Ensuring Plant Nutrition through Sustainable Soil Management Strategies: Assessing Research Progress and Challenges

The ‘Soil and Plant Nutrition’ section of Agronomy (ISSN 2073-4395) is dedicated to sharing high-quality research articles, reviews, and communications that explore the latest scientific trends and advancements in the field. This section focuses on the crucial objective of enhancing soil quality and agricultural productivity while acknowledging the inherent link between the two. This emphasis has been driven by the escalating global food demand, which has compelled scientists and farmers to confront the challenges posed by climatic change and the footprint of conventional farming practices [1]. Therefore, in order to promote the preservation of soil health and the prevention of the uncontrolled depletion of resources, it is necessary that current research centers on smart management practices and aligns with sustainable principles, which are both key priorities for Agronomy. In this Editorial, our objective is to thoroughly analyze the research papers published in the ‘Soil and Plant Nutrition’ section in order to investigate how extensively researchers have identified soil and plant improvement methods and strategies that promote sustainability. This vision of sustainability encompasses environmental stewardship, efficient resource use, and the long-term viability of agricultural systems. Through a comprehensive review of these scholarly articles, we aim to uncover the progress made in adopting and implementing sustainable practices for soil and plant improvement and to identify any gaps or areas that require further research.

From 2017 to 2023, 1345 scientific papers were published in the ‘Soil and Plant Nutrition’ section. Figure 1 depicts the dynamic trend in the number of publications over the years, offering insights into the research output within the domain. To conduct a more focused and detailed literature analysis, we narrowed down the bibliography to the years 2022–2023, representing the latest scholarly progress in the field. Specifically, we extracted 1729 keywords found in the 427 published papers to construct a bibliometric network via the software VOSviewer. Keywords were considered if they co-occurred at least three times and reached a threshold of 104 occurrences. A visual representation of the most frequent and strongest links observed in the network is presented in Figure 2. Overall, this bibliometric analysis provides valuable insights into the prevailing research themes and trends within the field of soil and plant nutrition. The keywords ‘Yield’, ‘Nitrogen’, ‘soil fertility’, ‘biochar’, and ‘soil organic matter’ emerged as the most prominent and frequently discussed research topics in the context of soil and plant nutrition. These areas of interest have garnered significant attention within the research community. On the other hand, it is worth noting that research areas such as microbial inoculants, arbuscular mycorrhizal fungi (AMF), and biofertilizers exhibit relatively lower link strength despite their significance with respect to modern sustainable agriculture.

Our bibliometric analysis (Figure 2) yielded keywords signifying the researchers’ specific focus areas. Complementing this analysis,

Table 1. Cluster output based on co-keyword analysis.

Cluster	Color	Links	Link Strength	Occurrence	Label
1	Red	99	116	82	Soil Amendments and Soil Health
2	Green	71	83	68	Optimization of soil management for Crop Productivity
3	Dark blue	70	76	60	Mycorrhizal Fungi and Nutrient Uptake
4	Yellow	57	60	51	Biostimulants and Plant Growth
5	Purple	56	57	45	Soil dynamics in changing climate
6	Light blue	41	45	36	Nitrogen cycling, Rhizosphere Interactions, and Salinity Mitigation
7	Orange	30	33	39	Yield and Soil Fertility Enhancement Strategies
8	Brown	32	44	27	PGPM
9	Pink	65	76	50	Interconnectedness of Bacterial Community Structure, Soil Nutrient Availability and Yield
10	Light red	32	39	25	Soil Contaminants and Pollution

demonstrates an overview of the clustering results, highlighting the primary themes of research that emerged from the co-keyword evaluation. By referring to our results, it is evident that extensive research has been dedicated to investigating strategies for improving soil fertility, as addressing this factor is fundamental in paving the way to maximized yield potential [2]. It is evident that numerous of studies have mainly focused on the implementation of soil organic amendments and their impact on various soil properties and functions (e.g., soil organic carbon sequestration, soil macroaggregate formation, and soil enzymatic activities and the behavior of herbicides in the environment) [3,4,5]. These amendments encompass a range of materials, including manure, compost, rice straw, vermicompost, and gypsum, which are utilized alone, mixed, or in combination with chemical fertilizers. Among all the organic amendments, we can see that biochar appears to be the most promising, as it is backed by a substantial body of research. The utilization of biochar has shown significant potential in various applications, and the research findings verify its potential benefits in improving nitrogen availability, soil nitrogen retention, absorption, and utilization [6]. While a multitude of research papers have examined the application of organic amendments as enhancers of soil physical properties and chemical features, thereby directly contributing to optimal plant growth and development [7,8,9,10], a subset of research has also focused on their indirect effects influencing plant physiology and root system water potential [11,12,13].

The category of biostimulants has also received a significant amount of attention, as evident from their frequent occurrence as a keyword, which indicates their potential as effective tools for addressing abiotic stress factors that limit agricultural productivity (e.g., salinity, nutrient deficiencies, and drought) [14]. Most of the articles cover the impact of humic ameliorative amendments, seaweed extracts, and amino acids on soil and plant growth, and their influence on yield potential as well as the mitigation of abiotic stress factors [15,16]. Within this category, humic substances have exhibit the highest occurrence and link strength, emphasizing the strong belief of the scientific community in their significance in terms of plant growth and development.

Beyond the utilization of organic amendments and biostimulants as soil improvers, our results indicated that many studies have also focused on alternative soil management optimization approaches that can enhance soil health and increase crop productivity. The integration of sustainable practices, as opposed to conventional methods, has the potential to revolutionize agricultural production; practices such as reduced tillage, crop rotations, crop diversification, strip cropping, and cover crop adoption are specifically designed to improve soil health by enhancing soil structure, promoting organic matter accumulation, reducing erosion, and fostering beneficial microbial activity [17,18,19,20]. These measures ultimately lead to improved soil health and resilience, which are crucial factors for sustainable and productive agriculture.

Our analysis showed that even though the existing research on beneficial microorganisms in the ‘Soil and Plant Nutrition’ section is noteworthy, there is still much to explore and investigate. While several studies have examined the use of microorganisms for plant growth, stress alleviation, or remediation purposes [21,22], the body of research in this vital area remains relatively limited, especially as the scientific community considers the use of microbial inoculants to be among the most sustainable and eco-friendly agricultural practices. Additionally, there are only a few studies dedicated to the impact of soil amendments or management practices on microbial abundance, diversity, and activity. Over the years, the excessive use of chemical fertilizers by farmers, driven by global demand and economic interest in attaining high yields, has led to detrimental effects on soil biological properties, posing a severe threat to agricultural sustainability [23]. Understanding how these practices influence the abundance and diversity of beneficial microorganisms will allow us to develop targeted strategies for enhancing soil health and promoting long-term agricultural sustainability.

Upon examining the research patterns, we have observed the interdisciplinary nature of the ‘Soil and Plant Nutrition’ section, which contains up-to-date publications and ongoing efforts to advance our knowledge of practices that promote soil health, agricultural productivity, and ecological balance. Overall, the contributions made by Agronomy, particularly in the ‘Soil and Plant Nutrition’ section, play a vital role in promoting sustainable agricultural practices that not only increase productivity but also prioritize the well-being of the soil. Considering the current research dynamics, we anticipate witnessing an expanding scope of knowledge on plant-growth-promoting microorganisms in the future given their paramount significance in numerous essential soil processes and plant growth. As researchers delve deeper into these areas of study, we can work towards achieving a harmonious balance between agricultural development and environmental stewardship, thus ensuring a more sustainable and resilient future for agriculture.