A comparative Study of the Content of some Microelements in the Soil of the Mouradia Agricultural Project in Babil Governorate

The current study included the selection of three agricultural fields from the soil of the Muradia Agricultural Project of the Directorate of Agriculture in Babil Governorate. Thirty-four samples were taken from them at a surface depth of 0-30 cm, for the purpose of a comparative study of the content of some microelements through soils of various fields with agricultural use. As the size distribution of the soil classes was mostly dominated by silt, and thus the type of tissue ranged from a silty clay mixture to a silty mixture. The soil interaction values ranged between 7.0-7.90, and the electrical conductivity ranged between 1.31-6.23 ds m-1 in all study soils, except for the unexploited comparison soil samples in which the soil interaction values were between 7.36-8.30, and the electrical conductivity ranged between 8.39-24.36. ds m-1. The soil content of organic matter was 10.30-20.00 and 3.40-9.60 g kg-1, respectively. The values of the exchange capacity of the positive ions varied in the soils of the current study, as they ranged between 9.090-14.9 cmol charge kg-1, and its height in other soils ranged between 16.5-25.91 cmol charge kg-1. The values of available iron ranged between 4.12-8.39 mg kg-1 in all the study soils, except for the unexploited comparison soil samples in which it was 4.04-7.63 mg kg-1, while manganese ranged between 5.20-3.55 and 3.16-4.88 mg kg-1, respectively. While copper is between 0.86-2.58 and 0.81-1.99 mg kg-1, respectively, and zinc is 0.87-1.51 and 0.78-1.06 mg kg-1, respectively.


Introduction
The study of the reality of fertility and the behavior of micronutrients acquires an importance no less than the importance of macronutrients such as nitrogen, phosphorus and potassium, for their vital role in increasing production and improving quality.It is necessary to determine the fertilizer needs of the microelements, depending on the characteristics of the soil.This requires evaluating the fertility of these elements in agricultural soils by determining and estimating their content available for the plant [1].Accordingly, the study was directed to achieve the following objectives:  Studying the size distribution of the soil classes of the Mouradia Agricultural Project. Studying some physical and chemical properties of the soil of the current study and evaluating the availability of micronutrients (iron, manganese, copper).

Materials and Methods
The study area was chosen at the site of the Al-Muradia Agricultural Project of the Directorate of Agriculture in Babil Governorate, which is about 20 km south of the city of Hilla, the center of the governorate.23`08``-44°23`29``E.As it was determined by the location device (GPS), and geographically the study area is located within the sedimentary plain, the central part of Iraq, bordered from the north by Baghdad governorate, from the south by Najaf and Diwaniyah governorates, from the east by Wasit governorate, and from the west by Karbala and Anbar governorates, as Babil governorate is one of the Euphrates governorates middle.The site for sampling was determined in the study area by selecting three fields from the Mouradia Agricultural Project, the first field is exploited with the wheat crop in the previous season and operations are being added to it, and the second field is exploited with the millet crop in the previous season without any addition of fertilizers and the third field is not exploited (a deserted field), as the three fields were networked and the distance between each site and another was random, and the samples were obtained from the surface depth 0 -30 cm, with 10 samples for the first field, 10 samples for the second field, and 14 samples for the third field, as the total samples obtained were 34 samples, and their coordinates were determined by a device GPS and the auger drilling machine was used to obtain these samples.Thirty-four samples were collected from the three fields representing the study area, air-dried and ground with a wooden hammer on plastic pieces, then passed through a plastic sieve with a diameter of 2 mm, and kept in plastic boxes.Scientific methods and all necessary requirements were followed in preparing the samples to conduct physical and chemical analyses.The pipette method mentioned in [2] was used to determine the proportions of the soil separations, as the separations (sand, silt, and clay) were calculated, and the texture classes of the study soils were determined by the special triangle of the proportions of the initial particles represented by sand, silt, and clay, according to the classification of (USDA).Removing the binding materials represented by calcium carbonate, by adding acidified sodium acetate at pH = 5, removing the organic matter by hydrogen peroxide with a concentration of 30%, and adding the dispersed substance (hexa metaph sphate Sodium) for the purpose of dispersing those particles.The degree of soil reaction was estimated using the glass electrode in an extract.Soil (1:1) according to the method mentioned in [3] The electrical conductivity (ECe) was estimated in the soil extract (1:1) by means of the Ec-Meter.The organic matter was estimated in two samples.The soil was treated by wet oxidation method, using potassium dichromate according to the method of [2].The exchange capacity of the positive ions (CEC) was estimated by the sodium acetate method as mentioned in [4] .Iron, manganese, zinc and copper (ready) were extracted from the soil using the chelated compound DTPA and calcium chloride, as a solution was prepared containing M (0.005) of the compound DTPA (Diethylenetriamine pentaacetic acid) with M (0.01) calcium chloride (CaCl2.2H2O)with M (0.1).Triethanolamine (TEA), the reactivity of the solution was set at 7.3 according to the method of [5]

