Impact of acidified carbon on maize growth, yield and grains nutrients concentration under normal irrigation and osmotic stress

2.1 Experimental site and design

A pot study was done in the research area of Pesticide Quality Control Laboratory Multan. The design of the study was a completely randomized design (CRD). Treatments were applied in 2 factorial arrangements of treatment were made i.e., drought levels and AC.

2.2 Acidified carbon

For the manufacturing of AC modified methods of Sultan et al. (2020) was adopted. For pH and EC characterization of AC, deionized water and AC were mixed in a 20:1 ratio (Shi et al., 2017). Digestion of AC was done by di-acid mixture HNO₃:HClO₄ (2:1 ratio) at 280 °C on the hot plate. Phosphorus was assessed in AC via the yellow colour method on a spectrophotometer (Chapman and Pratt, 1961). Potassium, calcium and sodium were determined in digested material by a PFP-7 flamephotometer (Donald and Hanson, 1998). For examining total N in AC, Kjeldhal’s distillation was carried out for (Bremner, 1996). Ash content (AC) and volatile matter (VM) in AC were analyzed by heating at 550 °C and 450 °C respectively in a muffle furnace (Danish et al., 2019). For fixed carbon Noor et al. (2012) equation was used $$\mathrm{F}\mathrm{i}\mathrm{x}\mathrm{e}\mathrm{d}\mathrm{C}\mathrm{a}\mathrm{r}\mathrm{b}\mathrm{o}\mathrm{n}\left(\%\right)=100-(\%\mathrm{V}\mathrm{o}\mathrm{l}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{l}\mathrm{e}\mathrm{M}\mathrm{a}\mathrm{t}\mathrm{t}\mathrm{e}\mathrm{r}+\%\mathrm{A}\mathrm{s}\mathrm{h}\mathrm{C}\mathrm{o}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{n}\mathrm{t})$$

The characteristic of AC is provided in Table 1.

2.3 Drought stress and soil characterization

The drought stress was maintained based on soil field capacity (FC). For control, normal irrigation was provided at the rate of 70%FC (70FC). Mild drought stress was applied by minimizing the irrigation water to maintain the FC of 50% (50FC). For severe drought stress, 30%FC was maintained by irrigation water (Danish and Zafar-ul-Hye, 2019).

Assessment of soil separates sand, silt and clay was made using hydrometer. Finally, USDA textural triangle was followed for computation of soil texture (Gee and Bauder, 1986). Soil EC and pH were determined by making 1:10 and 1:1 w/v ratio mixture of soil and deionized water. Soil organic matter was assessed via ferrous ammonium sulfate and potassium dichromate (Sparks et al., 1996). Soil available P was examined on spectrophotometer at 880 nm using Olsen extracting solution (Kuo, 1996). However, soil available K was analyzed on flame photometer by using ammonium acetate as extracting reagent (Donald and Hanson, 1998).

2.4 Treatment plan and NBC application

A total of nine treatments was applied with 3 replications. The treatments include control (No AC) + normal soil irrigation (70FC), 70FC + 0.75%AC, 70FC + 1.50%AC, mild drought stress (50FC), 50FC + 0.75AC, 50FC + 1.50AC, severe drought stress (30FC), 30FC + 0.75AC and 30FC + 1.50AC. On a w/w basis, AC was applied in the soil as per the treatment plan manually.

2.5 Irrigation water characteristics

The characteristics of tap water were pH (7.12), EC (0.54 dS/m), carbonates (0.00 meq./L), bicarbonates (5.17 meq./L), chlorides (0.10 meq./L) and Ca + Mg (1.21 meq./L) (Estefan et al., 2013).

2.6 Seeds collection and sowing

Healthy maize seeds YH 1898 were selected on visual and manual basis. Initially five seeds were sown in each pot. Later after germination, thinning was done and 2 seedlings were maintained per pot.

2.7 Fertilizer application

Nitrogen was added at the rate of 227.24 kg ha⁻¹ in three separates. At the time of sowing, phosphorus and potassium were added at the rate of 143.26 kg ha⁻¹ and 91.93 kg ha⁻¹ (Saboor et al., 2021).

