فصلنامه حفاظت منابع آب و خاک
سال سیزدهم شماره 3 (پیاپی 51، بهار 1403)

One of the biggest challenges of the rainfall-runoff model is to accurately determine the rate of water infiltration into the soil as one of the parameters that determine the size and shape of the hydrographs of historical floods. The studies conducted in different climates that show different morphometry of the earth indicate the weakness of widely used methods such as SCS-CN in determining the rate of water infiltration into the soil. For the SCS-CN method, as the soil storage index approaches infinity, the soil moisture ratio approaches 1, and this is due to the limitation of the SCS-CN method. In this research, focusing on this weakness in the basic relationships of loss calculations, and an integrated approach in determining the infiltration of water into the soil, the magnitude of the historical floods in the watershed was analyzed. The importance of this analysis can be in verifying the magnitude of floods, which is the criterion for determining structures or crisis control programs.

Considering that in order to solve the problem of infiltration calculations at the basin scale, and based on the new equations to determine flow losses, a homogeneous but raster criterion is needed, in this research, based on the sensitivity of the produced flow to the amount of losses in the probabilistic investigation of the index humidity and flow ratio, a depth-infiltration model was prepared from the two-dimensional comprehensive model in the range. In this study, based on the new relationships of losses determination, numerical calculations were done in the software and script environment sequentially and based on the outputs of the hydrological model. First, the HEC-HMS rainfall-runoff model structure was generated with Arc Hydro and HEC_GeoHMS extensions in Shadegan catchment. Then, infiltration parameters were determined by SMA method in the analysis of remote sensing images from the basin. In the next stage, the development of the primary continuous model, calibration and validation was done focusing on soil moisture information. After determining the soil moisture relationship based on the results of the soil wetting model, the artificial unit occurrence hydrograph was determined by determining the flood volume based on the SCS-CN and VIC combined method. 

The general results of the implementation of the hydraulic model of the flood plain showed that the maximum inflow was equal to 3023 cubic meters per second at the 90th hour of the event, and the maximum outflow flood was at the 93rd hour with a figure of 2137 cubic meters per second. The discharge value is assumed to be 0 at the beginning of the calculations. The flow volume at the end of the calculations was equal to 141.03 million cubic meters, which is the remaining volume of 918.36 million cubic meters in the whole event. The difference between the inlet and outlet discharge was calculated as a deficiency of about 6.14%. Also, the layer of flow depth changes shows that the water level in the plain is trying to be at a possible and reasonable level by filling the lower points. So that a large part of the volume of water from the southern strip of the borders of Trava for the active area of modeling will eventually flow into the sea. However, the direction of water movement has even been estimated to be perpendicular to the direct path towards the sea in some cases. These results indicate a maximum depth of 16.4 units in some areas, with a minimum depth of 5.3 units. The important point is that in the plains, according to the cell size, definitely in some cases much lower depths can be calculated. The average depth in active cells is 11.9 meter calculated locally. These figures can change according to different rainfall events.

The results showed that it is possible to verify the infiltration based on the new base distribution equations with a probabilistic condition in the estimation of the basin shape parameter. The amount of hydrograph calibration in response to water infiltration in soil is dependent on the correct estimation of initial soil moisture. Flow losses in large-scale watersheds are obtained more suitably based on SCS-based distribution equations. Numerical and hydrological models such as HEC-HMS or modelers such as HEC_GeoHMS are completely dependent on the DEM raw layer introduced for the purpose of upstream demarcation. Changes in land cover in flat areas can actually produce a closed border of the watershed compared to the reality of the land in different simulation models. According to the basic assumptions such as calibration coefficients, the single hydrograph method can be a good substitute for areas without rainfall-runoff statistics. The TUFLOW software model gave the best response to one-dimensional to two-dimensional flow for Shadgan plain according to the type of boundary conditions.

Nowadays, by increasing the water demand in different sectors, the withdrawal amount from groundwater resources is increasing leading to more drawdown of Markazi province aquifers. One of the most suitable methods for the optimal management of groundwater resources is the analysis of the behavior of aquifers in various conditions using mathematical models. The objective of this paper is to investigate the effects of withdrawal for agricultural and industrial consumptions on the groundwater level of the Shazand plain located in Markazi Province and the impact of a 20% increase in irrigation efficiency of farms in the case of the development of under pressure and low-consumption systems using the GMS numerical model.

