The relationship between soil nitrate distribution and growth rate of Capsicum frutescens in subsurface flow constructed wetland integrated with household septic tank

Abstract

Domestic wastewater treatment unit consisted of a single chamber septic tank and Subsurface Flow Constructed Wetland (SFCW) was built in Yogyakarta, Indonesia. SFCW played a significant role as secondary treatment of septic tank effluent. This study aimed to analyze the soil nitrate and its distribution in sand layer of SFCW. The SFCW had a depth of 0.2 m of coral and sand layers with two leach pipes that were installed in the depth of 0.3 m along the garden and planted with chili (Capsicum frutescens). Soil nitrate content of SFCW and plant growth were analyzed for 8 weeks of observation. Soil samples were taken in different direction, both vertical and horizontal. In vertical direction, samples were taken with three different depth (10, 15, and 20 cm) from the surface. In horizontal direction samples were taken with three different distance from outlet pipe. Soil nitrate obtained in vertical direction was significantly different (P<0.005) with soil nitrate at the depth of 20 cm was higher than 15 cm and 10 cm. However, the soil nitrate obtained in horizontal direction was not significant (P>0.05). The soil nitrate has positive correlation with plant growth, the higher soil nitrate will increase the plant growth.