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Aims: The aim of this study was to establish a method to collect root exudates from olive plants. The method was validated by determining the effect of root exudates on the viability of Verticillium dahliae conidia and microsclerotia. Methods: Three collection media (deionized distilled water, 0.01 M CaSO4 solution, Hoagland nutrient solution) and four collection periods (2, 4, 6, 12 h) were assessed to identify the most appropriate combination for root exudate collection in olive plants ('Picual'). To validate the method, root exudates were collected from olive cultivars with different susceptibilities to V. dahliae ['Frantoio' (resistant); 'Arbequina' (moderately susceptible), and 'Picual' (highly susceptible)] and treated or not treated with two microorganisms (Bacillus amyloliquefaciens PAB-024; Aureobasidium pullulans AP08) or two phosphite salts (Naturfos®; Phoscuprico®). The effect of root exudates on the germination of V. dahliae conidia and microsclerotia was evaluated in vitro. The dissolved organic carbon in the root exudates was estimated. Results: A 0.01 M CaSO4 solution and 4 h were confirmed to be the preferred medium and timing combination to collect root exudates from olive. Root exudates from 'Arbequina' and 'Picual' significantly induced conidia and microsclerotia germination in comparison with the control without exudates. AP08 was the most effective treatment to enhance the effectiveness of root exudates in decreasing conidia and microsclerotia viability. Root exudates from 'Picual' or, 'Frantoio' treated with AP08 showed the highest levels of organic carbon. Conclusions: The collection method for root exudates developed herein was useful to assess the effect of root exudates from olive plants and the olive-V. dahliae interaction. [ABSTRACT FROM AUTHOR]

• A multi-site (6), multi-year (3) field experiment was conducted. • Vine-growing areas differing in grape quality also differed in some soil properties. • Must quality related to soil limestone and nutrient content in premium-grade areas. • High tartaric acid content in must in the premium-grade area of Moriles Altos. • Standard-grade area (Ruedos) related to higher soil sand contents and larger grapes. There is a growing interest among consumers in some world regions in high-quality products including wine. In this work, we examined the unique quality wines obtained in the Montilla − Moriles wine Protected Designation of Origin (PDO) (Córdoba, southern Spain). Specifically, we assessed the influence of soil properties on the production and quality of Pedro Ximénez grapes in the Montilla − Moriles PDO terroir in six vineyards typical of three different production areas, namely: Sierra de Montilla and Moriles Altos (two premium-grade areas), on soils known as "albariza", characterized by their parent material (mainly marls and limestones), with a high calcium carbonate content and low organic matter content; and one standard-grade area (Ruedos), with soils developed on varied materials including Miocene marls, which are steeply and highly eroded. Representative soil profiles were evaluated and a field experiment to conducted to obtain data on grape production and quality over a period of three years in the six vineyards. Wine quality in the premium-grade areas was strongly influenced by physical characteristics of the vineyards (altitude and age), and also by some soil properties (limestone, poorly crystalline Fe oxides, and available P, Zn and Cu), production-related characteristics (leaf surface area exposed to solar radiation) and oenological variables (tartaric acid content). By contrast, quality in the standard-grade area was more closely related to soil sand and available Mn, and also to scarcely available P and Zn; however, grape bunches were more abundant and grapes larger (100-berry weight) in this area, and the must produced was richer in malic acid. These results suggest that soil properties in each premium-grade area of the Montilla-Moriles PDO (viz., Sierra de Montilla and Moriles Altos) set them apart from each other and distinguish them from the standard-grade area (Ruedos). Such soil properties are associated to consumer-appreciated quality-related parameters. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this work were (i) to find a soil indicator to predict durum wheat yield response to Zn fertilization, (ii) to compare the effect of various Zn fertilization strategies on wheat yield and Zn biofortification in calcareous Vertisols of southern Spain, and (iii) to assess the effect of these Zn fertilization strategies on crop P uptake (durum and bread wheat). Methods: Different Zn fertilization strategies, soil application (0.3–10 kg ha−1) and foliar spraying (two rates, different growth stages), were tested in wheat crops under field conditions in the period 2012–2019. Results: A simple soil indicator failed to predict durum wheat response to Zn fertilization. Only one of the combinations tested increased wheat yield in the 11 field experiments carried out. Zinc foliar spraying (1.28 kg ha−1) was effective for wheat biofortification when applied at early booting (durum wheat) or flowering, and also when splitting this application between stem elongation and flowering stages (bread wheat). The foliar treatments produced the highest zinc use efficiencies (6–19%) and soil applications the lowest (0.2–1.3%). Moreover, foliar treatments increased grain Zn concentrations by 12–51% while soil application increased such concentrations by only 4–13%. None of the Zn fertilization strategies altered P uptake. Conclusion: No yield increase in wheat is expected from Zn fertilization for the application methods and rates used here and the soils studied (calcareous Vertisols under Mediterranean climate). However, foliar applications at and after early booting stage are promising for durum and bread wheat biofortification. [ABSTRACT FROM AUTHOR]

