The Role of Biochar and Perlite in Improving some Physical Properties of Clay Loam and Sandy Loam Soil

A laboratory experiment was carried out in the laboratory of the Department of soil sciences and Water Resources, College of Agriculture – the University of Diyala, where the experimental factors was the soil type factor (clay loam and sandy loam) and the soil conditioners agent by adding biochar at the level of 1 and 2% and symbolized by B1 and B2 and perlite at the level of 1 and 2% and symbol it has P1 and P2, and it was added according to the soil dry weight, with three replications, CRD design, and plastic tubes were used to incubate the treatments for 14 weeks. The results showed an increase in the water infiltration in the clay loam soil by an increase of 23% when using biochar ratios 1 and 2%, while the infiltration decreased in the sandy loam soil by a decrease of 16 and 31% when using biochar 1 and 2%, while the use of perlite in the proportions of 1 and 2% increased the infiltration. In the sandy loam soil. This applies to the saturated hydraulic conductivity values. The Bulk density soil decreased when using biochar ratios 1 and 2% in the clay loam soil with decrease rates of 13 and 26%, and it also decreased when using perlite ratios 1 and 2% with decrease rates of 10 and 13%, and it also decreased when using ratios 1 and 2% biochar with sandy loam soil with decrease rates of 11 and 17%. The soil porosity increased when 1 and 2% biochar was used in the clay loam soil with an increase of 15 and 7%, and it increased when 1 and 2% perlite was added in the same soil with an increase of 5 and 6%.


Introduction
Improve some soil properties, different types of conditioners are used, and soil conditioners are among the technologies used to improve the soil of arid and semi-arid regions due to problems related to their physical, chemical, fertility and vital properties that prevent plant growth.Improvers are defined as organic or chemical substances of natural or manufactured origin, as they are classified from a physical point of view into (hydrophobic or hydrophilic substances) that are added to the soil to reduce soil losses due to erosion by improving soil structure, increasing its stability, and improving the water and fertility qualities in the soil.By increasing water and nutrient holding capacity and availability and saving soil from loss [1] Soils with a high content of sand separation are soils with low or no productivity due to their poor ability to retain water, The water quickly infiltrates to the bottom, and these soils are often found in a dry state, and thus they are exposed to wind erosion due to their loose texture and lack of vegetation cover [2].1259 (2023) 012020 IOP Publishing doi:10.1088/1755-1315/1259/1/012020 2 Biochar is a porous organic carbon compound that is produced through the process of pyrolysis of biomass at temperatures ranging between 300-1000 degrees Celsius and under conditions of lack of oxygen.Many studies confirmed that adding it to the soil improves many physical properties of the soil such as Bulk density, total porosity, soil moisture content, and hydraulic conductivity [3].Perlite is a material resulting from heating silicon volcanic rocks from 900 to 1000 degrees Celsius [4].This heating results in countless air gaps that absorb water by 430% of their volume.Perlite is a sterile medium free of diseases, bush seeds, a good germination medium [5] Perlite helps the soil to aerate, and conserve water and is a medium suitable for the growth of plant cuttings.It has a moderate pH and is light in weight.It is used as a carrier for fertilizers, herbicides, and pesticides [6].

Materials and Methods
A laboratory experiment was conducted in the laboratory of the College of Agriculture at the University of Diyala, and clay loam soil samples were used from the Al-Abbar area in Diyala Governorate, which is located at longitude 44° 38' 58.482" east and north latitude 33° 51' 14.326" while samples were taken.Sandy loam soil samples from an area near the shoulder of the Diyala River, which is located at longitude 44° 39' 03.299" east and north latitude 33° 51' 51.210" and the samples were taken from the surface horizon (0-0.3) m.The samples were air-dried and grounded with a wooden hammer and passed through a sieve with a diameter of 2 mm.The experiment was carried out according to a completely randomized design (CRD) with two factors, the first factor is the first soil type which is symbolized by (C) for clay loam soil and the second type is sandy loam soil and its symbol is (S).The second factor included five levels and included perlite biochar treatments, which are: without addition Comparison) for coal and perlite and B 1 adding biochar at the level of 1% and B 2 adding biochar at the level of 2% and P 1 adding perlite at level of 1% and P 2 adding perlite at the level of 2% and added about the dry weight of the soil, an iron base was designed to carry plastic pipes vertically, The treatments were incubated for 14 weeks and hydrated to the limits of the field capacity of each texture.Plastic pipes with a diameter of 0.1016 m and a length of 0.3 m were used, and their concave cover was used, as a central hole was pierced with an auger of 10 mm in diameter, and a layer of gravel 0.02 m thick and a layer of glass wool was placed at the base of the pipe.The surface of the inner pipes was covered with a layer of wax to prevent water leakage from the sides.perlite and biochar are made from wheat crops at a temperature of 300 degrees Celsius with a sieve with a diameter of 2 mm.The water conductivity of saturated soil was estimated by shedding a fixed water column of 1 cm, according to the volume of water descending the column with time.The saturated conductivity was calculated by using Darcy's equation [7].

