Foliar Fertilization of Rice After Midseason1

Abstract

AbstractFoliar fertilization of rice (Oryza saliva L.) with solutions containing N, NPK, and NPKS during reproduction promises to increase yields and affect grain composition. These foliar applications could avoid N depletion as soil N is the major source for late season uptake. To test this hypothesis field experiments were conducted for 3 years with solutions applied at and/or after panicle initiation (2‐mm panicle) in different proportions, and at different rates and times. Applications of N (157 kg/ha) on the soil prior to flooding (preflood) increased yields, ranging from 771 to 2,370 kg/ha, over the no N check but did not affect composition of brown rice. Increases (0.13 to 0.75%) in N concentration of brown rice were associated with foliar applied N of 50 kg/ha or greater, with or without P+K+S at mid‐boot (12‐ to 15‐cm panicle internodes) stage. Split application (panicle initiation and mid‐boot) increased N concentration more than when the total amount of nutrients were applied in one application (panicle initiation). The first or early applications (mid‐boot — 1976; panicle initiation — 1977 and 1978) were effective in increasing yields and the later applications (post flower — 1976; mid‐boot — 1977 and 1978) were more effective at increasing N concentration in brown rice. Differences in P, K, and Zn in brown rice were not related to timing or amount of foliar nutrients applied. Calcium and Mg in brown rice were unaffected.The results indicate that foliar fertilization of rice with solutions high in N at or after panicle initiation can increase yields. A split application can increase yields and N concentration in brown rice.