The main aim of this study was to elucidate the effect of individual and joint fertilization with P and Zn on maize plants grown on typical Mediterranean soils with a limited Zn availability. For this purpose, we examined the effects of P and Zn fertilization individually and in combination on growth, yield and grain protein content in maize grown in pots filled with three different Mediterranean soils (LCV, FER and INM). Phosphorus and Zn translocation to grain was impaired, and aboveground dry matter and yield at harvest reduced by 8–85% (LCV and FER), in plants treated with Zn or P alone relative to unfertilized (control) plants. In contrast, joint fertilization with P and Zn enhanced translocation of these nutrients to grain and significantly increased aboveground dry matter (30% in LCV, 50% in FER and 250% in INM) and grain Zn availability in comparison with control plants. Also, joint application of both nutrients significantly increased grain P (LCV) and Zn (LCV and FER) use efficiency relative P and Zn, respectively, alone. Yield was increased between 31% in LCV and 121% in FER relative to control plants, albeit not significantly. Fertilization with P or Zn significantly influenced the abundance of specific proteins affecting grain quality (viz., storage, lys-rich and cell wall proteins), which were more abundant in mature grains from plants fertilized with Zn alone and, to a lesser extent, P + Zn. Sustainable strategies in agriculture should consider P–Zn interactions in maize grown on soils with a limited availability of Zn, where Zn fertilization is crucial to ensure grain quality. [ABSTRACT FROM AUTHOR]

Although cherry-tomato is becoming more popular in the last years, there are no specific recommendations for P and K fertilization or liming strategies for this specific variety. Our aim was to assess rates of P and K and liming strategies in order to improve the yield of cherry-tomato grown on an Oxisol with a limited P-availability. Two pot experiments were developed. In the first-one, a two-factor factorial design was developed with 4 P (first-factor) and 4 K rates (second-factor), being these rates the 0%, 50%, 100%, and 200% of the recommended fertilization for tomato in South-Brazil. In the second experiment, the soil pH (4.3) was adjusted to 5.5, 6.0, and 6.5 with limestone. Soil P-availability, plant growth, diameter, number of fruits and cherry tomato yields were increased with the P addition, while a non-significant effect was observed after adding K. The highest yield was produced with 50% of the suggested amount of P for tomato in comparison with the non-fertilized plants (yield increase of 674%), while higher P rates (100% and 200%) produced a lower yield increase. The significant effect of soil liming was observed on increase of the flower bunches number when the soil pH was amended to 6.5. Cherry-tomato requirements seem to be different from the recommended for other varieties. Our results indicate that higher yields were achieved with a lower amount of chemical inputs than the recommended for tomato in general, stressing the importance of P for tomato cherry production over the other factors assessed here. [ABSTRACT FROM AUTHOR]

