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Saline-alkali soils have poor N storage capacity, high N loss and inadequate nutrient supply potential, which are the main limiting factors for crop yields. Vermicompost can increase organic nutrient content, improve soil structure, and enhance microbial activity and function, and the Ca2+ in flue gas desulfurization (FGD) gypsum can replace Na+ and neutralize alkalinity in saline-alkali soils though chemical improvement. This study aimed to determine if vermicompost and FGD gypsum addition could improve the N storage capacity through decreasing NH 3 volatilization and 15N/NO 3 − leaching from saline-alkali soils. The results indicate that the combined application of vermicompost and FGD gypsum led to the displacement and leaching Na+ in the upper soil layer (0–10 cm), as well as the neutralization of HCO 3 − by the reaction with Ca2+. This treatment also improved soil organic matter content and macroaggregate structure. Also, these amendments significantly increased the abundance of nifH and amoA genes, while concurrently decreasing the abundance of nirK gene. The structural improvements and the lowering of Na + concentration in and alkalinity decreased cumulative NH 3 volatilization, and leaching of 15N and NO 3 − to the deep soil layer (20–30 cm). FGD gypsum increased the 15N stocks and inorganic N stocks of saline-alkali soil, whereas vermicompost not only increased the 15N and inorganic N stocks, but also increased the total N stocks, the combination of vermicompost and FGD gypsum can not only increase the available N storage capacity, but also enhance the potential for N supply. Therefore, vermicompost and FGD gypsum decrease N loss and increase N storage capacity through structural improvement, and lowering of Na+ concentration and alkalinity, which is crucial for improving the productivity of saline-alkali soil. • Decreasing Na + could reduce NH 3 volatilization, NO 3 − leaching and 15N loss rate. • Decreasing alkali and increasing amoA genes could reduce NH 3 volatilization. • Vermicompost and FGD gypsum improved available N storage capacity. • Vermicompost increased the total N stock to enhance potential for N supply. [ABSTRACT FROM AUTHOR]

We know that fruit production, especially in the Mediterranean, will need to adapt to climate change to ensure the sustainability of fruit tree-based agroecosystems. However, there is a lack of evidence on the long-term effects of this change on sustainability indicators. To fill this gap, we used a fruit tree model, QualiTree, to analyze the impacts ofclimate change on the ecosystem services provided by apple orchards in south-eastern France. To do this, a blooming model was parameterized to simulate blooming date on the basis of climate data, and QualiTree was supplemented with a model of nitrogen processes in the tree and a soil module describing resource input (irrigation, mineral and organic fertilization), transfer in the soil (water and nitrogen) and metabolic transformation-immobilization (mineralization, (de)nitrification). This type of extension makes it possible to simulate a wide array of ecosystem services, including C sequestration, nitrate leaching and nitrous oxide emissions. The model was compared with data from an apple orchard in southeastern France. The predicted daily mean and variability over time of fruit growth, composition and soil water content were consistent with observed data. QualiTree was then used to assess the potential impacts of climate change on the ecosystem services supplied by apple orchards. For this purpose, weather variables from 2020 to 2100 were generated for three contrasted greenhouse gas emission scenarios, and simulations were performed under two irrigation schemes (no restriction and restricted use of water). Model outputs indicated that, on average, marketable apple yields would increase until 2050 and then subsequently decrease. The fruit refractometric index, an indicator of fruit quality, was projected to sharply decrease with the intensity of climate change. Ecosystem services such as C sequestration by the orchard will decrease with climate change severity, mainly due to a higher mineralization of soil humus, whereas N 2 O emissions will increase with larger denitrification rates. Soil water availability, fertility, drainage and leaching were predicted to depend more on the irrigation strategy than on climate change severity. The new functions performed in QualiTree broadened its predictive capabilities and allowed for a better understanding of ecosystem service delivery in fruit orchards under varying climate conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Abstract Catch crop (CC) mixtures of non-legumes (nL) and legumes (L) have been promoted as a strategy to achieve two different goals: to decrease the risk of nitrate leaching and to enhance the nitrogen supply to the subsequent crop. To investigate if two-component mixtures of nL + L have advantages over pure nL stands experiments were carried out over a two year period (2013–2015) at two contrasting field sites in Denmark. Nitrogen (N) uptake by the CCs was measured by aboveground biomass sampling, and N leaching by ceramic suction cups. When grown in pure stands, white clover (Trifolium repens) on coarse sand and common vetch (Vicia sativa) on sandy loam were less effective at reducing N leaching than perennial ryegrass (Lolium perenne) and fodder radish (Raphanus sativus). When the proportion of the nL + L in mixtures was similar or favored the nL, leaching was not significantly different from the nL in the pure stand. However, during one of the years on the sandy loam L (vetch) almost outperformed nL (fodder radish), resulting in N leaching from nL + L similar to L. The yield of the following spring barley was only significantly different from the yield in the plots with previously bare soil in one of the years on the coarse sandy soil. It is concluded that in nL + L mixtures L can take over and thereby lower the effect of the CCs on N leaching while not necessarily enhancing the N supply for the subsequent crop. Highlights • In monocultures legumes were less effective at reducing N leaching than non-legumes. • Non-legume/legume mixtures were as effective as non-legume catch crops in reducing N leaching. • When non-legume/legume mixtures are not balanced N leaching was similar to that from legumes. • Use a catch crop only increased the subsequent spring yield on the sandy loam in one of the years. • The catch crop had no effect on the yield of the subsequent crop on the clay soil. [ABSTRACT FROM AUTHOR]

