施N模式与稻草还田对土壤供N量和水稻产量的影响

Effects of Application of N Fertilizer and Incorporation of Rice Straw on Soil Nitrogen Supply and Rice Yield.

通过田间试验研究了2a定位试验后不同施N模式和稻草还田对双季稻作系统土壤供N能力和水稻生产的影响。结果表明：施用N肥显著增加土壤NH4^＋-N和可矿化N含量，显著提高稻田系统生产力，且随着稻草配合施用，施N效果更加明显。移走稻草情况下N肥增产率为30．3％～31．3％；稻草还田情况下，N2（全年施N量240kg·hm^-2）处理N肥增产率为36．7％，1kg纯N增产谷粒12．1kg．均显著低于N1、N3（全年施N量180kg·hm^-2）处理，后者增产率为40．4％～41．1％，1kg纯N增产谷粒17．7～18．0kg，且N1、N3处理（施N量相同，但各时期施N比例不同）间差异不显著。配施N肥后稻草还田可以提高土壤供N能力，连续处理2a，土壤可矿化N比移走稻草处理提高32．1％～50．0％。稻草还田时适当配施N肥增产效果明显，N1、N3处理下稻草还田增产率分别达8．7％和8．4％，而N2处理下稻草还田的表观增产效果降低，稻草还田增产率仅为5．1％。年稻草还田量为7500kg·hm^-2的红壤稻田系统，年适宜配施N量为180kg·hm^-2各时期施N优化比例为基肥30％，分蘖肥30％，穗肥40％。

A two-year field experiment was conducted to investigate effects of application of N fertilizer and incorporation of rice straw on nitrogen supplying capacity of the soil and rice yield under a double rice cropping system. Results indicate that soil NH4^＋-N, mineralizable N and rice yield was significantly increased when the soil received N fertilizer, and the effect was more significant when rice straw was incorporated as well, showing a yield increase by 36.7% （ in Treatment N2 ,240 kg · hm^-2 ） ,and 40.4% -41.1% （ in Treatment N1 and N3 , 180 and 180 kg · hm^-2 ） respectively. In Treatment N2 one kilo of N increased grain yield by 17.7-18.0 kg, which was quite similar in Treatment N, and N3. The two treatments had the same total N application rate but differed in rate of each application. Rice straw incorporation in addition to N application,for two years in a row increased soil N supply,and the mineralizable N increased by 32.1%-50.0%. With a proper N application rate, incorporation of rice straw could show more significant yield-increasing effect. It increased yield of the crop by 8.7% and 8.4% in Treatments N1 and N3,respectively,but only 5.1% in Treatment N2,which was higher in N application rate. In the red soil paddy fields with a total of 7 500 kg · hm^-2 of rice straw incorporated into the field each year, the recommended N fertilizer application rate is 180 kg · hm^-2 per year,of which 30% is applied as basal dressing,30% as sidedressing at the tillering stage and 40% as sidedressing at the booting stage.