Fertilizer use in tea: the case of nitrogen
1997
Owuor, P.O.
Application of nitrogen fertilizers lead to increased tea production but reduces resultant black tea quality. However, it lowers soil pH and causes nutrient imbalance in the soil by inducing availability of high amounts of aluminium and manganese while reducing the levels of the cations and available phosphorus in the soil. This imbalance of soil nutrients can hinder economic tea production and make soils unsuitable for future use. The yield response to nitrogen varies with cultivars such that for some cultivars application of low quantities of nitrogen produces higher response while application of high amounts produces low responses. Economic yield responses can only be attained by application of up to 200 to 250 kg/N/ha/year for cultivars which respond well to fertilizers. These rates are lower than 100 kg/N/ha/year for cultivars which give poor response to fertilizers. The extent of response however, cannot be predicted from the actual yields as there are poor yielding cultivars which respond better to fertilizers than some moderately yielding cultivars leading to situations in which better returns per applied units of nitrogen is obtained from lower yielding cultivars.
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