Impact of perlite and biochar on barley growth and output in clay soil

A field experiment was conducted in clay-textured soil during the agricultural season 2021-2022 at Al-Muthanna Governorate, Al-Suwayr District - Albugrad region, longitude "5. 16' 36°31, and a latitude '0'. 52' 27 ° 45, to study the effect of biochar and perlite on the growth and yield of barley in clay soil. The experiment used a Randomized Block Design (RCBD) with two factors and three replicates. The biochar factor treatments included four levels of biochar at the level (0% B0, 0.5% B1, 1% B2, 1.5% B3). In comparison, the treatments of the second factor perlite included four levels. They are the addition of agricultural perlite at the level (0% P0, 0.5% P1, 1% P2, 1.5% P3). Mixing biochar with agricultural perlite for all treatments with soil to a depth of 30 cm. Barley ( Hordeum vulgare L.) cultivar Iba 99 was planted on 1/11/2021. Crop service operations were carried out from adding chemical fertilizers, jungle control and irrigation until the end of the ex-periment and harvest on 9/9/2022. The results showed the superiority of the B3 biochar treatment (1.5% biochar) in improving most of the physical and chemical properties of the soil, plant height, number of branches and total yield, the superiority of the B2 biochar treatment (1% biochar) in recording the highest weight of 1000 grains, the treatment of perlite P1 (0.5% perlite) was superior in recording the highest weight of 1000 grains, the superiority of the B3P3 interaction treatment in recording the highest value of the number of branches in the plant


Introduction
Today, the world's countries are facing significant challenges in the agricultural field, including Iraq.At the forefront is achieving sustainable food security based on increased national production to meet the needs of the growing population of agricultural products, plants and animals.Estimates indicate that the population of Iraq will reach 51 million in 2025 1 .This number will double in 2050, which requires achieving a sustainable increase in agricultural production over the years and decades.It reaches 50% in some crops and 100% in other crops and products 2 .Countries and significant organizations were seeking to confront this modernization that faces agriculture in the world, the share of the Food and Agriculture Organization in achieving food security and preserving natural resources while minimizing the effects of climate change 3 .Developing more sustainable agricultural systems and improving weak rural economies requires significant changes in agricultural management.Soil degradation, including reduced fertility and increased erosion, is a significant concern in global agriculture.Long-term soil cultivation can lead to the deterioration and depletion of organic matter.In recent years, soil degradation must be tackled in simple and sustainable ways.The growing interest in biochar application focuses on amending nutrient-poor soils for ecological restoration, including carbon sequestration.Biochar is a promising resource for soil fertility management; biochar can be defined as a solid fine-grained material obtained by charring biomass in isolation or with little oxygen.It can be added to the soil to improve its properties, increase the availability of elements and reduce environmental pollution 4 .In recent years, many studies and research aimed at reducing water consumption in the agricultural sector have been conducted, including the use of some natural and chemical products that are added to the soil or plants to reduce evaporation and provide as much water as possible for the roots of plants, they were called moisture preservatives.One of these materials is perlite 5 .Perlite is small white granules 1 to 5 mm in diameter, resulting from the heating of silicon volcanic rocks to 900-1000°C and as a result, the grain size increases from 4 to 20 times its original size 6 .This heating creates countless air vacuoles that absorb water up to 430% of its volume, making it accessible to the plant's roots when needed.Agricultural perlite has a high water absorption capacity, as it improves soil aeration and drainage.Thus, the plant roots are ventilated and can retain water and fertilizer for a long.Spacing between irrigation periods reduces water and fertilizer consumption.It also can exchange wave ions and is neutral at a pH between (6.5-75).Therefore, it provides a balanced environment for the interaction of the plant and is considered a sterile medium free of weed and disease seeds.It is an inorganic material and therefore not subject to change or decomposition, which reuses it for several seasons, acts as an insulating material, reduces high temperatures harmful to plants, protects plant roots from extreme temperature drops, is clean and odorless, and is lightweight 7,8 .The barley crop is the fourth crop globally.The second nationally to come after the wheat crop, as it is used as food for humans and fodder for animals and is included in several industries.However, the primary use of it is animal feed, and this crop is witnessing an increasing interest in expanding cultivated areas and increasing productivity globally and locally.Especially in its use for fodder, but in Iraq, the cultivated area for the year 2021 is 3,029 thousand dunums, an increase of 31.7% compared to the 2020 season, and its average yield based on the cultivated area is 86.2 kg/dunum.The barley crop production is estimated at 267 thousand tons in the winter 2021.Through the Muthanna Governorate, the harvested area was 237,858 dunums, and its production was 132,230 tons, with an average yield of 507 kg/dunum.The fluctuation of rainfall amounts from year to year and the insufficient water share, especially in the last decade in the irrigated areas, required adopting an agricultural policy that fits the data affecting production, which is to focus on adopting the appropriate varieties for its cultivation areas with high productive efficiency with minimal German consumption and the adoption of a breeding program The yield corresponds to these goals.Therefore, the current study aims to demonstrate the effect of biochar and perlite on the growth and yield of barley in clay soil.

