Soil acidity is the major soil chemical constraint that limits agricultural productivity in the highlands of Ethiopia receiving high rainfall. This study was conducted to evaluate the effect of different lime rates determined through different lime rate determination methods on selected soil chemical properties and yield of maize ( Zea mays L. ) on acidic Nitisols of Mecha district, Amhara Region, Ethiopia. The experiment had 10 treatments (0, 0.06, 0.12, 0.18, 1, 2, 3.5, 4, 7 and 14 tons ha −1 lime) that were calculated by three lime rate determination methods and applied through three lime application methods (spot, drill and broadcast). The experiment was arranged in randomized complete block design (RCBD) with four replications. N at the rate of 180 kg ha −1 and P at the rate of138 P 2 O 5 kg ha −1 were applied to all plots. A full dose of P and lime as a treatment were applied at planting; whereas N was applied in split, 1/2 at planting and 1/2 at knee height stage. One composite soil sample before planting from experimental site and again one composite sample from each experimental unit were taken after harvest to analyze soil chemical parameters following appropriate laboratory procedure. Liming showed a positive significant difference on pH-H 2 O, pH-buffer, cation exchange capacity (CEC) and exchangeable bases but it had an inverse and significant effect on exchangeable acidity (EA). However, it didn't show any significant difference on soil C and N. Grain and above-ground biomass of maize yields had significant differences among treatments. The highest grain and biomass yields (7719 and 18180.6 kg ha −1 , respectively) were obtained from application of broad cast method while the lowest (6479 and 15004.6 kg ha −1 , respectively) were obtained from control treatment. Drill lime application method provided better efficiency with over 200% cost reduction advantage compared to the broadcast method to ameliorate the same level of acidity. Application of 3.5 tons ha −1 lime in the drilling method is recommendable to ameliorate soil acidity. However, from an economic point of view, application of 0.12 tons ha −1 lime applied in the micro-dosing method is more profitable due to low variable cost.

Summary The potential yield of improved maize varieties usually cannot be fully realised mainly due to inappropriate soil nutrient management practices in most parts of Ethiopia. Site-specific fertiliser recommendations are rarely used in the farming systems of Ethiopia. There is also a lack of data to develop or validate decision support tools for targeting specific crop production. A study was conducted for three consecutive rainy seasons (2016–2018) in the maize belt of the north-western parts of the Amhara National Regional State of Ethiopia. The objectives were to obtain the maximum achievable yield potential of maize, determine the most yield-limiting nutrients and create a database of maize responses to applied nutrients so that decision support tools could be developed for the study areas. Treatments were individual nutrients (nitrogen (N), phosphorus (P) and potassium (K)) and combinations of the three. In some treatments, NPK was also combined with sulphur, zinc, lime and compost. Two hybrid maize varieties (BH-540 and BH-660) adaptable to the study areas were used. BH-540 was used for the Mecha district, while BH-660 was used for the south Achefer, Jabitahnan–Burrie–Womberma districts. Maize yield increased by more than 50% due to fertiliser applications compared to without fertiliser. The study showed that the possibility of increasing maize productivity to more than 12 t ha-1 for the study sites. The most yield-limiting nutrient in the study sites was N, followed by P; K was not a yield limiting. Without N the yield of both varieties was non-significant from the control (without added nutrients). Maize grain yield did not respond to application of lime, compost, zinc and sulphur. The result also showed very high variability across sites, indicating that it is important for policymakers, farmers and investors to consider site-specific fertiliser recommendations. Finally, a database containing intensive plant response to NPK for maize was generated and could be used as input in site-specific decision support tools development.

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