2.8 Data collection

At vegetative maturity plants were harvested. Shoot and root length, shoot fresh and dry weight, root fresh and dry weight were examined soon after harvesting. For dry weight analysis, samples were oven-dried at 65 °C for 48 h.

2.9 Gas exchange attributes

An IRGA (infrared gas analyzer) was utilized for the determination of photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (E) (Danish and Zafar-ul-Hye, 2019; Saboor et al., 2021).

2.10 Chlorophyll contents

For analyses of chlorophyll contents, 80% acetone was used. Final calculations were made using following equations (Arnon, 1949). $$\mathrm{C}\mathrm{h}\mathrm{l}\mathrm{o}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{h}\mathrm{y}\mathrm{l}\mathrm{l}\mathrm{a}\left(\mathrm{m}\mathrm{g}{\mathrm{g}}^{-1}\right)=\frac{12.7\times \left(\mathrm{A}\mathrm{b}\mathrm{s}\mathrm{o}\mathrm{r}\mathrm{b}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}663\right)-2.69\times \left(\mathrm{A}\mathrm{b}\mathrm{s}\mathrm{o}\mathrm{r}\mathrm{b}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}645\right)\times \mathrm{V}\mathrm{o}\mathrm{l}\mathrm{u}\mathrm{m}\mathrm{e}\mathrm{M}\mathrm{a}\mathrm{d}\mathrm{e}}{1000\times (\mathrm{S}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}\mathrm{W}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t})}$$ $$\mathrm{C}\mathrm{h}\mathrm{l}\mathrm{o}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{h}\mathrm{y}\mathrm{l}\mathrm{l}\mathrm{b}\left(\mathrm{m}\mathrm{g}{\mathrm{g}}^{-1}\right)=\frac{22.9\times \left(\mathrm{A}\mathrm{b}\mathrm{s}\mathrm{o}\mathrm{r}\mathrm{b}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}645\right)-2.69\times \left(\mathrm{A}\mathrm{b}\mathrm{s}\mathrm{o}\mathrm{r}\mathrm{b}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}663\right)\times \mathrm{V}\mathrm{o}\mathrm{l}\mathrm{u}\mathrm{m}\mathrm{e}\mathrm{M}\mathrm{a}\mathrm{d}\mathrm{e}}{1000\times (\mathrm{S}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}\mathrm{W}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t})}$$ $$\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}\mathrm{C}\mathrm{h}\mathrm{l}\mathrm{o}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{h}\mathrm{y}\mathrm{l}\mathrm{l}(\mathrm{m}\mathrm{g}{\mathrm{g}}^{-1})=\mathrm{C}\mathrm{h}\mathrm{l}\mathrm{o}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{h}\mathrm{y}\mathrm{l}\mathrm{l}\mathrm{a}+\mathrm{C}\mathrm{h}\mathrm{l}\mathrm{o}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{h}\mathrm{y}\mathrm{l}\mathrm{l}\mathrm{b}$$

2.11 Electrolyte leakage

Electrolyte leakage (EL) was measured using the method by Lutts et al. (1996). $$\mathrm{E}\mathrm{l}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{r}\mathrm{o}\mathrm{l}\mathrm{y}\mathrm{t}\mathrm{e}\mathrm{l}\mathrm{e}\mathrm{a}\mathrm{k}\mathrm{a}\mathrm{g}\mathrm{e}(\%)=\left(\frac{\mathrm{E}\mathrm{C}1}{\mathrm{E}\mathrm{C}2}\right)\times 100$$

2.12 Statistical analysis

All the data was sorted out using standard statistical procedures (Steel et al., 1997). Two factorial ANOVA and Fisher's LSD were applied for the comparison of treatments. Origin2022Pro software was used for making paired comparison graphs (OriginLab Corporation, 2021).