Size Distribution of Soil Classes
Table 1 shows the size distribution of the soil classes of the study site, and the tissue class, as the silt separation content ranged between 310 -610 g kg -1 .The soils exploited with the wheat crop recorded the highest content of silt separation, while the lowest was in the soils exploited with the millet crop.
As for the content of clay separation, it ranged Between 127 -550 g kg -1 , as it was the highest content in the exploited soils of the wheat crop and the lowest in the abandoned soils.While the sand particles recorded a content ranging between 60-406 g kg -1 , and the highest was in the soils of the left and the lowest in the soils exploited with the wheat crop.The results indicated the dominance of SiCL and SiL in most of the study soils.And that the distribution of the soil classifiers of the study reflects the state of the soils within the sedimentary plain region, of which the study soils are part of, resulting from the sedimentation of the Euphrates River after the decrease in the velocity of the water current in it at this site, which led to a high content of silt and clay particles in its soil at the expense of the content of sand particles.It reflects the remoteness of the study soils from the source of river sedimentation and the velocity of the flow rate, which gives strength to the water by carrying the weakly gradated particles at distances less than the fine particles that are easy to carry to greater distances [6] .The high content of silt is due to the conditions of sedimentation and the nature of soil use, as the increase in the content of silt and its distribution within high ranges is due to the effect of sedimentation, addition, transportation and soil management processes.The river, the area was affected by ancient floods, the area was affected by dust storms, the area was affected by sedimentation processes.It is noted that the clay content came second after silt in terms of dominance in the soils of A study, as agricultural operations have little effect on the distribution of clay content, as well as the impact of movement and movement of clay mechanically with irrigation water and plant roots on the distribution of clay content in those soils [7].

Soil Reaction pH Soil
According to the results of Table 2, the soil reaction values (pH) ranged between 7.00-8.30,as the soils of the study area are classified as neutral to moderately basic.That these values fall within the normal range of values of the degree of soil interaction measured in Iraqi soils that reflect the calcareous nature of it [8], and are identical to what [9] indicated that the range of soil interaction degree for arid and semi-arid regions ranges between.7 -9, and the reasons for this can be attributed to the fact that the study area is among the sedimentary soils of calcareous origin in which basic positive ions predominate [10].
Table 2. Some chemical properties of soil samples at the site of the current study.

Electrical Conductivity
Table 2 shows the values of the electrical conductivity, which ranged between 1.31-24.36ds m -1 in all the study soils, and the highest value was in the uncultivated soils, and the lowest value in the soils exploited in the cultivation of the wheat crop (fertilized), and that this wide variation in the conductivity values Electricity is attributed to the effect of the ground water level rise and the concentration of salts in it and the movement of part of it by the capillary characteristic, and the prevailing climatic conditions of high temperatures and the amount of high evaporation and lack of precipitation, and leaving the soil without cultivation, all of which encourage the accumulation of salts on its surface with the passage of time and the high values of electrical conductivity in uncultivated soils, while soil cultivation processes and the role of agricultural exploitation that provide moisture reduce the salt concentration in The soil, in addition to what the exploited soils are exposed to from a variety of agricultural services, including irrigation operations, and successive washing that contribute to the dissolution of salt ions and their descent to the bottom, and thus reduce these The values in the exploited soils, which indicates that the studied soils have very low salinity to high salinity according to the specifications of the hydrological soil survey and its investigations in Iraq [11] .Especially since these soils are dominated by magnesium and calcium chloride salts, as a result of the accumulation of unhydrated salts represented by sodium and magnesium chlorides and sulfates [12].The salinity content is a determining factor for soil fertility and crop cultivation, as the salts affect the physical properties and the movement of water within the soil body and the accompanying deterioration of the building condition and soil porosity, which is reflected in the availability of nutrients in the soil [13].

Soil Organic Matter Content
The results showed in Table 2 the values of the total content of organic matter for the study soils, as its content ranged between 3.40-20.00g kg -1 , and the highest content was recorded in the soils exploited in the cultivation of the wheat crop (fertilized), and the lowest value in the uncultivated soils (comparison soils), As it appears through the results that the content of organic matter was variable in the soils of the study, and that this discrepancy is due to the nature of agricultural exploitation and its role in secreting quantities of organic matter, as well as the type of vegetation, as [14] showed that the variation in the distribution of organic matter in the soil It is due to the difference in the type of vegetation cover, and the difference in the rate of decomposition of plant residues due to the variation in biological activity and the ability to decompose organic matter and sequester it in the surface layer due to the effect of the dominance of minerals forming complexes on the surfaces of their ion exchange.Observing the results, it appears that there is an increase in the amount of organic matter in the soils of the study and its accumulation in the surface layer as a result of the accumulated residues of plant residues, or it may be due to the presence of vegetation cover left in some of these soils for a significant period of time because they are not exploited agriculturally.