Ks=VL/(At (h+L))
Since: Ks = saturated hydraulic conductivity of soil (cm m-1 ) V = volume of water coming down from the column (cm 3 ) A = cross-sectional area of the soil column (cm 2 ) t = time (minutes) L = length of soil column (cm) h = height of the water column (cm) The soil water infiltration was estimated using a Mini disk infiltrometer according to [8] method, as the readings were taken every 30 seconds for sandy loam soil and 1 minute for clay loam soil, and the values were calculated using a Microsoft Excel file. Figure 1 shows the parts of the Mini disk infiltrometer.The bulk density was estimated according to the core method, as the diameter and height of the cylinder were 4.9 and 5.1 cm, respectively.The samples were dried in the oven at a temperature of 105 °C for 24 hours.The bulk density was calculated by dividing the dry soil mass by the cylinder volume, as shown.In [9] The particle soil density was estimated using the Pycnometer method and according to the method mentioned by [10].The porosity was estimated from the value of bulk and particle density according to the equation given in [11]: f= {1-ρ b /ρ s } × 100 Since: f = soil porosity (percentage) ρb = bulk density (Mg m 3 ) ρs = particle density (Mg m 3 )

Water Infiltration in Soil (cm h -1 )
Table 1 shows the effect of the addition of biochar and perlite on the values of soil water infiltration cm -1 for the two soil, clay and sandy loam, and the two treatments, with 1 and 2% addition rates for biochar and perlite, as the results showed that the addition of biochar by 2% had a significant effect on the increase the infiltration perlite.In the clay loam soil, its value amounted to 4.04 cm hr -1 compared to the control treatment, in which the infiltration reached 3.10 cm hr -1 , with an increase of 23%, while the addition of biochar at rates of 1 and 2% led to a significant decrease in the infiltration values of the sandy loam soil, as it amounted to Its value was 5.53 and 4.53 cm hr -1 , respectively, compared to the control treatment, in which the infiltration reached 6.63 cm hr -1 , with a decrease of 16 and 31%, respectively.And for the percentage of addition of 2%, as the infiltration reached 4.10 cm hour -1 , with an increase of 24%.As for the sandy loam soil, the perlite increased the water infiltration as its value reached 7.32 cm hour -1 , compared to the control treatment, with an increase of 9%.This means that taking the same letter for each factor or the interaction between them did not differ significantly (P ≤ 0.05) according to Dunkin's multiple range test.
The reason for the increase in water infiltration in the clay loam soil is due to its decrease in density due to the low density of biochar and its high porosity, while in the sandy loam soil, the biochar reduced the soil bulk density and increased the porosity.These results are consistent with the findings of [12], which found an increase in water infiltration in the soil when adding biochar, and because biochar has smaller pores than perlite, it retains water holding for a longer time and a smaller amount than in perlite.Reducing the infiltration in these soils because of the use of biochar compared to the use of perlite.As for the reason for the increase in the values of the water infiltration in the soil when adding perlite, it is because adding it worked to improve some of the physical properties of the two soils, including bulk density and porosity.These results agree with what was preached by [13].

Saturated Hydraulic Conductivity (cm h -1 )
The results presented in Table 2 show the values of the saturated hydraulic conductivity in the clay loam and the sandy loam, and the percentages of adding 1 and 2% to biochar and perlite.The results showed an increase in the saturated hydraulic conductivity when treated with 2% biochar and its value was 0.46 cmh -1 compared to the control treatment of 0.17 cmh -1 for the clay loam soil with an increase of 63%, while the water conductivity decreased when the treatment was 2% biochar and its value was 0.83cmh -1 compared to the control treatment of 1.35 cm h -1 for sandy loam soil with a decrease of 38%.As for perlite percentages, the water conductivity increased when treated with 2% perlite, its value was 0.49 cmh -1 for the Clay loam soil with an increase of 65%, and the water conductivity increased when treated with 2% perlite and reached 2.09 cm hr -1 in the sandy loam soil with an increase of 35%.Biochar worked to increase the water conductivity values in the clay loam soil due to the decrease in the bulk soil density and the increase in its porosity and aggregations, and this is consistent with the findings of [3], while biochar reduced the water conductivity in the sandy loam soil, due to the low bulk density due to the high micropores, which must be filled before draining Water is under the influence of gravity, as found by [14].The use of perlite led to an increase in water conductivity in the two soils, due to the decrease in the bulk density values and the increase in the moisture content values.Thus, it reduces the effect of drying and wetting processes and the accompanying dispersion and demolition of the soil aggregates and the occurrence of blockages to its pores, which lead to a decrease in the water conductivity values, according to what was explained by [13], the increase in water conductivity is a result of the use of perlite with sandy loam soil, this is due to its larger pores compared to biochar.This means that taking the same letter for each factor or the interaction between them did not differ significantly (P ≤ 0.05) according to Dunkin's multiple range test.

