Soil Proprieties Research Articles

The Olive Mill Pomace: A Sustainable Biofertilizer to Improve Soil Proprieties and Plant Nutrient Uptake

The Olive Mill Pomace: A Sustainable Biofertilizer to Improve Soil Proprieties and Plant Nutrient Uptake

Integrated effect of saline water irrigation and phosphorus fertilization practices on wheat (Triticum aestivum) growth, productivity, nutrient content and soil proprieties under dryland farming

Wheat (Triticum aestivum) is the most common and oldest crop in Morocco and MENA region countries, cultivated both for human and animal nutrition. In Morocco, the irrigated perimeter of Tadla is the major wheat growing area affected by soil and groundwater salinity problematic. Previous studies have shown that phosphorus (P) fertilization can mitigate the negative effects of salinity on different crops. Thus, field experiments from the combination of four levels of irrigation water salinity and three P-fertilization rates were conducted during two successive growing seasons (between 2019 and 2021) at the National Institute of Agronomic Research (INRA), Tadla, Morocco. Our main objective was evaluating the potential of P-fertilization to improve wheat growth, productivity and quality under saline water irrigation practices. The crop simulation model APSIM, was also tested to assess its performance in simulating wheat growth, productivity, phosphorus and nitrogen nutrient dynamics in soil-plant system under saline conditions. Results showed that appropriate P-fertilization under saline conditions contributed to minimize the effect of salinity and improved wheat growth and production. Also, it was found that increasing P-fertilization improved nutrient uptake, and consequently the plant nutrient content. A good agreement between the measured and APSIM model simulated growth and yield state variables, as well as the plant and soil-N content. However, a model uncertainty and relevant limitations in simulating plant- and soil-P content output were identified and discussed. Overall, our finding suggests that appropriate P-application minimizes the adverse effects of high soil salinity and can be adopted as a coping strategy in wheat cultivation under saline water irrigation practices.

Geostatistics and Sample Density of Chemical Attributes for Soil under Sugarcane and Agroforestry in Humaitá – AM, Brazil

There is a lack of studies focusing on spatial variance of chemical attributes in Amazonas, Brazil. The objective of this study was to evaluate geo-statistics and sample density of chemical attributes in soils under sugarcane and agroforestry, Humaitá, Amazon state, Brazil. The research was carried out in the municipality of Humaitá, Amazon state, the areas were in meshes of 70 m x 70 m regularly spaced by 10 m, with 64 points per area, and then soil samples were collected in layers of 0.0-0.2 m and 0.4-0.6 m. We performed chemical analyses of the proprieties of soil. Then, it was applied descriptive statistics, geo-statistics and sample density techniques based on semivariogram coefficient of variation and range. As a result, we observed spatial dependence for most of the chemical proprieties in the two areas. Based on Cline, sugarcane presented a sample density of 237 (0.0-0.2 m) and 225 (0.4-0.6 m); and agroforestry had 356 (0.0-0.2 m) and 465 (0.4-0.6 m) points per hectare. Yet in the range sample density, sugarcane showed 30 (0.0-0.2 m) and 5 (0.4-0.6 m), whereas agroforestry areas had 23 (0.0-0.2 m) and 9 (0.4-0.6 m) points per ha.

Under-vine cover crops: Impact on physical and biological soil proprieties in an irrigated Mediterranean vineyard