The Exchange Capacity of Positive Ions
The results of Table 2 show that the values of the exchange capacity of the positive ions for the study soils ranged between 9.09-25.91cmol charge kg -1 , and the highest value was in the soils exploited with the (fertilized) wheat crop, and the reason for that is attributed to the root zone of the crops grown in the soil, especially wheat.The effect of increasing the content of organic matter and the exchange capacity of positive ions, which reflects the ability of the soil to retain nutrients and the ability to supply it to plants [15].The lowest value is within unexploited soils, as these values were different in the study soils, and the reason for this is due to the difference in the total content of organic matter, the degree of its decomposition, the soil content of soil composts, and the type of clay minerals in it.In addition to the role of organic matter in its effect and the negative charges it carries that have the ability to adsorb positive ions and thus raise the values of the exchange capacity of positive ions [16] and the role of the amount of clay in increasing the exchange capacity of positive ions [17].In general, it was The study soils are low in the exchange capacity of positive ions, despite their content of organic matter and clay.The reasons for this can be attributed to the fact that the study area is of sedimentary soils of calcareous origin in which basic positive ions predominate, as the carbonates work on encapsulating the surfaces of clay minerals, which leads to blocking sites exchange and thus reduce the values of the exchange capacity of the positive ions.

Iron Available
Table 3 indicates that the content of available iron in the soil exploited with the wheat crop ranged between 5.18-8.39mg kg -1 , and its content in the soil exploited with the millet crop ranged between 4.12-7.85mg kg -1 , while its content in the soil left (uncultivated) ranged between -4.04 7.63 mg kg -1 , as it is considered a good ready-content soil, according to the values determined by [1] by the extraction method of DTPA and calcium chloride, and the reason is due to the conditions of sedimentation and the surrounding conditions, so the extraction solution is regulated at the reaction point 7.3 and that 60% of calcium The additive in the form of calcium chloride binds with the chelated compound DTPA, as it works to create a balanced system at the mentioned reaction degree of the extraction solution, and 75% of the compound Triethauolamine (TEA) ionizes in the form of HTEA +, which exchanges with the calcium and magnesium ions that dominate the exchange complex in soil systems Calcium, and this works to increase its content in the soil solution, which leads to raising the degree of interaction and hinders the dissolution of carbonate minerals present in the soil, which encourages the chelated compound (the remaining amount of it) to bind with iron and extract it, which may represent ready-made iron plants, and this was shown by the results [18] .As the superiority of DTPA and calcium chloride is attributed to the efficiency of the chelating compound DTPA and its high ability to chelate it and bind to ready-made soil iron and its formation of complexes with high stability and stability, because it possesses chemically active groups such as the groups of amines NH2 and groups of acetate CH 3 COO-in the form of ring or open chains linked to iron with two types of bonds: Covalent and coordinate bonds), which gives it high stability in different soils, especially calcareous, with a reaction degree (7.8-8.4).It is also attributed to the high organic matter content of the surface soil, which increases the process of binding nutrients, including iron, to the organic matter, and thus increases the available iron content in the soil [19].Or the reason may be due to the redistribution of soil ions, including iron, during the summer, as the high temperatures cause the elements to move by capillary action towards the surface of the soil and thus accumulate, or it is due to the help of the growing roots by drawing the iron ion from the deep horizons and accumulating it in the surface horizons.Hence the accumulation of iron ions in the soil surface.

Manganese Available
Table 3 indicates that the available manganese content in the exploited soils of the wheat crop ranged between 4.12-5.20 mg kg -1 , and its content in the exploited soils with the millet crop ranged between 3.55-5.08mg kg -1 , while its content in the soils left (uncultivated) ranged between -3.16 4.88 mg kg -1 , as it is considered a good ready-content soil, according to the values determined by [1] by the DTPA extraction method.On solubility within wide limits of the degree of reaction, also due to the possibility of the extraction solution DTPA used in withdrawing an amount of manganese bound with lime even though it is not ready for the plant, as the extraction solution can extract manganese from soil components except manganese associated with sand, silt and clay according to what He mentioned it [20].It is also attributed to the high organic matter content of the surface soils, as the organic matter works to increase manganese through the formation of complex compounds (organic -mineral).Or the formation of manganese chelating compounds in the soil solution, which increases the process of binding the Mn element to the organic matter, and thus increases its manganese content and makes it ready.

Copper Available
Table 3 indicates that the content of available copper in the soil exploited with the wheat crop ranged between 0.97-2.58mg kg -1 , and its content in the soil exploited with the millet crop ranged between 0.86-2.32mg kg -1 , while its content in the soils left (uncultivated) ranged between -0.81 1.99 mg kg -1 , as it is considered a good ready content soil, according to the values determined by [1] by the DTPA extraction method, due to sedimentation conditions and the surrounding conditions, and due to the high surface soil content of organic matter resulting from the addition of organic matter from Plant residues and their roots that work to reduce soil interaction, which increases the readiness of copper, in addition to that the organic matter has a high affinity with copper even when copper is present in low concentrations, which increases the process of chelation of the copper element and thus increases the soil content of copper.

Conclusions
 The soils of the study area vary in salt content, especially the left soils.
 Soil reaction values were inclined towards basicity and were close in all soil samples. High conductivity values in the left soils. The volumetric distribution of the soil classes was dominated by silt, and the texture ranged from mixed silty to silty mixed. The results showed that the readiness of the elements in the soils of the study varied between medium and good.

Table 1 .
Size distribution of soil classes of the current study fields and texture class.

Table 3 .
Iron, manganese and copper prepared in the study soils