A LEUCAENA LEUCOCEPHALA—BASED INDIGENOUS FALLOW SYSTEM IN CENTRAL PHILIPPINES: THE NAALAD SYSTEM

ABSTRACT

The Naalad system is an indigenous agroforestry practice developed by farmers more than 100 years ago in a small village in central Philippines. This study is the first attempt to scientifically document and evaluate the system. Six farm parcels at different stages of fallow and cultivation were selected as case studies. Farmers' practices were documented through interviews and record keeping. Soil samples were collected and selected chemical properties and bulk density were analyzed. Carbon (C) storage and sequestration were estimated by converting existing biomass data to C content.

Results showed that there are two modifications in the Naalad system compared with common shifting cultivation systems in the Philippines. First, Leucaena leucocephala trees are planted in the fallow fields to shorten the fallow period to 5–6 years. The fallow field is also used as a source of fodder for cattle. Second, branches of Leucaena are used in the cultivated fields to serve as a fascine-like structure called balabag. These structures help to conserve the soil.

Soil analysis revealed that there were no significant changes in soil properties within the fallow and cultivated fields over time. Similarly, there appeared to be no differences in the soil properties between the cultivated and fallow fields. The low levels of soil organic matter, P and K in the soil could indicate that the soils are being progressively depleted, albeit very slowly.

Fallow fields are estimated to contain an average of 16 t C ha^-1 in above-ground biomass, and sequester 5.3 t C ha^-1 yr^-1.

Key words:

• agroforestry
• carbon sequestration
• indigenous fallow system
• fascine
• nutrients
• soil