Fertilization Tests of MAP Recovered from Sewage for Germination and Growth of Zostera marina

Abstract

As a new recycling way for MAP (magnesium ammonium phosphate) recovered from sewage, effects of MAP fertilization on raising seedlings of eelgrass (Zostera marina) were studied for reproducing the seagrass bed as a hotspot of high bioproduction and biodiversity. In a biodegradable pot, 80 mL of silica sand and 10 seeds of eelgrass were placed and 0-200 mg of MAP was applied at 3-cm depth. As a closed circulation system, a 1.3-L plastic bottle contained these two sets, 1 L of artificial seawater, and a small pump. Germination ratio, leaf number, plant height, root length of eelgrass, nutrient concentrations of seawater, and oxidation-reduction potential (ORP) of sediment were measured for 100 days. As a result, the MAP application improved the germination ratio with a decrease in ORP, and nutrients eluted from MAP promoted the growth of eelgrass leaves. However, MAP application of >100 mg inhibited the eelgrass growth. It was supposed that the optimum MAP application for seedling eelgrass is 50 mg for 80 mL of silica sand.