Due to climate change, the frequency and duration of flood events are predicted to increase in many regions of the world. This is expected to cause large changes in soil functioning and to a progressive decline in soil quality such as reduced rates of nutrient cycling, enhanced greenhouse gas emissions and loss of soil biodiversity. There is a knowledge gap, however, on how temperate agricultural soils under different management practices (e.g. manure application) respond to prolonged river or coastal flooding. The main objective of this work was to determine the effects of a simulated prolonged flooding with saline and freshwater on soil N cycling, following application of a low C:N organic amendment (broiler litter) at two temperatures, representative of a winter and a spring flood event. Using laboratory mesocosms we simulated prolonged winter (6 °C) and spring (14 °C) flooding of soil amended with broiler litter. We also compared the effects of inundation with either river (freshwater) or coastal (saline) water. An agricultural grassland soil (Eutric Cambisol) was subjected to different combinations of treatments (flood with fresh or saline water, winter vs spring temperatures, with/without poultry manure). The impact of these treatments on soil solution N dynamics, greenhouse gas emissions (CO 2 , CH 4 , N 2 O) and microbial community structure (by PLFA analysis) were evaluated over an 11 week simulated flood event followed by an 8 week soil recovery period (without flood). Overall, potential losses of NH 4 + and cumulative GHG emissions were increased by flooding and the presence of manure. CH 4 emissions were found to dominate under freshwater flooding conditions and N 2 O under saline flooding. Significant releases of GHG occurred during both flooding and after floodwater removal. Temperature was less influential on regulating GHG under the different treatments. These releases in GHG were associated with disruption in N cycling and changes in soil microbial composition and these changes persisted after floodwater removal. Extreme flooding negatively impacts soil functioning, however, the magnitude of any changes remain critically dependent on flood duration and source of flood water, and management conditions. Further work is required at the field scale to understand the molecular basis of the responses observed in this study. [ABSTRACT FROM AUTHOR]

Although entomopathogenic fungi (EPF) are best known for their ability to protect crops against insect pests, they may have other beneficial effects on their host plants. These effects, which include promoting plant growth and conferring resistance against abiotic stresses, have been examined in recent years to acquire a better understanding of them. The primary purposes of the present study were (i) to ascertain in vitro whether three different strains of EPF (viz., Metarhizium, Beauveria and Isaria) would increase the Fe bioavailability in calcareous or non-calcareous media containing various Fe sources (ferrihydrite, hematite and goethite) and (ii) to assess the influence of the EPF inoculation method (seed dressing, soil treatment or leaf spraying) on the extent of the endophytic colonization of sorghum and the improvement in the Fe nutrition of pot-grown sorghum plants on an artificial calcareous substrate. All the EPFs studied were found to increase the Fe availability during the in vitro assay. The most efficient EPF was M. brunneum EAMa 01/58–Su, which lowered the pH of the calcareous medium, suggesting that it used a different strategy (organic acid release) than the other two fungi that raised the pH of the non-calcareous medium. The three methods used to inoculate sorghum plants with B. bassiana and M. brunneum in the pot experiment led to differences in re-isolation from plant tissues and in the plant height. These three inoculation methods increased the leaf chlorophyll content of young leaves when the Fe deficiency symptoms were most apparent in the control plants (without fungal inoculation) as well as the Fe content of the above-ground biomass in the plants at the end of the experiment. The total root lengths and fine roots were also increased in response to fungal applications with the three inoculation methods. However, the soil treatment was the most efficient method; thus, its effect on the leaf chlorophyll content was the most persistent, and the effects on the total root length and fine roots were the most apparent. In conclusion, EPF improved the Fe nutrition of the sorghum plants, but their effects depended on the inoculation method. [ABSTRACT FROM AUTHOR]

BACKGROUND Zinc deficiency, a major problem in crops grown on soils low in available Zn, is even more important in phosphorus-rich soils. This work aimed to elucidate the effects of soil P and Zn levels, and of fertilizer application, on yield and Zn concentration in cereal grains. RESULTS Wheat and barley were successively pot-grown on 20 calcareous Vertisols low in available Zn and ranging widely in available P. Grain yield in the plants grown on the native soils was positively correlated with Olsen P but not with diethylenetriaminepentaacetic acid ( DTPA)-extractable Zn except for wheat on P-rich soils. Grain Zn concentration was negatively correlated with Olsen P. Grain Zn uptake differed little among soils. Application of P to the soils increased grain yield insignificantly and P concentration significantly; however, it reduced grain Zn concentration (particularly at low Olsen P values). Applying Zn alone only increased grain Zn concentration, whereas applying P and Zn in combination increased yield and grain Zn concentration at low and high Olsen P values, respectively. CONCLUSION Applying P alone to plants grown on calcareous Vertisols low in available P and Zn may in practice reduce grain Zn concentrations while not increasing grain yield significantly. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Iron (Fe) deficiency chlorosis, a major nutritional problem in plants growing on calcareous soils, is related to the content and reactivity of soil iron oxides and carbonates. The effects of other soil components, however, need elucidation. In this paper we tested the hypothesis that application of high doses of phosphorus (P) to the soil can aggravate Fe chlorosis. RESULTS Lupin and sorghum were grown on 24 calcareous soils. Leaf chlorophyll concentration ( LCC) in lupin decreased with increasing available P/available Fe ratio in the native soil but LCC in sorghum was unaffected by that ratio. Application of P to the soil resulted in significant reduction of LCC and dry weight in lupin. In sorghum, LCC and dry weight were positively affected by P fertilisation for soils poor in available P whereas the opposite effect was generally observed for the P-rich soils. In another experiment where olive plants were pot-grown on two soils during the 2009-2011 period, P fertilisation affected LCC negatively only in 2009 and 2011 and in the soil that was poorer in iron oxides. CONCLUSION Application of fertiliser P to Fe chlorosis-inducing soils is likely to aggravate this deficiency. However, this effect depends on the plant and the Fe and P statuses of the soil. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

