Integrated Management and Efficient Use of Nutrients in Crop Systems

The sustainability of global food production relies heavily on the ability to optimize the nutrient economy in cropping systems around the world. Most human food production begins in crop fields. Although the pathway from field to table may be shorter or longer, the process always starts with the crop building its biological yield from available nutrients. As the global population continues to expand while plant nutrient stocks on Earth remain finite, it is increasingly necessary to ensure the sound management and increased efficiency of existing nutrient pools to meet the nutritional demands of present and future generations. It is critical to integrate the utilization of all available nutrient resources, both primary and secondary, as well as their associated biogeochemical processes.

The Special Issue entitled “Integrated Management and Efficient Use of Nutrients in Crop Systems” sought to compile a series of articles that addressed several key areas of concern. These areas included the assessment of soil nutrient levels and availability, the diagnosis of crop nutrient needs, the control of nutrient availability through biotic and abiotic factors, plant nutrition strategies involving external nutrient carriers, opportunities to enhance crop nutrient use efficiency, crop nutrient removal and nutrient losses, nutrient balances in crop systems, the legal, economic, and environmental aspects of nutrient management in cropping systems, and farmer awareness and nutrient management perspectives across various world regions.

Ultimately, this Special Issue brings together seven research articles that provide valuable insights into the complex interactions among soils, plants, fertilizers, microbial communities, and water resources. The studies in this issue highlight both fundamental processes and applied solutions.

The focus of four articles [1,2,3,4] is on matters pertaining to nitrogen, the most essential plant nutrient for crop production, yet also one of the most problematic environmental pollutants. In addition to nitrogen, two of these papers address the role of carbon compounds in crop production and environmental quality. The prevention of carbon loss from agricultural soils is a serious contemporary concern. In turn, the challenges associated with nitrogen management in specific regions of the world have a dual nature. While nitrogen deficiency leads to inadequate food production in certain regions, an excess of nitrogen has been shown to result in detrimental environmental consequences in others. Scientific explorations that could contribute to resolving these contrasting issues are of great importance. To address this need, Gil et al. [1] investigated the mineralization of nitrogen and carbon from organic amendments and fertilizers used in sandy soils in Florida. The findings of the study indicate that processed organic fertilizers exhibited a faster rate of inorganic nitrogen release compared to poultry manure-based amendments. However, the latter resulted in higher levels of CO₂ emissions. The temperature-dependent mineralization observed in their study carries significant implications for nutrient cycling in warm-climate crop systems, particularly in regions characterized by sandy soils. Skowrońska et al. [2] examined the role of urease and nitrification inhibitors in modifying carbon and nitrogen cycling in a maize agroecosystem in Poland. Their results showed that inhibitors were effective in reducing N₂O emissions under urea ammonium nitrate (UAN) treatments but had limited impact when combined with farmyard manure. This work contributes to the growing field of climate-smart fertilization strategies. Microbial diversity and its influence on nitrogen transformation were explored by Liu et al. [3], who demonstrated that sugar beet root exudates significantly promote the abundance of ammonia- and nitrite-oxidizing bacteria in the rhizosphere. Their findings offer a compelling argument for the pivotal role of the rhizosphere environment in nitrogen mineralization and the sustainability of high-input crops such as sugar beet. At the watershed scale, Kim et al. [4] analyzed the spatial correlations between nitrogen budgets and water quality across varied land cover types in South Korea. Their study reveals strong relationships between nitrogen inputs and both surface and groundwater quality, particularly in areas with more than 10% agricultural land. These findings emphasize the importance of spatially explicit nutrient management strategies and the use of high-resolution data in agricultural policy planning. Moreover, they provide valuable information for the development of strategies to reduce nitrogen pollution.

In this Special Issue, one article focuses on phosphorus management in crop systems. The linear and wasteful economy of the primary resources of this element has raised concerns about the future security of its supply to sustain crop production. The sustainable use of phosphorus necessitates a transition to a circular economy, which involves the recovery and reuse of this element. In response to this need, Jastrzębska et al. [5] examined the effects of biofertilizers produced from renewable phosphorus sources (sewage sludge ash, animal bones, and dried animal blood) on the grain quality of wheat grown under Polish conditions. Their results confirm that these biofertilizers do not adversely affect technological and nutritional grain quality parameters, suggesting their viability as substitutes for conventional phosphorus fertilizers.

The remaining two papers [6,7] are articles on different topics, with a common focus on nutrient content in crops. Using yerba mate (Ilex paraguariensis) as a model, a species of cultural and economic importance in South America, Lisboa et al. [6] presented a compositional nutrient diagnosis (CND) methodology to identify nutrient sufficiency levels in crops. They ascertained that yield is not directly correlated with individual nutrient levels but is rather contingent on the balance among multiple nutrients. This finding provides a valuable diagnostic framework for nutrient management in yerba mate cultivation. The CND method may assist in the prevention of nutrient deficiencies in plants and the mitigation of excessive nutrient accumulation in the soil. The latter effect is instrumental in reducing the risk of contamination of local surface and subsurface waters. Finally, Sienkiewicz et al. [7] investigated the long-term effects of fallowing strategies on the yields and chemical compositions of subsequently cultivated strategic crops (winter rape, winter wheat, and spring wheat). They found that vegetative fallows, particularly with forage legumes like fodder galega (Galega orientalis) and with smooth brome (Bromus inermis), significantly improved the yield and nutrient content of subsequent crops. These results underscore the potential of regenerative land management practices to reconcile productivity and environmental goals.

The diversity of topics presented in this Special Issue reflects the complexity of nutrient use in crop systems and the necessity of interdisciplinary collaboration. It is also noteworthy that the contributing authors represent scientific institutions from four continents—North and South America, Asia, and Europe—underscoring the global relevance of the challenges addressed and the international scope of research in this domain.

It is my hope that this Special Issue will serve as a valuable resource for researchers, practitioners, and policy makers seeking to advance sustainable and efficient nutrient management in agriculture.