THE EFFICIENCY OF FERTILIZER NITROGEN IN IRRIGATED, DIRECT-SEEDED RICE (ORYZA-SATIVA L) IN EUROPE

Data from 35 experiments with direct seeded rice, performed between 19 81 and 1991 by national research institutes in five major rice growing countries of Europe were analyzed to estimate the average efficiency of fertilizer nitrogen (N). Pooled data from a four year regional surv ey (1984-1988) on rice-based farming systems in the Camargue-region (4 3-degrees 20'-43-degrees 40' N) in the south of France, were used to p erform a similar analysis. Experimentation during two years (1989-1990 ) was carried out to assess the value of the N-utilization efficiency within the range of N-limited growth and to obtain information on the N-efficiency under controlled conditions. At reduced basal dressing of N on soils with high soil organic matter content, the apparent N-reco very was estimated at 0.21 to 0.32 kg N uptake per kg N applied. Avera ge agronomic efficiency ranged from 12 to 17 kg grain dry mass per kg N applied. High basal N-application on these soils resulted in yield l oss. No consistent yield response to fertilizer-N input was found on s oils with less than two percent organic matter, irrespective of fertil izer timing. These results confirm the important role of soil organic matter in rice cultivation. An average apparent N-recovery of 0.18 was obtained with split application of N under controlled experimental co nditions in the Camargue. Using a controlled release fertilizer, value s of 0.58 and 32 kg.kg-1 were obtained for the apparent N-recovery and agronomic efficiency, respectively. Hence, disregarding the economic feasibility, considerable scope exists for improving N-efficiency in E uropean rice cultivation.