Search Results (203)

Accurately characterizing crop–soil nitrogen dynamics is essential for precision nitrogen management in maize production, yet soil mineral nitrogen (soil N_min) remains difficult to monitor under field conditions. This study evaluated whether UAV-derived maize canopy traits could be used to indirectly estimate soil N_min in black soils through a cascaded modeling framework. Multi-stage UAV multispectral observations, agronomic variables, and machine learning were integrated into a cascaded framework in which aboveground nitrogen uptake (ANU) was first predicted and then used as an intermediate variable for soil N_min and yield estimation. UAV-derived vegetation indices showed stronger relationships with ANU than with soil N_min across growth stages, indicating that canopy spectral signals more directly reflected plant-level nitrogen accumulation. XGBoost achieved the best performance for ANU and soil N_min prediction, with R² values of 0.94 and 0.82, RMSE values of 15.99 kg ha⁻¹ and 6.42 mg kg⁻¹, and rRMSE values of 13.4% and 17.6%, respectively. Predicted ANU was the most influential variable for soil N_min estimation, and the framework also captured the nitrogen response pattern of yield. These results indicate that UAV-based canopy sensing can support the indirect estimation of soil N_min through crop nitrogen status, as well as nitrogen response diagnosis and data-informed nitrogen management in maize production. Full article

Permafrost peatlands in high-altitude regions store substantial amounts of organic carbon, yet the biogeochemical consequences of thermokarst collapse remain poorly understood. Using a space-for-time substitution approach, we selected four habitats representing a thermokarst development sequence in the Altai Mountains peatlands—slightly collapsed peat mounds (P1), severely collapsed peat mounds (P2), thawed herbaceous peat (PB1), and thermokarst ponds (PB2)—and conducted in situ greenhouse gas flux monitoring, soil physicochemical analysis, enzyme activity assays, and structural equation modeling. We found that thermokarst development fundamentally altered the greenhouse gas source–sink balance through three interconnected mechanisms. First, CO₂ fluxes shifted from net emission in P1 (684.1 mg m⁻² h⁻¹) to net uptake in PB2 (−25.6 mg m⁻² h⁻¹), driven primarily by the oxidative loss of mineral-associated organic carbon in the 40–60 cm layer (71.3% loss), whereas lateral dissolved organic carbon export accounted for only 12.3% of total carbon loss. Second, CH₄ fluxes in PB2 (3.8 ± 0.7 mg m⁻² h⁻¹) reached approximately 43% of the theoretical maximum, with this suppression associated with phosphorus limitation (total phosphorus < 0.05 g kg⁻¹) and a marked reduction in alkaline phosphatase activity. Third, N₂O uptake increased along the thaw sequence to −28.6 μg m⁻² h⁻¹ in PB2, with the 40–80 cm layer contributing 42% more than the surface layer. This increase in N₂O uptake occurred when the soil C/N ratio exceeded 300, a threshold that reflects the substantial stoichiometric imbalance between carbon and nitrogen following thermokarst development. These findings demonstrate that the transition from peat mounds to thermokarst ponds alters the net greenhouse gas source–sink balance through changes in MAOC stability, phosphorus availability, and carbon-to-nitrogen stoichiometry. Our results provide empirical constraints for evaluating carbon-climate feedbacks in cold-region peatlands. Full article

Panicum turgidum is an important keystone forage grass crucial for ecosystem stability in arid and semi-arid rangelands of Asia and Africa. This study aimed to investigate the use of beneficial bioinoculants for enhancing the growth and acclimatization of micropropagated desert grass under controlled environmental conditions. Tissue-cultured plants were transferred to pots with a sand–soil mixture (1:1, v/v) and kept in a temperature and light-controlled environment (25 ± 2 °C, 100 µmol m⁻²·s⁻¹, and 16/8 light/dark photoperiod) for 10 weeks. We used a factorial approach to investigate the effects of the arbuscular mycorrhizal fungus (AMF) Rhizophagus fasciculatus, Trichoderma harzianum, and Bacillus subtilis on transplanted desert grass plants. Two AMF levels control (AMF, 5%; w/w) or without AMF (NAMF); and three microbial inoculation treatments (T. harzianum, B. subtilis, and a combination of T. harzianum + B. subtilis) were employed. Microscopic investigation indicated the extent of AMF colonization in the roots of micropropagated P. turgidum plantlets during acclimatization. Growth parameters with shoots and roots, chlorophyll and carotenoid content, and nitrogen uptake were all improved in bioinoculants-treated plants. Under non-AMF conditions, co-inoculation with T. harzianum and B. subtilis resulted in the highest biomass and root traits, whereas under AMF conditions, T. harzianum alone or with AMF was generally most effective. In the plants treated with the combination of inoculants, heatmap correlation, principal component analysis, and hierarchical clustering demonstrated positive association between growth and physiological traits and the absorption of mineral nutrients, although these associations varied among treatment combinations. These findings highlight the potential of beneficial bioinoculants to improve the growth and acclimatization of micropropagated desert grass plants, providing a foundation for tailored bioinoculant compositions towards the rehabilitation of degraded grazing lands. Full article