Despite their potential benefits, cover crops in vineyards under to Mediterranean climate conditions are still not widespread, especially in the vine row. This under-vine space is normally kept weed-free through the application of herbicides and/or tillage. In this work, we evaluate the effect of a Trifolium fragiferum L. under-vine cover crop (UV) on soil quality, as reflected by a variety of physical, chemical, and biological soil indicators. 15 months after under-vine cover crop implementation, total (SOC) and particulate (POC) organic carbon storage, and soil aggregation (abundance (WSA) and mean weight diameter (MWD) of water stable aggregates) were compared with a control without cover (T) at 0–15 cm. In addition, for three consecutive years after under-vine cover crop implementation, the evolution of soil microbial communities was monitored through the determination of soil basal respiration, soil microbial biomass carbon and nitrogen (MBC and MBN), and community-level physiological profiles (CLPPs). The establishment of the under-vine cover crop resulted in higher values of SOC (27.78 Mg·ha−1 in UV vs. 20.71 Mg·ha−1 in T, +33%) and POC (4.75 Mg·ha−1 in UV vs. 2.73 Mg·ha−1 in T, +74%), as well as aggregation parameters (MWD: 1.82 µm in UV vs. 1.56 µm in T, +17% and WSA: 84.68% in UV vs. 71.58% in T, +18%). An evolution towards progressively greater values of biological activity (basal respiration) and microbial biomass was detected in under-vine cover crop soils as time elapsed. It was concluded that the Trifolium fragiferum L. under-vine cover crop led to soil quality improvement in our Mediterranean climate vineyard. Interestingly, this positive effect was noticed shortly after its implementation.

Brassica carinata Seed Meal as Soil Amendment and Potential Biofumigant

Brassicaceae products have been extensively studied for their biofumigant activity; despite this, few investigate their effect on soil proprieties. This paper aims to describe the effect on soil fertility by adding the seed meal of Brassica carinata at three different doses corresponding to field dose (3 tons/ha), 10 and 100 fold this dose in organic soil. The organic carbon balance was evaluated by analysing the oxidisable, humified and mineralised carbon fractions. Microbial activity was measured by enzymes linked to the carbon, phosphorous and sulphur cycles—β-glucosidase, phosphatase and arylsulphatase, respectively. The amount corresponding to 30 t/ha was the best solution for the mineralised carbon and humic carbon ratio. In contrast, there was a substantial increase in the organic substance’s mineralisation level at the maximum dose, not offset by a relative rise in humification. No repression was observed in the metabolic activity of the microorganisms, their abundance or the main enzymatic activities and, in the conditions tested, a release of only a volatile isothiocyanate occurred, limiting the biofumigant effect. Therefore, these combined factors allow us to assert that the amendment with this type of material at the intermediate dose could positively affect the phosphorus cycle, the soil structure, and fertility.

Roles of Arbuscular mycorrhizal Fungi as a Biocontrol Agent in the Control of Plant Diseases.

Arbuscularmycorrhizal fungi (AMF) are a class of beneficial microorganisms that are widely distributed in soil ecosystems and can form symbionts with 80% of terrestrial higher plants, and improve the nutritional status of plants. The use of AMF as a biocontrol method to antagonize soil-borne pathogens has received increasing interest from phytopathologists and ecologists. In this paper, the mechanisms of resistance to diseases induced by AMF and the application of AMF to plant fungal, bacterial, and nematode diseases have been summarized. This study aimed to enhance the potential use of AMF as a biological control method to prevent plant diseases in the future. Root morphological alteration characteristics were explained, including the influence of AMF on root structure, function, and the regulation of AMF via secondary metabolites. AMF can improve the rhizosphere environment by influencing the physical and chemical proprieties of soil, enhancing the growth of other beneficial microorganisms, and by competing with pathogenic microorganisms. Two microorganism types may compete for the same invasive sites in root systems and regulate nutrition distribution. AMF can induce the host plant to form defense systems, including improving phytohormone concentrations, inducing signal substrate production, gene expression regulation, and enhancing protein production.

Calorific Value of Festuca rubra Biomass in the Phytostabilization of Soil Contaminated with Nickel, Cobalt and Cadmium Which Disrupt the Microbiological and Biochemical Properties of Soil

