Effect of crop sequence and nitrogen levels on rice productivity

Two field trials were conducted at the farm of El-Gemmiza Agriculture Research Station in 2011/2012 and 2012/2013 to study the effect of three nitrogen (N) levels and three crop sequences; CS1 (wheat / rice), CS2 (fahl berseem/sugar beet/rice) and CS3 (faba bean/rice) on the productivity of rice. Three levels of nitrogen used for rice crop were as follows: 75% kg N/fed. (N1), 100% kg N/fed. (N2) and 125% kg N/fed (N3) of the recommended N fertilizer rate for rice (70 kg N/fed). The experimental trial was based on a split plot design in a randomized complete block arrangement having three replications.
Results showed that crop sequence has significant increased grain yield/fed, plant height, straw yield/fed, panicle grains weight and no of filled grain/ panicle in both seasons, except,   panicle length in the second season.
Straw yield and grain yield, 1000-grain weight and No of panicle/hill of rice were significantly affected by nitrogen levels in both seasons, and unfilled grains (%), plant height, No. of filled grains/panicle and panicle grains weight in the first season and panicale length in the second season.
The crop sequence of CS3 (faba been/rice) had great effect on the productivity of rice yield and yield components. Grain yield and most attributes were significantly affected by nitrogen fertilizer in both seasons. Increasing nitrogen fertilizer levels up to 125% kg N/fed of the recommended nitrogen rate of rice resulted in marked increases in grain yield (t/fed), straw yield, 1000-grain weight and No. of panicle/hill in both seasons.
The highest gross return was obtained with CS2.
Generally, it can be concluded that fertilizing with 125% kg N/fed of the recommended nitrogen rate of rice could improve the productivity of rice crop under the conditions of the present study. Higher rice yields were obtained after legume based sequence (CS3).