Examination of the Effectiveness of Controlled Release Fertilizer to Balance Sugarcane Yield and Reduce Nitrate Leaching to Groundwater

Abstract

Groundwater pollution by nitrate leaching from sugarcane fields in Okinawa is recognized as a critical issue. Controlled release fertilizer (CRF) has the potential to reduce N leaching from cropping systems. The study focused on confirming the effectiveness of CRF at balancing sugarcane yield and reducing nitrate leaching from sugarcane fields via a water footprint (WF) approach. A lysimeter study was conducted using four treatments: (i) bare land, (ii) P and K fertilization without N, (iii) urea fertilization, and (iv) CRF application. According to the results, for both plant cane and ratoon, the total sugarcane dry weight obtained for CRF was higher compared to urea application. The cumulative nitrate-N leaching of the plant cane season for all treatments was higher than of the ratoon season. For the total crop cycle (plant cane plus ratoon), heavier nitrate-N leaching was observed in the urea-applied condition than in the CRF-applied condition. For both crop seasons, the total sugarcane WF of the CRF application (plant cane: 192.33 m3 /t, ratoon: 190.47 m3 /t) was lower than that of the urea application (plant cane: 233.47 m3 /t, ratoon: 237.59 m3 /t). WF values indicated that the CRF application had a lower impact on the groundwater of the area.