Abstract:
The aim of this study was to develop a simple and quantitative system for coffee yield
estimation and nutrient input advice, so as to address the problem of declining annual
coffee production in Tanzania (particularly in its Northern coffee zone), which is related to
declining soil fertility. The study was conducted between 2010 and 2013 at TaCRI
Lyamungu, with source data taken from Hai and Lushoto districts, Northern Tanzania. An
earlier model QUEFTS, developed for maize but under similar conditions as those of
Arabica coffee (Coffea arabica) in the study areas was used as a benchmark. Secondary
fertilizer trial data were used in model calibration for coffee, while adding two more steps
related to balanced nutrition and the economics of integrated soil fertility management
(ISFM). Primary soil analytical data and calculated yields on basis of tree number were
used for model testing. The result was a new model which we hereby call SAFERNAC
(Soil Analysis for Fertility Evaluation and Recommendation on Nutrient Application to Coffee). The model consists of three modules: SOIL (the soil properties of interest),
PLANT (all the crop and crop management parameters such as physiological nutrient use
efficiency, plant density, maximum yields per tree) and INPUT (nutrient inputs – organic
and inorganic). It consists of two subsequent parts – a baseline approach (no input) for
coffee land evaluation; and an integrated soil fertility management (ISFM) approach that
involves application of nutrient inputs, for ISFM planning and design of fertilizer
experiments. The model was checked for accuracy of the adjusted equations, and found
to be capable of reproducing the actual yields by 80-100%. The new model is a useful tool
for use in coffee farms.