First, the conceptual and numerical model of the Shazand aquifer was executed in the GMS software and calibrated in the steady state. Then, the model was recalibrated in a transient state for the statistical period from October 2015 to September 2019. To examine the reactions of the model to the changes of important and effective parameters, the sensitivity analysis of the model was performed and the model was verified for the statistical period of October 2019 to September 2021. Then, the changes in the groundwater level in the aquifer under two reference management scenarios and increasing irrigation efficiency were investigated and compared. In the reference scenario assuming the continuation of the current conditions and in the efficiency increase scenario assuming a 20% increase in irrigation efficiency, the simulation of changes in the groundwater level in the entire Shazand plain for the upcoming 20 years from October 2021 to September 2041 was carried out.

Based on the obtained results, the RMSE error value related to the steady state recalibration is about 0.7 meters and the average RMSE error value in the transient state in all months of simulation in two recalibration and validation periods is less than 0.6 meters, which shows the high accuracy of the model in simulating the groundwater level in the whole plain. The sensitivity analysis showed that the changes in specific yield and hydraulic conductivity parameters have the greatest effect on the fluctuations of groundwater in the whole plain. The results showed that in the reference scenario, the drop in the groundwater level at the end of the 20-year operation period is 3.95 meters. In the scenario of a 20% increase in efficiency, with the reduction of extraction from wells due to the increase in irrigation efficiency, the amount of drop will reach 2.76 meters, in which case the amount of drop will be mitigated by 1.2 meters.

According to the results, the highest drop in the groundwater level in both reference and increase in efficiency scenarios in the central areas of the plain is 9.2 and 6.9 meters, respectively, and the lowest drop in the western areas of the plain is 1 and 0.5 meters, respectively. Considering that the agricultural sector has the greatest impact on the level drop in the aquifer in the central areas of the plain, it is better to focus management plans to control withdrawal from the aquifer, such as increasing efficiency or modifying the cultivation pattern, on this sector. In case of the implementation of systems under pressure and increasing efficiency in the plain, the amount of drawdown in the region will be mitigated to some extent, but the problem will not be solved and it is necessary to implement supplementary programs to cultivate high consumption plants instead of high consumption crops and in the industry sector instead of extracting groundwater, treated municipal wastewater should be used.

The slopes of watersheds in nature have three converging, divergent and parallel shapes in terms of plan shape and three convex, concave and flat shapes in terms of floor curvature. In general, there are 9 shapes and geometries for hillslopes, which are called complex hillslopes. Past researches have shown that the topography and geometry of the complex hillslopes have an effect on many hydrological characteristics of the domains, such as the degree of saturation. The degree of saturation of the domain points depends on the concentration of subsurface flow at each point, which is influenced by the shape of the design and topography of the domain.The purpose of this research is the effect of topography on the surface sliding of the complex hillslopes of the watersheds using SINMAP and TOPMODEL models.

In this research, the TOPMODEL model was used to check the degree of saturation of the complex hillslopes, and the equations of this model were modified so that it could consider the topography of the domains, and the results of the saturation in the TOPMODEL model were transferred to a sliding model called SINMAP. And the effect of domain topography on the stability of complex domains was investigated and compared with MATLAB coding and drawing shapes. It should be noted that the aforementioned models are used based on hydrological and topographical data. The methods used in this research are generally applicable to all geographical and climatic regions. 

Considering that in this research, the saturation index was calculated from TOPMODEL, which indicates the degree of concentration of subsurface flow at any point of the domain and determines the saturation of different points of the domain and has a significant effect on the stability of compex hillslopes and based on the average the stability coefficient of the slopes, on average, convex slopes have more stability than flat and concave slopes, and divergent slopes have more stability than convergent slopes, and the higher the saturation layer thickness and soil hydraulic transfer coefficient, the more stable the slope is. and as the amount of effective rainfall increases and as a result the soil moisture increases, the stability of the slopes decreases.

