Research On Effect Of Nitroent, Potassium And The Balance Of Nutrient In Rice-rapeseed Rotation System In Different Regions

Poddy-Upland rotation is a kind of classical Farming system, the rice-rapeseed rotation system is rather pervasively in south region of our country. In our country, soil potassium continues dropping, which becomes the primary restrict factor to futhur develop agriculture. Because potassium resource lacks in our country, reasonable applying potash fertilizer becomes the main measure to promote our agricultural development in current and future. And also potassium application combined with nitrogen have significance on increasing fertilizer efficiency and decreaseing nitrogen pollution. This article studied the effect of N, K application on yield, economic profit, nutrient accumulation, N and K fertilizer efficiency, nutrient balance and soil fertility in rice-rapeseed rotation syetem in Honghu country in the center of Hubei in middle area in Yangtze River(HH) and Qichun country in east of Hubei(QC). The main results were as follows:1. The application of N, K significantly increased rice and rapeseed yield at QC and HH sites, which obtained good effect on yield in rice-rapeseed rotation system. At QC site the rice and rapeseed yield reached the highest at 150 kg K₂O /hm² and increased by 1495 kg/hm² and 159 kg/hm² respectively. At HH site the rice and rapeseed yield reached the highest at 187.5 kg K₂O /hm² and increased by 3007 kg/hm² and 403 kg/hm² respectively. While N application increased rice and rapeseed yield by 1878 kg/hm² and 1350 kg/hm² at QC site, and 4178 kg/hm² and 1293 kg/hm² at HH site.2. In Rice-rapeseed rotation system, N and K increased nutrient accumulative cotent of crops. The amount of nutirtions absorbed by crops was the most when the application of K fertilizer was 187.5 kg per hm². The accumulation of K was 349.1 kg/hm² and N was 205.1 kg/hm² at QC site. While at HH site K accumulative content was 553.3 kg/hm² and N accumulation was 279.9 kg/hm². Nutritions absorbed by crops decreased with K, N deffiency or FPM.3. In Rice-rapeseed rotation, K application increased N and K apparent efficiency. At QC site K apparent efficiency was the highest with 112.5 kg K₂O/hm² application which was 66.9%. And N apparent efficiency was 35.0% with 150 kg K₂O/hm² application that was the highest. At HH site N and K apparent efficiency reach the highest which were 46.8% and 67.1% with 187.5 kg K₂O/hm².4. At QC site the application of N and K on rice and N on rapeseed all abtained high profit, but K application on rapeseed didn't abtain profit. At HH site N and K application...