Browsing by Author "Mrema, J."

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    Economic optimization of nutrient application to coffee in Northern Tanzania using SAFERNAC
    (International Journal of Plant & Soil Science, 2014-06-30) Maro, Godsteven, P.; Janssen, Bert, H.; Msanya, B. M.; Mrema, J.
    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 -1 TZS kg . 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 -1 of 1250 and 2500 TZS kg , 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.
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    Effect of pigeon pea-groundnut intercropping system on selected soil properties
    (International Journal of Plant & Soil Science, 2014-02-14) Phiri, A. T.; Msaky, J. J.; Mrema, J.; Kanyama, G. Y.; Msanya, B. M.
    On average Malawi is losing of 40 kg N ha-1 and 6.6 kg P ha-1 annually. Additionally, nutrient use efficiency (NUE) is low as a result of declining levels of soil organic matter (SOM) and associated deficiencies of other macro and micronutrients. This is usually below 20 kg maize grain kg-1 of nutrients applied. To investigate on the possibility of improving NUE a study was initiated in the 2011/12 cropping season with a parallel trial mounted along side in the second season, both were laid in a randomized complete block design replicated three times. The trials involved planting of pigeon pea as monocultures or as intercrops. The main trial had eight treatments while the parallel trial had ten treatments. After the first season legume biomass in some plots of the main trial was buried into the soil. Soil characterization was conducted before treatment application in the first and second year. Data were analyzed using genstat and subjected to analysis of variance at 5% level of confidence. Means were separated using the least significant difference. Generally, the soil chemical characteristics for soil samples collected in all the treatment plots both in the main and parallel trial indicate that the soil has low fertility. The organic carbon (OC), cation exchange capacity CEC (NH4OAc), and total N (%) was low, and was at 1.4 %, 3.5-3.6 cmol (+)/kg soil, 0.12%, while available phosphorus (Mehlich 3) was marginally adequate (mean=21.5 mg kg-1 and 22.1 mg kg-1). The soil texture which was predominantly sandy clay loam to sandy clay coupled to the low CEC suggest potential high leacheability of nutrient elements more especially nitrogen as nitrate. Inevitably, if the soil is not properly managed crop yield could be reduced drastically.