Root nitrogen acquisition is a central belowground process that determines how efficiently plants capture nitrogen from the rhizosphere and influences fertilizer demand and environmental nitrogen losses. Root N transporters, including nitrate, ammonium, amino acid, and peptide transporters, provide the molecular basis for inorganic and organic N uptake. However, root N acquisition is not determined solely by plant transport systems but is also shaped by rhizosphere microbial communities that regulate N mobilization, transformation, and availability. In addition to bacteria and archaea, saprotrophic fungi and mycorrhizal associations contribute to organic matter decomposition, N mineralization, and symbiotic N transfer. Mechanistically, transporter activity may alter rhizosphere N gradients and substrate availability, while root exudates and microbial metabolites can influence microbial recruitment, root physiology, and transporter expression. Evidence from rice NRT1.1B and OsLHT1 suggests that specific N transporter genes can influence rhizosphere microbiome assembly, although direct genetic evidence remains limited to a small number of transporter systems and crop contexts. This review synthesizes current knowledge on root N transporter diversity, rhizosphere microbial N cycling, organic N availability, and transporter–microbiome feedbacks in root-level N acquisition. By integrating plant physiology, soil microbiology, and rhizosphere ecology, this review proposes a conceptual framework in which root N transporters and microbial communities act as interconnected components of belowground N acquisition. Future integration of transporter-informed breeding, microbiome management, and fertilization strategies may improve root N capture while reducing reliance on synthetic N inputs. Full article

Sustainable crop production in nutrient-poor sandy soils requires fertilization strategies that improve nutrient uptake while reducing environmental impact. This study evaluated anaerobic cattle manure digestate and carbon dot biostimulants as alternatives to conventional mineral NPK (nitrogen–phosphorus–potassium) fertilizer for corn (Zea mays L., cv. AG 1051) during vegetative development. A randomized greenhouse experiment compared nine treatments over three successive 45-day cycles, assessing shoot-tissue macronutrient content (N, P, K) and morphological parameters (shoot dry weight, stem diameter, and plant height). Digestate delivered approximately 1.4× more phosphorus and 8.4× more potassium per pot than mineral NPK, although nitrogen inputs were matched (~77 mg pot⁻¹). Digestate-based treatments achieved shoot dry weight 132% above control and 63% above mineral fertilizer (p < 0.001), with biomass advantages sustained across all three cycles while mineral fertilizer effects dissipated entirely by Cycle 3. Phosphorus content was the strongest biomass predictor (r = 0.86, p < 0.001), and a significant nitrogen–phosphorus antagonism (r = −0.59, p < 0.001) revealed relevant nutrient interaction dynamics. The higher biomass observed under digestate-based treatments reflects both the higher total P and K inputs from digestate and the beneficial effects of organic matter on nutrient bioavailability in this phosphorus-limited system. Carbon dot biostimulants did not improve biomass when applied alone (values at or below control), but they contributed to intermediate biomass gains when combined with nutrient sources, functioning as nutrient uptake enhancers rather than standalone fertilizers. Principal component analysis (74.3% variance explained) classified the nine treatments into three distinct treatment clusters. These findings support digestate valorization as a circular-economy alternative to conventional mineral fertilization, offering higher biomass under N-equivalent application and sustained residual effects in nutrient-poor sandy soils. Full article