Bulk Density (Mg m 3 )
Table 3 shows the values of the Bulk soil density and the percentages of adding biochar and perlite 1 and 2% in the clay loam and sandy loam soils, The results showed a significant decrease in the Bulk soil density in the clay loam soil when treated with 1 and 2% of biochar, and its values were 1.12 and 0.95 Mg m 3 , respectively, compared to the control treatment of 1.30 Mg m 3 , with a decrease of 13 and 26%, The Bulk soil density decreased significantly when treated with 1 and 2% perlite, and its values were 1.17 and 1.12 Mg m 3 , respectively in the clay loam soil with a decrease of 10 and 13%.Biochar significantly reduced the Bulk soil density in the sandy loam soil when treating 1 and 2% biochar, with values of 1.21 and 1.12 Mg m 3 , compared to the control treatment of 1.36 Mg m 3 , with a decrease of 11 and 17%.The Bulk soil density decreased significantly in treatments 1 and 2% for perlite and their values were 1.23 and 1.20 Mg m 3 , respectively, with a decrease of 9 and 11% in the sandy loam soil.Biochar significantly reduced the bulk density of clay soil and sandy loam, due to the decrease in the bulk density of the used biochar, which amounted to 0.34 Mg m 3 , and the decrease in the bulk density of perlite, which amounted to 0.50 Mg m 3 , and because of their high porosity, which is consistent with What was found by [3], and [15].Table 3.The effect of adding biochar and perlite in the values of bulk soil density, Mg m -3 .4 shows the values of the particle soil density for the clay loam soil and the sandy loam and the percentages of adding biochar and perlite 1 and 2%.It was observed that the particle soil density decreased when treated with 1 and 2% biochar, and its density values were 2.46 and 2.31 Mg m -3 , respectively, in the clay loam soil, compared with the control treatment of 2.54 Mg m -3 , with a decrease of 3 and 9%, and it decreased significantly with the same treatments and values 2.58 and 2.49 Mg m -3 , compared with the control treatment 2.69 Mg m -3 at decrease per cent of 4 and 7% in sandy loam soil.The particle soil density decreased when the treatment was 1 and 2% for perlite and its values were 2.47 and 2.42 Mg m -3 , with decreased rates of 8 and 10% in the clay loam soil, and it also decreased with the same two treatments with values of 2.58 and 2.55 Mg m -3 , with decreased rates of 4 and 5%. in sandy loam soil.The particle soil density decreased in the two soils due to the difference in the physical and mineral properties of biochar and soil material, and the high quartz density (2.70 Mg m -3 ) in sandy loam soil compared to the particle biochar density, which is usually less than (1 Mg m -3 ), according to what was found it [12] as for the decrease in the particle soil density as a result of the use of perlite, this is due to the decrease in the particle density of perlite, which amounted to 0.739 Mg m -3 , according to what showed [16].This means that taking the same letter for each factor or the interaction between them did not differ significantly (P ≤ 0.05) according to Dunkin's multiple range test.

Soil Porosity (%)
Table 5 shows the values of porosity in the clay loam and the sandy loam soil, and the percentages of adding biochar and perlite 1 and 2%.The results show that the porosity of the clay loam soil increased significantly when the treatment of 1 and 2% of biochar, which reached 54.18 and 58.75%, respectively, compared with the control treatment of 49.91%, with rates of increase of 7 and 15%., the porosity of the clay loam soil increased with the treatments 1 and 2% for perlite, and its values were 52.70 and 53.66%, respectively, with an increase of 5 and 6%, The porosity of the sandy loam soil increased with the treatment of 1 and 2% for biochar and its values were 53.05 and 54.78% compared with the control treatment of 47.36%, with rates of increase of 10 and 13%, while the porosity of the sandy loam soil increased with the treatments 1 and 2% for perlite and its values were 52.32 and 52.90% for the Sandy loam with an increase of 9 and 10%.

Table 1 .
The effect of adding biochar and perlite on the rate of water infiltration in the soil cm hour -1 .

Table 2 .
The effect of adding biochar and perlite in the saturated water conductivity values of soil cm hour -1 .

Table 4 .
The effect of adding biochar and perlite in the particle soil density values, Mg m -3 .

Table 5 .
Effect of adding biochar and perlite in soil porosity % values.