Sustainable Yield Intensification in Philippine Cassava Systems

This project is intended to generate (1) the scientific information required to establish nutrient uptake–yield relationships for cassava, (2) determine the agronomic use efficiency for individual nutrients, which aids in the development of fertilizer recommendations, and (3) establish 4R-consistent nutrient management practices for smallholder growing systems. This project was first implemented in the Philippines in 2015 and will run through 2018.

The project uses an approach that successively reduces the risk for growers to invest in fertilizers and thereby aids in fertilizer market development. The approach consists of (a) analyses of existing data to derive nutrient uptake functions for cassava, (b) completion of the information with data from on station trials and trials in commercial fields that demonstrate economic viability and validate nutrient uptake functions, and (c) development of a Nutrient Expert® (NE) Cassava Philippines. Therefore, we will (1) determine the parameters for internal nutrient efficiency, response to individual nutrients and attainable yields from nutrient omission trials on stations, then (2) verify parameters in trials in farmers’ fields and develop a Beta version of NE Cassava, then (3) use the Beta version to generate fertilizer recommendations for a selected number of farmer’s fields, and (4) examine the field results jointly with stakeholders and refine the models as needed.

In 2015, cassava harvest was completed in Laguna (on-station), Isabela (on station) and Butuan (2 farmers’ fields). Initial results indicate positive response from fertilization including a substantial yield response to K application. Planting for the second crop has been completed at two sites (Laguna and Butuan). Plant tissue and soil analyses and yield data from the harvested sites are currently being summarized.

While it is known that cassava responds to fertilization, lack of quantitative knowledge on the response to fertilizer and the uncertainty surrounding that response under specific conditions is a major obstacle to further development of the market for cassava fertilizers.