Efficient use of nutrients in fine aroma cacao in the Province of Los Ríos-Ecuador

Soil nutrients are vital to high production of cacao (Theobroma cacao L.); however, excessive use of fertilizers affects the environment and profitability of this crop. This research aimed to determine the efficient use of nutrients (EUN) for nitrogen (N), phosphorus (P) and potassium (K) in four fine aroma cacao clones (EET-576, EET-575, EET-103, and CCN-51), which are economically important in Ecuador. The experiment design used split plots, with four treatments and four repetitions. The treatments consisted of applications of different doses of N-P-K (kg ha-1): TR (control), T1 (N59-P29-K118), T2 (N74-P37-K148), and T3 (N88-P44-K176). The results showed highly significant differences for the agronomic (AE) and recovery (RE) efficiency of N-P-K in terms of the clone and treatment. The highest efficiencies were presented for clone CCN-51 and the lowest in clone EET-103. The treatment that obtained the highest efficiency was T2 for clones CCN-51, EET-575 and EET-576, except for EET-103 that reached the highest efficiency with T1. The lowest efficiencies were obtained in T3. The highest yields were presented in clone CCN-51, followed by EET-575, later EET-576, and finally EET-103. Influence of the genotypes on the maximum limit of nutrient absorption was evident under the studied conditions, suggesting that it determines the efficient use of nutrients for each clone in interaction with this specific cultivation area.