Efficient nitrogen (N) management in perennial fruit orchards is constrained by species-specific differences in N demand and fruit N removal, which can result in distinct soil N uptake patterns even under similar fertilization regimes. This study assessed whether apple (Malus domestica Borkh.) and sweet cherry (Prunus avium L.) orchards differ in soil mineral nitrogen (Nmin) composition by analyzing nitrate (NO₃⁻) and ammonium (NH₄⁺) stocks in topsoil (0–20 cm). Soil samples were collected in spring from a long-term orchard experiment over two consecutive years and from a commercial orchard on two sampling dates in Germany. In apple orchards, Nmin was dominated by NO₃⁻ (83%), whereas cherry orchards showed a more balanced composition (42% NO₃⁻ and 58% NH₄⁺). These patterns were consistent across years, sites, fertilization types (mineral or organic), and key soil properties, including total organic carbon and total nitrogen, but were not explained by these factors. The elevated NH₄⁺ proportion in cherry soils suggests a species-associated pattern in soil N dynamics. Overall, the results highlight species-associated differences in soil Nmin composition between apple and sweet cherry orchards. Accounting for tree species differences may therefore improve N management and enhance N use efficiency in apple and sweet cherry production. Full article

In the context of sustainable agriculture and the need to reduce mineral nitrogen inputs, intercropping cereals with legumes is increasingly considered a promising strategy to enhance nutrient use efficiency and improve feed quality. However, the effects of such systems, combined with varying nitrogen fertilization levels, on the dynamics of micronutrients in soil and plant biomass remain insufficiently explored. Field research was conducted in central Poland, in Ciechanów, from 2021 to 2023, during the months of April through July each year. The aim of the study was to analyze the impact of intercropping spring barley and spring triticale with narrowleaf lupin and varying mineral nitrogen fertilization (0–60 kg N ha⁻¹) on the concentration and uptake of Mn, Cu, Zn, and Fe in the soil and green matter intended for fodder. It was shown that both the sowing pattern and the level of N fertilization significantly differentiated the concentration of microelements in the soil and their concentration and uptake with the yield. As the proportion of lupine in the mixture increased, the post-harvest soil showed higher concentrations of Mn (2–8%), Cu (2–9%), Zn (9–33%), and Fe (4–10%), accompanied by a marked increase in their levels in green matter, ranging from 6% to 94% depending on the micronutrient. The highest uptake of micronutrients was obtained in intercropping systems with a predominance of legumes, especially with moderate fertilization (40–60 kg N ha⁻¹), where the growth ranged from 16% to as much as 139%. Compared to single-species crops, the intercropping system was characterized by higher efficiency of soil resource use and better mineral quality of the feed. The results indicate that the integration of legumes with cereals can be an effective tool for improving feed security while reducing the intensity of mineral fertilization, in line with the principles of sustainable agriculture. Full article

Meadow arnica is a valuable medicinal plant, used in both the pharmaceutical and cosmetic industries. The aim of the study was to determine the influence of arbuscular mycorrhizal fungi (AMF) on the development, yield, and quality of flower heads (raw material) of meadow arnica grown in an organic farming system. The inoculation of plants with AMF improved the mass of above- and underground organs, including the mass of raw material, as well as the content of chlorophylls and general sugar in the leaves, followed by enhanced starch storage in the roots. The content of phenolics in the raw material was determined using high-performance liquid chromatography (HPLC). The following flavonoids were assessed here: cynaroside, rutin, hyperoside, cosmosiin, astragalin, and diosmetin, as well as the phenolic acids: neochlorogenic, chlorogenic, caffeic, ferulic, rosmarinic, cichoric, 3,4-di-O-caffeoylquinic, and 1,5-dicaffeoylquinic acids. The contents of these substances were higher in non-inoculated plants than in inoculated ones, which contradicts most studies conducted to date on medicinal and aromatic plants. Nevertheless, the results are interesting primarily because of the beneficial developmental changes in inoculated plants, as evidenced by a significantly higher mass of arnica flower heads, more efficient uptake of mineral nutrients from the soil, and lower nitrogen levels in aboveground organs. Full article

