The pyrolytical fingerprint of nitrogen compounds reflects the content and quality of soil organic carbon

The increasing land degradation is a problem that affects many soils in countries with a Mediterranean climate. In this aspect the soil organic matter (SOM) plays an important role, due to its progressive biodegradation parallels to desertification and the concomitant emissions of CO2 to the atmosphere. These facts make basic research on the structure and composition of SOM important for soil conservation. Organic N-compounds in soil are of particular interest due to their chemical structure and speciation status in the SOM which can play an important role in soil N bioavailability and in the whole biogeochemical activity of the soil. For this reason, studying the possible relationships between the different N-compounds and soil properties, such as SOM content and its chemical characteristics, can provide new information on the stabilization and storage of organic C in soil. For this research, 30 soils from Spanish ecosystems with a wide range of SOM content were selected. The molecular composition of SOM in whole soil samples including N-compounds, was analyzed by analytical pyrolysis (Py-GC/MS). A parallel characterization of SOM quality was carried out using solid state 13C NMR and UV–vis spectroscopy. Based on their chemical structure, the N-compounds identified by Py-GC/MS were classified into seven main groups: indoles, pyridines, pyrazoles, benzonitriles, imidazoles, pyrroles and quinolines. Multivariate statistical analyses were used to explore the relationship between the distribution of the above compounds and the SOM content. A significant predictive model was obtained for the SOM using partial least squares (PLS) regression, which was used to predict SOM content using the pyrolytic N-compounds as descriptors. This would show that there is a relationship between the patterns of N-compounds and the biogeochemical mechanisms involved in the different C storage levels the soils. Also, multidimensional scaling (MDS) and principal components analysis (PCA) showed to what extent the individual N-compounds are informative of status and quality of the humic acid fraction of SOM. As a whole, the results obtained by Py-GC/MS suggest that indoles, alkylindoles, alkylbenzimidazoles and alkylpyridines could be indicators of SOM accumulation while unsubstituted benzonitrile and pyridine are related to SOM qualityThis work was supported by grants CGL2013-43845-P and BES2014-069238 from the Spanish Ministry of Economy and Competitiveness (MINECO

Past and future impacts of urbanisation on land surface temperature in Greater Cairo over a 45 year period

Rapid and unplanned urbanisation can lead to altered local climate by increasing land surface temperature (LST), particularly in summer months. This study investigates the Urban Heat Island (UHI) in Greater Cairo, Egypt, using remote sensing techniques to estimate LST of summer months over 45 years (1986, 2000, 2017, and predicted year 2030). The research objectives and steps were, 1- mapped land use/ land cover (LULC), 2- conducted spatiotemporal analysis of LST, with a comparison of change in LST across different land cover types, 3- predicted future LST for 2030, and 4- examined this temporal change for a hot-spot area (ring road) and a cool-spot area (the River Nile). The results showed that urban areas have increased over the last 30 years by 179.9 km2 (13 %), while agriculture areas decreased by 148 km2 (12 %) and water bodies decreased by 6 km2 (0.5 %). The mean LST over Greater Cairo increased over time, from 31.3 °C (1986) to 36.0 °C (2017) and is predicted to reach 37.9 °C in 2030. While a notable rise of mean LST in the Cairo ring road buffer zone (88 km2), where it was 31.1 °C (1986), and 37 °C (2017) due to the triple increase of urban areas on account of agriculture areas, and the LST it may reach 38.9 °C by 2030. The mean LST increased slightly more in urban hot-spot areas than in cooler cultivated areas. UHI may induce a modification in the local climate that can negatively affect agricultural land, and human thermal comfort and unfortunately lead to a less sustainable environment

Rapid urbanisation threatens fertile agricultural land and soil carbon in the Nile delta

Agriculture land in Egypt represents only 3.8% of the total area. The Nile delta provides two thirds of Egypt's agriculture land, but is threatened by urban sprawl. The paper aims to quantify urban expansion over a 45 year period using 6 time points from 1972 to 2017, and its impacts on agricultural potential, soil organic carbon stocks, and implications for water use. The study used multi-temporal satellite data and remote sensing techniques (Maximum Likelihood supervised classification, and NDVI), soil sampling and analysis, data on water irrigation, and agroecological system and ecosystem services model (MicroLEIS, InVEST) to assess the effects of land use change. Urban area increased by a factor of 5, from 452 km2 in 1972 to 2644 km2 in 2017. The greatest losses occurred to the fertile Vertic Torrifluvent soils on the older delta, which lost 1734 km2. Soil organic carbon (0–75 cm depth) lost as a result of soil sealing from urbanisation rose from 25,000 to 141,000 Mg C over the 45 years. As a result of increased pressure on delta land, agriculture expanded into the higher desert areas outside the delta, on marginal land sustained by intensive fertiliser use and irrigation, which in turn puts pressure on water use. Therefore, rapid urban expansion has resulted in a loss of soil carbon and a shift in agriculture from fertile soils to marginal soils, requiring more capital inputs, which is ultimately less sustainable. Modelling suggested that soil management improvement could make better use of fertile soils within the Delta currently affected by high salinity and poor drainage. Future planning should encourage urban expansion on the less fertile soils outside of the delta, while improving suitability of existing agricultural land and minimising land degradation within the delta

