Sustainability of commercial vegetable production under fallow systems in the uplands of Mindanao, The Philippines

The quality of fallow lands in northern Mindanao, the Philippines, was assessed with a farm survey and soil sampling in order to understand land-use dynamics under upland commercial vegetable production systems. Twenty-one percent of commercial vegetable growers practiced fallow systems, with an average re-cultivation period of four years. The soils of the fallow lands were highly acidic, nutrient poor, and higher in exchangeable aluminum compared to lands currently under cultivation. Land fallowing was more prominent on large farms and those with higher farm labor requirements. Two distinct groups of land fallowers were identified. The first represented fallowers with a positive net return from vegetable crops while the second, and larger, group represented land fallowers with negative net return from vegetable crops. Re-cultivation of fallow lands was more common in the second group. To rejuvenate fallow lands, timber tree planting was the most preferred option of the first group while fruit trees were preferred by the second group. In light of the apparently slow rate of soil fertility regeneration, the lack of capital among most land fallowers, and the increasing demand for arable land to raise farm income, planting of trees on cultivated lands before their being set aside as fallow for natural fertility regeneration is suggested as a potential measure to increase farm income and the sustainability of upland commercial vegetable production under fallow systems.