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Grasslands are declining worldwide and are often impacted by industrial activities, including infrastructure development. Current best management practices for low-disturbance development on grasslands include the use of wooden access mats as temporary work platforms and roadways to mitigate soil compaction and rutting due to heavy traffic. We assessed the impacts of heavy traffic (TON), and the impacts of the same heavy equipment driven over top of access mats (AM), on soil physical, hydrological, and nutrient responses in sandy and loamy soils in the Dry Mixedgrass prairies over a 2-year period. We also assessed how the timing (early vs. late in the growing season) and duration (6 vs. 12 vs. 24 weeks) of AM and TON affected the same metrics. Compared to undisturbed soils, TON increased soil penetration resistance (15 cm depth) up to 93% in loamy and up to 101% in sandy soils, and decreased water infiltration rates from 53 to 71%, respectively. Notably, the negative impacts of TON on soil physical characteristics and hydrology were larger in sandy vs. loamy soils, and when moist soils were exposed to traffic early in the growing season. AMs were effective at mitigating soil compaction from industrial traffic when used on sandy soils. However, AM use increased the supply of total nitrogen and other plant macro- and micro-nutrients, particularly in soils subject to longer (12-24 wk) mat placement. Results indicate TON may have long-lasting effects on grassland (particularly sandy) soils, and that AM use represents an effective tool to mitigate traffic impacts. Further, early-season traffic should be avoided when soils are moist (whether with AM or not), and AMs should be placed on soils for limited durations (≤6 wk) to minimize potential nutrient losses., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nitrogen (N) and phosphorus (P) have key roles in leaf metabolism, resulting in a strong coupling of chemical composition traits to metabolic rates in field-based studies. However, in such studies, it is difficult to disentangle the effects of nutrient supply per se on trait-trait relationships. Our study assessed how high and low N (5 mM and 0.4 mM, respectively) and P (1 mM and 2 μM, respectively) supply in 37 species from six plant functional types (PTFs) affected photosynthesis (A) and respiration (R) (in darkness and light) in a controlled environment. Low P supply increased scaling exponents (slopes) of area-based log-log A-N or R-N relationships when N supply was not limiting, whereas there was no P effect under low N supply. By contrast, scaling exponents of A-P and R-P relationships were altered by P and N supply. Neither R : A nor light inhibition of leaf R was affected by nutrient supply. Light inhibition was 26% across nutrient treatments; herbaceous species exhibited a lower degree of light inhibition than woody species. Because N and P supply modulates leaf trait-trait relationships, the next generation of terrestrial biosphere models may need to consider how limitations in N and P availability affect trait-trait relationships when predicting carbon exchange., (© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.)

Marine dinitrogen (N2) fixation fuels primary production and thereby influences the Earth's climate. Yet, its geographical distribution and controlling environmental parameters remain debatable. We measured N2 fixation rates from the two spatially and physicochemically contrasting regions of the Arabian Sea during the winter monsoon: (a) the colder and nutrient‐rich waters in the northern region owing to winter convection and (b) the warmer and nutrient‐poor waters in the southern region unaffected by winter convection. We found higher N2 fixation rates at the surface of northern region due to convective mixing driven supply of phosphate (intuitively iron also) from the underlying suboxic waters. N2 fixation was favored by high nutrient concentrations in the euphotic waters, whereas remained unaffected by nutrient availability in the aphotic waters. We conclude that diazotrophs dwelling in the euphotic zone chose phosphate over fixed nitrogen‐poor waters. However, we found that among oligotrophic waters, anticyclonic eddy extremes the barrier of fixed nitrogen supply, and thereby, elevates N2 fixation. While the Arabian Sea loses about 20%–40% of the global ocean fixed nitrogen, we estimate that N2 fixation in the Arabian Sea offsets only up to 42% of its fixed nitrogen‐loss by denitrification, but this offset could be higher if diazotrophic activity is further examined up to the deeper depths of the Arabian Sea. Plain Language Summary: Phytoplankton facilitate the removal of greenhouse carbon dioxide gas from the atmosphere. However, phytoplankton's carbon dioxide assimilation ability is largely controlled by the reactive forms of nitrogen (N, such as ammonium, nitrate and nitrite). In contrast, the N‐limited environments often create a suitable niche for diazotrophs—organisms genetically proficient to convert dinitrogen (N2) gas to a reactive form of N. Previous research has hypothesized close spatial coupling between N2 fixation and N‐loss processes because the latter result in an N‐deficit, that is, a conducive condition for diazotrophs. Here, we measured N2 fixation rates in and above the N‐loss dominated waters of the Arabian Sea. The highest N2 fixation occurred near the coast of the Arabian Sea. We found relatively high N2 fixation rates above the waters with the highest N‐loss owing to convective mixing driven supply of nutrients such as phosphate and probably iron. N2 fixation rates below the sunlit layer were consistent but low. Our study showed that physical processes substantially influence N2 fixation by affecting nutrients supply. Key Points: Winter convection elevates N2 fixation through the enhanced supply of nutrients from the suboxic waters to the surface waters of the Arabian SeaDiazotrophy offsets up to 42% of the Arabian Sea's denitrification deficitWinter convective mixing strengthens the long‐held hypothesis of coupling between N‐gain and ‐loss processes [ABSTRACT FROM AUTHOR]