3.1 Shoot length and root length

Results showed that the effects of AC application rates and variable levels of irrigation water were significant on the shoot length of maize. A significant increase in shoot length was noted where 1.50AC and 0.75AC were applied under normal irrigation (70FC), mild drought (50FC) and severe drought (30FC) compared to control (0AC). Treatment 1.50AC performance significantly better for improvement in shoot length than 0.75AC under 70FC, 50FC and 30FC (Fig. 1A). A maximum increase of 20.65, 26.71, and 47.14% in shoot length was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (96.13, 69.22, and 82.60%) in shoot length than 0AC under 70, 50, and 30FC respectively. Fig. 1B is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for shoot length.

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Fig. 1

Effect of AC application rates on shoot (A) and root length (C) of maize grown under normal, mild, and severe drought stress. Bars are means of 3 replicates ± SE. Variable letters on bars are showing significant changes (Tukey test; p ≤ 0.05). A parallel plot is showing the interaction of variables for shoot and root length of maize grown under normal, mild, and severe drought stress. The color scheme is showing the data range for shoot (B) and root length (D) affected by treatments. AC = acidified carbon; FC = Field capacity; AC = acidified carbon; FC = Field capacity.

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It was noted that the impacts of AC application rates and variable levels of irrigation water were significant on the root length of maize. A significant enhancement in root length was observed where 1.50AC and 0.75AC were added under mild drought (50FC) and severe drought (30FC) over control (0AC). Treatment 1.50AC differed significantly better for increase in root length than 0.75AC under 70FC, 50FC and 30FC (Fig. 1C). The maximum increase of 13.95, 24.39, and 32.19% in root length was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (70.09, 77.58, and 69.76%) in root length than 0AC under 70, 50, and 30FC respectively. Fig. 1D is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for root length.

3.2 Shoot fresh and dry weight

The influence of AC application rates and variable levels of irrigation water was significant on the shoot fresh weight of maize. A significant increase in shoot fresh weight was observed where 1.50AC and 0.75AC were incorporated under 70FC, 50FC, and 30FC than control (0AC). Application of 1.50AC remained significantly better for improvement in shoot fresh weight than 0.75AC under 70FC, 50FC, and 30FC (Fig. 2A). A maximum increase of 23.79, 46.13, and 102.40% in shoot fresh weight was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (78.46, 70.67, and 135.22%) in shoot fresh weight than 0AC under 70, 50, and 30FC respectively. Fig. 2B is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for shoot fresh weight.

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Fig. 2

Effect of AC application rates on shoot fresh (A) and dry (C) weight of maize grown under normal, mild, and severe drought stress. Bars are means of 3 replicates ± SE. Variable letters on bars are showing significant changes (Tukey test; p ≤ 0.05). A parallel plot is showing the interaction of variables for shoot fresh (C) and dry (D) weight of maize grown under normal, mild, and severe drought stress. The color scheme is showing the data range for shoot fresh weight affected by treatments. AC = acidified carbon; FC = Field capacity.

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A significant enhancement in shoot dry weight was noted in 1.50AC and 0.75AC under 70FC, 50FC and 30FC over control (0AC). Application of 1.50AC was significantly better for an increase in shoot dry weight compared to 0.75AC under 70FC, 50FC, and 30FC (Fig. 2C). A maximum increase of 26.62, 70.83, and 77.19% in shoot dry weight was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (73.92, 109.60, and 121.51%) in shoot dry weight than 0AC under 70, 50, and 30FC respectively. Fig. 2D is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for shoot dry weight.

3.3 Root fresh and dry weight

Significant changes in root fresh weight were noted under the application of AC application rates and variable levels of irrigation water. Treatments 1.50AC and 0.75AC caused significant improvement in root fresh weight under 70FC, 50FC and 30FC compared to control (0AC). Application of 1.50AC caused a significant increase in root fresh weight compared to 0.75AC under 70FC and 50FC (Fig. 3A). The maximum increase of 14.42, 29.29, and 82.82% in root fresh weight was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (53.34, 49.51, and 104.42%) in root fresh weight than 0AC under 70, 50, and 30FC respectively. Fig. 3B is elaborating on the interaction of variables under application rates and variable levels of irrigation water for root fresh weight.

