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Start Over Author "Huang, Na" Publisher elsevier b.v.
181 results on '"Huang, Na"'

49. Nitrogen fertilizer use and climate interactions: Implications for maize yields in Kansas.

Author

Huang, Na, Lin, Xiaomao, Lun, Fei, Zeng, Ruiyun, Sassenrath, Gretchen F., and Pan, Zhihua

Subjects
*NITROGEN fertilizers, *GREENHOUSE gas mitigation, *CLIMATE change adaptation, *FIXED effects model, *FERTILIZER application
Abstract

While climate change threatens maize growth and production, appropriate N fertilizer use (N) can help mitigate this threat and stabilize or improve maize yields. Accurate application of N fertilizer is of increasing interest as an adaptation measure for climate change by reducing greenhouse gas emissions and increasing economic returns. The objectives of this study are to: 1) clarify how maize yields respond to N fertilizer use under changes in temperature and precipitation, and 2) explore the effects of various climate conditions on N fertilizer use efficiency. We used a long-term and county-level maize N fertilizer use and climate dataset from 1981 to 2019 in Kansas to determine the impact of N fertilizer use on maize yield. We developed a panel data model with fixed effects, incorporating explanatory variables, including the interaction of growing-degree-days (GDD) with N fertilizer use (GDD it *N it), extreme-degree-days (EDD) with N fertilizer use (EDD it *N it), and precipitation (Precip) with N fertilizer use (Precip it *Nit), along with a non-linear N-fertilizer use term. Then, the adaptive effects of N fertilizer use on climatic risks for maize were examined and the county-level results were aggregated into the nine crop reporting districts, as defined by the U.S. Department of Agriculture's National Agricultural Statistics Service. Our results show that: 1) an increase in N fertilizer use magnified the negative effects of higher EDD on maize yield but enhanced the positive effects of higher GDD and precipitation on maize yield, impacts which were increasingly evident moving from western to eastern regions across Kansas; 2) hotter environments reduced maize yield by 7% in the west; conversely, warmer and wetter environmental conditions contributed to 2.4% yield gains in the southeast; changes in N fertilizer use impacted maize yield to a lesser extent than climate changes; and 3) under the averaged climate conditions, the optimal N fertilizer rate increased from northwestern (average 50 kg N ha−1) to eastern (average 158 kg N ha−1) regions in Kansas. Our results reveal the interaction between climate and N fertilization on maize yield and clarify how the efficiency of N fertilizer use is affected by various climatic conditions. Our findings highlight the quantifiable interactions between climate and N fertilizer use when evaluating dynamic N fertilizer applications and climate change adaptations. [Display omitted] • Climate change impact (−10 to 8%) affected maize yield more than the impact of changes in N fertilization (−4 to 2%). • Increased N fertilizer use led to greater yield as GDD and precipitation increased. • Increased N fertilizer use reduced yield as EDD increased. • Adjusting N application to climatic conditions will improve N use efficiency. [ABSTRACT FROM AUTHOR]

Published
2024
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50. Exploring the influence of local urban heat features on park cooling effects: Insights from Chinese cities.

Author

Zhou, Yi, Luo, Yuchao, Yi, Xincheng, Lun, Fei, Hu, Qiyuan, Huang, Na, Wen, Gaohui, Zhou, Hao, and Hu, Xianhui

Abstract

Urban parks are vital for mitigating urban heat, yet debate persists on whether local urban heat features hinder or enhance park cooling effects. Therefore. We employed Google Earth Engine and Landsat 8 OLI to map the average summer daytime land surface temperature (LST) across China during 2017–2019. This allowed us to evaluate park cooling effects and calculate local urban heat island intensities (LUHI) around each park. Findings revealed that: (1) urban parks had an average cooling intensity (PCI) of 1.38 °C, with Blue and Green Parks demonstrating superior cooling effects, particularly in arid regions. (2) Parks in hotter urban areas exhibited enhanced cooling effects, with notable PCI differences of over 0.4 °C among different LUHI regions, especially for Blue and Green Parks. However, this effect was not observed in the central subtropical (CST) and central temperate (CT) zones. (3) Hotter urban areas had larger Threshold Value of Efficiency (TVoE), particularly for Blue and Green Parks (0.11–0.46 ha), with CT zone parks displaying the largest TVoE among climate zones. (4) The variations in park cooling effects attributed to LUHI primarily stem from differences in land cover composition and their thermal properties. More importantly, our study underscores the greater influence of local urban heat features over urban heat characteristics on park cooling effects. Therefore, local urban heat features surrounding urban parks must be taken into account when planning urban green spaces, what's more, a larger park was more efficient in hotter urban areas. • Quantifies the cooling effects of 13,868 urban parks in 276 Chinese cities. • Describes the diverse local urban heat features of Chinese urban parks. • Demonstrates improved parks cooling effects in hotter urban areas. • Explains the mechanisms behind how cooling effects change with local heat features. [ABSTRACT FROM AUTHOR]

Published
2024
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