As a key metabolite with high medical values in industrial hemp, cannabidiol (CBD) has been paid increasing attention. However, how nutrient supply affects the CBD content and yield of hemp remains unclear. Therefore, an aeroponic experiment with nine treatments (A1~A9) was conducted to evaluate the effects of different concentrations of nitrogen (N, at 4.0, 6.0, and 8.0 mmol L−1), phosphorus (P, at 1.0, 1.5, and 2.0 mmol L−1), and potassium (K, at 3.0, 4.0, and 5.0 mmol L−1) on the growth, CBD content, and biomass of hemp. Results showed that at A7 (N8P1K5) (N, P, K: 8, 1, 5 mmol L−1) markedly enhanced the dry weight of shoot and inflorescence with an increment of 208.7% and 435.7% respectively; the equivalent number of total CBD content in inflorescence was increased by 41.8%, and the CBD yield was increased by 7.0 times compared with A3 (N4P2K5). Correlation analysis revealed that N was positively related to the CBD yield, while P or K had a negligible effect on CBD yield. In conclusion, nutrient supply would dramatically influence the growth and CBD yield of hemp. Under the experimental conditions, A7 (N8P1K5) is the most suitable choice to cultivate hemp and achieve a higher CBD yield. [ABSTRACT FROM AUTHOR]

Aims The leaves of almost all terrestrial plant species are colonized by endophytic fungi. Compared to agronomic grasses, which usually harbor few endophytes, native grasses generally possess greater endophyte species diversity. Existing studies examining endophyte effects on natural grasses under competition normally considered the infection status (infected or uninfected), and rarely considered endophyte species. Methods We examined the effects of endophyte infection and of endophyte species on the interspecific competitive ability of a subdominant species, Achnatherum sibiricum , at two nitrogen levels (high nitrogen and low nitrogen). Achnatherum sibiricum plants infected by two different species of endophyte (Epichloë sibirica and E. gansuensis) and uninfected plants were grown in monoculture and binary mixtures with a dominant species, Stipa grandis (six individuals per species for monocultures and three + three individuals of each species in mixtures). Shoot and root biomass, tiller number and total phenolic concentration were measured after 3 months. Moreover, the aggressivity index was calculated to compare the competitive ability of A. sibiricum relative to S. grandis. Important Findings Both E. gansuensis (Eg)- and E. sibirica (Es)-infected A. sibiricum plants showed a greater competitive ability than the uninfected plants under high nitrogen supply, while the opposite result occurred under low nitrogen supply. At high nitrogen levels, Eg plants had a higher tiller number and a greater shoot biomass inhibitory effect on S. grandis than Es plants had when growing in mixture, while Es plants showed better root growth performance than Eg and uninfected plants under mixture conditions at all nitrogen levels. A higher concentration of phenolic compounds in Eg plants than in Es plants might contribute to the higher inhibitory effect of Eg plants on competing plants. Our study indicates that the interaction between endophyte infection and nitrogen availability can alter the competitive ability of the host plant A. sibiricum but that these two endophyte species work in different ways, which may influence the coexistence of A. sibiricum with the dominant species. [ABSTRACT FROM AUTHOR]

