EFFECT OF ORGANIC AND SYNTHETIC MULCHES ON YIELD OF BASIL UNDER DRIP IRRIGATION

Abstract

Small-scale herb growers in the U.S. Virgin Islands traditionally water their crops with sprinkler cans and garden hoses. This method is inefficient and consumes large amounts of water, a scarce resource in the islands. Introduction of drip irrigation has reduced water use in vegetable production. Integrating this system with mulches may further cut water use, making herb production more profitable. Basil ( Ocimum basilicum ) was grown in plots with organic (compost or straw) and synthetic (black plastic or weed barrier) mulches. A no mulch control plot was also included. All plots were drip irrigated to maintain soil moisture at -30 kPa. Total plant fresh weight and leaf fresh and dry weights were highest in the compost mulch treatment. Fresh and dry basil yields in black plastic mulched plots were almost identical with those in compost mulch, but did not differ from other treatments. Black plastic mulch reduced water use 46% compared with 27% for compost or straw mulch. All mulch treatments resulted in increased water use efficiency. Organic mulches reduced surface soil temperature, while synthetic mulches increased soil temperature 2-5°C.