Multivariate Analysis for Assessing Irrigation Water Quality: A Case Study of the Bahr Mouise Canal, Eastern Nile Delta

Water scarcity and suitable irrigation water management in arid regions represent tangible challenges for sustainable agriculture. The current study aimed to apply multivariate analysis and to develop a simplified water quality assessment using principal component analysis (PCA) and the agglomerative hierarchical clustering (AHC) technique to assess the water quality of the Bahr Mouise canal in El-Sharkia Governorate, Egypt. The proposed methods depended on the monitored water chemical composition (e.g., pH, water electrical conductivity (ECiw), Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, and SO42−) during 2019. Based on the supervised classification of satellite images (Landsat 8 Operational Land Imager (OLI)), the distinguished land use/land cover types around the Bahr Mouise canal were agriculture, urban, and water bodies, while the dominating land use was agriculture. The water quality of the Bahr Mouise canal was classified into two classes based on the application of the irrigation water quality index (IWQI), while the water quality was classified into three classes using the PCA and AHC methods. Temporal variations in water quality were investigated, where the water qualities in winter, autumn, and spring (January, February, March, April, November, and December) were classified as class I (no restrictions) based on IWQI application, and the water salinity, sodicity, and/or alkalinity did not represent limiting factors for irrigation water quality. On the other hand, in the summer season (May, June, July, August, and October), the irrigation water was classified as class II (low restrictions); therefore, irrigation processes during summer may lead to an increase in the alkalinity hazard. The PCA classifications were compared with the IWQI results; the PCA classifications had similar assessment results during the year, except in September, while the water quality was assigned to class II using the PCA method and class I by applying the IWQI. Furthermore, the normalized difference vegetation index (NDVI) around the Bahr Mouise canal over eight months and climatic data assisted in explaining the fluctuations in water quality during 2019 as a result of changing the crop season and agriculture management. Assessments of water quality help to conserve soil, reduce degradation risk, and support decision makers in order to obtain sustainable agriculture, especially under water irrigation scarcity and the limited agricultural land in such an arid region

Past and future impacts of urbanisation on land surface temperature in Greater Cairo over a 45 year period

Rapid and unplanned urbanisation can lead to altered local climate by increasing land surface temperature (LST), particularly in summer months. This study investigates the Urban Heat Island (UHI) in Greater Cairo, Egypt, using remote sensing techniques to estimate LST of summer months over 45 years (1986, 2000, 2017, and predicted year 2030). The research objectives and steps were, 1- mapped land use/ land cover (LULC), 2- conducted spatiotemporal analysis of LST, with a comparison of change in LST across different land cover types, 3- predicted future LST for 2030, and 4- examined this temporal change for a hot-spot area (ring road) and a cool-spot area (the River Nile). The results showed that urban areas have increased over the last 30 years by 179.9 km2 (13 %), while agriculture areas decreased by 148 km2 (12 %) and water bodies decreased by 6 km2 (0.5 %). The mean LST over Greater Cairo increased over time, from 31.3 °C (1986) to 36.0 °C (2017) and is predicted to reach 37.9 °C in 2030. While a notable rise of mean LST in the Cairo ring road buffer zone (88 km2), where it was 31.1 °C (1986), and 37 °C (2017) due to the triple increase of urban areas on account of agriculture areas, and the LST it may reach 38.9 °C by 2030. The mean LST increased slightly more in urban hot-spot areas than in cooler cultivated areas. UHI may induce a modification in the local climate that can negatively affect agricultural land, and human thermal comfort and unfortunately lead to a less sustainable environment.Ministry of Higher Education of the Arab Republic of Egypt PD230National Research Centre (Egypt) 1205050Jiangsu Provincial Department of Science and Technology BE202230

