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Application of controlled-release urea increases maize N uptake,environmental benefits and economic returns via optimizing temporal and spatial distributions of soil mineral N 被引量:1
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作者 mingxue sun Juan LI +6 位作者 Lili ZHANG Xiaomeng SU Ning LIU Xiaori HAN Songjiang WU Zhentao sun Xiangdong YANG 《Pedosphere》 SCIE CAS CSCD 2024年第1期222-235,共14页
The creation of controlled-release urea (CRU) is a potent substitute for conventional fertilizers in order to preserve the availability of nitrogen (N) in soil,prevent environmental pollution,and move toward green agr... The creation of controlled-release urea (CRU) is a potent substitute for conventional fertilizers in order to preserve the availability of nitrogen (N) in soil,prevent environmental pollution,and move toward green agriculture.The main objectives of this study were to assess the impacts of CRU’s full application on maize production and to clarify the connection between the nutrient release pattern of CRU and maize nutrient uptake.In order to learn more about the effects of CRU application on maize yields,N uptake,mineral N (N_(min)) dynamics,N balance in soil-crop systems,and economic returns,a series of field experiments were carried out in 2018–2020 in Dalian City,Liaoning Province,China.There were 4 different treatments in the experiments:no N fertilizer input (control,CK);application of common urea at 210 kg ha^(-1)(U),the ideal fertilization management level for the study site;application of polyurethane-coated urea at the same N input rate as U (PCU);and application of PCU at a 20% reduction in N input rate (0.8PCU).Our findings showed that using CRU (i.e.,PCU and 0.8 PCU) may considerably increase maize N absorption,maintain maize yields,and increase N use efficiency (NUE) compared to U.The grain yield showed considerable positive correlations with total N uptake in leaf in U and 0.8 PCU,but negative correlations with that in PCU,indicating that PCU caused excessive maize absorption while 0.8 PCU could achieve a better yield response to N supply.Besides,PCU was able to maintain N fertilizer in the soil profile 0–20 cm away from the fertilization point,and higher N_(min)content was observed in the 0–20 cm soil layer at various growth stages,particularly at the middle and late growing stages,optimizing the temporal and spatial distributions of N_(min).Additionally,compared to that in U,the apparent N loss rate in PCU was reduced by 36.2%,and applying CRU (PCU and 0.8 PCU) increased net profit by 8.5% to 15.2% with less labor and fertilization frequency.It was concluded that using CRU could be an effective N fertilizer management strategy to sustain maize production,improve NUE,and increase economic returns while minimizing environmental risks. 展开更多
关键词 apparent N loss fertilization management green agriculture maize yield N balance N use efficiency
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中间品进口多元化、产品关系与中国出口企业技术创新 被引量:1
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作者 李平 孙明雪 《产业经济评论(山东)》 2022年第1期75-96,共22页
本文利用2000~2007年中国工业企业和海关数据,考察了中间品进口多元化对中国出口企业技术创新的影响。研究发现,中间品进口多元化显著促进了中国出口企业技术创新水平的提升,这种促进作用的产生既得益于进口中间品种类多元化也得益于来... 本文利用2000~2007年中国工业企业和海关数据,考察了中间品进口多元化对中国出口企业技术创新的影响。研究发现,中间品进口多元化显著促进了中国出口企业技术创新水平的提升,这种促进作用的产生既得益于进口中间品种类多元化也得益于来源地多元化。进一步研究显示,作用结果因企业贸易方式、进口来源地属性和出口目的地属性不同而有所差异。此外,从企业进口中间品与自身生产品间的替代与互补关系入手,通过中介效应模型探究中间品进口多元化对出口企业技术创新产生影响的传导机制,发现中间品进口多元化主要是通过产品间替代关系的显现来帮助企业实现专业化生产,打造核心竞争力,进而促进出口企业技术创新水平的提升。 展开更多
关键词 中间品进口多元化 产品关系 专业化生产 技术创新
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