Water Lettuce (Pistia stratiotes L.) as Base Material for Composting

Abstract

This research aims to study the quality of derived compost using water lettuce (Pistia stratiotes L.), a nuisance aquatic plant causing severe damage to waterways in Thailand and other tropical regions, as a major composting material together with dry leaves and pig manure. Three sets of the compost consisting of water lettuce, dry leaves, and pig manure at the ratio of 7:4:0 (T1), 7:4:1 (T2) and 7:4:3 (T3) by wet weight, respectively were composted for 21 days. All treatments used water lettuce as base material fermented in a composter for seven days and cured in a perforated plastic black bag for fourteen days. Among all treatments, the optimum ratio of raw materials in producing quality compost was determined as T3 (water lettuce, dry leaves and pig manure at a ratio of (7:4:3). Pig manure addition was found to hasten the compost process. The ratio of T3 product with decomposition maturity from 21 days of treatment yielded quality compost that met all Thai Agricultural Commodity and Food Standards ( ≥ 1%N and ≥ 0.5%P). This T3 treatment produced the best quality compost comparing plant nutrients, nitrogen (3.0%) and phosphorus (2.6%) to the other treatment scenarios investigated. Thus, water lettuce, an often-problematic weed found in rivers and canals, can rather be used as a base material for composting to enhance crop growth and for environmental benefits like reducing water pollution, use of chemical fertilizers and greenhouse gas emissions.