针对黄河三角洲盐碱稻田土壤磷素有效性低、淋失严重的问题.采用田间定位试验,探究了生物炭及改性生物炭添加对土壤磷有效性和磷素淋失风险的影响.试验设4个处理:(1)空白对照,CK;(2)常规施肥,NPK;(3)常规施肥+秸秆源生物炭8000kg/hm2;(4)常规施肥+秸秆源铁改性生物炭8000kg/hm2.结果表明:相比于NPK处理,生物炭及改性生物炭处理后表层土壤速效磷、全磷含量显著增加,其中速效磷含量增加41％以上.土壤全磷含量随土壤深度增加而降低,在60～80 cm 土层中改性生物炭处理土壤全磷含量最低.土壤金属氧化物、有机碳及可溶性有机碳与土壤全磷、速效磷及水溶性磷存在显著正相关关系,表明土壤磷、金属氧化物和有机质可能存在共迁移;改性生物炭添加后土壤磷素饱和度显著降低.综上所述,改性生物炭添加降低土壤磷素淋失风险.
Effects of Biochar and Modified Biochar Application on Phosphorus Leaching in the Coastal Saline-alkaline Paddy Soil
Aiming at the problems of low phosphorus(P)availability and serious leaching in saline-alkaline paddy soil of Yellow River Delta,the effects of biochar and modified biochar addition on soil P availability and P leaching risk were investigated by field experiments.There were four treatments:(1)control,CK;(2)conventional fertilization,NPK;(3)conventional fertilization+straw source biochar 8000 kg/hm2;(4)conventional fertilization+straw source iron modified biochar 8000 kg/hm2.The results showed that,compared with NPK treatment,the content of total P was significantly increased with the addition of biochar and modified biochar,and the content of available P increased by more than 41％.Soil P content decreased with the increase of soil depth,and the soil total P content was the lowest in 60-80 cm soil in modified biochar added treatment.Meanwhile,soil metal oxides,soil organic carbon and dissolution organic carbon were positively correlated with soil total P,available P and water-soluble P,indicating that soil P,metal oxides and organic matter may co-migrate in soil profile.Soil P saturation decreased after the addition of modified biochar,which further indicated that the addition of modified biochar reduced the risk of soil P leaching.Therefore,biochar especially modified biochar,plays an important role in increasing soil P availability and reducing soil P leaching in the Yellow River Delta.
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