1. Introduction

“Soil and Plant Nutrition” (https://www.mdpi.com/journal/agronomy/sections/Soil_Plant_Nutrition) is a core section of the MDPI journal Agronomy (ISSN 2073-4395), whose publication volume ranks second among all 13 sections, second only to “Crop Breeding and Genetics”. This section has received widespread attention in research community, as it focuses on reporting the latest developments in specific cutting-edge fields, and facilitates communication and cooperation among research communities. “Soil and Plant Nutrition” provides a platform for original research results in the broad areas of soil science, technology, management, and their impacts on plant nutrition. Papers published in this section will enhance the international scientific community’s perceptions of edaphic factors that could influence plant nutritional physiology, crop yield, stress response, rhizosphere nutrition, nutritional genetics and nutritional ecology. In the long run, it will drive scientific research and sustainable technology development with soil science and crop nutrition. This editorial aims to provide an overview of recent popular research topics, pointing out pressing research problems that contain the potential for breakthrough progress.

2. Current spotlights in soil and plant nutrition

The section “Soil and Plant Nutrition” objectively reflects the recent research trends of agricultural soil and crop nutrition.  The crop yield, nitrogen of plant and soil, and plant growth remain the continuous focus of attention in this field, and crop quality, management and carbon of crop/soil, phosphorus and fertilization are also frequently studied. Moreover, the exploration of biochar application, bacterial community of soil/plants, and organic amendments has made the research topics in soil and plant nutrition more diverse.

For instance, vermicompost is the product of earthworm (e.g. Eisenia andrei) digestion and aerobic decomposition via the activities of micro- and macro-organisms at room temperature. Biochar, vermicompost, and compost are currently receiving attention as soil organic amendments [1], and had salient influences on growth parameters, nitrate and chlorophyll content of Swiss chard and other crops [2]. Biochar and compost application either alone or in combination affected vegetable yield in a volcanic Mediterranean soil [3]. Vermicomposting technology could help reduce the content of potentially toxic elements in sewage sludge [4]. These issues are the typical research focuses. However, the complex interactions between earthworm, soil bacteria, fungi and other soil biota are still little known. Research efforts in this area will help formulate targeted strategies to make full use of their synergistic interactions in controlling heavy metal pollution in farmland and improving plant nutrition.In some arid zones, the poor quality of management led to the increase in the concentration of heavy metals in the soil [5]. Engineering new effective synthetic consortia could be effective in the environmental bioremediation of soil pollutants and heavy metals [6]. Tomato fruit quality and soil nutrients were improved via foliar spraying fulvic acid under stress of heavy metals copper and cadmium [7]. It is expected to identify more soil compounds, plant/microbial metabolites and develop them into formulations for controlling soil pollution and improving the quality of agricultural products. On the other hand, further studies are warranted to delve into the rational combination and use of macro and trace elements. Nitrogen and zinc application at different growth stages of rice showed positive effects on yield, grain zinc, and nitrogen concentration in rice [8]. Copper, zinc, and boron fertilization was essential for improving micronutrient supply, crop nutrition, yield and quality [9].

The journal Agronomy is also rich in the articles of maize, wheat, humic acid and relevant fields. For example, humic substances and biochar modified digestates were effective in improving soil quality and increasing corn biomass accumulation [10]. Humic acids incorporated into urea at different proportions increased winter wheat yield and optimized fertilizer-nitrogen fate [11]. Durum wheat treated with seaweed- and humic acid-based biostimulants showed improved grain yield and quality traits [12].

In recent decade, knowledge gaps in the crop yield and soil nutrients with respect to manure, N accumulation and straw return are being filled via intensive investigations. In India, integrated nutrient management enhanced yield, improved soil quality, and conserved energy under the lowland rice–rice cropping system [13]. In Vietnam, bacterial strains of Luteovulum sphaeroides W22 and W47 produced δ-aminolevulinic acid and improved soil quality, growth and yield of saline-irrigated rice cultivated in salt-contaminated soil [14]. In Northeast China, long-term straw return generally increased soil organic matter (SOM) in the black soil region [15]. When combined with other conservation tillage approaches, e.g., no tillage or reduced tillage, the appropriate amount of straw mulch helped efficiently retain nitrogen, improve soil fertility and mitigate the emission of greenhouse gas especially nitrous oxide [16, 17]. Under various tillage regimes, the bacterial community, microbial community and arbuscular mycorrhiza fungi (AMF) are closely related with soil health, soil aggregates and long-term fertilization, etc. [18, 19]. The elite plant-growth-promoting microorganisms (PGPM) as inoculants, especially the genera Azospirillum, Pseudomonas, Bacillus, rhizobia, and AMF, are an important strategy to improve forage biomass, and increase the productivity and sustainability of livestock production [20]. AMF positively influenced plant nutrients, photosynthesis, and metabolites of cereal crops [21]. The significant changes of bacterial and fungal communities in the soil helped understand why organic fertilizer had a great effect on soil improvement [16-19, 22].

Recent studies also address nitrogen, plant nutrition and phosphorus, and related issues such as grain yield, Saccharum and N use efficiency, etc. There were interactive effects of biochar, nitrogen, and phosphorous on the symbiotic performance, growth, and nutrient uptake of soybean [23]. The pre-flowering and post-flowering indicators of N economy showed yield predictive value in high yielding winter wheat [24]. The foliar application of amino acids mitigated the deleterious effects of salt stress on soybean plants [25]. In order to achieve sustainable agriculture under the scenario of climate change, SOM, humic substances, and photosynthesis, as well as soil amendment, quality and mycorrhiza, etc., should be further studied as a whole and in depth. Humic substances of Chernozem of different land use could be conducive to environmentally sustainable agriculture [26]. Mould-based bioherbicides could be a safe alternative to chemical pesticides and promote sustainable farming [27]. The water mode (moisture regime) showed profound impacts on the N₂O emission from black soil, as well as the associated impacts on both soil fertility and global warming [18, 19]. The above research hotspots, keenly perceived and actively promoted by the section “Soil and Plant Nutrition”, will ignite a new wave in the next decade.

3. Prospects

 In view of the above, the section “Soil and Plant Nutrition” publishes outstanding works reflecting the broad categories of interest in these fields:

Ÿ   Soil quality for crop (both food crop and medicinal crop [16, 17]) health and human/planet comfort.

Ÿ   Soil pollution, source characterization and relevance to plant nutrition.

Ÿ   Fertilizers and fertilization techniques.

Ÿ   Soil/plant nutrition management, policy control, monitoring, and modelling.

Ÿ   Soil–plant nutrition interaction and sustainable agriculture.

As a multidisciplinary and interdisciplinary section, “Soil and Plant Nutrition” reflects the broad categories of interest in biochar and compost, soil fertility and mineral fertilization, main crops and humic acid, crop yield, soil nutrients and manure, microbial community, soil health and aggregates, nitrogen/carbon, phosphorus and grain yield, SOM, sustainable agriculture and climate change, pollutant/nutrient transformation and fate, soil quality, monitoring and modelling, and environmentally friendly fertilization techniques. The research findings represent the basic and essential information to allow administrators, policymakers, scientists, engineers, designers, managers, owners, and operators to provide a sustainable, safe, and healthy soil environment for human/ecosystem survival. As an editor, the first author would like to see healthy competition from researchers and practitioners representing diverse stakeholders to continuously enhance the attractiveness of “Soil and Plant Nutrition”. Soil, like Batman, represents a powerful and mysterious force. Through our unremitting efforts, we are uncovering its mysterious mask to make it better serve humanity and planet.

References

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