Productivity of Maize (Zea mays L.) and Mung bean (Vigna radiate L. Wikzek) in Homegardens and Cropping Fields under Subsistence Conditions

Low sustainability is an inherent character of tropical smallholder farming systems. These systems can be developed through sustainable agricultural practices such as inclusion of green manure (eg: Gliricidia sepium). Field experiments were conducted using three treatments (T1- NPK + 3 t/ha Gliricidia, T2- Zero fertilizer + 3 t/ha Gliricidia and T3 – zero fertilizer + zero Gliricidia) to assess the productivity of maize (Zea mays L.) and mung bean (Vigna radiate L. Wikzek) in homegardens and extensive cropping fields in the 2007/8 maha and 2008 yala seasons located on three elevation categories [flat (slope < 10%), moderate (slope 10 - 30%) and steep (slope > 30%)] in the Meegahakiula region of Sri Lanka. The study included 30 homegardens and adjacent cropping fields to represent different elevation categories. Soil samples were obtained initially by considering the rooting depth of maize at 10 cm intervals up to a 60 cm depth to determine changes in fertility. Plant samples were obtained at full crop maturity to quantify biomass production and seed yields. Incorporation of green manure improved the soil properties of homegardens significantly when compared to cropping fields, although the impact declined with increasing inclination and the soil depth. The decline in soil properties was greater in fields than in homegardens. The greatest yield improvement of maize and mung bean in terms of total biomass and seed was observed in homegardens in the flat and moderate elevation categories. However, the yields of steep fields were better than that of homegardens in the same elevation class, which indicate the significance of fallowing. The higher productivity of homegardens under subsistence conditions was clearly observed in this field study.

DOI: 10.4038/tar.v21i2.2598

Tropical Agricultural Research Vol. 21(2): 168-176 (2009)