Page 7 - Vol.37-No.2

CROP PROTECTION

SULPHUR BRIGHTENS THE BREW FOR TEA

The tea crop’s requirement for sulphur of the famous Assam teas. Field trials in Young leaves are the hardest hit by
is very high at 16 to 26 kg/hectare (ha) this tea-growing area of North Eastern sulphur shortfalls. They develop an un-
per annum, but not surprising since tea India showed soils could become seri- healthy-looking pale yellow colour and
grows naturally on volcanic soils created ously depleted of sulphur through con- a general yellowing of inter-veinal areas.
by the same geological processes that tinuous picking unless appropriate fer- New shoots are smaller and internodes
generate elemental sulphur. tilizer application was in place. (distance between leaves) shorter due
Sulphur content of fresh green tea Sulphur deficiency to a slow-down in growth which may
leaves should be maintained at 0.08% be followed by general shoot necrosis
to 0.20% of total dry matter to achieve Sulphur shortfalls on tea estates are when sulphur deficiency persists. Con-
maximum yields for processing into high nothing new. Sulphur deficiency symp- sequences for yield and quality of tea
quality tea products. 1.0 t (tonne) of fin- toms in tea bushes, commonly called are severe and especially new shoots
ished tea product requires 5 t of freshly ‘sulphur yellows’ or ‘yellow disease’, comprising bud and 2-3 leaves select-
picked leaves that will have extracted no have long been recognized in tea grow- ed and picked to manufacture the finest
less than 10 kg of sulphur from the soil. ing areas around the world. Sulphur is grade tea. To make matters worse leaf
Tea production, by its very nature, with central to plant nutrition. The nutrient is yellowing symptoms are exacerbated by
regular plucking of the youngest and needed for synthesis of sulphur-contain- lower temperatures. These are the very
most nutrient-rich foliage will deplete ing essential amino acids like cysteine conditions experienced at night on the
soil nutrients including sulphur without and methionine and for the manufacture hillsides where tea is typically grown.
fertilizer application. of chlorophyll pigments. When sulphur Sulphur is known to enhance frost resis-
is in short supply chloroplasts break tance of tea bushes.
down and with it the normal dark-green ‘Sulphur yellows’ has proved to be
colour of healthy tea foliage. ongoing problem in a number of key
African tea growing countries includ-

Pioneering

Plant Health

Picking tea leaves at Jorhat in Assam,
North East India (Picture courtesy Omex) With over 40 years experience, OMEX is a trusted
and reliable brand, exporting to over 80 countries
When averaged out over the entire tea Highly concentrated liquid foliar fertilizers
bush sulphur content of leaves at 0.08% 100% water soluble for fertigation
to 0.20% is way down in the list of nutri- and foliar application
ents, but when nutrient analysis is target- Full range of macro element,
ed on the third-youngest unfurled leaf micro element and biostimulant Manufacturer
sulphur at 0.50% shoots up to rank equal formulations and exporter of
third with phosphorus. These latter fig- Improves yield and quality innovative plant
ures are clearly important given that tea TM nutrient foliar
pickers select new shoots comprising eba technology fertilizers
terminal buds (golden tips) and young
leaves for processing into finest grade
teas. Plucking the terminal bud plus 3
leaves gives the highest yield of quality
shoots and about 25% more than the bud
plus 2 leaves. Shoots which include this
third leaf process into premium teas with
high concentrations of two important tea
chemicals, polyphenols (tannins) and
theine (tea caffeine).
Up to 40% of the sulphur absorbed by
tea roots is re-cycled into the soil as fall-
en leaves and pruning waste, but there
remains a considerable shortfall. Tea
harvests weighing in at 3000 kg will have
removed some 6 to 9 kg of sulphur/ha/
year from the soil, say researchers at the OMEX Agrifluids Ltd.
internationally famous Tocklai Experi- Saddlebow Road, Kings Lynn, Norfolk, UK.
mental Station in Jorhat India and home Tel: +44 (0)1553 817500 Email: agrifluids@omex.com www.omex.com

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Vol. 37 No. 2 5