Inherent Properties and Fertilizer Effects of Flooded Rice Soil

摘要

At the Fogera plain, Ethiopia rice is mainly grown under wet conditions. Therefore, understanding the nature of flooded soils is essential for better management of applied and native nutrients. Accordingly, field and laboratory experiments were conducted to study the major inherent properties and effects of applied mineral N and P fertilizers on soil total N and available P. A factorial combinations of N (0, 30, 60, 90, 120 and 150 kg N ha^-1) and P (0, 13.2, 26.4, 39.6 and 52.8 kg P ha^-1) fertilizers were applied using a randomized complete block design with four replications. The soil was characterized as Pellic Vertisol. Surface soil analyses indicated that the experimental field was clayey in texture (71.25% clay) and slightly acidic (pH 5.61) in reaction. Total N (0.28%), organic carbon (3.0%), percent base saturation (79.39%), cation exchange capacity (52.90 meq/100 g soils) and Olsen?s available P (36.20 ppm) were high while available K was medium (265.23 ppm). In the soil profile study, clay content, pH, percent base saturation and cation exchange capacity increased with depth whereas total N, organic carbon, available K and P declined. The Olsen?s method extracted the highest amount of P and was associated positively and strongly with number of panicles m^-2 (r = 0.460**) and the number of spikelets panicle^-1 (r = 0.487**) over Bray II. Besides, total N slightly decreased while available P slightly increased in the soil after harvest. The study revealed that the Olsen? method was superior over Bray II in predicting available P in flooded rice soil.