Materials and Methods
A field experiment was carried out during the winter agricultural season (2020-2021) at Al-Muthanna Governorate, Al-Suwayr District, Albugrad region, which was geographically located at longitude 5".16 ´36°31 and latitude 0´´.52 ´ 27 ° 45 in clay soil.The land was prepared for settlement and modification operations and was plowed by two plows, orthogonally, utilizing a turntable plow, then the soil was softened.Divide the field into three sectors with dimensions of 50 x 200 = 100 m 2 , leaving a distance of 2 m (a guard area) between one block and another and a distance of 1 m between one experimental unit and another.Each block was divided into 16 experimental units with a 2 x 2 = 4 m 2 distance.Barley (Hordeum vulgare L.) cultivar Iba 99 was planted on 1/11/2021 at a seeding rate of 120 kg ha -1 in lines.The distance between one line and another is 20 cm, with 10 lines in each experimental unit.Thinning operations were performed on the plants after germination of the third true epicotyl, adding the chemical fertilizer to all the experimental units evenly and according to the tried fertilizer recommendation.Nitrogen fertilizer was added as urea (N% 46; at 100 kg ha -1 ) 9 in two batches at planting and after 45 days of planting.Phosphate fertilizer was added all at once when planting with 100 kg ha -1 as mono superphosphate fertilizer.Potassium fertilizer was added in an amount of 40 kg ha -1 .Pipes carried out irrigation, and the irrigation water quantities were determined for all experimental units based on the mechanical irrigation meter, adding the amount for the washing requirements until the end of the experiment and harvesting on 9/4/2022.The initial physical and chemical properties were measured and estimated for the field soil used in the study with three replicates for a depth of 0-30 cm according to the methods shown below in Table 1.Soil P.H. was estimated based on Jackson 10 , Electrical conductivity (E.C.) in a soil solution based on Page et al. 11 , the availability of nitrogen, phosphorous and potassium was estimated based on Page et al. 11 , the cation exchange capacity according to Black et al. 12 , organic matter according to Jackson 5 , bulk density according to Black et al. 12 .

Plant height:
The results in Table 3 showed significant differences in the levels of biochar addition in plant height.In contrast, treatment B3 (1.5% biochar) recorded the highest plant height of 80.65 cm, with a significant difference from other treatments except for treatment B1, with an increase of 6.36% compared to the control treatment B0, which recorded a plant height of 75.83 cm.The results showed no significant differences in the values of B1 and B2 treatments.The results in the table showed no significant differences in the levels of perlite addition in plant height, which may not have a role in the plant height process.The results in Table 3 also indicate that there is a significant effect of the interaction between the levels of biochar and perlite, as treatment B0P2 recorded the highest plant height of 86.47 cm, with an increase of 37.98% by the comparison treatment B0P0, followed by treatment B2P0, which reached 85.00 cm.

Number of branches:
The results show in Table 4 that there are significant differences in the plant's biochar addition levels.In contrast, treatment B3 (1.5% biochar) recorded the highest number of branches (4.38) branches per plant, with a significant difference from the rest of treatments B1 and B2, with a significant increase of 28.45% over the comparison treatment B0, which recorded the lowest number of branches per plant, which amounted to 3.41 branches per plant, it was followed by treatment B2 (1% biochar), which amounted to 3.90 branches for each plant, with a significant increase of 14.37%.In comparison, treatment B1 (0.5% biochar) was not significant.The results shown in Table 4 indicate that there were no significant differences in the levels of perlite addition in treatment P3, which gave the highest value for the number of branches, which amounted to 4.06 branches for each plant, despite an increase of 18.21% over the comparison treatment P0, which recorded 3.86 and a significant difference with P1 and P2.The additions P1 and P2 were not significant.The results show significant differences in the interaction between the levels of biochar and perlite added to the soil.The B3P3 treatment recorded the highest value of 4.73 branches for each plant, which did not differ significantly from the level of B0P3 biochar addition.It was followed by the treatment B2P3, which scored 4.53 with a significant increase of 44.73% over the comparison treatment B0P0.

grains weight:
The results in Table 5 show that there were significant differences in the levels of biochar addition in the weight of one thousand grains, whereas treatment B2 (1% biochar) recorded the highest grain weight, which amounted to 36.04 g, with a significant difference from the rest of the treatments except for treatment B3 (1.5% biochar), with a significant increase of 11.65% over the control treatment B0, which recorded a grain weight of 32.28 g, this was followed by treatment B3, which recorded a grain weight of 35.84 g, with a significant increase of 11.02% over the control treatment B0.The results in Table 5 indicate that there are significant differences in the levels of adding perlite to the soil, as the treatment P1 recorded the highest weight of the average grain was 38.02 gm, which differs significantly with all transactions, as for the addition coefficients P2 and P3, there are no significant differences.The results also show significant differences in the levels of interaction between biochar and perlite when added to the soil.Treatment B1P2 recorded the highest weight of the interference, which amounted to 41.16 g, with an increase of 41.93% over the control treatment, B0PO, which amounted to 29.00 g.