The choice of optimal plant species for phytoremediation and organic fertilization plays an important role in stabilizing the functions of soils contaminated with heavy metals. The influence of nickel, cobalt and cadmium on the biomass yield and calorific value of Festuca rubra, heavy metal concentrations in soil and plants and the microbiological, biochemical and physicochemical proprieties of soil were analyzed in a pot experiment. The tolerance index (TI) describing Festuca rubra’s ability to tolerate heavy metals, as well as the translocation (TF), accumulation (AF) and bioaccumulation (BF) factors of heavy metals in Festuca rubra were calculated. The experiment was conducted in two series: In soil fertilized and not fertilized with compost. Nickel and cobalt significantly inhibited the growth and development of Festuca rubra. The experiment demonstrated that this plant species can be grown on soil contaminated with heavy metals. Festuca rubra contained on average 46.05% C, 34.59% O, 5.91% H, 3.49% N, 0.19% S and 9.76% ash. Festuca rubra has a stable calorific value which is not affected by heavy metals; therefore, biomass harvested from heavy metal-polluted soil can be used for energy generation. The calorific value of Festuca rubra ranged from 15.924 to 16.790 MJ kg−1 plant d.m., and the heat of combustion from 17.696 to 18.576 MJ kg−1. It has a stable calorific value which is not affected by heavy metals, therefore biomass harvested from heavy metal-polluted soil can be used for energy generation. Festuca rubra is particularly useful for the phytostabilization of soil contaminated with cadmium and cobalt. Compost minimizes the adverse effects of heavy metal pollution on the microbiological, biochemical and physicochemical properties of soil.

Soil Properties of a Tef-Acacia decurrens-Charcoal Production Rotation System in Northwestern Ethiopia

A tef-Acacia decurrens-charcoal production rotation system, a unique indigenous climate-smart agricultural technology of northwest Ethiopia, is increasingly seen as a promising strategy for improving soil properties. This study investigated the effect of the tef-Acacia decurrens-charcoal production rotation system on soil properties. In total, 112 soil samples (7 treatments × 4 depths × 4 replicates) were collected and analyzed inside and outside randomly selected charcoal production spots in the tef-Acacia decurrens-charcoal production rotation system and from an adjacent tef monocropping system. The soil properties examined generally exhibited significant variation between the tef monocropping system and the tef-Acacia decurrens-charcoal production rotation system, and between soil depths, as well as with respect to charcoal production spots in the system. The system resulted in a significant increase in SOC, TN, available phosphorus, available sodium, available nitrate and ammonium in general, and in total contents of K, P and Mn in the 0–20 cm depth. Charcoal production in the system significantly increased the total content of P, Al, and Fe, as well as the available nitrate and sulfate in the charcoal production spot. The variation in soil proprieties between the land use types and with respect to charcoal production spots in the TACP system were possibly due to the effect of the Acacia decurrens trees, and fire and fine charcoal residues from charcoal production, indicating the capacity of the tef-Acacia decurrens-charcoal production rotation system to improve soil properties.

Validation of Rapid and Low-Cost Approach for the Delineation of Zone Management Based on Machine Learning Algorithms

Proximal soil sensors are receiving strong attention from several disciplinary fields, and this has led to a rise in their availability in the market in the last two decades. The aim of this work was to validate agronomically a zone management delineation procedure from electromagnetic induction (EMI) maps applied to two different rainfed durum wheat fields. The k-means algorithm was applied based on the gap statistic index for the identification of the optimal number of management zones and their positions. Traditional statistical analysis was performed to detect significant differences in soil characteristics and crop response of each management zones. The procedure showed the presence of two management zones at both two sites under analysis, and it was agronomically validated by the significant difference in soil texture (+24.17%), bulk density (+6.46%), organic matter (+39.29%), organic carbon (+39.4%), total carbonates (+25.34%), total nitrogen (+30.14%), protein (+1.50%) and yield data (+1.07 t ha−1). Moreover, six unmanned aerial vehicle (UAV) flight missions were performed to investigate the relationship between five vegetation indexes and the EMI maps. The results suggest performing the multispectral images acquisition during the flowering phenological stages to attribute the crop spatial variability to different soil proprieties.