On the Use of Multivariate Analysis and Land Evaluation for Potential Agricultural Development of the Northwestern Coast of Egypt

The development of the agricultural sector is considered the backbone of sustainable development in Egypt. While the developing countries of the world face many challenges regarding food security due to rapid population growth and limited agricultural resources, this study aimed to assess the soils of Sidi Barrani and Salloum using multivariate analysis to determine the land capability and crop suitability for potential alternative crop uses, based on using principal component analysis (PCA), agglomerative hierarchical cluster analysis (AHC) and the Almagra model of MicroLEIS. In total, 24 soil profiles were dug, to represent the geomorphic units of the study area, and the soil physicochemical parameters were analyzed in laboratory. The land capability assessment was classified into five significant classes (C1 to C5) based on AHC and PCA analyses. The class C1 represents the highest capable class while C5 is assigned to lowest class. The results indicated that about 7% of the total area was classified as highly capable land (C1), which is area characterized by high concentrations of macronutrients (N, P, K) and low soil salinity value. However, about 52% of the total area was assigned to moderately high class (C2), and 29% was allocated in moderate class (C3), whilst the remaining area (12%) was classified as the low (C4) and not capable (C5) classes, due to soil limitations such as shallow soil depth, high salinity, and increased erosion susceptibility. Moreover, the results of the Almagra soil suitability model for ten crops were described into four suitability classes, while about 37% of the study area was allocated in the highly suitable class (S2) for wheat, olive, alfalfa, sugar beet and fig. Furthermore, 13% of the area was categorized as highly suitable soil (S2) for citrus and peach. On the other hand, about 50% of the total area was assigned to the marginal class (S4) for most of the selected crops. Hence, the use of multivariate analysis, mapping land capability and modeling the soil suitability for diverse crops help the decision makers with regard to potential agricultural development

Modeling Agricultural Suitability Along Soil Transects Under Current Conditions and Improved Scenario of Soil Factors

Agricultural land suitability evaluation is a good way to distinguish soil suitability in order to improve the soils by addressing major limitations. This study investigated the influence of soil factors variability on the suitability of 12 Mediterranean crops in southern Spain. To represent the variability in elevation, lithology, and soil, two latitudinal and longitudinal soil transects (TA and TB) were considered and sampled in 63 representative points at regular 4. km intervals. This research also aimed to determine how to maximize soil potential by improving limiting factors as drainage, carbonate content, salinity, and sodium saturation. Soil suitability evaluation ranged between optimum and not suitable classes along TA and TB. The decrease in the severity of soil limiting factors in the improved scenario leads to an increase in soil suitability for the 12 crops along TA and TB transects, except in segments with shallow soils and very coarse texture. Soil evaluation and spatial analyses of soil suitability for the 12 crops under current situation and improved scenario, including optimum and not suitable soils, are helpful to achieve a sustainable land management in the studied area. The improvement of soil limitation it could be as adaptation strategies for the long term of environmental changes as climate changes, this work has a real impact, which means the results valuable and easy to grasp for the decision makers

Climate change impacts on agricultural suitability and yield reduction in a Mediterranean region

Climate change impacts are a serious threat to food provisioning, security and the economy. Thus, assessing agricultural suitability and yield reduction under climate change is crucial for sustainable agricultural production. In this study, we used two sub-models of the agro-ecological decision support system MicroLEIS (Terraza and Cervatana) to evaluate the impacts of climate change on land capability and yield reduction or wheat and sunflower as major rainfed crops in different Mediterranean soil types (in Andalucia, Southern Spain). The Terraza sub-model provides an experimental prediction for the bioclimate deficiency and yield reduction, while the Cervatana sub-model predicts the general land use suitability for specific agricultural uses. Sixty-two districts in Southern Spain were modeled and mapped using soil data and the A1B climate scenario (balanced scenario) for three 30-year periods ending in 2040, 2070 and 2100, respectively. Our results showed that the majority of agricultural soils were suitable for wheat production, and less for sunflowers, especially under projected climate change scenarios. Extreme impacts of climate change were observed in the soil types Typic Xerofluvents and Calcic Haploxerepts, where the land capability was reduced from Good and Moderate classes to the Marginal class. This was especially observed in sunflower crops by 2100. Yield reduction of sunflower was much higher than the reduction for wheat, especially under the projected climate periods, where the results for 2100 showed the severest effect on crop yields with about 95% of the sunflower area showing yield reductions. This high variability of the evaluation results demonstrates the importance of using soil factors, climate and crop information in conjunction in decision-making regarding the formulation of site-specific soil use and management strategies