Sustainable Yield Intensification in Philippine Cassava Systems

The project in the Philippines, between 2015 and 2018, 1) generates the scientific information that is required to establish nutrient uptake –yield relationships for cassava; 2) determines the agronomic use efficiency for individual nutrients, which aids in the development of fertilizer recommendations; and 3) establishes 4R-consistent nutrient management practices for smallholder growing systems. The project uses an approach that successively reduces the risk for growers to invest in fertilizers, and thereby aids in market development for our industry. The approach consists of: (a) analyses of existing data to derive nutrient uptake functions for cassava, (b) integration 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® tool for Cassava for the 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; (2) verify parameters in trials in the farmers’ fields and develop a Beta version of the Nutrient Expertfor Cassava; (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 model as needed.

Project field implementation started in July 2014. In 2015-2016, results of two years of cassava cropping at three sites in Laguna (on-station), Isabela (on station) and Butuan (two farmers’ fields) indicated positive response to fertilization, which includes substantial yield response to K application. The establishment of cassava nutrient omission-plot trials in 16 regions of the Philippines began in 2016 through the Department of Agriculture Regional Field offices (3 to 6 farms in each region, a total of 45 farms). Plant and soil analyses, and data processing from the harvested sites are on-going. In 2017, the Beta version of Nutrient Expert® for Cassava will be developed and validated in farmers’ fields, and a manual for 4R Cassava Nutrient Stewardship will be published.

Whilst 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 the development of the cassava fertilizers market.