Impact of Salinity on the Behavior of Fungi

Salinity of the soil and water is one of the principal environmental elements that might influence the soil proprieties, crop production, distribution plant pathogens and their associated diseases. In addition to preventing plant growth and development, salinity also has an impact on antagonistic and pathogenic of numerous fungi. In addition to its direct effects on crops, salinity has been a significant problem that causes additional damage by enhancing the predisposition of plants to biotic diseases. However, salinity may either a potential antifungal agent by reducing mycelia growth, sporulation and conidial germination or increases the virulence of diseases by promoting the production of enzymatic activities including cellulase, pectin lyase, and polygalacturonase by the microorganisms. The effect of this environmentally agent on the growth and reproductive parameters differs between species, either directly or indirectly. There are numerous fungal species that can grow in situations with high salt concentrations; the majority of them are halotolerant, but there are also some halophilic species that can only flourish in salty conditions. The aim of this review is to characterize behavior fungal regarding salinity, in order to develop an integrated pest management strategy that incorporates biological, chemical, and cultural control approaches for disease management, economical effective, and extremely appealing for better crop quality and environmental sustainability in these salinity-related conditions.

Surface runoff prediction and comparison using IHACRES and GR4J lumped models in the Mono catchment, West Africa

Abstract. This study aims to assess simulated surface runoff before and after dam construction in the Mono catchment (West Africa) using two lumped models: GR4J (Rural Engineering with 4 Daily Parameters) and IHACRES (Identification of unit Hydrographs and Component flows from Rainfall, Evapotranspiration and Stream data) over two different periods (1964–1986 and 1988–2010). Daily rainfall, mean temperature, evapotranspiration and discharge in situ data were collected for the period 1964–2010. After the model's initialization, calibration and validation; performances analysis have been carried out using multi-objectives functions developed in R software (version 3.5.3). The results indicate that statistical metrics such as the coefficient of determination (R2), the Kling–Gupta Efficiency (KGE), the Nash–Sutcliffe coefficient (NSE) and the Percent of Bias (PBIAS) provide satisfactory insights over the first period of simulation (1964–1986) and low performances over the second period of simulation (1988–2010). In particular, IHACRES model underestimates extreme high runoff of Mono catchment between 1964 and 1986. Conversely, GR4J model overestimates extreme high runoff and has been found to be better for runoff prediction of the river only between 1964 and 1986. Moreover, the study deduced that the robustness of runoff simulation between 1964 and 1986 is better than between 1988 and 2010. Therefore, the weakness of simulated runoff between 1988 and 2010 was certainly due to dam management in the catchment. The study suggests that land cover changes impacts, soil proprieties and climate may also affect surface runoff in the catchment.

Update of land use/land cover and soil texture for Brazil: Impact on WRF modeling results over São Paulo

Land Use/Land Cover (LULC) and soil texture play a key role in meteorological models because they determine the vegetation and soil proprieties that interfere in the exchange of energy, moisture, and momentum between the land surface and the atmosphere. Additionally, LULC and soil texture are relevant input datasets in meteorological models affecting their results and future applicability as in weather researches and air quality modeling. Brazil has a complex and heterogeneous LU, and it has faced significant LULC changes in the past years. Therefore, this paper aims to update the LULC, using the national product MapBiomas, and soil texture data, by SoilGrids, to replace the default input data in the Weather Research and Forecast (WRF) model for São Paulo, Brazil. Aiming to evaluate the impact of those input data on WRF simulations, five cases were simulated using WRF v4.1.3 with 1 km of grid resolution, and combinations of “Default” and “Updated” input data. Sixty-days simulations from March 15th to May 15th of 2015, covering the transition of wet to dry season, were performed and evaluated with observational data over São Paulo State. The results showed significant differences in the classifications of LULC and soil texture in the entire domain between the default and updated data. The updated data is more realistic and coherent with local characteristics, being more representative, as an example over Santos city area being correctly classified as urban and built-in updated LULC and not water, as in the default. The comparison between the modeled results with observations data has shown a similar behavior for temperature and humidity for the five cases at the monitoring stations grid cells because the LULC changes were between classes with similar land parameters, such as albedo, roughness length, and soils moisture, although the Default classes are not accurate. However, the latent and sensible heat fluxes were ways more sensitive to the LULC/soil texture changes in the WRF model. Additionally, reasonable differences were observed over the entire modeling domain for these two variables. The updated land surface data provoked low temperatures at 9h and 17h UTC, less humidity at 9h UTC, and more humidity at 17h UTC, especially in the north part of the modeling domain, the area which has faced more LULC and soil changes. The PBL height was also affected by the updated data, probably caused by the impact at heat flux over the domain, causing a variation from 30% to 70% over the modeled grid cell, which may have a higher impact on air quality modeling. Thus, it is recommended to update the land surface data for Brazil to avoid misclassification of LULC and soil texture, even if the comparison at monitoring stations has shown similar behavior between the default and updated land surface data. Additionally, updates in the land parameter inside the model are required to represent each LULC/soil class better.