Root-zone nitrogen fertilization (RZF) can increase crop N uptake and yield, yet the underlying rhizosphere N-cycling functional mechanisms remain insufficiently resolved. In a field experiment with winter oilseed rape (Brassica napus L.), RZF was compared with conventional fertilization (CF) under the same N input rates, alongside a zero-N control (N0). Compared with CF, RZF significantly increased seed yield (by 0.44 t ha⁻¹) and aboveground N uptake (by 20.45 kg ha⁻¹), while simultaneously enriching rhizosphere mineral N pools (NH₄⁺–N and NO₃⁻–N by 54.50% and 56.02%, respectively). Shotgun metagenomics revealed that RZF reprogrammed rhizosphere N-cycling functional potential, characterized by enhanced nitrogen fixation, reduced nitrification and denitrification, and a tendency toward increased assimilatory nitrate reduction. These module-level shifts were supported by concordant changes in key functional genes, indicating greater genetic potential for N retention and assimilation (nifD, glnA, gltB, nasA, napB, nrfA) and reduced potential for nitrification- and denitrification-driven N losses (amoB/C, narI, nirK, norB). Taxonomic composition analysis showed enrichment of Bradyrhizobium and suppression of key nitrifier taxa (Nitrosospira and a Nitrososphaeraceae-affiliated taxon) under RZF. Rhizosphere pH exhibited the strongest Mantel correlation with multiple N-cycling modules, and rhizosphere available N (AN; sum of NH₄⁺–N and NO₃⁻–N) was positively associated with plant N traits and yield. Structural equation modeling supported a pathway in which a functional balance index (retention/assimilation vs. loss/oxidation) increased AN (0.22), and AN strongly promoted yield (0.90). Collectively, these results elucidate a rhizosphere-centered mechanism whereby localized N placement strengthens soil–plant N coupling and enhances crop productivity through reprogramming microbial N-cycling functional potentials, positioning rhizosphere N processes as a key mechanistic bridge for microbiome-informed optimization of root-zone fertilization. Full article

Legume crops, such as the common bean (Phaseolus vulgaris L.), are significant in many Sub-Saharan African (SSA) countries, including Eswatini, due to their numerous health benefits, including high protein, fiber, vitamins, and mineral content. Common beans are a staple food in many parts of the world and play a crucial role in nitrogen fixation, thereby improving soil fertility. A field experiment was conducted at Malkerns research station, Eswatini, using 27 common bean genotypes to assess their ability for N-fixation and water relations using the ¹⁵N and ¹³C natural abundance techniques. The data revealed significant differences among the common bean genotypes. Genotypes Cim-Rm-36 and Mwctz20a-Rm19 recorded an increase in plant growth by (6% and 5.74%), N content (5.69% and 5.97%) and greater C content (6.1% and 5.67%) while genotype Mwctz20a-Rm19 also showed an increase in N-fixation (155.73 kg.ha⁻¹). Genotype Mwctz20a-Rm-4 had the highest grain yield (1747.39 kg.ha⁻¹), while genotype Cim-Rm-14-Als61 had the highest N concentration (3.50%), indicating efficient N uptake. The genotypes with the lowest δ¹³C values (−27.38‰ to −28.06‰) suggested similar water use efficiency among the genotypes. The findings of this study revealed that common beans can make a significant contribution to N fertility under drought conditions. Genotypes Cim-Rm-36, Mwctz20a-Rm19, and Mwctz20a-Rm-4 showed desirable characteristics and can be good candidates for possible inclusion in breeding programs. These results have implications for improving common bean production in drought-prone areas and promoting sustainable agriculture practices. Full article

