长期稻虾共作模式下稻田钾素平衡状况及合理施钾量研究

Study of potassium balance and potassium application rate in long-term integrated rice-crayfish mode

通过田间试验,研究了长期稻虾共作模式和中稻单作模式下农田生态系统钾素的输入、输出特征、平衡状况以及不同施钾量对直播水稻产量和钾肥利用效率的影响。结果表明,稻虾共作模式钾输入总量为134.3kg/hm^(2),主要由化肥、饲料、降雨及灌溉水等带入,分别占输入总量的46.3%、10.3%、5.5%和34.8%;相对于中稻单作模式,稻虾共作模式由饲料和灌溉水输入的钾大幅增加。稻虾共作模式钾输出总量为119.4 kg/hm^(2),主要由水稻籽粒、商品虾、渗漏以及排水带出,分别占输出总量的26.5%、5.0%、41.2%和27.3%,相对于中稻单作模式,以上4种途径钾输出均大幅增加。两种模式下钾表观平衡均出现盈余,且稻虾共作模式系统钾的盈余量低于中稻单作模式。同等施钾量条件下,长期稻虾共作模式的水稻产量、钾肥偏生产力和钾肥利用率较中稻单作模式分别平均提高了14.1%、14.2%和5.6%,且水稻增产主要是通过增加有效穗数来实现的。中稻单作模式和稻虾共作模式施钾量分别达到47.3 kg/hm^(2)(即K_(2)O施用量57.0 kg/hm^(2))和21.6 kg/hm^(2)(即K_(2)O施用量26.0 kg/hm^(2))时能够维持农田生态系统钾素平衡,而K_(2)O施用量分别达到82.2和85.0 kg/hm^(2)时水稻能够获得较高的产量。

Through field experiments,the effects of the long-term integrated rice-crayfish mode and the rice monoculture mode on potassium(K)input and output characteristics,balance status,and different K application rates on the yield of direct-seeded rice and potash fertilizer use efficiency were studied.The results showed that the K input of the integrated ricecrayfish mode was 134.3 kg/hm^(2),which were mainly brought by chemical fertilizer,fodder,rainfall and irrigation water,accounting for 46.3%,10.3%,5.5% and 34.8% of the total input,respectively.Compared with the rice monoculture mode,the K input of fodder and irrigation water of the integrated rice-crayfish mode increased greatly.The total K output of the integrated rice-crayfish mode was 119.4 kg/hm^(2),mainly including rice grain,commercial shrimp,leakage and runoff,accounting for 26.5%,5.0%,41.2% and 27.3% of the total output,respectively.Compared with the rice monoculture mode,the K output of the above four ways increased significantly.The apparent balance of K in the two modes was surplus,and the surplus of K in the integrated rice-crayfish mode was lower than that in the rice monoculture mode.Under the same K application rate,the rice yield,K partial productivity and K utilization rate of the integrated rice-crayfish mode were 14.1%,14.2% and 5.6% higher than that of the rice monoculture mode respectively.Compared with the rice monoculture mode, the long-term integrated rice-crayfish mode could increase the yield mainly by increasing the number of effective panicles. In a word,when the K application rate of the integrated the rice monoculture mode and rice-crayfish mode of rice and shrimp reach 47.3 kg/hm^(2)(K_(2)O application 57.0 kg/hm^(2))and 21.6 kg/hm^(2)(K_(2)O application 26.0 kg/hm^(2)),respectively,the K balance of farmland ecosystem could be maintained;when the K_(2)O application amount reach 82.2 and 85.0 kg/hm^(2) respectively,higher yield could be gotten.