I only got 41.3kg of winged yam this year. What went wrong?

In drought, my food garden depends on recycled water. On an average day my waste water system supplies 250 litres for hand watering. That’s less than 1 litre per square metre per day. Yams are flood and drought tolerant, so you always get a crop, however yield is reduced by drought.

Last year was the driest gardening year of my life. Between July and December 2012, my garden had one soaking shower of rain. When 63mm fell on 18th November it hit hot, parched soil and barely moistened the surface. Despite cloudless skies and hot, windy weather, I could only give my yams one weekly ration of waste water.

So today I was disappointed to lift just 41.3kg of winged yam (Dioscorea alata) from a row 6m long by 60cm wide: that’s 17.2kg of yam per square metre instead of 20 – 30 kg per sq m.

This low yield is still generous when compared to potato. Many subtropical gardeners struggle to produce a decent crop of spuds. Our warm soils and damp, humid coastal conditions help aggressive fungal diseases ruin these cool temperate crops.

My average crop of potatoes is 35kg per 10 sq metres, or 3.5kg per sq metre. It’s a very light return. And then I have to find room in a fridge and keep them in the dark so they remain edible.

So even my worst yam harvest has yielded 13.7 kg more per sq metre than potato. They’re washed clean of soil and sitting in boxes under my house where they will remain fresh and edible for at least another three months.

If you want to try yams, local community gardens and local Seed Saver Networks (LSN’s) may offer them to members, and occasionally they are sold by Asian fruit shops. I share my surplus during my Open Days.

Thrifty yams: adaptable, space and energy saving, productive and easy to store. They taste and cook like potato, but the starch is far more sustaining.

In a warming world, where rainfall is increasingly unreliable, grow yams for family food security.

Edible roots
Aerial potato, Dioscorea batatas
Arrowroot, Canna edulis
Cassava, Manihot esculenta
Cassava, Manihot esculenta ‘Variegata’
Cocoyam, Xanthosoma saggitifolia
Eschallot, Allium cepa var. aggregatum
Jerusalem artichoke, Helianthus tuberosus ‘Dwarf Sunray’
Yam, Winged, Dioscorea alata
Sweetpotato, Ipomoea batatas ‘Marguerite’

Edible leaves
Basil, sacred, Ocimum tenuiflorum
Cassava, Manihot esculenta
Cassava, Manihot esculenta ‘Variegata’
Celery stem taro, aka Tahitian spinach, Alocasia esculenta
Chaplu, Piper methysticum
Chervil, Anthriscus cerefolium

Chickweed, Stellaria media
Chinese cabbage, Brassica rapa var. pekinensis ‘Tokyo Bekana’
Chinese cabbage, Brassica rapa var. chinensis ‘Chokito’
Chinese cabbage, Brassica rapa var. chinensis ‘Red Choi’
Chinese celery, aka smallage, Apium graveolens
Chinese spinach, Amaranthus tricolor ‘Flying Colours’ (last picking today)
Chives, Allium schoenoprasum
Curry leaf, Murraya koenigii
Curry leaf bush, Helichrysum italicum
Garlic chives, Allium tuberosum
Good King Henry, aka Lincolnshire spinach, Chenopodium bonus-henricus
Green amaranth, Amaranthus viridis
Heart leaf ice-plant, Aptenia cordifolia
Huauzontle, Chenopodium berlandieri
Japanese parsley, Cryptotaenia japonica
Kaffir lime, Citrus hystrix
Kangkong, Ipomoea aquatica
Lebanese cress, Aethionema coridifolium
Leek, Multiplier, Allium ampeloprasum var. porrum
Lemongrass, Cymbopogon citratus
Lemongrass, Native, Cymbopogon flexuosus
Lettuce, Lactuca sativa ‘First Fleet’
Lettuce, Lactuca sativa ‘Purple Royal Oakleaf’
Lovage, Levisticum officinale
Love-lies-bleeding, Amaranthus caudatus
Mint, native, Mentha satureoides
Mizuna, Red, Brassica juncea var. japonica
Mustard, Red, Brassica juncea
Okinawa spinach, Gynura bicolor
Parsley, Petroselenium crispum ‘Italian flat-leaved’
Peperomia pellucida
Phillip Island hibiscus, Hibiscus insularis
Radicchio, Cichorium intybus
Society garlic, Tulbaghia violacea ‘Variegata’
Society garlic, Tulbaghia violacea ‘Fairy Stars’
Stinking Roger, Tagetes minuta
Sweetpotato, Ipomoea batatas ‘Ace of Spades’
Sweetpotato, Ipomoea batatas ‘Marguerite’
Swinecress, Lepidium didymum
Turmeric, Curcuma longa
Variegated four seasons herb, Plectranthus amboinicus ‘Variegatus’
Vietnamese mint, Persicaria odorata
Welsh onion, aka spring onion, scallion, Allium fistulosum
Perennial Welsh onion, aka perennial spring onion, scallion, Allium fistulosum
Warrigal greens, Tetragonia tetragonioides
Water hyssop, Bacopa caroliniana

Edible petals
Begonia x semperflorens
Pigeon pea, Cajanus cajan

Edible pods
Winged bean, Psophocarpus tetragonolobus

Edible seed
Chilean wine palm, Jubaea chilensis
Pigeon pea, Cajanus cajan

Fruit
Chilli, Capsicum annuum ‘Portuguese Peri Peri’
Chilli, Capsicum annuum ‘Siam Gold’
Chilli, Capsicum annuum ‘Red Cayenne’
Eggplant, Solanum melongena ‘Caspar’
Eggplant, Solanum melongena ‘Little Finger’
Kaffir lime, Citrus hystrix
Lemon, Citrus limon ‘Meyer’
Lime, Australian, Citrus x latifolia
Lime, Tahitian, Citrus x latifolia
Mouse melon, Melothria scabra
Pepino, Solanum muricatum

Medicinal / Spices
Aloe vera – leaf juice used to heal sunburn, scratches
Bulbine frutescens – leaf juice used to treat burns, rashes, as an infusion for sore throats
Cinnamon, Cinnamomum verum
Cardamom, False, Alpinia nutans
Galangal, Alpinia galangal – spice used like ginger with similar properties
Ginger, Zingiber official – spice that helps decongestion of catarrh, aids digestion, blood flow
Greater celandine, Chelidonium majus – stem juice kills warts on hands
Krachai (root), Boesenbergia rotunda
Phillip Island hibiscus, Hibiscus insularis – used as a tea to soothe sore throats
Rosemary, dwarf, Rosmarinus officinalis ‘Benenden Blue’
Rosemary, fastigiate, Rosmarinus officinalis ‘Miss Jessopp’
Turmeric, Curcuma longa – spice with anti-cancer properties
86 taxa

Jerry Coleby-Williams

18^th July 2013