The increased demand for food worldwide has led to the widespread use of synthetic chemical fertilizers. Since the Green Revolution, the use of such chemical fertilizers has been in high demand as a nutrient input in agriculture. The increased application of fertilizer to upsurge crop yields is not suitable for the long term and leads to nutrient loss, as well as severe environmental and ecological consequences. In contrast to conventional fertilizers, nano fertilizers, which are designed at the 1–100 nm size, provide focused nutrient delivery, decreased leaching, and improved plant absorption. They accomplish this by greatly increasing crop yields, enhancing fertilizer usage efficiency, and facilitating sustainable farming in the face of obstacles, including resource scarcity, climate change, and a projected population size of 10 billion by 2050. In comparison to typical NPK fertilizers at equal nutrient rates, nano fertilizers enhanced crop yields by an average of 20–23% across cereals, legumes, and horticulture crops according to studies conducted between 2015 and 2024. In particular, using nano urea with rice increased grain yields by 28.6% with 44% less nitrogen input, and applying nano zinc to wheat increased yields by 31.2% and improved the grain’s Zn content by 41%. Through targeted foliar or soil application, nano fertilizers frequently increase nutrient use efficiency (NUE) by more than 50% as opposed to 30–50% for conventional fertilizers. Nano fertilizer is prepared based on the encapsulation of plant essential minerals and nutrients with a suitable polymer matrix as a carrier and then delivered as nano-sized particles or emulsions to the plants. Natural plant openings like stomata and lenticels in plant parts facilitate the uptake and diffusion, leading to higher NUE. This review provides an overview of current knowledge on the development of advanced nano-based and smart agriculture using nano fertilizer to improve nutritional management. Furthermore, nanoscale fertilizers and their formulation, nano-based approaches to increase crop production, the different types of fertilizers that are currently available, and the mechanism of action of the nano fertilizers are discussed. Thus, it is expected that a properly designed nano fertilizer could synchronize the release of nutrients in crop plants as and when needed. Full article

Robust quantification of greenhouse gas (GHG) balances in tea plantations is critical for evaluating their contribution to agricultural carbon neutrality. This study aimed to develop data-driven models to quantify soil organic carbon (SOC) sequestration and N₂O emissions in Chinese tea plantations, evaluate their net GHG balance at the national scale, and assess the mitigation potential under alternative nitrogen management scenarios. Using a comprehensive national dataset, we compared multiple machine learning (ML) approaches with a conventional multiple linear regression (MLR) model to simulate N₂O emissions and SOC changes in Chinese tea plantations. All ML models substantially outperformed the MLR model, with the Random Forest (RF) algorithm achieving the highest predictive accuracy. The RF models yielded R² values of 0.68 for N₂O emissions and 0.67 for SOC changes, with no significant prediction bias. Variable importance and marginal effect analyses revealed strong non-linear controls. Mineral N fertilizer input was the dominant driver of N₂O emissions, followed by organic N input, soil clay content, and SOC. In contrast, SOC dynamics were primarily regulated by organic carbon inputs, tea plantation age, climate variables, and soil pH. National-scale simulations indicated an average N₂O emission intensity of 9.03 kg N₂O ha⁻¹ yr⁻¹ and a mean SOC sequestration rate of 0.88 t C ha⁻¹ yr⁻¹. Overall, SOC sequestration offset N₂O emissions, rendering Chinese tea plantations a net GHG sink (−2525 Gg CO₂-eq yr⁻¹). Scenario analyses showed that mineral N reduction increased net GHG uptake by 1804 Gg CO₂-eq, while organic fertilizer substitution achieved a substantially larger mitigation potential of 5961 Gg CO₂-eq. By integrating SOC sequestration and N₂O emissions within a unified modeling framework and applying machine-learning-based national-scale simulations, this study provides a more comprehensive and data-driven quantification of GHG balances in tea ecosystems, offering a scientific basis for evaluating their role in agricultural carbon neutrality strategies. Full article

Management of legume cover crops to reduce their cost by using no-tillage and reducing seed rate could increase their adoption. Despite the growing interest in cover crops, no information exists simultaneously regarding the potential of different species and how the sowing method and seed rate affect nitrogen (N) contribution and the yield of the subsequent maize crop. During a four-year field trial, under irrigated conditions in the Ebro valley (NE Spain), three leguminous cover crop species (pea, common vetch and hairy vetch), two cover crop seeding methods (conventional tillage and no-tillage) and two seeding rates (normal and 25% reduced) were tested and compared with a control treatment without a cover crop. The aboveground cover crop biomass and the N derived from biological fixation (BNF); aboveground biomass and total N in weeds; soil mineral nitrogen; and the effect on maize grain yield and N content were evaluated. Pea and common vetch produced more biomass (+76%) and had a higher N uptake (+50 to 60%) compared to hairy vetch. The sowing of the cover crops after no-tillage combined with a reduced sowing rate reduced biomass production by 14%. The percentage of nitrogen derived from the atmosphere (Ndfa) was above 60% for all species and the differences in total N derived from biological fixation (BNF) among treatments were related to the aboveground biomass. The introduction of cover crops reduced weed growth compared to the control especially in the no-tillage treatment. Cover crops increased maize grain yield by 12% and N uptake by 17% compared to the control treatment without a cover crop. Full article