Based on the results obtained in this research, in the downstream parts, the concave slopes are more stable than the upstream part of the slope, while it is the opposite in the convex slopes. Compared to the saturation index, the local slope of the domain points is a much more important factor in determining the stability of the domains. Based on the average saturation index, convex domains are more stable than concave and divergent domains are more stable than convergent domains. It should be noted that in flat slopes with different plan shapes, the slope value is constant, but the degree of saturation of flat-convergent slopes is more than that of smooth-divergent slopes, and it has made some points of the flat-convergent slope more unstable, and the stability value is from top to side. The bottom becomes less and the end parts of the smooth-convergent domain are in an unstable state, but the entire smooth-parallel and smooth-divergent domains are in a stable state.

It is necessary to predict the effects of climate change on agricultural production in the coming periods in order to ensure the food security of the strategic plant wheat, which plays an essential role in international treaties. Models that generate artificial climate data, such as valid GCM models, are used to investigate the effects of climate change on various systems and are able to model climate parameters for a long period of time using scenarios approved by the Intergovernmental Panel on Climate Change. In the current research, two information sources, LARS-WG and DKRZ, were used to generate climate change data of the Qazvin plain in the period of 2021-2100, then the actual evapotranspiration values of Parsi spring wheat were calculated by the Aquacrop model in different planting dates and the amount of their changes Compared to the base course.

In this research, from the data obtained from the DKRZ web database and the LARS-WG model, to calculate the three variables of minimum temperature, maximum temperature and precipitation, related to Qazvin observation station and five atmospheric general circulation models of the fifth IPCC report (EC-EARTH , GFDL-CM3, HadGEM2-ES, MIROC5, MPI-ESM-MR) were used under two emission scenarios of 4.5 and 8.5 in future rounds (2021-2040, 2041-2060, 2061-2080, 2081-2100). Using the obtained data and applying the Aquacrop model, the amount of actual evaporation-transpiration of spring wheat on 5 different planting dates (15 Bahman, 1 Esfand, 15 Esfand, 1 April and 15 April) was calculated and the amount of their changes compared to the period the base was checked.

Observations show that with cultivation on 15th of Bahman and 1st of March under the climatic conditions obtained from the LARS-WG model in scenario 4/5; In the future period (2040-2021), transpiration will increase compared to its value in the base period, but in the periods (2041-2060, 2061-2080 and 2081-2100) and in the scenario 4.5 and 5.8 from the LARS model - WG average real evapotranspiration will decrease compared to its value in the base period. DKRZ database under scenarios 4.5 and 8.5 predicts a decrease in the average actual evapotranspiration compared to its value in the base period for these two dates in each of the next 4 periods. by planting on March 15, April 1 and April 15, according to the results of the climate conditions of the LARS-WG model and the DKRZ database under scenarios 4/5 and 8/5, in each of the next 4 periods; The average actual evapotranspiration will decrease compared to its value in the base period.

The results show that the average real evapotranspiration will increase compared to its value in the base period, on the two dates of February 15 and March 1 in the period of 2040-2021 in the climate conditions obtained from the LARS-WG model under scenario 4.5.If cultivation is carried out in the rest of the dates, according to the results of the climatic conditions of the LARS-WG model and the DKRZ database under scenarios 4.5 and 5.8, in each of the next 4 periods, the average real evapotranspiration will decrease compared to its value in the base period Will have. The highest evaporation-transpiration in the future periods will occur with cultivation on April 15, under the climate conditions obtained from the LARS-WG model under scenario 4/5 and in the period of 2040-2021. Its value is equal to 289.9 mm (with a standard deviation of 18.33 mm). The lowest evaporation-transpiration in the future periods with cultivation on 15th of Bahman, under the climatic conditions obtained from the DKRZ database under scenario 8.5 and in the period 2081-2100, which is equal to 166.6 mm (with a standard deviation of 82.5 mm).:

The recently introduced concept of soil security stems from deep scientific concern about global soil degradation and its impact on sustainable development. Although land degradation is a physical process, its main drivers are rooted in the socio-economic and political environment. Soil security by integrating five dimensions, including soil condition and capabilities, soil biophysical aspects, as well as capital, covers the relationship and legislation of socio-economic and political factors affecting soil. Therefore, the aim of this study is to identify and validate soil security indicators with fuzzy Delphi technique.

The current research is applied in terms of its purpose and it is qualitative research in terms of the type of research. Also, the current research is a descriptive (non-laboratory) type of researches that was conducted with a survey method. The information needed for this research was mainly obtained through survey and library methods, and in this regard, secondary data such as scientific and gray documents and several reports of government documents that describe the studied area were used. The information required for this research has been collected according to the objectives determined by the questionnaire. In total, 30 experts in relevant departments and institutions were used to complete the study.