Biological yield (ton ha -1 )
The results in Table 6 show no significant differences in the levels of biochar addition in the plant's biological yield values.It indicates in the table that there were no significant differences in the levels of perlite addition in the values of the biological yield.The results in the table show significant differences in the levels of interaction between biochar and perlite added to the soil.In contrast, treatment B0P2 recorded the highest weight of the biological yield, reaching 17.91 tons ha -1 , with an increase of 44.79%, with a significant difference with the addition treatments B0P1, B1P2, B1P3, B2P2, B3P2, this was followed by treatment B0P3 which amounted to 17.78 tons ha -1 , with an increase of 43.73% compared to the control treatment which recorded the lowest weight of the biological yield of 12.37 tons ha -1 .6. Effect of biochar and perlite and their interaction on the plant's biological yield (ton ha -1 ).

Total yield (ton ha -1 )
The results of Table 7 show that there are significant differences in the levels of vegetable charcoal added to the soil in the values of the total yield, whereas B3 outperformed all treatments by registering the highest weight of the total yield, which amounted to 6.27 tons ha -1 , with an increase of 48.23% over the comparison treatment, it was followed by treatment B2, which amounted to 4.77 tons ha -1 , with an increase of 12.77% over the control treatment, which recorded the lowest weight of the total product, which amounted to 4.23 tons ha -1 , as for treatment B1, it was 4.70 tons ha -1 , with a significant difference with comparison treatment B0.The results in Table 7 also showed no significant differences in the levels of perlite addition in the total yield.The table shows significant differences in the interaction levels of charcoal and perlite added to the soil.Treatment B0P3 recorded the highest weight of grains in the interactions, which amounted to 7.18 tons ha1 with a significant difference with all treatments except treatment B3P3, with an increase of 125.79% compared to the comparison treatment B0P0, which recorded the lowest weight of grain yield, which amounted to 3.18 tons ha1, followed by treatment B3P3 which amounted to 6.50 tons ha1 With an increase of 104.40% over the comparison treatment.7. Effect of biochar and perlite and the interaction between them on the total yield of the plant (ton ha -1 ).

Discussion
The reason for the superiority of the B3 addition treatment in increasing the plant height compared to the comparison treatment B0 and the high addition treatments may be attributed to the superiority of the B3 addition treatment in improving most soil properties such as moisture content and weighted diameter rate.This improved the conditions suitable for plant growth, such as balancing soil moisture and stability, positively reflecting the increase in plant height.The decrease in plant height when treatment B2 compared with other treatments, may be due to an increase in the moisture content of the soil significantly beyond the limits of the field capacity, affects air and water balance, negatively reflected on plant growth and height, and these results agree with 13 , 14 .Similarly, The reason for this trait increasing for the interaction treatment B0P2 may be due to the role of biochar and perlite in improving the physical properties of the soil and reducing the electrical conductivity, as well as its role in providing nutrients and their readiness for absorption by the roots, reflected positively in the increase in the spread of roots and plant growth and thus increase in the height of the plant compared to the comparison.Moreover, the superiority of treatment B2 in the weight of 1000 grains may be attributed to the fact that B3 retains nutrients in the soil.These results agree with the findings of 15 that increasing the levels of biochar addition has a positive effect on growth and yield in barley.However, these results were consistent with the findings of Kondrlove and 16 mechanisms that increasing the levels of biochar addition to the soil leads to an increase in the growth of the plant and the vegetative system, which is reflected positively on the biological yield and production.Also, these results were in agreement with the findings of 17 , which shows that the role of organic improvers in increasing plant yield was due to its role in providing the plant with nutrients, especially nitrogen, phosphorous and potassium, and improving the physical properties of the soil, reflected in an increase in the vegetative growth of the plant and thus an increase in the total grain yield 18 .

Conclusions
The results showed the superiority of the B3 biochar treatment (1.5% biochar) in improving most of the physical and chemical properties of the soil, plant height, number of branches and total yield, the superiority of the B2 biochar treatment (1% biochar) in recording the highest weight of 1000 grains, the treatment of perlite P1 (0.5% perlite) was superior in recording the highest weight of 1000 grains, the superiority of the B3P3 interaction treatment in recording the highest value of the number of branches in the plant.