The world's and the domestic maize growing technological development depends on the applied agricultural engineering largely. The most important thing the harmonic NPK nutrition solution to the crop increase and the reduction of the crop fluctuation. During our research we examined the different nutriment elements, and their proportions in monoculture long-term experiment of maize. The experiment was set up in Hungary at Szarvas in the experimental field of the University of Szent István, Faculty of Agricultural and Economics Studies, in Galambos. We reveal the plant physiology and technological contexts in our examinations, that the bases of the modern nutrient solutions, and the scientific bases of the efficient development of the maize growing system. We examined 64 nutrient combination in the experiment, 4 nitrogens portion (0 kg ha-1, 70 kg ha-1, 140 kgha-1 and 210 kgha-1), 4 phosphoruses portion (0 kg ha-1, 40 kgha-1, 80 kgha-1 and 120 kgha-1) and 4 potassiums portion (0 kg ha-1, 60 kg ha-1, 120 kg ha-1 and 180 kgha-1) in different combinations. On the parcels all possible combinations get to a setting, which makes the examinations of the interaction of the nutriment elements. The setting of the experiment onto the bases of the old fertiliser experiment of Faculty on a similar manner, on similar principles, modernized to the scientific and practical claims of our days. We established that the role of the phosphorus and the potassium are smaller in the experiment, they affect the physiological processes of the maize advantageously mostly. The effect has on the average yield is smaller because it is based on the interaction of the different nutriment elements. The analysis of variance of the yields supported this, we experienced that the effect of nitrogen has the most significant difference. In our experiment the largest effect from among the examined three nutriment elements the nitrogen showed it, we experienced a smaller effect in case of the phosphorus and the potassium. From among the examined parameters significant differences only the nitrogen treatments could to justify, the effects the phosphorus and the potassium mostly trend character, the border of the significance was attained in a little proportion only. In the experiment the average yields were between 3,65 t ha-1 and 13,9 t ha-1. [ABSTRACT FROM AUTHOR]

Observations were carried out in the eastern part of Hungary. In this experiment we studied the nutrient supplyreaction of four apple cultivars (Golden Delicious, Granny Smith, Idared and Jonathan Csány) under different Nand NPK-doses. The following fruit quality parameters were detected: fruit diameter, fruit height, fruit weight, fl esh fi rmness, colour-cover and we studied the thicket of foliage of trees. The research results showed, that N-fertilization has a great effect on fruit quality. This appears in the cases of increase of fruit largeness. The increase is proportional to N-levels. Moderate N-doses plus PK-addition had also positive effects. The nutrient supply increased vegetative area in addition to the generative parts, in particular pure N fertilizer. But the thicked foliage hindered the growth of fruit weight and colour-cover, also decreased the fruit quality. And decreased the fl esh fi rmness of cultivars, that has a negative effect on storageability.

Carbon, nitrogen, and phosphorus (C, N, P) stoichiometry influences the growth of plants and nutrient cycling within ecosystems. Indeed, elemental ratios are used as an index for functional differences between plants and their responses to natural or anthropogenic variations in nutrient supply. We investigated the variation in growth and elemental content of the rootless terrestrial bromeliad Tillandsia landbeckii, which obtains its moisture, and likely its nutrients, from coastal fogs in the Atacama Desert. We assessed (1) how fog nutrient supply influences plant growth and stoichiometry and (2) the response of plant growth and stoichiometry to variations in nutrient supply by using reciprocal transplants. We hypothesized that T. landbeckii should exhibit physiological and biochemical plastic responses commensurate with nutrient supply from atmospheric deposition. In the case of the Atacama Desert, nutrient supply from fog is variable over space and time, which suggests a relatively high variation in the growth and elemental content of atmospheric bromeliads. We found that the nutrient content of T. landbeckii showed high spatio-temporal variability, driven partially by fog nutrient deposition but also by plant growth rates. Reciprocal transplant experiments showed that transplanted individuals converged to similar nutrient content, growth rates, and leaf production of resident plants at each site, reflecting local nutrient availability. Although plant nutrient content did not exactly match the relative supply of N and P, our results suggest that atmospheric nutrient supply is a dominant driver of plant growth and stoichiometry. In fact, our results indicate that N uptake by T. landbeckii plants depends more on N supplied by fog, whereas P uptake is mainly regulated by within-plant nutrient demand for growth. Overall, these findings indicate that variation in fog nutrient supply exerts a strong control over growth and nutrient dynamics of atmospheric plants, which are ubiquitous across fog-dominated ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Nitrogen is a necessary element for much of seaweed physiology, and is the most common limiting nutrient for marine macroalgae. Therefore, the content of nitrogen in algal tissue is often considered a useful indicator of algal productivity. However, the significance of algal nitrogen content in the field is understudied. We used a factorial manipulation of light and herbivory at three sites in order to evaluate how three factors (light, herbivory, wave exposure) affect the nitrogen content of the brown alga Fucus gardneri. We found that nitrogen content was a function of (1) nitrogen supply via amount of water flow and (2) irradiance, possibly via photoinhibitory effects. This research shows that local effects, by shifting nutrient allocation, can change nitrogen content over spatial scales of centimeters. [Copyright &y& Elsevier]

