Influence of nitrogen on the growth and use efficiency of rainfed lowland rice in northwest Ethiopia

Abstract

Rice productivity in Fogera Plain of Ethiopia is low due to poor soil nitrogen management. A field experiment was conducted for two years during the main cropping seasons of 2017 and 2018 in Fogera Plain to study the effect of N fertilizer rates and application methods on productivity and nitrogen use efficiency of lowland rice. The experiment was conducted using a factorial arrangement of six levels of N rates (46, 92, 138, 184, 230, and 276 kg N ha−1) and two levels of application methods (farmers’ practice and mud-balls form) with the control, laid out in a randomized complete block design (RCBD) in three replicates. Results revealed that N rates had a significant effect on the growth, biomass and grain yields, and N use efficiency of rice. Interaction effects of application methods by N rates had only a significant effect on N use efficiency of rice. Generally, rain-fed lowland rice grain yield (4.2–5.2 tons ha−1) positively responded to fertilizer N rates from 138 to 276 kg ha−1. Nitrogen use efficiency was highest at the low and intermediate levels of N and low on highest levels of N. From this study, mud-balls making Urea is a tedious and labor intensive work. Rather, hence, nitrogen use efficient methods of Urea supergranule tablet should be used based on the recommended 276 kg ha−1 nitrogen rate to exploit more grain yield of rain-fed lowland rice without yield penalty in Fogera Plain.