key signs to watch: “Yellowing leaves and lack of vegetative growth in the early growing stages,” MacFarlane says, “and wilting plants. These are important markers.” Recognizing these markers – and knowing what’s behind them – is crucial.






To be a successful potato farmer, like MacFarlane, is a tremendous challenge. Underground plants (roots, tubers, bulbs and stems) are actually plant organs, with a complex anatomy. These crops require special care: since their yields are underground, their condition may not be fully known until harvest. Worldwide, underground crops – including potatoes and ginger – are leading agricultural products. The potato, for example, is a major crop in about 130 countries. According to the FAO, root and tuber crops like potatoes are second only to cereals as the leading worldwide source of dietary carbohydrates. And ginger, once a regional product, is now grown, sold and desired globally. But despite how prevalent these crops are, growing them is tricky work, requiring the ability to observe tiny, almost imperceptible changes in anatomy and the ability to foretell what may be happening underground.


Keeping the Potatoes Coming

On his farm in Ixopo, South Africa, Craig MacFarlane values staple crops like potatoes:

“Root vegetables produce nutritious food, packed with energy and minerals.” During South Africa’s double sowing seasons – a first season in May through June, and a second season in November – potato farmers begin planting. Four to eight weeks later, the crops are ready to harvest, even in South Africa’s semi-arid conditions. “Potatoes have a unique ability to grow in harsh conditions, and are hardy due to something special – a fibrous root system.”

But this is where problems may start: While potato roots may be strong, they are typically not more than 60 centimeters long. MacFarlane explains: “Potatoes are shallow rooted compared to cereals, for example, which can root to at least 100 centimeters in depth.” As a result, potato roots are often unable to take up the nutrients and soil moisture at the depths where they are most available within soil. Potato crops also have specific soil preferences. “Potatoes will grow in just about any well-drained soil,” MacFarlane adds, “but they dislike soggy soil. Because they grow underground, they can expand more easily in loose, loamy soil than in heavy, compacted, clay soil that keeps plant roots from getting the air and water they need.”

2,247,495 - South African potato production was more than two million tonnes in 2014. This is an increase of almost 400,000 tonnes since 2009.


Source: FAOSTAT, crop data




Potato harvesting in South Africa


Dirk Uys, an agricultural manager at Bayer, agrees:

“In South Africa, our challenges are aggravated by availability of water for irrigation.” Potato growers have difficulty finding suitable fields to grow potatoes, which puts tremendous pressure on rotation practices. “As a result, fungus-based tuber diseases, such as powdery scab and silver scurf, are increasing. Nematodes remain a major issue as well.” For many growers, crop protection products, when used as directed, are vital for prevention of these diseases. “Tuber health is an area of research focus,” says Uys. “We hope to introduce scientifically-based products, including biologics, in the near future.” At the same time, aphids are a problem since they can carry potato plant viruses. Uys describes an environmentally sustainable approach: “Farmers use an integrated program which includes both product rotation as well as physical inspection of the fields,” in order to identify and remove infested plants.

As a grower, MacFarlane understands the importance of starting with a quality product: “All aspects of growing potatoes have gotten so expensive that farmers can’t afford for anything to go wrong.” His strategies continue even after the crops have been harvested: “Green manuring of your lands will have a positive impact on your next rotation,” he adds. “Getting microbial activity in the soil helps in aerating the soil and improves drainage.” When growing root vegetables, MacFarlane notes, farmers have to focus on what’s happening beneath their feet. “Any extra nutrients we can work into the soil will assist in higher yields.”


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