The results of the study showed that from soil capability aspect soil erosion rate index and in terms of soil organic carbon index have the most validity in measuring soil security. In relation to soil security, the index of cultural values has a high priority to measure soil security. Also, in this dimension, indicators of active soil science graduates, soil management skills and access to statistics and information were removed. In terms of soil capital, the index of total production is a highly reliable index for measuring soil security. In this dimension, three indicators of wet or dry agricultural land, trading value of land and benefit from irrigation water were removed. In the dimension of soil security legislation, the index of soil protection projects is mentioned as the most valid indicator for measuring soil security.

This study is the first attempt to collect indicators of five dimensions of soil security to evaluate soil security in Iran. Identification of soil security assessment indicators has led to obtaining a list of important indicators approved by the country's soil experts, which can be made available to other researchers in the future to assess the soil security situation in different parts of the country. According to the study process, a total of 38 indicators were identified and validated for each dimension of soil security. Finally, eight indicators were removed from this total in the study process.

Rice is one of the most important agricultural products in the world. Rice cultivation in Iran has great economic and social importance. Mazandaran province is one of the most important rice production centers in Iran, accounting for 44% of the Iran's rice production. Due to the high consumption of water in the agricultural sector, the optimal use of water resources in agriculture is necessary.The water required by rice is directly related to evapotranspiration. The most reliable method of calculating evapotranspiration is using a lysimeter. The purpose of this experiment is to calculate the evapotranspiration of different varieties of rice using mini-lysimeters and to introduce the best variety for cultivation.

The experiment was conducted as randomized complete block design with three replications and eleven treatments, at Rice Research Institute of Iran (Amol) during the 2020. The treatments included different rice varieties in 11 levels T1: AR2, T2: AR6, T3: AHS, T4: DAH, T5: 1117, T6: 952, T7: 956, T8: E104, T9: S715, T10: Tarom, and T11: Shiroodi. Mini lysimeters with open bottom and closed bottom had a diameter of 60 cm and a height of 50 cm. Field soil was sampled from 0 to 30 cm depth and studied in the laboratory. The date of transplanting was similar in all rice cultivars The planting density of seedlings was 20×20 cm and 7 seedlings were placed in lysimeter. The lysimeters were placed 6 cm above the ground in the soil. The seeds were planted in a treasury and the seedlings were placed in the lysimeter after 30-35 days (after 3-4 leaves and height 25-20 cm). Water management in lysimeters was in the form of flooding (5 cm). Finally, variance analysis of the obtained data was done using SAS software and the mean of the treatments were compared through the least significant difference (LSD) test at 5% probability level.

The results showed that different varieties and lines of rice was effective on infiltration, evapotranspiration, yield, water consumption and were statistically significant at 1% level of probablity. The highest and lowest evapotranspiration with averages of 4938.7 and 3747 m3/ha belonged to T9 and T5 treatments, respectively. The highest and lowest yields with averages of 7773.7 and 2938.1 kg/ha belonged to T8 and T6 treatments, respectively. The highest and lowest values of deep percolation were observed with averages of 303.3 and 185.3 mm in T9 and T5 treatments, respectively. The highest and lowest amount of applied water with averages of 9972 and 7600.3 m3/ha belonged to T9 and T5 treatments, respectively. The highest and lowest water productivity with averages of 0.98 and 0.3 kg/m3 were related to T8 and T9 treatments, respectively. The results showed that the length of the plant growth period was different in the tested cultivars and lines and it was effective on the amount of water consumption..

Finally, in the normal conditions of the region, line E104 is introduced as the best treatment due to the production of maximum grain yield, while in water shortage conditions, the line 1117 is recommended for planting due to less water consumption.

The source of many qualitative and quantitative problems of water resources is the activities that are done in a watershed. Therefore, reviewing the planning strategies of watershed can lead to the reduction of these challenges therefore it is necessary to assess the effects of operating of these strategies before implementing them.