Abstract: Nitrogen leaching from urine patches has been identified as a major source of nitrogen loss under intensive grazing dairy farming. Leaching is notoriously variable, influenced by management, soil type, year-to-year variation in climate and timing and rate of urine depositions. To identify early indicators for the risk of N leaching from urine patches for potential usage in a precision management system, we used the simulation model APSIM (Agricultural Production Systems SIMulator) to produce an extensive N leaching dataset for the Waikato region of New Zealand. In total, nearly forty thousand simulation runs with different combinations of soil type and urine deposition times, in 33 different years, were done. The risk forecasting indicators were chosen based on their practicality: being readily measured on farm (soil water content, temperature and pasture growth) or that could be centrally supplied to farms (such as actual and forecast weather data). The thresholds of the early indicators that are used to forecast a period for high risk of N leaching were determined via classification and regression tree analysis. The most informative factors were soil temperature, pasture dry matter production, and average soil water content in the top soil over the two weeks prior to the urine N application event. Rainfall and air temperature for the two weeks following urine deposition were also important to fine-tune the predictions. The identified early indicators were then tested for their potential to predict the risk of N leaching in two typical soils from the Waikato region in New Zealand. The accuracy of the predictions varied with the number of indicators, the soil type and the risk level, and the number of correct predictions ranged from about 45 to over 90%. Further expansion and fine-tuning of the indicators and the development of a practical N risk tool based on these indicators is needed. [Copyright &y& Elsevier]

The main objectives of this study were to evaluate the stability of three different composts and to study the N dynamics in soil incubated with the composts under laboratory conditions. The composts were produced from sheep manure processed by static pile composting (C1) and from cattle and sheep manure processed by dynamic pile composting (C2 and C3 respectively). Laboratory incubation assays were carried out at 28 °C to determine the amount of N mineralized and N leached under extreme rainfall conditions in the first 30 days after application of doses of each compost equivalent to 170 and 450 kg ha−1 of N. There were no differences in the values of these parameters in samples of the composts produced by the static (C1) and dynamic (C3) systems, and both composts behaved in the same way when applied to soil. The chemical characteristics of the three final composts, the respiration rates and the lack of stimulation of total microbial biomass indicated that the composts were stable. However, the final C/N ratio was slightly higher in C2 than in C1 and C3 (14 compared with 10 and 11) as was the respiration rate of the high dose of C2 indicating that C2 was more labile, and thus less stable than C1 and C3. Compost C2 generated the highest N mineralization rates after application of different doses (6.5 and 13.1%), as well as the highest N supplying potential (54.7 and 36.2%), and thus the highest rate of mineral N leaching (16.8 and 16.5 mg L−1 of NO3–N), probably as a result of the slight difference in lability. The N release after compost application was very low and thus the leaching potential was also low, indicating that high doses of mature compost (>170 kg ha−1 of N) could be applied to soil. [Copyright &y& Elsevier]