Effective fertilizer application in sugarcane cultivation to reduce eutrophication and acidification of coral reef seas

Abstract

Coral ecosystems nurture high biodiversity and bioproductivity, even in tropical and subtropical seas, in which nutrient levels are low. However, there is concern that these ecosystems are rapidly declining. Apart from the abnormal increase in the seawater temperature, the eutrophication of coral-supporting seawater has also drawn considerable attention, especially inside the reefs. Based on the results obtained from our previous studies of several coral islands in the Ryukyu Islands, Japan, this report shows that the uncontrolled application of fertilizer during the cultivation of sugarcane, the main crop on the islands, which is especially concentrated in the very early stage of sugarcane production, ultimately induces the eutrophication and acidification of lagoon seawater. This report also suggests an improved method of fertilizer application that will both reduce the nitrates loaded into the local environment and provide an agricultural benefit to local farmers.