牛粪和生物炭对苹果根系生长、土壤特性和氮素利用的影响

Effects of cow dung and biochar on root growth,soil properties and nitrogen utilization of apple

以两年生红富士/平邑甜茶苹果为试材,采用15N同位素示踪技术,研究牛粪与生物炭不同配比对苹果根系生长、土壤特性和氮素吸收利用的影响,为苹果生产中合理施肥及可持续发展提供依据。试验共设6个处理:对照(CK)、100%牛粪(T1)、75%牛粪+25%生物炭(T2)、50%牛粪+50%生物炭(T3)、25%牛粪+75%生物炭(T4)和100%生物炭(T5)。结果表明,牛粪和生物炭混施可显著改善土壤理化性状,增加土壤有机质、碱解氮、速效磷和速效钾含量,降低土壤容重。苹果根际土壤中的微生物均以细菌占绝对优势,放线菌次之,真菌含量最少;添加牛粪和生物炭均显著提高了根际土壤的细菌、放线菌和真菌数量,其中T2处理细菌、放线菌和真菌数量均达到最高。牛粪和生物炭混施还可促进苹果根系生长,根尖数、根表面积和根系活力等指标均在T2处理达到最高,分别较对照提高47.90%、33.47%、44.67%。表明T2处理可显著促进苹果根系的生长和根系活力的提高。与对照相比,牛粪和生物炭混合处理显著提高了苹果各器官的Ndff值、全氮量和15N吸收量,提高了15N利用率和15N残留率,降低了15N损失率。各处理15N利用率和15N残留率趋势为牛粪和生物炭混合处理最高,单施牛粪或生物炭处理次之,对照最低; 15N损失率呈相反的变化趋势。其中以T2处理效果最好,15N利用率和15N残留率最高, 15N损失率最低, 15N利用率较对照提高5.51%, 15N损失率较对照降低14.52%。综合分析认为, 75%牛粪+25%生物炭处理(T2)对苹果根系生长、土壤特性和氮素吸收利用的效果最好。

Two-year-old‘Fuji’apple(Malus domestica Borkh.cv Red Fuji/Malus hupehensis)trees were used to study the effect of cow dung and biochar on soil properties,and apple root growth,nitrogen uptake and utilization using 15N isotope tracer technique.The study aimed at providing reference for rational fertilization and sustainable apple development and production.There were 6 treatments in the study-no cow dung or biochar(CK),100%cow dung(T1),75%cow dung+25%biochar(T2),50%cow dung+50%biochar(T3),25%cow dung+75%biochar(T4)and 100%biochar(T5).The results showed that combined application of cow dung and biochar improved soil physical and chemical properties,and increased soil contents of organic matter,alkali-hydrolyzale nitrogen,available phosphorus and available potassium,but reduced soil bulk density.The soil contents of organic matter,alkali-hydrolyzale nitrogen,available phosphorus and available potassium decreased gradually with decreasing cow dung proportion,and they were highest under T1,which increased by respectively 97.31%,19.01%,24.37%and 32.73%over CK.There was no significant difference between T1 and T2 in terms of the contents of the variables.Soil bulk density decreased with gradual increase in biochar proportion.The difference between T4 and T5 treatments was not significant.Soil bulk density under T4 or T5 treatment was significantly lower than that of CK and T1.Bacteria population was highest in rhizosphere soil,followed by actinomyces,and fungus content was lowest.The addition of cow dung and biochar significantly increased the number of bacteria,actinomycetes and fungus in rhizosphere soil.The population of bacteria,actinomycetes and fungus was highest in T2 treated soil.The cow dung and biochar mixture also promoted apple root growth.Root tip,root surface area and root activity were highest in T2 treated soil,with respective increases of 47.90%,33.47%and 44.67%over that of CK.Compared with CK,the cow dung plus biochar significantly improved the Ndff value,total nitrogen and 15N absorption of various organs of apple.It also increased 15N utilization and residual rate,while reducing 15N loss rate.The utilization rate and the residual rate of 15N were higher under treatments of mixed cow dung and biochar.Single application of cow dung or biochar was second and CK treatment the lowest.The loss rate of 15N showed the reverse trend.T2 treatment showed best with the highest 15N utilization rate and residue rate and lowest 15N loss rate.Under T2 treatment,while 15N utilization ratio increased by 5.51%,15N loss rate decreased by 14.52%compared with CK.Comprehensive analysis showed that the 75%cow dung+25%biochar treatment(T2)had the best effect on apple root growth,soil characteristics and nitrogen absorption and utilization.