Using Jand and Mesquite for environmental progress and management: Improvement soil proprieties and carbon sequestration ability in different organs

AbstractThe present study was conducted to estimate the amount of carbon sequestration in soil containing Jand (Prosopis cineraria) and Mesquite (Prosopis juliflora) and control area at different soil depths (0–15 and 15–30 cm), as well as its organs (root, shoot and leaves) and some soil characteristics in the Anbarabad region, southeastern part of Kerman province, Iran. This study was carried out by two separate factorial experiments. The first factor was the type of plant species in both experiments. The second factor was the plant organs in experiment I and different soil depths in experiment II. The results showed that the carbon stored at two depths of 0–15 and 15–30 cm in P. cineraria (21.39 and 24.36 t/ha) and also in P. juliflora was 23.70 and 24.857 t/ha, respectively. Effects of Soil type under the canopy and soil depths on carbon sequestration were significant. Both plants had the highest amount of organic carbon in the roots and shoots. However, the lowest amount of organic carbon obtained in leaves. Effect of soil depth on carbon sequestration was significant and also the interaction of species and organs on the amount of stored organic carbon were significant. Soil texture, especially clay content, has a great effect on soil carbon sequestration. The highest carbon sequestration was obtained in Mesquite (24.03a ± 1.113 t/ha) and the lowest carbon sequestration was obtained in Jand (20.87b ± 0.203 t/ha).

IMPACT OF SULPHUR AND BIOCHAR APPLICATIONS ON SOIL PROPERTIES AND PRODUCTIONS OF WHEAT AND SOYBEAN YIELDS IN SOILS HAVING TEXTURE

Lysimeter experiments were conducted during two consecutive seasons of winter 2017/2018 and summer season 2018 for wheat and soybean at EL-Gemmieza Agriculture Research Station, El Gharbiya Governorate to study the influence of sulphur and biochar on soil proprieties, productivity of wheat and soybean yields in soils have different texture classes. The experiments were lay out in a split plot (SP) design with three replicates. The main plots were occupied with three different types of soils (clay, calcareous and sandy soils), sub plots were devoted to soil amendments i.e T1: control, T2: sulphur (1.50 Mg ha-1), T3: biochar (5 Mg ha-1) and T4: sulphur (1.50 Mg ha-1) + biochar (5 Mg ha-1). Results indicated that application of sulphur or biochar and individually and in combination led to an increase in available N, P, K, cation exchange capacity, total porosity, organic matter, exchangeable Ca, Mgand K while EC, pH, bulk density and soil hydraulic conductivity high significantly decreased in sandy and calcareous soils. On the contrary, soil hydraulic conductivity high significantly increased by different treatments in the clay soil. Grain and straw yields as well as N, P and K concentration and uptake of wheat and soybean were high significantly increased by all application sulphur and biochar. Consequently the improvement of soil types on all properties can be arranged in the following order sandy soil < calcareous soil < clay soil. The combination application of biochar and sulphur (T4) lead to significant increase in yield of wheat and soybean (grain and straw).

