Tools for sustainable oil palm production. In situ fertilizer studies for plantations in Ecuador.

The specific objectives of this project are to develop a management tool for the Orellana Agricultural Cooperative (CAO) to estimate the agronomic and economic results of fertilizer use and to use this model to establish fertilizer trials for other oil palm growers. A Central Composite Design (CCD) factorial experiment was designed in order to study the effect of N, K and Mg fertilizer rates on the growth of immature plants and on fresh fruit bunch (FFB) yield and oil extraction rate. With our design, five rates of each nutrient were used. Plots of 36 plants were set for each treatment, but actual measurements were carried out only in the 16 internal plants (effective plot). As there was no FFB production in 2012, only leaf rate production, leaf area and leaf biomass were measured, and samples of a reference leaf were taken to measure nutrient content using tissue analysis.

Preliminary results suggest that for this site, Mg rates and K:Mg ratio are the main drivers of biomass growth, with maximum leaf biomass obtained with high rates of Mg (above 0.25 kg MgO per plant per year) and intermediate rates of K (about 1.6 kg K per plant per year). Fertilizer N and the interaction between N and K did not have a significant effect on leaf production and leaf biomass. The mineral analysis did not reflect significant changes in N, K or Mg contents among treatments, which may be due to the original reserves of the plant before the experiment began and because of the concentration of nutrients in smaller plants with less canopy. This study will continue indefinitely at the CAO plantation. The Ecuadorian Oil Palm Growers Guild (ANCUPA) plans to expand similar fertilizer trials in at least one new plantation. Ecuador-14