To increase ruminant production efficiency, the environmental impact of growing forage must be reduced, through lowering system inputs and increasing crop resilience to extreme weather. Here we examined the role of red clover (cv. AberClaret) in minimising nitrogen (N) requirements, alongside two novel grass varieties, (1) a festulolium (cv. AberNiche), developed for drought tolerance, with potential for deep-rooting, and (2) a ryegrass hybrid (cv. AberEcho), developed for high-sugar content, which may enhance ruminant N-uptake in-vivo. Field trials were conducted at two UK sites, growing festulolium and ryegrass ± red clover (at 29% of the seed mix weight) at a range of N fertilisation rates (0 – 600 kg N ha−1) for 2 years (six harvests). We assessed sward performance (N offtake, herbage quality, and grass N use efficiency), rooting depth and N transfer from clover to grasses using 15N natural abundance. Across both sites and years, dry matter yield and herbage-N content were overall greater from the swards that included clover. Dry matter yields from festulolium were not greater than from ryegrass under the drought conditions experienced in 2018, despite its greater root mass. Agronomic efficiency of fertiliser N was similar between grasses (19 – 22%), however the festulolium more effectively used endogenous soil N than the ryegrass. Inclusion of clover in the sward affected forage quality, with increased crude protein and metabolisable energy content and reduced sugar and fibre (NDF) content. Among the grass types, metabolisable energy was greater and NDF content less for ryegrass than for festulolium. A strong reliance on biological N fixation (80 – 94%) for clover was observed, however, N transfer from clover to the neighbouring grass was not evident from the ẟ15N signatures. We conclude that red clover is a viable fertiliser-N replacement strategy in short-term leys, and that grass varieties with improved herbage quality may provide a better option for optimising sward performance than drought tolerant grass varieties. • Festulolium gave no yield advantage over a ryegrass hybrid under drought conditions. • Ryegrass hybrid provided higher quality feed without compromising yield. • Herbage yields were greater when red clover was included within the sward. • Inclusion of red clover with grass increased sward N and metabolisable energy content. • Including red clover in grass swards replaced the need for N fertilization. [ABSTRACT FROM AUTHOR]

Background and aims: The possible influence of phosphorus (P) on iron (Fe) deficiency chlorosis in susceptible plants needs elucidation. In this work, we tested the hypothesis that Fe chlorosis can be aggravated at high levels of P in the substrate. Methods: Chickpea, lupin and peanut (in a preliminary experiment), and lupin and sorghum (in a second, factorial experiment) were successively grown on artificial substrates consisting of mixtures of Fe oxide-coated sand (FOCS), calcium carbonate (calcite) sand (CCS) and quartz sand to which phosphate was added at different doses. Results: The proportion of FOCS in the substrate had a significant positive effect on leaf chlorophyll concentration (as estimated via SPAD) in all crops. In the factorial experiment, the SPAD value was negatively affected by the proportion of CCS in the dicot (lupin) but not in the monocot (sorghum). In the preliminary experiment, increasing the P dose generally had little effect on the SPAD of plants grown on the FOCS-rich substrate but a negative effect on those grown on the FOCS-poor substrate. In the factorial experiment, the P dose negatively affected SPAD in both lupin and sorghum. Conclusions: Iron acquisition by the plant is negatively influenced by P probably because the solubility of the Fe oxides decreases with increasing coverage of their surfaces by sorbed phosphate. [ABSTRACT FROM AUTHOR]