The formation of lysigenous cavities (aerenchyma) in the root cortex of maize, Zea mays L. cv. Capella, under well-aerated conditions has been studied in relation to the composition of the nutrient solutions. Nitrogen, either supplied as nitrate or as ammonium, reduced the cavity formation by the roots. This reduction was most apparent at nitrate concentrations above 2 mM. Cavities were increasingly formed when the nitrate concentration was decreased and they reached their largest dimensions in roots growing in water. Thus, inadequate availability of nitrogen leads, under aerated conditions, to deterioration of cortex cells and cavity formation in the maize roots. It is suggested that cavity formation in these roots is connected with reduced nitrogen assimilation. [ABSTRACT FROM AUTHOR]

We studied the effects of light quality and nutrient supply on growth and nitrogen accumulation in silver birch (Betula pendula Roth) seedlings to test three hypotheses: (1) growth of birch seedlings is sensitive to changes in light quality; (2) the response of birch seedling growth to light quality depends on nutrient supply; and (3) assimilation and allocation of nitrogen by birch seedlings are affected by light quality. The two light regimes simulated the spectral quality of sunlight and shadelight, but did not differ in photosynthetic photon flux density, and the two nutrient supply regimes differed in the rate of supply, but not in the composition, of mineral nutrients. [ABSTRACT FROM PUBLISHER]

CO2 enrichment is expected to alter leaf demand or nitrogen and phosphorus in plant species with C3 carbon dioxide fixation pathway, thus possibly causing nutrient imbalances in the tissues and disturbance of distribution and redistribution patterns within the plants. To test the influence of CO2 enrichment and elevated tropospheric ozone in combination with different nitrogen supply, spring wheat (Tritium aestivum L. cv. Minaret) was exposed tothree levels of CO2 (361, 523, and 639 mu l litre-1, 24 h mean from sowing to final harvest), two levels of ozone (28.4 and 51.3 mu l litre-1) and two levels of nitrogen supply (150 and 270 kg ha-1) in a full-factorial design in open-top field chambers. Additional fertilization experiments (120, 210, and 330 kg N ha-1) were carried out at low and high CO2 levels. Macronutrients (N, P, K, S , Ca, Mg) and three micronutrients (Mn, Fe, Zn) were analysed in samples obtained at three different developmental stages: beginning of shoot elongation, anthesis, and ripening. At each harvest, plant samples were separated into different organs (green and senescent leaves, stem sections, ears, grains). According to analyses of tissue concentrations at the beginningof shoot elongation, the plants were sufficiently equipped with nutrients, Elevated ozone levels neither affected tissue concentrations nor shoot uptake of the nutrients. CO2 and nitrogen treatments affected nutrient uptake, distribution and redistribution in a complex manner. CO2 enrichment increased nitrogen-use efficiency and caused a lower demand for nitrogen in green tissues which was reflected in a decrease of critical nitrogen concentrations, lower leaf nitrogen concentrations and lower nitrogen pools in the leaves. Since grain nitrogen uptake during grain filling depended completely on redistribution from vegetative pools in green tissues, grain nitroge [ABSTRACT FROM AUTHOR]