Impact of Cover Crops on Soil Quality Parameters of Coconut (Cocos nucifera L.)-Grown Red Yellow Podzolic Soil

Degradation of soil quality as a result of the long-term coconut cultivation is a challenge for sustainable coconut production. This study was conducted to assess the changes in soil quality of coconut-grown Red Yellow Podzolic soil under two widely grown cover crops of Puereria phasioloides (Fabaceae) and Brachiaria brizantha (Poaceae) compared to coconut land with no cover crop (control). Coconut lands were located in the low country intermediate zone-IL1 of Sri Lanka. The soil samples were collected and analyzed for physical, chemical and biological properties. Results indicated that the soils from coconut cultivation with P. phasioloides were superior in most of the properties compared to those of B. brizantha and the control. Soil from coconut land with P. phasioloides was significantly higher in, electrical conductivity, organic carbon content (0.66%), number of bacterial colonies (19.76×106 CFU/g) and microbial activities (1.55 mg CO2/day). There were no significant differences between top soil (0 cm – 11 cm) and sub soil (11 cm - 42 cm) for pH, electrical conductivity and organic carbon. Soils under P. phasioloides and B. brizantha showed higher aggregate stability and low bulk density compared to control. Water availability at the field capacity was higher (32.98%) in soils under B. brizantha in the (32.98%) in soils under B. brizantha in the top soil. The study revealed that as a cover crop P. phasioloides has a higher potential in improving soil qualities in coconut lands.