Maize (Zea mays L.) is one of the most important staple food crops globally. One-third of global maize production is located in areas with high or extreme water scarcity and concurrently faces the challenge of low nitrogen use efficiency. Therefore, achieving synergistically high-efficiency water and nitrogen utilization in maize production is of great significance for agricultural sustainable development and global food security. In recent years, more articles have focused on the physiological mechanisms and management practices of efficient water and nitrogen utilization in maize. Unfortunately, there is a relative scarcity of research on the interactive effects between water and nitrogen on the development of young ears, which plays a crucial role in maize productivity. By compiling the most pertinent publications, this review endeavors to consolidate the existing knowledge on the interactive effects between water and nitrogen on maize production. Moreover, it advances potential physiological mechanisms and strategies for high-efficiency water and nitrogen utilization in terms of root system functioning, phytohormones, metabolism, and organ development. The changes in the availability of water and nitrogen have a significant impact on the development of young ears during the critical period, which in turn directly determines the grain number per ear and grain weight.

Improper emissions from industrial activities pose toxicological risks to groundwater safety. Based on an environmental forensic identification case involving livestock (sheep) damage caused by groundwater pollution in a pastoral area, we comprehensively evaluated groundwater quality risks, toxicological risks, and pollution sources using multivariate statistical methods, the Nemerow index method, and a non-carcinogenic health risk model. The potential specific pollutants in the region mainly included calcium, potassium, sodium, magnesium, manganese, fluoride, chloride, sulfate, ammonia nitrogen, total dissolved solids, and nitrate. An evaluation of the groundwater health risk factors showed that fluoride, nitrate, and manganese pose higher health risks (HQ > 1), as fluoride > nitrate > manganese. This suggests that these three pollutants were the primary causes of livestock damage. Identification of pollution sources using multivariate statistical analysis revealed that the main pollutants in the groundwater originate from two rare earth enterprises in the surrounding industrial park, followed by the emissions from animal husbandry. This study provides guidelines into comprehensive regional toxicological risk assessment and source tracing, offering an identification method for similar forensic environmental damage cases.