This research is carried out in the Hashtgerd basin is located in the central part of Alborz province. After making the semi distributed hydrological model (SWAT), this model has been developed to convert quantity and quality of surface water resources. For this purpose, the statistics of hydrometric stations Fashand, Dehsomeh and Najmabad and qualitative data of nitrate of the index station were calibrated and validated as control points. After model sensitivity analysis, its calibration process was conducted using SWAT-CUP software with SUFI2 algorithm and 500 iteration and the best values of selected parameters were obtained. Then, impact of implementing management scenarios are required such as modifying cropping pattern and improving irrigation methods to enhance the agricultural efficiency for improving agricultural state and reducing the contaminations. At last assessing the vulnerability of the Hastgerd aquifer using seven DRASTIC parameters by overlaying layers, ranking and weighing was assessed.

The results of the monthly surface runoff simulation were tested by Nash-Sutcliffe indicators and coefficient of determination. The results above 0.7 which showed that the simulation was done with good precision showed that simulation was done with proper precision(results over 0.7). The results of the Nitrate calibration and validation show that the NS was 0.83 and 0.7 and the R2 was estimated .87 and 0.89. These values indicate the proper performance of the model and approve high correlation between the observed and simulated data. After determining the vulnerability map of the Hashtgerd aquifer along the density of wells correcting the weights of the model layers, the central part of the plain is the most vulnerable.

Two management scenarios were modeled including the change in the cropping pattern and improvement of the irrigation efficiency to assess the quality and quantity variation in surface resource. It was indicated, by modifying the cropping pattern and reducing water exploitation, the amount of surface runoff was increased. However, the density of Nitrate was reduced by 5 to 20 percent in different months. With implementation of scenarios, the water consumption in the agriculture sector will be reduced from the 85.3 MCM to 59.8 MCM. The final vulnerability index of the aquifer varied between 44 to 90 by using DRASTIC method.

Because safflower contains more than 90% of unsaturated fatty acids, it can play an important role in expanding the area under cultivation of oilseeds and providing oilseeds in the country. Considering the lack of water and the need to investigate the behavior of the safflower plant in low irrigation conditions, it is necessary to have a proper estimate of its performance under water stress conditions. This oilseed plant needs areas with little winter and spring rainfall during the flowering period and is drought tolerant and has long roots with a high ability to absorb water from deeper soil profiles.

In order to estimate the yield production function and yield components of safflower plant variety Sina under water stress conditions, an experiment was carried out in a research farm located in Kermanshah province. This research was conducted using the data collected in two crop years in a research farm in Kermanshah. The yield response factor was implemented at three levels of 70, 60 and 30% of water requirement based on soil moisture balance in three iterations. Based on the data of the first year, the two production functions of Raes and Tafteh, yield response factors of the plant were determined and evaluated using the data of the second year. To calculate the growth degree day (GDD), two methods of direct calculation and modified average were used. The maximum possible temperature for growth is about 30 degrees and the minimum temperature for growth is 0 degrees as the recommended and acceptable low limit (no trend). In this research, the maximum value of 30 degrees and the base temperature value of 4 degrees were taken from the water requirment system database(niwr.ir). Then different periods of phenology were calibrated with this index. Also, the relationship between GDD index and transpiration evaporation coefficients and yield response factors and irrigation requirement were investigated.

The findings showed that the yield response factors of safflower plant to water stress varies between 0.5 and 1.2 in different growth periods and the highest sensitivity is in the flowering period and the middle period of this plant. Also, the results of the investigation of the two production functions showed that the values of the statistical indicators for both functions are the normal error value of 5% and the efficiency value of both functions is about 97%. The results show that the lowest average evapotranspiration in different treatments was related to the 30% water requirement treatment with 189.8 mm and the highest was related to the 100% water requirement treatment with 632.7 mm.

Based on the obtained results, the Sina safflower plant is most sensitive to dehydration in the middle and flowering stages, and the yield response factors reaches its maximum in this stage (about 1.2) and water stress is not recommended at this stage. On the other hand, Rees and Tafteh function with the presented yield response factors can estimate the results with acceptable accuracy in water stress investigation based on the presented coefficients. On the other hand, in the absence of plant data and complete meteorological data, only by using the GDD index can evaluate the values of plant coefficient and plant sensitivity to water stress and plant irrigation requirement  with appropriate accuracy.

pollution of water resources and the increase of pollution in natural water resources such as lakes and wetlands, considering their fragile nature, as one of the crises facing the country, in addition to the inflow factors, depends on the quantitative situation in aquatic ecosystem itself. On the other hand, the important problem of Anzali wetland as the area studied in this research is the increasing pollution of its water in the fragile conditions of climate change. Therefore, considering the main problem raised for Anzali wetland, the aim of the research was to investigate the water quality index in the inlet streams of Anzali wetland. .

