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Indium gallium nitride (InGaN)-based light-emitting diodes (LEDs) are considered a promising candidate for red-green-blue (RGB) micro displays. Currently, the blue and green LEDs are efficient, while the red ones are inefficient for such applications. This paper reports our work of creating efficient InGaN-based orange and red LEDs on silicon(111) substrates at low current density. Based on the structure of InGaN yellow LEDs, by simply reducing the growth temperature of all the yellow quantum wells (QWs), we obtained 599 nm orange LEDs with peak wall-plug efficiency (WPE) of 18.1% at 2    A / cm 2 . An optimized QW structure was proposed that changed two of the nine yellow QWs to orange ones. Compared with the sample containing nine orange QWs, the sample with two orange QWs and seven yellow QWs showed similar emission spectra but a much higher peak WPE up to 24.0% at 0.8    A / cm 2 with a wavelength of 608 nm. The improvement of peak WPE can be attributed to the improved QW quality and the reduced active recombination volume. Subsequently, a series of efficient InGaN-based orange and red LEDs was demonstrated. With further development, the InGaN-based red LEDs are believed to be attainable and can be used in micro LED displays.

Nutrients, such as nitrogen and phosphorus, provide vital support for human life, but overloading nutrients to the Earth system leads to environmental concerns, such as water and air pollution on local scales and climate change on the global scale. With an urgent need to feed the world's growing population and the growing concern over nutrient pollution and climate change, sustainable nutrient management has become a major challenge for this century. To address this challenge, the growing body of research on nutrient budgets, namely the nutrient inputs and outputs of a given system, has provided great opportunities for improving scientific knowledge of the complex nutrient cycles in the coupled human and natural systems. This knowledge can help inform stakeholders, such as farmers, consumers, and policy makers, on their decisions related to nutrient management. This paper systematically reviews major challenges, as well as opportunities, in defining, quantifying, and applying nutrient budgets. Nutrient budgets have been defined for various systems with different research or application purposes, but the lack of consistency in the system definition and its budget terms has hindered intercomparison among studies and experience‐sharing among researchers and regions. Our review synthesizes existing nutrient budgets under a framework with five systems (i.e., Soil‐Plant system, Animal system, Animal‐Plant‐Soil system, Agro‐Food system, and Landscape system) and four spatial scales (i.e., Plot and Farm, Watershed, National, and Global scales). We define these systems and identify issues of nitrogen and phosphorus budgets within each. Few nutrient budgets have been well balanced at any scale, due to the large uncertainties in the quantification of several major budget terms. The type and level of challenges vary across spatial scales and also differ among nutrients. Improvement in nutrient budgets will rely not only on the technological advancement of scientific observations and models but also on better bookkeeping of human activity data. While some nutrient budget terms may need decades, or even centuries, of research to be well quantified within desirable levels of uncertainties, it is imperative to effectively communicate to interested stakeholders our understanding of nutrient budgets so that scientists and a variety of stakeholders can work together to address the sustainable nutrient management challenge of this century.