施钾对湖南主要双季稻区钾肥效应及钾素平衡的影响

Effect of potassium application on its efficiency and balance in double rice regions in Hunan Province

研究了不同施肥处理(在丘陵双季稻区和洞庭湖双季稻区分别施以0,112.5,150.0,187.5 kg/hm^2的K_2O)对水稻单产和钾肥效应及钾素平衡的影响.结果表明,洞庭湖双季稻区稻田中缓效钾和全钾含量均较高,土壤供钾能力强,土壤中钾基本上能够满足水稻对钾素营养的需要,能够获得较高的单产,施钾效果不显著.在2类双季稻区土壤上施用氮肥的增产效果明显大于施用钾肥的.由差值法测得,丘陵双季稻区和洞庭湖双季稻区早稻NPK_1,NPK_2,NPK_3处理的平均钾素利用率分别为28.8%,43.0%,晚稻NPK_1,NPK_2(1-1),NPK_3处理的分别为44.4%,26.5%.在每季水稻施钾量(施K_2O)为112.5,150.0,187.5 kg/hm^2的条件下,钾素平衡处于亏缺状态,但钾素的亏缺随钾肥用量的增加而降低(洞庭湖双季稻区的NPK_3处理出现了钾素盈余).

The effect of potassium application on rice yield, potassium efficiency and potassium balance double rice regions was studied by applying 0, 112.5, 150.0, 187.5 K2Okg/hm^2 K fertilizer in field experiment. The results showed that the contents of K slowly available and total K of in Dongting lake double rice regions is obviously higher than that in hilly double rice regions. In Dongting regions, due to high soil K supply capacity from the soil itself K from the soil can meet rices K requirement basically for high grain yield; The effect of potassium application was not remarkable while in type 2 double rice regions, the yield increase produced by N fertilizer application was much higher than that by K fertilizer application in. The balance evaluation led to the conclusion： the average value of K recovery for early rice in three treatments NPK1, NPK2, NPK3 in the two kinds of double rice regions was 28.8%and43.0%, respectively ; while that for late rice in three treatments NPK1 , NPK2（1-1）, NPK3 was44.4% and 26.5%, respectively with potassium application of 112.5, 150.0, 187.5 K2Okg/hm2, there was a deficit in potassium balance, while and the deficit amount of its decreased with K application increasing （even surplus in NPK3 treatment in Dongting Lake double rice regions）.