施肥对稻虾共作池水质影响的田间试验

Field Experiment on Effect of Fertilization on Water Quality in a Rice-Red Swamp Crayfish Co-cultivation Pond

2018年春季,按总无机养分相同的原则,在湖北省荆州市太湖农场(30°24’49"N,111°359’55"E)3个可种植面积5333m2、围埂和虾沟各666.7 m2的占地6667 m2稻虾(克氏原鳌虾Procambarus clarkii,又叫小龙虾)共作单元中小龙虾养殖期,向虾沟撒施:1)有机无机复混菌肥(FA),N-P2O5-K2O百分含量为10-4-6,45 kg/hm2;2)有机肥(OF),N-P2O5-K2O为2.5-0.6-2.9,分次施入虾沟,每次用量150 kg/hm2;稻作期施用:1)有机无机复混肥(FB),N-P2O5-K2O为18-10-12,含有中微量元素硅锌,450 kg/hm2;2)掺混肥(FC),N-P2O5-K2O为28-15-5,涂层控氮(涂层氮≥15%),375 kg/hm2;3)腐殖酸掺混肥(FD),N-P2O5-K2O为26-10-12,涂层控氮(涂层氮≥15%),375 kg/hm2,观测稻虾共作期的水质。结果表明:(a)在春季小龙虾养殖期,适量施用有机无机复混菌肥和有机肥,养殖沟水中氨氮0.053~0.22 mg/L、亚硝态氮0.004~0.022mg/L、水体透明度20~35 cm、pH7.8左右,水体浮游生物量高于不施肥虾沟,施用有机无机复混菌肥培藻效果尤佳;(b)在稻虾共作期,大量施肥影响了田面水和虾沟水的水质,小龙虾进入稻田活动的时间延迟15d以上。因此,要增加小龙虾在田间与水稻共生的时间,须在水稻插秧或直播前将肥料施入土壤,不宜不施基肥,而在返青分蘖期大量田间撒施。

Three rice-crayfish(Procambarus clarkii)units of each 5333 m^2 plantable area,666.7 m^2 surrounding ridge and 666.7 m^2 crayfish ditch were planted in Taihu Farm(30°24′49″N,111°59′55″E)in Jingzhou City,Hubei Province.During the period of crayfish culture,first organic-inorganic compound bacterial fertilizer(FA)with N-P2O5-K2O percent of 10-4-6 and second organic fertilizer(OF)with N-P2O5-K2O percent of 2.5-0.6-2.9 at a rate of 150 kg/hm^2 were sprayed in crayfish ditches in the spring of 2018.First organic-inorganic compound fertilizer(FB)with N-P2O5-K2O percent of 18-10-12,containing trace elements silicon and zinc,at a rate of 450 kg/hm^2,and second mixed fertilizer(FC)with N-P2O5-K2O percent of 28-15-5,coated nitrogen(coated nitrogen level>15%)at a rate of 375 kg/hm^2;3)humic acid mixed fertilizer(FD)with N-P2O5-K2O percent of 26-10-12,coated nitrogen(coated nitrogen level>15%)at a rate of 375 kg/hm^2 were applied during rice-crayfish symbiotic period in the spring of 2018 to evaluate the water quality in rice-crayfish co-cultivation ponds.The results showed that first proper application of bio-organic compound fertilizer(BCF)and organic fertilizer(OF)met the needs of crayfish growth in crayfish culture period in spring,with ammonia nitrogen level of 0.053~0.22 mg/L,nitrite nitrogen level of 0.004~0.022 mg/L,Secchi disc(water transparency)of 20~35 cm,and pH about 7.8;plankton biomass in the water was increased compared with the control ponds without fertilizing,especially application of BCF.During the rice-crayfish co-cultivation period,the quality of surface water and crayfish ditch water was affected by large amount of fertilization,and the time of crayfish entering the paddy field was delayed by more than 15 days.It is necessary to apply fertilizer to the soil before transplanting or direct seeding of rice in order to increase the time for crayfish to coexist with rice in the field,and it is unsuitable that base fertilizers are not applied and a large number of surface application to be done for rice in seedling establishment to returning green tillering stage.Second in the symbiotic period of rice and crawfish,a large number of surface fertilization affected water quality in field surface and in the canal with crayfish,which resulted in a delay for more than 15 days for crayfish entering into paddy field from the canal.Thus,fertilizer must be put in paddy soil before rice transplanting or direct seeding in order to increase symbiotic duration of rice-crayfish farming.