in this research, in order to collect the required information in the period of 2019-2019 in the study area of Anzali wetland, the monthly rainfall statistics of different meteorological stations from the General Directorate of Meteorology and Statistics and geological maps and the characteristics and values of the hydraulic coefficients, wetland extension limits, possible observation station data, seasonal and permanent rivers' measured rivers’ flow data, tolls and rivers' location limits were obtained from the regional water joint stock company. In this study, using the water quality analysis code (UWQV), the amount of water quality changes in the seasonal periods of Anzali lagoon was analyzed in Sentinel-2 and Sentinel-3 images.

The average spatial distribution of the green spectrum (chlorophyll index) in different seasons showed that its numbers indicate the status of the quality index and chlorophyll, so that it is equal to 0.15 in autumn, 0.13 in winter, 0.06 in spring, and the summer season was equal to 0.13. The statistical results of the discharge of the rivers leading to the Anzali wetland, in all the coordinates of the lagoon lake, a similar seasonal trend was observed between the discharges due to the similarity of the feeding catchment basin, and this is while each of the average figures is 27 respectively. 0.0, 0.23, 0.08, 0.08 and 0.23 have shown the standard deviation of coordinate distribution.

Analyzing the water quality of Anzali wetland based on the changes in the chlorophyll index, and the changes in the amount of chlorophyll from one season to another showed a strong fluctuation, which confirmed the results of this research compared to other researchers. Also, the state of water health sediments shows a strong fluctuation in autumn, winter, summer, and spring seasons to a large extent.

Biochar is a carbon-rich charcoal material resistant to decomposition, which is produced by heating biomasses in an oxygen-free environment or with limited oxygen. It is used with the aim of increasing organic carbon and improving the physical, chemical and biological characteristics of the soil. Thus its use in the low-fertile soils of hot and dry regions of Iran, which are often deficient in organic carbon, is important. Addition to its high stability in the soil, biochar can sequester atmospheric carbon dioxide in the soil for several hundred to several thousand years. In addition, it can improve soil fertility for a long time by affecting its physical, chemical, and biological properties. The stability of biochar is affected by several factors, such as the characteristics of biochar and soil, the interaction of biochar with soil components and environmental factors, which are examined in this article. Therefore, it is important to use biochar in the soils of arid and semi-arid regions of Iran, which are often deficient in organic carbon.

In this review article, while investigating the evidences of the high stability of biochar in the soils, the   most effective factors the fate of biochar in the soil, including the mechanisms of biochar removal from the soil, biochar stabilization in the soil, and interactions of biochar with soil components, and the gaps and required research areas are presented.

Biochar is higher resistant to degradation than the original carbon compounds in biomass. However, by interacting with soil components, biochar undergoes changes over time and is removed from the soil. The intensity of these changes and biochar residence time in the soil depends a lot on the type of biochar; So, biochars produced from grassy biomass and biochars produced at low temperatures are less stable. In addition, biochar interacts with all soil components, including organic matter, mineral particles, nutrients, living organisms, and soil water and atmosphere, and the result of these interactions determines the stability of biochar in soil. External factors such as the presence of plant and induced root changes, wind and water erosions, leaching, and fire also affect the fate of biochar in the soil. Among these, considering the interactions between microorganisms and biochar in soil, it seems that soil microorganisms play the most important role in the decomposition and destruction of biochar in soil. However, mechanisms such as the entrapment of biochar particles inside aggregates, binding of biochar with organic and inorganic components of soil, and inactivation of soil enzymes by biochar can increase the stability and durability of biochar in soil.

Considering the very high stability of biochar in soil and the necessity of increasing soil organic carbon as the main factor of soil fertility factor, the use of biochar in Iranian soils it can directly and indirectly improve the fertility of these soils while increasing soil organic carbon. However, after biochar is added to the soil, it interacts with the soil components and its characteristics change and evolve over time (aging). However, due to the novelty of biochar technology and the wide range of its application fields, our information on its interactions with various soil components, its long-term changes and developments in the soil and environment, and its long-term effects on the soil and the environment are not yet clearly defined and much research is needed in this field.