Economic Optimization of Nutrient Application to Coffee in Northern Tanzania Using SAFERNAC

The aim of this work, as an extension to SAFERNAC model, was to establish economically optimum combinations of N, P and K application to Arabica coffee in the Northern coffee zone of Tanzania. The study was conducted in Hai and Lushoto districts between 2010 and 2012. Prices of nutrient inputs and those of parchment coffee were introduced into the original SAFERNAC model, which was used to obtain yields from a soil of known properties receiving different levels of input N, P and K from both organic and inorganic sources (ISFM). The costs of these were derived from experience in Northern Tanzania, while coffee prices were estimated to range between 1250 and 2500 TZS kg-1. The result was economically optimum N:P:K ratios that give highest net returns and value : cost ratios in situations of low, medium and high soil fertility. It was also shown that farmers’ decision to deviate from the optimum and the allowable level of such deviation, depend much upon the prices of nutrient inputs in equivalent terms. In the medium-fertility situation (which applies in the study districts), the highest yield increment was noted with the maximum amount of N and P. The optimum application rate was 310 kg N and 200 kg P per ha, where the profit margin (the gap between gross returns and costs) is highest. This is an indication that soil-available K is likely to suffice the needs of the crop for optimum productivity, but this is largely dependent on the K fluxes in different soil types. The optimum rates were tested with actual soil data in the two study districts, against 5 tons of farmyard manure and a combination of the two. At both the coffee prices of 1250 and 2500 TZS kg-1, ISFM intervention (combination of organic and inorganic inputs) was more profitable than the other options, while coffee production showed to be more profitable in Hai than Lushoto

Temporal variations in the abundance of three important insect pests of coffee in Kilimanjaro Region, Tanzania

Temporal variation in abundance of white coffee stem borer (WCSB), antestia bug and coffee berry borer (CBB) were investigated between September 2007 and August 2008 at medium altitude (1200-1600 m.a.s.l) and high altitude (1600-2100 m.a.s.l) areas in Kilimanjaro region. A multistage random sampling method was used to select farms and trees for sampling in the two locations making a total of 810 trees. Insects were counted every month to establish the population size. High populations of antestia bugs and CBB were recorded during the short and long rains, during flowering and fruit development. WCSB increased gradually during short and long rains. Populations of WCSB were high at high altitude compared to medium altitude and occurrence of CBB at medium altitude was observed where it was not common in the past. Since the population size of WCSB was high in all locations and it is the most damaging insect pest, it is recommended that more attention should be focused on management of this pest

Exploring the Nutrient Release Potential of Organic Materials as Integrated Soil Fertility Management Components Using SAFERNAC

The aim of this study was to establish the nutrient release potential of different organic materials and assess their role in integrated soil fertility management for coffee using the new coffee yield model SAFERNAC. It involved an incubation experiment conducted at TaCRI Lyamungu Screenhouse for 180 days between April and September 2011. Cattle manure, coffee leaves, pulp and husks, Albizzia leaves and four green manure plants – Mucuna pruriens, Lupinus albus, Canavalia ensiformis and Crotalaria ochroleuca were mixed with two soil types – Eutric Nitisols from Lyamungu, Hai district and Humi-Umbric Acrisols from Yoghoi, Lushoto district. The mixing ratio was 5% organic to soil, the mixture was moistened to FC and incubated in 10 litre plastic containers arranged in RCBD (10 treatments and 3 replications) at room temperature. Duplicate soil samples were taken at day 0, 3, 8, 15, 26, 45, 74, 112 and 180 and analyzed for NH4+-N, NO3-N, available P and exchangeable K. The cumulative Nmin, P and K values resulting from the treatments were used to estimate their relative contribution to the soil nutrient pool and later exposed to the new model SAFERNAC for yield estimation under different nutrient management options (1 to 10 tons organics per ha alone on one hand and supplemented with 160 kg N, 60 kg P and 160 kg K). The tested organics differed significantly (

Developing a Coffee Yield Prediction and Integrated Soil Fertility Management Recommendation Model for Northern Tanzania

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 farm

Temporal variations in the abundance of three important insect pests of coffee in Kilimanjaro Region, Tanzania

Temporal variation in abundance of white coffee stem borer (WCSB), antestia bug and coffee berry borer (CBB) were investigated between September 2007 and August 2008 at medium altitude (1200-1600 m.a.s.l) and high altitude (1600-2100 m.a.s.l) areas in Kilimanjaro region. A multistage random sampling method was used to select farms and trees for sampling in the two locations making a total of 810 trees. Insects were counted every month to establish the population size. High populations of antestia bugs and CBB were recorded during the short and long rains, during flowering and fruit development. WCSB increased gradually during short and long rains. Populations of WCSB were high at high altitude compared to medium altitude and occurrence of CBB at medium altitude was observed where it was not common in the past. Since the population size of WCSB was high in all locations and it is the most damaging insect pest, it is recommended that more attention should be focused on management of this pest