Organo-mineral Amendment Options for Enhancing Soil Fertility and Nutrient Composition and Yield of Fluted Pumpkin

Abstract

Fluted pumpkin (Telfairia occidentalis Hook F.) is an important vegetable in the tropics. However, its supply can fall short of demand, even when grown with irrigation, partly due to low fertility of arable soils. This study evaluated the effects of the use of synthetic fertilizer (15N–15P–15K) alone or combined with some organic amendments (rice husk dust, rice husk ash, poultry litter) at varying ratios on soil fertility and pumpkin yield. Soil chemical properties at harvest in amended plots were improved relative to the control. Amendment enhanced the nutrient composition of pumpkin leaves. Leaf yields assessed biweekly from 6 to 16 weeks after planting (WAP) were similar regardless of treatment but with overall highest values in poultry litter–amended plots and lowest values in the control, except at 16 WAP when rice husk dust plus N–P–K had higher values than others. Yields generally peaked at 14 WAP, followed by a drop at 16 WAP. Soil available P status influenced leaf K and Mg content at 8 WAP, but soil K+ status had a greater influence on the leaf content of these nutrients. Soil available P, total N, and K+ explained about 32%, 50%, and 37%, respectively, of variation in leaf yield at 10, 12, and 14 WAP, respectively. Use of rice husk ash or poultry litter alone or combined use of rice husk ash and N–P–K has the potential for restoring fertility of degraded soils and increasing productivity of fluted pumpkin.