The production of industrial waste has increased in the last decades along with world population. Wastes are used in agriculture as fertilizers and soil amendments depending on their composition, dynamics in soil and effects on plant growth. The aim of this study was to assess the effect of industrial saline wastewater from heparin production on soil chemistry and plant yield in a subtropical soil in Brazil. Five rates of industrial saline wastewater (0, 10, 20, 40 and 60 m3 ha−1 year−1) were applied as fertilizer in a corn -soybean rotation on an Oxisol with limited nutrient availability. Five soils sampling were done: before and after the first application of the industrial wastewater (2017, corn), before and after the second application of wastewater (2018, soybean) and two years after the first application (2019). Soil K, Ca, Mg, Na content and CEC increased immediately after the application of wastewater but they returned to former values with time due to plant uptake and lixiviation. Wastewater application significantly increased corn (all rates) and soybean (only with the highest rate) yields around 103–250% and 50%, respectively, in comparison with no wastewater application. However, the highest rate temporally increased soil Na content and electrical conductivity (up to 650 and 800%, respectively). Although nutrient uptake, chlorophyll content and corn and soybean yields were enhanced, the use of high rates of industrial saline wastewater could cause soil salinization (mainly in locations with low rainfall), affecting soil chemistry and physical parameters due to clay dispersion, and pollution or water bodies. • Industrial saline wastewater, from pharmaceutical industry, can be an alternative as fertilizer for crops. • Industrial saline wastewater increase chemical elements content in soil, notably the Na content. • Na content from industrial saline wastewater rapidly decrease in soil under subtropical climate. • Industrial saline wastewater application increased corn and soybean yields significantly. [ABSTRACT FROM AUTHOR]

The use of nitrogen (N) fertilizers is essential to produce enough food for the growing worldpopulation. Their uncontrolled use in agroecosystems has environmental implications, suchas the release of gaseous pollutants (as N2O and NH3) and eutrophication of waterbodies (due to NO3− and other dissolved N forms). The main objective of thisstudy was to assess different strategies to minimize N pollution associated withagroecosystems. Field experiments located in North Wales and Southwest England focused on (i) assessingN offtake, N loss pathways, and the environmental and societal externalities associated withthe use of different inorganic N fertilizers [urea (U), ammonium nitrate (AN) and U + ureaseinhibitors (UI) in grasslands]; (ii) the study of two different grass varieties (AberEcho-high insugar content and AberNiche-drought resistant) subjected to different N rates (0-600 kg Nha−1) and with/without red clover (at two N rates only: 0 and 50 kg N ha−1), tostudy which combination was more appropriate from the point of view of primaryproductivity and environmental protection; and (iii) the use of nitrification inhibitor (NI)and pH reduction to mitigate gaseous N losses (N2O and NH3) when an organic(food-based digestate from a biogas plant) N source was applied to a winter-wheatcrop. NH3 emissions were reduced by 48-65% in grassland under the U + UI treatment relativeto U alone, and by 95% under the acidified digestate relative to non-acidified digestate forwinter-wheat. N2O emissions were not significantly reduced through the use of NI in anyway. The use of UI, acidification of organic N fertilizer and clover in combination with thelowest N rates minimised N losses. [ABSTRACT FROM AUTHOR]