IMPACT OF SULPHUR AND BIOCHAR APPLICATIONS ON SOIL PROPERTIES AND PRODUCTIONS OF WHEAT AND SOYBEAN YIELDS IN SOILS HAVING TEXTURE

Lysimeter experiments were conducted during two consecutive seasons of winter 2017/2018 and summer season 2018 for wheat and soybean at EL-Gemmieza Agriculture Research Station, El Gharbiya Governorate to study the influence of sulphur and biochar on soil proprieties, productivity of wheat and soybean yields in soils have different texture classes. The experiments were lay out in a split plot (SP) design with three replicates. The main plots were occupied with three different types of soils (clay, calcareous and sandy soils), sub plots were devoted to soil amendments i.e T1: control, T2: sulphur (1.50 Mg ha-1), T3: biochar (5 Mg ha-1) and T4: sulphur (1.50 Mg ha-1) + biochar (5 Mg ha-1). Results indicated that application of sulphur or biochar and individually and in combination led to an increase in available N, P, K, cation exchange capacity, total porosity, organic matter, exchangeable Ca, Mgand K while EC, pH, bulk density and soil hydraulic conductivity high significantly decreased in sandy and calcareous soils. On the contrary, soil hydraulic conductivity high significantly increased by different treatments in the clay soil. Grain and straw yields as well as N, P and K concentration and uptake of wheat and soybean were high significantly increased by all application sulphur and biochar. Consequently the improvement of soil types on all properties can be arranged in the following order sandy soil < calcareous soil < clay soil. The combination application of biochar and sulphur (T4) lead to significant increase in yield of wheat and soybean (grain and straw).

Comparative Performance of Integrated Nutrient Management between Composted Agricultural Wastes, Chemical Fertilizers, and Biofertilizers in Improving Soil Quantitative and Qualitative Properties and Crop Yields under Arid Conditions

The primary goal of integrated nutrient management (INM) strategies is to substitute a portion of chemical fertilizers with a more sustainable and environmentally safe organic compost in order to mitigate soil degradation, improve crop production, and protect the environment. Therefore, the present study was conducted to assess the impacts of different INM practices, namely full-dose NPK (T1), compost of cow manure at 5 t ha−1 (T2), compost of poultry manure at 5 t ha−1 (T3), compost of mixed sheep and camel manure at 5 t ha−1 (T4), 50% NPK combined with the mixture of the three types of composts at the rate of 5 t ha−1 (T5) or 10 t ha−1 (T6), and mixture of the three types of composts at the rate of 10 t ha−1 (T7), 15 t ha−1 (T8), or 20 t ha−1 (T9) with or without biofertilizers for each treatment on several physiochemical and biological proprieties of soil and final grain yield of field crops after 2 years of field-scale experiments. The results showed that all INM practices generally significantly (p &lt; 0.05) improved the initial values of all tested soil physiochemical and biological proprieties, whereas improvement was more prominent for the plots treated with T5–T9, compared with those treated with T1–T4. Seed inoculation with biofertilizers also significantly (p &lt; 0.05) increased different soil proprieties by 2.8–12.0%, compared to that of the non-inoculation treatment. Principal component analysis revealed that most soil chemical properties were closely associated with T5–T6 treatments, while most soil physical and biological properties appeared to be more related to T7–T9 treatments. Our results indicated that recycling agricultural wastes into new productive composts and integrating it into appropriate INM practices as shown in T5–T9 treatments may induce favorable changes in soil properties and improve crop production under arid conditions even in the short term.

Application of Inverse Distance Weighting in Mapping Some of Soil Chemical Properties in Ayn Hizam, Qaryat Batth and Taknis

Determining variabilities of soil properties is important for ecological modelling, environmental predictions, precise agriculture, and management of natural resources. This study was aimed to examine Inverse distance weight (IDW) to predict the spatial variability of Exchangeable Sodium Percentage (ESP), Calcium Carbonate Percentage (% CaCO3) soil pH, Electrical conductivity and % Gypsum . The study area selected for this work consists of Ayn Hizam, Qaryat- Batth and Taknis. Data for 220 randomly distributed representing soil profiles were encoded in spreadsheets, 198 of them were used for predicting the spatial variability in the GIS environment for ESP, % CaCO3, soil pH, Electrical conductivity and % Gypsum. The rest of Data (i.e. 22 representative soil profiles) were utilized to evaluate the maps produced using Kriging or IDW methods. The results showed that using IDW method was trustable because the values of RMSE and R2 for all the IDW maps were within the acceptable range. The study suggested adopting the Geostatistical methods for studying spatial prediction for different soil proprieties. In addition, the study recommended updating soil data for the study area.