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Fig. 3

Effect of AC application rates on root fresh (A) and dry (C) weight of maize grown under normal, mild, and severe drought stress. Bars are means of 3 replicates ± SE. Variable letters on bars are showing significant changes (Tukey test; p ≤ 0.05). A parallel plot is showing the interaction of variables for root fresh weight of maize grown under normal, mild, and severe drought stress. The color scheme is showing the data range for root fresh (C) and dry (D) weight affected by treatments. AC = acidified carbon; FC = Field capacity.

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Significant changes in root dry weight were observed under the application of AC application rates and variable levels of irrigation water. Treatments 1.50AC and 0.75AC induced significant enhancement in root dry weight under 70FC, 50FC and 30FC than control (0AC). Application of 1.50AC caused significant enhancement in root dry weight over 0.75AC under 70FC and 50FC (Fig. 3C). The maximum increase of 24.53, 40.93, and 59.17% in root dry weight was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (75.27, 66.42, and 80.30%) in root dry weight than 0AC under 70, 50, and 30FC respectively. Fig. 3D is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for root dry weight.

3.4 Grains yield

The use of AC at various application rates as amendment significantly influenced grain yield under the variable level of irrigation water. A significant enhancement in grains yield under 70FC, 50FC and 30FC confirmed the usefulness of 1.50AC and 0.75AC than control (0AC). It was observed that 1.50AC differed significantly best than 0.75AC and 0AC under 30FC, 50FC, and 70FC for an increase in grain yield. Furthermore, 0.75AC also caused significant improvement in grains yield compared to 0AC under 70FC, 50FC and 30FC (Fig. 4A). Maximum enhancement of 10.65, 17.33, and 9.72% in grains yield was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused maximum significant enhancement (18.21, 25.56, and 22.87%) in grains yield compared to 0AC under 70, 50, and 30FC respectively. Fig. 4B is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for grain yield.

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Fig. 4

Effect of AC application rates on grains yield of maize leaves grown under normal, mild, and severe drought stress. Bars are means of 3 replicates ± SE. Variable letters on bars are showing significant changes (Tukey test; p ≤ 0.05). A parallel plot is showing the interaction of variables for grain yield of maize grown under normal, mild, and severe drought stress. The color scheme is showing the data range for grain yield affected by treatments (B). AC = acidified carbon; FC = Field capacity.

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3.5 Grains nitrogen

Application of AC at different rates significantly influenced grain's nitrogen concentration under different levels of irrigation water. A significant enhancement in grains nitrogen concentration under 70FC, 50FC and 30FC confirmed the usefulness of 1.50AC compared to control (0AC). It was also noted that 1.50AC differed significantly best than 0.75AC and 0AC under 50FC and 70FC for improvement in grains nitrogen concentration. Furthermore, 0.75AC also did not cause significant improvement in grains nitrogen concentration compared to 0AC under 70FC, 50FC and 30FC (Fig. 5A). Maximum enhancement of 6.30, 6.15 and 3.58% in grains nitrogen concentration was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant enhancement (14.59, 16.31 and 21.44%) in grains nitrogen concentration compared to 0AC under 70, 50 and 30FC respectively. Fig. 5B is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for grain nitrogen concentration.

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Fig. 5

Effect of AC application rates on grains nitrogen (A), phosphorus (C) and potassium (E) concentration of maize grown under normal, mild, and severe drought stress. Bars are means of 3 replicates ± SE. Variable letters on bars are showing significant changes (Tukey test; p ≤ 0.05). A parallel plot is showing the interaction of variables for grains nitrogen (B), phosphorus (D) and potassium (F) concentration of maize grown under normal, mild, and severe drought stress. The color scheme is showing the data range for grain's nitrogen concentration affected by treatments (B). AC = acidified carbon; FC = Field capacity.

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A significant increase in grains phosphorus concentration under 70FC verified the efficacy of 1.50AC compared to control (0AC). Treatment 1.50AC differed significantly best than 0.75AC and 0AC under 70FC for enhancement in grains phosphorus concentration. Furthermore, 0.75AC also did not cause significant improvement in grains phosphorus concentration over 0AC under 50FC and 30FC (Fig. 5C). Maximum enhancement of 22.66, 8.15, and 8.70% in grains phosphorus concentration were noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant enhancement (46.51, 6.38 and 21.74 %) in grains phosphorus concentration compared to 0AC under 70, 50 and 30FC respectively. Fig. 5D is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for grain's phosphorus concentration.

