休闲稻田消解沼液生态效应及其对水稻安全生产影响研究

为研究利用休闲稻田消解沼液生态效应及对后季水稻安全生产、土壤肥力及质量的影响,在浙江省嘉兴市脱潜潴育型水稻土青紫泥田上,进行4年定位田间试验,考察了休闲季灌施不同用量沼液对水稻产量、稻谷、土壤中有害重金属含量差异以及土壤中养分含量的变化,提出休闲稻田沼液消解安全容量。研究结果表明：休闲稻田灌施沼液可有效消解单一水稻轮作制地区沼气工程冬春季产生的沼液,每公顷休闲稻田每年安全消纳沼液3000t,后季水稻可在不施化学氮、钾肥,减半施用磷肥的基础上获得与全化肥处理相近或略高的产量;休闲季灌施沼液对土壤肥力有明显改善作用,土壤有机质、全氮、碱解氮、有效磷、速效钾、缓效钾都明显高于不灌沼液处理,但除土壤速效钾和缓效钾外,各种养分含量年度递增趋势并不明显,没有出现养分过度累积导致的富营养化;与全化肥处理相比,休闲季灌施沼液后土壤及稻谷中有害重金属含量没有明显增加;综合沼液灌溉对产量、土壤质量、稻谷安全品质监测结果,在水稻生产安全、土壤可持续利用的目标下,确定休闲稻田沼液安全消解容量为N1500kg·hm-2。

The Ecological Effects of Fallow Paddy Field Disposal Biogas Slurry and Its Impact on the Following Rice Safety Production

The ecological effects of fallow paddy field disposal of biogas slurry（BS） were studied through a 4-year field experiments with a fallow-rice cropping system.We investigated the variations of soil nutrient contents after BS irrigation in fallow paddy field,and examined the difference of the following rice yields,heavy metal contents in rice grain and in soil with different BS irrigation treatments in the before fallow season.Results showed that,in the fallow-rice cropping system region,the quantity of BS disposal in the fallow paddy field could reached to 3 000 t·hm-2·a-1,and it would supply sufficient nutrient of N and K for the following rice production.The mean yield of following rice in BS treatment plots were similar or slightly higher than that in chemical fertilizer（CF） treatment with no extra nitrogen and potassium applications.Soil nutrient contents（O.M.,Total N,available N,available P,available K and slowly available K） after every season of BS irrigation were significant higher than that in chemical fertilizer treatment plots;However,except soil available and slowly available K,the increasing trend of other nutrients in the BS irrigation plots is not obvious,and there does not appear excessive accumulation of nutrients in eutrophication.Heavy metal contents（Cd,Pb,Hg and As） did not increase significantly in rice grain and in the soil with BS irrigation.We suggest that,based on nitrogen,a safe capacity of biogas slurry disposal in fallow paddy field was N 1 500 kg·hm-2·a-1 for the premise of ensuring rice production and food security,as well as soil environment safety.