• Extreme winter flooding negatively altered soil physical, chemical and biological indicators. • Soil available P was reduced by 42% in the flooded areas after the flood event. • Plant biomass in arable fields was reduced by 19–34% in flooded areas. • Total soil microbial biomass increased by 60% after flooding. • Grassland soils were more resilient than other crops. Evidence suggests that climate change is increasing the frequency of extreme weather events (e.g. excessive rainfall, heat, wind). The winter of 2013-14 saw exceptional levels of rainfall across the UK leading to extreme and prolonged flooding (up to 3 months with floodwater depths up to 3 m) in several low-lying agricultural areas (e.g. Somerset Levels, Thames Valley). The impact of extreme flooding and the speed of ecosystem recovery at the field-scale, however, remain poorly understood. The main objectives of this study were therefore to: (1) assess the effect of this extreme winter flooding event on a range of soil physical, chemical and biological quality indicators at 15 flood-affected sites (arable and grassland), (2) determine if these changes in soil health were reversible in the short term (< 1 year), and (3) to evaluate the effectiveness of different mechanical interventions (sward-lifting, subsoiling, slot-seeding and aerating) to accelerate the amelioration of the damage caused by winter flooding at 2 of the 15 sites. Once the floodwater had receded (April 2014), we found that several of the measured soil quality indicators were negatively affected in the flooded areas in comparison with non-flooded areas. This included a decrease in soil bulk density (by 19%), soil pH (by 0.4 units), and available P (by up to 42%). Flooding increased soil microbial biomass (60%), induced a shift in soil microbial community structure and reduced earthworm numbers. After 8 months of recovery, only soil pH remained significantly reduced (by 0.3 units) in the flooded areas in comparison to the unflooded areas. Flooding had a negative impact on the overlying vegetation at the arable sites (biomass production was reduced by between 19 and 34%) but had no major impact at the grassland sites in the long-term. In the flood amelioration experiment, the subsoiled plots produced grass with a higher nutrient content (e.g. N - up to 35%, Ca - up to 19% and Mg - up to 58%). However, the four different interventions appeared to have little positive impact on most of the soil quality indicators measured. In conclusion, extreme winter flooding was found to induce short-term alterations in key soil quality indicators and to destroy winter crops, although these effects did not persist in the longer term. Our results therefore indicate that the temperate agroecosystems evaluated here were highly resilient to winter flood stress and that recovery to a pre-flood state could be achieved within 1 year. Improved management strategies are still needed to speed up the rate of recovery after flood events to facilitate a faster return to agricultural production. [ABSTRACT FROM AUTHOR]

Abstract The frequency and intensity of extreme weather events (e.g. flood, drought) are predicted to increase for the foreseeable future and it is expected that these will negatively impact upon agroecosystem functioning. Our understanding of how grassland ecosystems respond to extreme weather events occurring at different times of the year, however, is lacking. To better understand the seasonal response of grassland to flooding, we subjected an agricultural grassland to an 8-week extreme flood event at three different temperatures (5 °C-winter, 15 °C-spring/autumn and 25°C-summer) and then followed its subsequent recovery for 9 weeks after floodwater removal. We focused on key indicators of ecosystem functioning including primary production, nutrient cycling, greenhouse gas (GHG) emissions, ammonia (NH 3) volatilization, and soil microbial communities. The experiment used intact soil mesocosms (1 kg) with indigenous vegetation collected from a grassland with no previous history of flooding. Flooding reduced biomass production by 18% at 5 °C, 50% at 15 °C and 95% at 25 °C. Flooding also significantly disrupted elemental cycling (nitrogen, phosphorus and carbon) as evidenced by an increased release of P, Fe and NH 4 + into the soil and overlying floodwater and large amounts of CH 4 and NH 3 released to the atmosphere (mainly during the flooding). These effects were more pronounced at higher temperatures (e.g. 45–700 kg CH 4 C ha−1 and 1–5 kg NH 3 N ha−1 at 15 and 25 °C, respectively). In addition, after floodwater removal this NH 4 + was rapidly nitrified leading to large losses of N 2 O (1.0–14.2 kg N 2 O N ha−1 at 5–25 °C, respectively). Especially at higher temperatures, flooding resulted in a reduction in soil microbial biomass (more than 58% of the equivalent unflooded treatment at 25 °C) and changes in microbial community structure (assessed by PLFAs). Further, some of these changes persisted after flood removal including a loss of actinomycetes, arbuscular mycorrhizal fungi and fungi. Overall, we conclude that ecosystem responses to extreme weather events are critically dependent on temperature with those occurring at higher temperatures having a greater negative impact than those at the lowest temperature (5 °C). The large potential release of CH 4 and N 2 O also suggests that flood events should be considered as a potential source of GHGs when comparing top-down and bottom-up calculations of national inventories, and that further work is needed to better refine GHG emission estimates for these events. Highlights • Flooding induced a rapid release of nutrients, especially at higher temperatures. • 700 kg CH 4 C ha−1 and 5 kg NH 3 N ha−1 were released in the flood phase at 25 °C. • During soil recovery, nitrification led to 1.0–14.2 kg N 2 O N ha−1 losses at 5–25 °C. • Flooding reduced soil microbial biomass, actinomycetes and arbuscular mycorrhiza. • Flooding reduced biomass production by 18% at 5 °C, 50% at 15 °C and 95% at 25 °C. [ABSTRACT FROM AUTHOR]