Grain's potassium concentration was significantly higher under 30FC, 50FC, and 70FC where 1.50AC was applied compared to control (0AC). Treatment 1.50AC was significantly better from 0.75AC and 0AC under 30FC and 50FC for increase in grains potassium concentration. Likewise, 0.75AC was significant for improvement in grains potassium concentration over 0AC under 30FC, 50FC and 30FC (Fig. 5E). Maximum enhancement of 16.67, 12.70 and 15.25% in grains potassium concentration was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant enhancement (21.21, 23.81 and 27.12%) in grains potassium concentration compared to 0AC under 70, 50 and 30FC respectively. Fig. 5F is elaborating on the interaction of variables under AC application rates and variable levels of irrigation water for grain potassium concentration.

3.6 Chlorophyll and carotenoids contents

Significant changes in chlorophyll a were observed under the addition of AC application rates and different levels of irrigation water. Treatments 1.50AC and 0.75AC differed significantly for enhancement in chlorophyll a under 70FC, 50FC and 30FC over control (0AC). The addition of 1.50AC induced significant improvement in chlorophyll a than 0.75AC under 70FC. However, both 1.50AC and 0.75AC remained statistically similar to each other for chlorophyll a under 50FC and 30FC (Table 2). The maximum increase of 15.78, 57.60, and 55.78% in chlorophyll a were noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (77.78, 92.85, and 84.95%) in chlorophyll a than 0AC under 70, 50, and 30FC respectively.

Treatments 1.50AC and 0.75AC were significantly different for increase in chlorophyll b under 70FC, 50FC and 30FC over control (0AC). Treatment 1.50AC induced significant enhancement in chlorophyll b over 0.75AC under 50FC and 70FC. However, both 1.50AC and 0.75AC remained statistically alike each other for chlorophyll b under 30FC (Table 2). Maximum increase of 20.70, 62.44 and 83.15% in chlorophyll b was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant increase (83.97, 102.75, 117.36%) in chlorophyll b than 0AC under 70, 50 and 30FC respectively.

Addition of 1.50AC and 0.75AC differed significantly for enhancement in total chlorophyll under 70FC, 50FC and 30FC over control (0AC). Application of 1.50AC caused a significant increase in total chlorophyll than 0.75AC under 50FC and 70FC. However, both 1.50AC and 0.75AC did not differ significantly from each other for total chlorophyll under 30FC (Table 2). The maximum increase of 18.85, 58.84, and 66.76% in total chlorophyll was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (78.81, 98.34, and 93.99%) in total chlorophyll over 0AC under 70, 50, and 30FC respectively.

A significant enhancement in carotenoids under 70FC, 50FC and 30FC validated the effectiveness of 1.50AC and 0.75AC over control (0AC). It was observed that 1.50AC performance was significantly best than 0.75AC and 0AC under 50FC and 70FC. On the other hand, 0.75AC also differed significantly for an increase in carotenoids than 0AC under 70FC, 50FC, and 30FC (Table 2). The maximum increase of 15.61, 32.26, and 44.22% in carotenoids was noted in 0.75AC over 0AC under 70, 50, and 30FC respectively. Similarly, the addition of 1.50AC caused a maximum significant increase (49.97, 55.77, and 66.83%) in carotenoids over 0AC under 70, 50, and 30FC respectively.

3.7 Gas exchange attributes and electrolyte leakage

A significant increase in photosynthetic rate (Pn) under 70FC, 50FC and 30FC confirmed the usefulness of 1.50AC and 0.75AC over control (0AC). It was noted that 1.50AC differed significantly best than 0.75AC and 0AC under 50FC and 70FC for enhancement in Pn. On the other hand, 0.75AC also differed significantly for increase in Pn than 0AC under 70FC, 50FC and 30FC (Table 3). Maximum increase of 9.80, 20.67 and 31.34% in Pn was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant increase (39.52, 29.04 and 38.42%) in Pn over 0AC under 70, 50 and 30FC respectively.