Groundwater-dependent ecosystems as transfer vectors of nitrogen from the aquifer to surface waters in agricultural basins: The fontanili of the Po Plain (Italy)

The most spread groundwater-dependent ecosystems in the River Po valley are semi-natural lowland springs called “fontanili”. They provide specific habitats and support high biodiversity, but are often strongly impaired by agricultural pollution. In the present study we seasonally monitored the discharge and nitrogen concentration of 48 fontanili from the Adda and the Ticino river basins. We observed a wide spatial variability of both NO3-N concentrations and flows. The annual NO3-N loads ranged from <1 to 75 t y−1 and < 1 to 29 t y−1 in the Adda and Ticino basins respectively. In the springs characterized by variable discharge the N loads were exported mostly during the summer season when water table level was elevated mainly due to irrigation. Upscaling the mean NO3-N load to each river catchment based on the total number of springs, we obtained an aerial export of 33.2 ± 6.0 and 12.5 ± 3.2 kg y−1 ha−1. Such loads accounted for the 30.4 and 21.5% of the N surplus estimated for the Adda and Ticino basins respectively.Random Forest analysis was performed to identify the most important environmental variables influencing the nitrate contamination in the spring waters. A total of 22 explanatory variables related to N sources, land uses, intrinsic hydrogeologic and soil proprieties, in “situ” and remotely sensed variables were considered. The percent of soil cultivated with maize in a 500 m radius buffer area surrounding the sampling site, the N from manure and the distance of each spring from the main river were the most effective factors in controlling the NO3-N concentration in the fontanili water.The outcomes of this work open up to achievable management prospects for the protection and recovery of fontanili waters, and can be particularly useful for water managers in identifying areas and sites where restoration plans should be a priority.

Does Arbuscular Mycorrhiza Determine Soil Microbial Functionality in Nutrient-Limited Mediterranean Arid Ecosystems?

Arbuscular mycorrhizal fungi (AMF) are determinant for the performance of plant communities and for the functionality of terrestrial ecosystems. In natural ecosystems, grazing can have a major impact on mycorrhizal fungi and consequently on plant growth. The objective of this study was to evaluate the statements referred above in Mediterranean arid areas in Tunisia. Root samples and rhizosphere soils of five dominant herbaceous plants were studied at six distinct arid sites differing on soil proprieties and grazing intensity. At each site, chemical and dynamic properties of the soil were characterized as well as the AMF colonization intensity and the soil functionality. Results showed that the mycorrhizal frequency and intensity and spore density, varied between plants in the same site and, for each plant, between sites and evidenced a positive effect of mycorrhized plants on soil microbial activity. Grazing and soil properties strongly affected AMF composition and the soil microbial and biochemical dynamics, which presented the lowest values at the sites with the highest grazing intensities. In conclusion, these results demonstrate that AMF improve soil biological properties, supporting the hypothesis that mycorrhiza and grazing compete for plant photosynthates, and highlight the importance of mycorrhizal symbiosis towards soil functionality under arid conditions.

Estimation of the undrained shear strength of east Port-Said clay using the genetic programming

Abstract (CPT) is a widely acceptable and reliable geotechnical in situ test. It provides quick and truthful large amount of data about soil proprieties. Undrained cohesion of clay is a main soil parameter that could be estimated from (CPT) results as it is directly correlated to the tip resistance through the empirical cone factor (Nk). Several studies have been carried out to determine reliable values of the (Nk) factor. This study focused on using (GP) to correlate the (Nk) value of east Port Said clay with consistency limits that can be easily determined. Records of 102 data sets were gathered from site & lab investigations in considered region consists of (CPT) results and corresponding triaxial, unconfined compression, consistency limits and physical properties tests. The collected data were divided into training set to develop the (GP) models and validation set to test the developed formulas which show prediction accuracies between 93% and 96%.