Reduced input production of herbs under sub-tropical conditions in Florida

Sweet marjoram, Origanum majoranna and Italian parsley, Petroselinum crispum var. neapolitanum were grown from 1997 to 1999 in light sandy soil using the full-bed polyethylene mulch-microirrigated production system. Experimental design was a split-plot replicated three times. In the main plots the herbs were grown with (FER) or without (NFE) injected nitrogen and potassium fertilizers. Sub-plots were 0.0, 4.5, 9.0 and 18.0 Mt/ha compost applied in a narrow band under the micro-irrigation tubing. In 1997-98 herbs were planted on 17 December and in 1998-99 on 22 October. Yields were evaluated in multiple harvests. Early yields (first two harvests) of sweet marjoram were similar with NFE or FER treatments with or without compost. In later harvests, yields increased with FER treatment and with increasing compost rates. Seasonal total yields of Italian parsley also increased with N and K applications and increasing compost rates. Length of growing season was shorter and yields, especially sweet marjoram yields, were lower in the December than in the October planting. Nitrogen and K applications had little or no effect on macro- and microelement concentrations in herb shoots. In the sill, very high P concentrations were found with 9.0 and 18.0 Mt/ha compost rates.