Effects of Biochar-Amended Media on Leaf Lettuce (Lactuca sativa L.) Growth in Raised-Bed Sloped Terrain System

Cyril John C. Nagal; Nelda R. Gonzaga; Apolinario B. Gonzaga Jr.; Renante D. Taylaran; Imelda U. Hebron; Judy Mae P. Bongay; April Joseph Ruby S. Salvo; Ariel M. Tan; Junrauh G. Manuel

Authors

Cyril John C. Nagal College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
Nelda R. Gonzaga College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
Apolinario B. Gonzaga Jr. College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
Renante D. Taylaran College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
Imelda U. Hebron College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
Judy Mae P. Bongay College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
April Joseph Ruby S. Salvo College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
Ariel M. Tan College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines
Junrauh G. Manuel College of Agriculture, University of Science and Technology of Southern Philippines, Misamis Oriental, 9004 Philippines

Keywords:

Biochar, Carbonized rice hull, Lettuce, Raised bed gardening

Abstract

The COVID-19 pandemic exposed critical vulnerabilities in global food systems, notably disrupting supply chains and limiting food access in developing countries. In response, home gardening emerged as a practical strategy to bolster household food security. However, hilly and sloped terrains—common across many Southeast Asian—present significant cultivation challenges. This study investigates the efficacy of biochar-amended growing media in enhancing the productivity of leaf lettuce (Lactuca sativa L.) cultivated in raised-bed gardens situated on sloped land in a highland province of the Philippines. A 2×6 factorial experiment was conducted using a Randomized Complete Block Design (RCBD), evaluating two lettuce varieties (‘Green Span’ and ‘Lollo Rosa’) across six growing media treatments, including incremental levels (5%, 10%, 15%) of carbonized rice hull (CRH) biochar amendment. Growth parameters assessed included plant height, leaf count, fresh weight, and yield per square meter. Results showed that biochar-enhanced media significantly improved lettuce growth and yield relative to conventional methods, with the 10% CRH treatment yielding the highest productivity. Specifically, this treatment resulted a 584.7% increase in marketable yield per plant and a 584.1% increase in extrapolated yield per 100 m² compared to the control group (garden soil only). Between the two varieties, ‘Green Span’ consistently outperformed ‘Lollo Rosa’ in terms of plant vigor, crown development, and total yield, producing more than three times higher marketable biomass. These results offer actionable insights for smallholder farmers and policymakers pursuing climate-resilient and nutrition-sensitive agricultural interventions in topographically constrained areas. By optimizing crop performance through resource-efficient amendments, the study charts a viable path for sustainable food production in sloped, underutilized landscapes.

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