Mixture Effect of Rock Phosphate and Triple Superphosphate on Maize Yield in Acid Soils of Côte d'Ivoire

Aims: Determine the optimum rock phosphate (RP) / Triple superphosphate (TSP) ratio for improved maize yield

Study Design: The experimental design was of random blocks with 3 replications.

Place and Duration of Study: The study was carried out in central Cote d'Ivoire, in a savannah area over 3 consecutive years 2019, 2020 and 2021.

Methodology: Eight treatments were tested: control T0, T0r (100 Kg urea ha-1 + 200 Kg NPK ha-1), T1 (300 Kg RP ha-1), T2 (270Kg RP ha-1 + 19,6 Kg TSP ha-1), T3 (240 Kg RP + 39,2 Kg TSP ha-1 ), T4 (180 Kg RP ha-1 + 78,4 Kg TSP ha-1), T5 (60 Kg RP ha-1 + 156,8 Kg TSP ha-1 ), T6 (196 Kg TSP ha-1 ). For maintenance, 200 Kg NPK ha-1 and 100 Kg urea ha-1 were added to all treatments except control. After harvest, yields were calculated, pH levels were measured at the beginning, after three months and at the end of the trial.

Results: the effect of the RP/TSP combination was effective in the second year. Ratio T3 obtained the best yield (5.71 t ha-1) and was more efficient than the treatment used for maize extension in Côte d'Ivoire (T0r). At the same time, the soil pH has become neutral, contributing to an improvement in soil fertility due to the gradual bioavailability of phosphorus from the solubilized phosphate rock.

Conclusion: Mixing RP and TSP in proportions of T3 (240 Kg RP + 39,2 Kg TSP ha-1) is effective in improving maize yields.