Evaluation of the Readiness of NPK Elements for the Soils 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, in order to evaluate the readiness of NPK elements through the 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 mg 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 9.09-14.9 cmol charge kg-1, and its height in other soils ranged between 16.5-25.91 cmol charge kg-1. The values of available nitrogen ranged between 23.00-48.18 mg kg-1 in all the study soils, except for the unexploited control soil samples in which it was 22.15-30.16 mg kg-1, while phosphorus ranged between -17.54-31.20 and 8.20-17.20 mg kg-1, respectively., while potassium ranged between 175.11-205.16 and 149.30-165.22 mg kg-1, respectively.


Introduction
Soil is a natural resource that is not equal to any other natural resource.An important position because of its wealth, as agricultural production depends mainly on the soil, as the good and permanent exploitation of agricultural soils means full use of it, and it also means raising its fertility and increasing crop productivity by applying modern methods in agriculture, and thus it can play a prominent role in agricultural development [1].Soil fertility is one of the main priorities that must be noted in soil management programs, as soil fertility works are among the tasks that must be evaluated in agricultural projects because of their relevance to production and control over its accuracy [2].Fertility assessment includes a number of operations that use field and laboratory diagnostics to find out the deficiency in nutrients and evaluate them for appropriate purposes for the best use of crop cultivation, as nitrogen, phosphorus and potassium are among the necessary and specific elements in 1259 (2023) 012006 IOP Publishing doi:10.1088/1755-1315/1259/1/012006 2 plant growth and increased productivity [3].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 Npk nutrients.

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 [4] 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 [5].
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 [4].The CEC exchange capacity was estimated by the acetate method Sodium as mentioned in [6].The available nitrogen in the soil was estimated by extracting the soil with a potassium chloride solution (KCl2 2M) using magnesium oxide, and the nitrate ion was reduced to ammonium by Devardaalloy and distilled after volatilization using the microcalcification device and flushing with sulfuric acid (H2SO4 0.005N) according to the method of Nelson and Keeney presented in [7]The available phosphorous in the soil was estimated by soil extraction with a sodium bicarbonate solution (0.5 M NaCo3) according to the Olsen method mentioned in [7], and the color of the extract was developed by means of ammonium molybdate and ascorbic acid, and it was measured using a spectrophotometer at a wavelength of 882.nanometers.Potassium (available) was extracted from the soil with a solution of ammonium acetate (NH4OAC) (1N) at pH = 7 according to the method presented in [7], and the measurement was done by means of a flame photometer.

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 [8].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 effect of movement and movement of clay mechanically with irrigation water and plant roots on the distribution of clay content in those soils [9].

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 [10] , and are identical to what [11] indicated that the range of soil interaction degree for arid and semi-arid regions ranges between.9-7, 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 [12].

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 [13].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 [14].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 [15].
Table 2. Some chemical properties of soil samples at the site of the current study.

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 20.00-3.40 g 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 [16] 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 [17].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 [18], and the role of the amount of clay in increasing the exchange capacity of positive ions [19].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.

Nitrogen Available
The results of Table 3 indicate that the available nitrogen content in the exploited wheat crop ranged between 36.20-48.18mg kg -1 , and its content in the exploited soils with the millet crop ranged from 32.00-41.16mg kg -1 , while its content in the abandoned soil ranged between 22.15-30.16mg kg -1  Noting that its content in cultivated soils is higher than its content in abandoned soils, due to the effect of agricultural exploitation in increasing its content, as the nitrogen element is subject to loss, leaching, movement and volatilization from the soil body, which leads to a variation of nitrogen in cultivated soils and abandoned soils.Good soil ready content in the soil identified by [3].The reason is that the surface soils have a good content of organic matter decomposed by microorganisms, in addition to the plants present on the surface of the soil that add nutrients, especially the nitrogen element, which leads to an increase in it.in the surface soil.This concept is consistent with what was found by [20], who indicated that organic matter is a criterion for soil quality and biological transformations and is used as a source of information for soil management.He mentioned that the addition of plant residues and their presence on the surface of the soil are in a state of decomposition due to their attack by microscopic soil organisms, and as a result, the nutrients important for plant nutrition, including nitrogen, increase.

Phosphorous Available
The results of Table 3 indicate that the content of available phosphorus in the soil exploited for the wheat crop ranged between 19.19-31.20 mg kg -1 , and its content in the soil exploited for the millet crop ranged between 17.54-25.19mg kg -1 , while its content in the soils left (uncultivated) ranged between 8.22 -17.20 mg kg -1 , as it is noted that the content of phosphorus in the exploited soils is higher than its content in the abandoned soils, and the reason is attributed to what was explained by [21] that the cultivated soils have the ready phosphorus higher than the abandoned soils (uncultivated).He attributed the reason to Additions of organic matter from plant residues and roots that reduce soil interaction.Which increases the readiness of phosphorus in the soil, and this was confirmed by [22] They pointed out that the addition of organic matter to the soil that is poor in it, after its agricultural exploitation, will work to increase the readiness of phosphorus by reducing the interaction of the soil, albeit in a limited way.In general, it is noted that the content of phosphorus varies between average and good according to the available phosphorus values in the soil that were determined by [3].It achieves two functions: the formation of complexes and the chelation of minerals, thus ensuring its survival in pursuit of the surface of the roots, in addition to its important role in facilitating the entry of major elements, including phosphorus, in the form of chelating compounds, into the roots [20].
Table 3.The available nitrogen, phosphorous and potassium in the study soil.

Potassium Available
The results of Table 3 indicate that the available potassium content in the exploited wheat crop ranged between 188.12-205.16mg kg -1 , and its content in the millet crop soils ranged between 175.18-190.24mg kg -1 , while its content in the left (uncultivated) soil ranged between 149.31 -165.22 mg kg -1 , as it is considered a good soil content, according to the values set by [3].This indicates that there is no potassium deficiency in all soil samples of the study, which means that there is no need for fertilization in order to raise crop production.Which require high amounts of potassium The reason for the increase in the available potassium in cultivated soils may be due to the processes of adding organic matter by cultivated plants and thus decomposing it by various microorganisms and thus the release of nutrients, including potassium [23], or due to the addition of fertilizers Potassium As for the reason for the high potassium in the left soil (unexploited agriculturally), it is due to the fact that the salinity of the soil has a great effect on the liberation of potassium in the soil and that the presence of naturally occurring salts or fertilizer salts in the soil increases the speed coefficient.Potassium liberation, that is, the left soil increases in the available potassium [24].

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.