Application of AC different application rates as amendment significantly affected transpiration rate (E) under level of irrigation water. A significant enhancement in E under 70FC, 50FC and 30FC verified the effectiveness of 1.50AC and 0.75AC over control (0AC). It was noted that 1.50AC was significantly best over 0.75AC and 0AC under 30FC, 50FC and 70FC for improvement in E. Furthermore, 0.75AC also remained significantly different for increase in E than 0AC under 70FC, 50FC and 30FC (Table 3). Maximum increase of 12.16, 17.26 and 21.38% in E was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant increase (45.54, 38.29 and 39.62%) in E over 0AC under 70, 50 and 30FC respectively.

Use of AC different application rates as amendment significantly impacted stomatal conductance (gs) under level of irrigation water. A significant enrichment in gs under 70FC, 50FC and 30FC validated the efficacy of 1.50AC and 0.75AC over control (0AC). It was noted that 1.50AC was significantly best over 0.75AC and 0AC under 70FC for improvement in gs. Furthermore, 0.75AC also differed significantly better for improvement in gs than 0AC under 70FC, 50FC and 30FC (Table 3). Maximum enhancement of 7.66, 15.77 and 38.98% in gs was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant enhancement (30.19, 26.58 and 46.62%) in gs over 0AC under 70, 50 and 30FC respectively.

Addition of AC different application rates significantly influenced electrolyte leakage under level of irrigation water. A significant decrease in electrolyte leakage under 70FC, 50FC and 30FC validated the efficacy of 1.50AC and 0.75AC over control (0AC). It was observed that 1.50AC performance was significantly best than 0.75AC and 0AC under 50FC and 70FC for decrease in electrolyte leakage. On the other hand, 0.75AC also differed significantly for decrease in electrolyte leakage than 0AC under 50FC and 30FC (Table 3A). Maximum decrease of 28.92, 36.49 and 36.80% in electrolyte leakage was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant decrease (63.85, 59.07 and 51.64 %) in electrolyte leakage over 0AC under 70, 50 and 30FC respectively.

3.8 Soil pH, EC, and organic matter

The effect of AC at different rates was significantly different for soil pH under the level of irrigation water. Soil pH was significantly lower under 30FC, 50FC, and 70FC where 1.50AC was applied compared to control (0AC). Treatment 1.50AC was significantly better from 0.75AC and 0AC under 30FC, 50FC and 70FC for decrease in soil pH. Likewise, 0.75AC was significant for decrease in soil pH over 0AC under 30FC, 50FC and 30FC (Table 3). Maximum decrease of 2.18, 2.42 and 2.50% in soil pH was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, the addition of 1.50AC caused maximum significant decrease (4.29, 4.17 and 3.67%) in soil pH compared to 0AC under 70, 50 and 30FC respectively.

Soil EC was significantly higher under 30FC, 50FC and 70FC where 0.75AC and 1.50AC was applied compared to control (0AC) (Table 3). No significant change was noted between 0.75AC and 1.50AC for soil EC under 30FC, 50FC and 70FC. Maximum enhancement of 30.22, 28.73 and 28.17% in soil EC was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant enhancement (31.00, 31.82 and 27.63%) in soil EC compared to 0AC under 70, 50 and 30FC respectively.

Soil OM was significantly higher under 30FC, 50FC and 70FC where 0.75AC and 1.50AC was applied compared to control (0AC) (Table 3). A significant change was observed between 0.75AC and 1.50AC for soil OM under 30FC, 50FC and 70FC. Maximum enhancement of 120.00, 111.54 and 111.11% in soil OM was noted in 0.75AC over 0AC under 70, 50 and 30FC respectively. Similarly, addition of 1.50AC caused maximum significant enhancement (172.00, 165.39 and 155.56%) in soil OM compared to 0AC under 70, 50 and 30FC respectively.