Abstract Soils around the world are being exposed to weather events which are unprecedented in recent history. To maintain the delivery of soil-related ecosystem services and to promote greater soil resilience it is essential to understand how plant-soil systems respond to these extreme events. In this study we replicated a recent period of extreme rainfall and prolonged spring flooding in a temperate grassland which had no previous history of flooding. Intact soil mesocosms (Eutric Cambisol) 1 kg weight were subjected to a simulated long-term spring flood (15 °C, 2 months) and maintained in the light with above ground indigenous vegetation (Lolium perenne L.) or dark with and without indigenous vegetation to simulate different flood typologies. In comparison to a no-flood control treatment, nutrient cycling, water quality, air quality (greenhouse gas emissions), habitat provision and biological population regulation shifts were evaluated. Flooding induced a rapid release of nutrients into the soil solution and overlying floodwater, resulting in potential nutrient losses up to 15 mg Fe, 16 mg NH 4 +, 360 mg DOC and 28 mg DON, per mesocosm. The presence of plants increased the rate of nutrient release (especially P), with the effects magnified when light transmission through the floodwater was restricted (1.3 mg P vs 0.2 mg P, per mesocosm). Flooding induced a rapid decline in redox potential and subsequent production of CH 4 , especially in the darkened treatments (10 and between 11 and 16 times higher than the control, without and with light restrictions, respectively). Upon removal of the floodwater, the accumulated NH 4 + was nitrified leading to a shift in greenhouse gas emissions, from CH 4 to N 2 O emissions. N 2 O was only significantly produced in the mesocosms kept under light restrictions (13 times higher than in other two treatments). Flooding eliminated earthworms, reduced grass production after soil recovery (from 28 g for control mesocosms to 11 g and <1 g for flooded mesocosms without and with light restrictions, respectively). Soil microbial biomass was also reduced (up to a 22–27% of the total PLFAs) and flooding induced shifts in microbial community structure, particularly a loss of soil fungi. The soil fungi content quickly recovered (4 weeks) when light was not restricted during the flood period, however, no such recovery was seen in the darkened treatments. Overall, we conclude that extreme flood events cause rapid and profound changes in soil function. Both the impact of the flooding and the time to recover is exacerbated when light is restricted (e.g. in sediment laden floodwater). In addition, our results suggest that the presence of flood-resilient plants can mitigate against some of the negative impacts of flooding on soil functioning. Highlights • Flooding eliminated earthworms and altered soil microbial community structure. • Flooding reduced the size of the microbial biomass and fungal content. • Vegetation played a vital role in preserving soil quality during flooding. • Decomposition of vegetation induced P loss in light restricted floodwater. • Impact of flooding was greater under light restricted floodwater conditions. [ABSTRACT FROM AUTHOR]