Artemisia maritima holds potential applications in the rehabilitation of degraded environments, particularly in salt-affected areas, for biosaline agriculture aimed at biomass production for further valorization and green biotechnology. The aim of the present study was to investigate the response of A. maritima to alterations in soil chemical composition, including differences in mineral supply, the addition of various sodium salts, and contamination with several heavy metals (cadmium, lead, copper, manganese, zinc), in order to establish a scientific basis for further applied research. Under standard fertilization conditions, the growth of A. maritima plants was restrained by nitrogen deficiency. Surplus nitrogen enhanced mineral uptake and growth, especially for shoots, and stimulated clonal development. Low to moderate (50 and 100 mmol L⁻¹) NaNO₃ treatment significantly stimulated shoot growth, while Na₂HPO₄ and NaHCO₃ treatments exhibited the most adverse effects at 200 and 400 mmol L⁻¹, resulting in reduced growth and biomass, and even the deterioration of the aboveground parts. Chlorophyll fluorescence parameters served as reliable early indicators of the detrimental effects of salinity associated with individual anions. Shoot macronutrient levels remained unchanged for phosphorus and calcium, while nitrogen increased in nitrate treatments. Root mineral nutrient content was more susceptible to salinity, with significant changes observed for all macro- and micronutrients, varying depending on the specific element and anion type. The alterations in mineral nutrition observed for each anion treatment exhibited distinct characteristics. A. maritima plants demonstrated high tolerance to all heavy metals, with roots being more susceptible compared to shoots. At the shoot level, statistically significant growth inhibition was evident only for 1000 mg L⁻¹ lead and 1000 mg L⁻¹ zinc treatments. A. maritima plants can be characterized as high accumulators of cadmium, lead, manganese, and zinc, and as extreme accumulators of copper in shoots. Nitrophily, clonal expansion with a help of bud-bearing roots, and the ability to accumulate relatively high concentrations of mineral elements in shoots are among the important physiological characteristics of A. maritima plants, enabling them to exhibit high resilience in environmentally heterogeneous habitats. Full article

More efficient use of nutrients by crops and their reduced dispersion in the environment are essential elements of sustainable agriculture. The purpose of the present experiment was to determine the effects of mineral (N_min) and spent mushroom substrate (SMS) nitrogen on Festulolium braunii yield, but also on the uptake of that chemical element, use efficiency, and its accumulation in the soil. Results indicated that organic waste applied together with mineral fertilizers increased plant utilization of nutrients, their soil content and, consequently, the yield. SMS was applied once at the beginning of the experiment at three levels: SMS₁—10; SMS₂—15; SMS₃—20 Mg·ha⁻¹, supplying plants with 75, 112, and 150 kg N·ha⁻¹. Supplementary mineral nitrogen was applied at three levels as well: N₁—30; N₂—68; N₃—105. Additionally, 180 kg N·ha⁻¹ was applied without SMS (N₄). Treatment significantly affected grass yield, daily growth, and productivity of 1 kg of nitrogen. Their values were the highest on the N₂ + SMS₂ plot (68 + 112 kg N·ha⁻¹). Nitrogen content was the highest in grass treated with mineral nitrogen without SMS (N₄). When the share of SMS nitrogen was higher, its content in the biomass was lower. The absorption of nitrogen (Nup) and its use efficiency (NUE) by plants on the plots with SMS and mineral fertilizers (105 + 75 kg N·ha⁻¹, as well as 68 + 112 kg N·ha⁻¹) were similar to the values recorded on the plot with mineral nitrogen only (N4). After two years, there was no increase in total nitrogen soil accumulation as a result of applied treatment. Mushroom substrate nitrogen allowed for a reduction of nitrogen fertilizer doses by 40 to even 60%. Such fertilizer treatment fits into the closed economy model based on minimizing the consumption of raw materials and on increasing environmentally friendly waste disposal. Full article