Intercropping potato with maize in lowland Philippines

Abstract

Abstract Three experiments in the lowland Philippines were set up on farmers' fields to evaluate the yield and economic benefit of intercropping maize with potato. In two experiments (1985–1986, 1987–1988) the effects of various temperature-reducing systems, involving mulch, irrigation and intercropping maize, were compared, singly and in all combinations. Plantings were made in early and mid-December in 1985, and early and mid-December and mid-January in 1987. When intercropped with potato, maize was planted at one-tenth of its sole-crop population, with plants equidistant from each other. In a third experiment (1987–1988), the timing of planting maize as an intercrop with potato, and the planting of maize as a strip-crop with potato, were also studied. Intercropping maize with potatoes, whether alone or in combination with mulch, irrigation or double-row planting system, reduced soil temperature during the day by 1–5°C. Temperature-reducing systems, including the intercropping with maize, were less effective in increasing yield and net returns for early plantings which were accompanied by excessive rains and cloud cover. Combined maize intercrop, irrigation, and mulching treatments gave additional tuber yield and net returns up to 10.7 t ha−1 and US$2525 ha−1 respectively, over the control in the 1985–1986 season. In the January planting season in 1987–1988, potato/maize intercrop, whether alone or on combination with irrigation, mulch, or both, resulted in additional yields of up to 4–7 t ha−1 and net returns of up to US$1720 ha−1 for the cultivar Berolina and US$1752 ha for Cosima. Intercropping maize with potato, irrespective of planting time relative to that of the potato, gave potato yields of 15.5–19.4 t ha−1, which did not differ significantly from the monocrop potato yield (18.6 t ha−1). The highest potato yield was produced when maize was planted within potato rows two weeks after planting the base crop, which suggests that, if planted earlier, the maize competed with the potato. Strip-cropping maize with potato reduced the yield and net returns to below that of monocrop potato. This reduction in potato yield was proportional to the reduction in potato population planted. The results suggest that to extend the period of planting potato beyond that optimal for sole potato, the use of temperature-reducing systems, including intercropping with maize, will be financially beneficial to the farmer.