不同类型生态区稻-稻种植制度中钾肥效应及钾素平衡研究

研究了在丘陵生态区和洞庭湖生态区稻-稻种植制度中钾肥对水稻产量和钾肥效应及钾素平衡的影响。结果表明,在施钾量为0、112.5、150和187.5K2O kg hm-2的条件下,在丘陵生态区红黄泥田上,150K2O kg hm-2的施钾水平已达到较高的产量;洞庭湖生态区的紫潮泥田中缓效钾与速效钾含量均较高,目前施钾效应不明显。两种类型生态区土壤上施用氮肥的增产效果明显地大于施用钾肥。丘陵生态区红黄泥田上的3个施钾处理两季水稻吸收来自肥料钾的百分数比例均高于洞庭湖生态区的紫潮泥田。丘陵生态区红黄泥田上的3个施钾处理早稻钾素利用率平均为35.0%,晚稻为51.8%;洞庭湖生态区紫潮泥的3个施钾处理早稻钾素利用率平均为27.1%,晚稻为42.6%。肥料氮的利用率随钾肥施用量的增加而提高,这一趋势在晚稻上更为明显。在每季水稻施钾量为112.5、150、187.5 K2Okg hm-2的条件下,钾素平衡出现亏缺。在早稻施氮量165N kg hm-2(丘陵生态区),150N kg hm-2(洞庭湖生态区)和晚稻施氮量180N kg hm-2的条件下,两种类型生态区土壤上的氮素平衡中氮均出现盈余,且氮素盈余量随钾肥用量的增加而下降。

Potassium Efficiency and Balance of the Rice-rice Cropping System in Different Types of Ecosystems

The paper dealt with the effect of rice yield and potassium efficiency and balance of the rice-rice cropping system in a hilly ecosystem and Dongting lake ecosystem.The results showed that the comparatively higher rice yield of 150K2O kg hm-2 than that of 0,112.5,and 187.5K2O kg hm-2 in reddish yellow clayey soil.Due to higher soil available K and slow available K content,the potassium efficiency was not obvious in the purple calcareous clayey soil derived from lake sediment in the Dongting lake ecosystem.The yield increase effect caused by N fertilizer was much bigger than that by K in the two type of soils.The ratios of fertilizer K uptake to total K uptake by rice from three treatments in the reddish-yellow paddy soil were higher than that in the purple calcareous clayey soil.The average value of K recovery in the three K application plots in the reddish yellow paddy soil was 35.0% for early rice and 51.8% for late rice;while 27.1% for early rice and 42.6% for late rice in the purple calcareous clayey soil.Fertilizer N recovery increased with K application increasing and this trend was more obvious in late rice.Under potassium application of 112.5,150 and 187.5 K2O kg hm-2 conditions,there was deficit in potassium balance.There was N surplus in nitrogen application of 165 N kg hm-2 in the reddish yellow paddy soil and 150N kg hm-2 in the purple calcareous clayey soil of early rice and 180 N kg hm-2 of late rice in both ecosystems,and the surplus amount of N decreased with K increasing.