• FO12 did not exert any evident pathogenic effects on eight herbaceous hosts. • FO12 promoted plant growth in cotton, cucumber, pepper, sunflower, and wheat. • FO12 colonized the root and stem tissues of all herbaceous hosts as an endophyte. • Confocal laser scanning microscopy imaging showed that FO12 root colorization progressed. The nonpathogenic strain Fusarium oxysporum FO12 has been characterized as an effective biological control agent against Verticillium dahliae in olive. Nevertheless, the endophytic role of FO12 in herbaceous hosts is still uncertain. Thus, the aim of this study was to demonstrate the nonpathogenic character of FO12 in eight V. dahliae -susceptible herbaceous hosts and to evaluate its ability to promote plant growth. To this end, plants of each host were grown in pots filled with sterile peat moss and inoculated by irrigation with a conidial suspension of FO12 (106 conidia ml−1) two times—at sowing and at the emergence of the first true leaves. Many plants irrigated with sterile distilled water were included as controls. Sampling was conducted at 7, 14, 21, and 28 days after the second inoculation. The fresh weight and length of the aerial parts, roots, and whole plants were determined at each sampling time. Fungal colonization was assessed via quantitative and qualitative methods, including microbiological isolation from roots and stems and confocal laser scanning microscopy (CLSM) imaging at each sampling time. FO12 exhibited the ability to endophytically colonize the roots and stems of the inoculated plants. However, the effect on growth and the degree of colonization varied depending on the host. FO12 did not exert any evident pathogenic effects or negative effects on plant growth or development. The growth of the eggplant, lettuce, and tomato plants in the FO12 treatment group was similar to that in the control group, whereas the relative area under the growth progress curve was significantly greater than that in the control group for plant length in cotton and cucumber; for root fresh weight in pepper, sunflower, and wheat; and for plant fresh weight in sunflower and wheat. These results highlight the need to continue researching the interaction between FO12 and V. dahliae in a wider range of plant species of agronomic interest. [Display omitted] [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi (EFs) are widely used as biological control agents. However, some strains of Beauveria bassiana and Metarhizium brunneum can also promote plant growth and increase nutrient uptake. We examined the effects of soil properties on the performance of Triticum durum inoculated by seed dressing with these EFs and grown on 12 agricultural soils. The plants were supplied with all nutrients except P and Zn (essential for yield and the grain quality of wheat). Fungal inoculation increased the grain yield and harvest index significantly with B. bassiana (17% and 14%, respectively) but not with M. brunneum (6% and 6%, respectively). The increase in grain yield was positively and moderately correlated with the soil available phosphorus (POlsen) in plants inoculated with B. bassiana and with the soil content in poorly crystalline Fe oxides with M. brunneum. In addition, the increase in aerial dry matter resulting from inoculation with B. bassiana was negatively correlated with soil available Zn. Furthermore, the observed increase in grain yields due to fungal inoculation resulted in P and Zn grain dilution (grain nutrient concentrations decrease). Inoculation with B. bassiana increased grain Zn uptake and the proportion of Zn in grain relative to that in aerial dry matter. Success in the mutualistic relationship between EF and wheat plants depends on the fungal strain and soil properties. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi (EF) have so far aroused little interest as plant growth promoters or nutritional enhancers while protecting the plant against insect pests and mites. In this work, we examined the performance of Triticum durum and Triticum aestivum plants pot‐grown on two unsterilized Zn‐poor calcareous Vertisols and inoculated with Beauveria bassiana or Metarhizium brunneum by application to soil or seed dressing. The effects of fungal inoculation were found to depend on crop species, soil type, sampling time and fungus application method. While the height of the control plants tended to be significantly greater than the height of inoculated plants at early and intermediate growth stages, the trend changed at more advanced plant stage of development, 56 days after sowing (DAS). This was supported by the significant increase in aerial dry matter (ADM) in T. aestivum plants treated with B. bassiana by seed dressing (17.4%) or with M. brunneum with soil application and seed dressing (20.6 and 26.9%, respectively) 69 DAS. In T. durum, at harvest, seed dressing with B. bassiana or M. brunneum had an overall positive but not significant effect on ADM or grain yield, whereas direct application to the soil slightly decreased grain yield (6.6 and 5.5%, respectively) and ADM (5.3 and 6.1%, respectively). In T. aestivum, none of the fungus–application method combinations affected yield at harvest significantly. Fungal inoculation had little influence on nutrient uptake, whereas application to soil increased Mn uptake and grain Mn concentration in T. durum. Zinc uptake was significantly increased only in T. aestivum grown on the soil with the lowest Zn content treated with M. brunneum. Grain Zn concentration tended to be inversely related to grain yield. These results support seed dressing with EF as a promising green technology for sustainable crop protection and production with no adverse effects on plant performance. [ABSTRACT FROM AUTHOR]

Fertiliser nitrogen (N) is essential for maintaining agronomic outputs for our growing population. However, the societal, economic and environmental impacts of excess reactive N from fertiliser is rarely assessed. Here the agronomic, economic and environmental efficacy of three N-fertiliser sources, ammonium-nitrate (AN), urea (U), and inhibited-urea (IU; with NPBT) were evaluated at two grassland sites. Dry matter yield and herbage quality were measured at each silage-cut. Additionally, NH3-N and N2O-N losses were measured and used to calculate the effective N source cost and externality costs, which account for associated environmental and societal impacts. We found no effect of different N sources on yield or herbage quality. However, NH3-N emissions were significantly reduced under the IU treatment, by 48-65%. No significant differences in cumulative N2O emissions were observed. Incorporating externality costs increased fertiliser prices by 1.23-2.36, 6.51-16.4, and 3.17-4.17 times the original cost, for AN, U and IU, respectively, transforming U from the cheapest, to the most expensive of the N sources examined. However, with no apparent yield differences between N-fertiliser sources there is no economic incentive for the land-manager to use the more environmentally and socially acceptable option, unless externality costs are incorporated into fertiliser prices at the point of sale. [ABSTRACT FROM AUTHOR]