Boosting productivity of rice and maize in rice-maize cropping systems requires efficient fertilizer management to improve the nutrition status of the soil. However, fertilizer rates for rice-maize cropping systems are conventionally calculated separately for each commodity regardless of the fertilizer residue of the preceding crop. This paper explores the impact of balancing and phasing nutrients for both crops on crop yields. It is based on an experiment conducted at the ICERI experimental farm in Maros during 2007. The experiment used a randomized block design with four replications of NPKS fertilizer in a rice-maize rotation. The findings show that the highest yield of both rice (5.01 t ha-1) and maize (8.30 t ha-1) were obtained by using a combination of four fertilizers (600 kg ha-1 urea, 200 kg ha-1 SP 36, 200 ha-1KCl and 100 kg ha-1 ZA) in equal proportions—50 per cent for rice and 50 per cent for maize. This finding suggests that fertilizer use efficiency and productivity of a rice-maize cropping system in the rainfed lowlands of Indonesia would be optimized if the fertilizer dosage was appropriately apportioned to the two crops.