基于氮素供应评估有机茶园氮肥施用的技术符合性

Assessment of technical compliance of nitrogen fertilization in organic tea plantation based on nitrogen supply

在有机生产管理和认证过程中,产品检测无法识别有机氮素和化学合成氮素,因此判断是否施用化学氮肥成为有机农业发展过程中亟需解决的问题。为了探索和评估有机生产中化肥的施用风险,本研究以云南省普洱市的5个有机茶园(分别命名为ZX、HLS、LS、YS和YCT)为研究对象,基于土壤-作物系统的氮素平衡原理,并结合绿肥、秸秆还田和土壤等非肥料氮供应情况和产量与氮素需求,估算相应茶叶产量条件下的氮肥施用量,进一步核算氮素满足率,评估2022年有机茶叶种植中化学氮肥施用的风险。结果表明:ZX、LS和YCT茶园的茶叶年产量较低,所需氮量分别为53.6、43.1 kg·hm^(-2)和27.4 kg·hm^(-2),其非肥料氮供应量均在93.8~128.2 kg·hm^(-2)之间,能够满足茶叶生产。HLS和YS两个茶园产量较高,非肥料氮供应无法满足茶叶生产,而YS茶园额外投入符合有机标准的有机氮肥63.0 kg·hm^(-2)(以N计),超过理论所需肥料氮投入量的50%。HLS茶园肥料氮施用不规范,存在施用化学氮肥的风险。研究表明,5个茶园的实际肥料措施与评估结果一致性较高,本研究提出的氮素满足率指标基于氮素平衡原理,能较好评估化肥氮施用技术符合性。有机茶园生产中,通过持续实施绿肥、秸秆还田等措施提高土壤肥力,是确保茶园生产可持续性和有机认证符合性的重要保障,应在有机农业中进一步验证和推广应用。

In organic production and certification,identifying the application of chemically nitrogen(N)fertilizers is a priority issue as it is impossible to differentiate organic and chemical N during the final agricultural product analysis.This study chose five organic tea gardens(ZX,HLS,LS,YS,and YCT)in Pu′er City,Yunnan Province,to explore and assess the risk of chemical fertilizer application in organic tea production of 2022.Based on the principle of N balance of the soil-crop system,and in combination with the supply of N from non fertilizer sources,such as green manure,straw incorporation,and soils,and with consideration of the N uptake from tea harvest yield,the study estimated the N fertilization quantity to meet with the tea production,and calculated the N satisfaction rate to assess the risk of chemical N fertilization risk in organic tea plantation.The results showed that the annual tea yields of ZX,LS and YCT tea gardens were low,and the N requirement was 53.6,43.1 kg·hm^(-2),and 27.4 kg·hm^(-2),respectively,the non-fertilizer N supplies ranged from 93.8 kg·hm^(-2)to 128.2 kg·hm^(-2),which were able to satisfy the tea production.The two tea gardens,i.e.,HLS and YS,had high tea yields,and their non fertilizer N supplies could not satisfy the tea production.The YS tea garden applied an additional 63.0 kg·hm^(-2)(calculated in N)from organic fertilizer complying with organic standards,which supplied more than 50%of the theoretical required fertilizer N input.HLS tea garden had high risk of chemical fertilizer N application,which was not in accordance with Chinese organic agriculture standard.The study shows that the actual fertilization of the 5 tea gardens studied is in high consistency with the assessment results,and the N satisfaction rate proposed in this study is based on the principle of N balance,which can well assess the technical compliance of fertilizer N use.In organic tea plantation production,the improvement of soil fertility through the continuous implementation of green manure,straw return to the field and other measures is an important guarantee to ensure the sustainability of tea plantation production and compliance with organic certification,and should be further verified and promoted for application in organic agriculture.