Soil Properties and Carbon Storage
The soil physical properties under different treatments are summarized in Table 1. The treatments include various organic amendments such as FYM, BC, VC, GM with mung, ST, as well as inorganic amendments. The soil physical parameters like sand, silt, and clay composition, moisture content, bulk density and pore space, mechanical resistance were recorded. Across all treatments, the soil composition in terms of sand, silt, and clay content showed minimal variation. However, it is noteworthy that treatments involving organic amendments generally exhibited slightly higher sand content compared to the control and RDF treatments. Conversely, clay content was slightly higher in treatments involving ST and RDF compared to organic amendment treatments. These variations, although minor, might have implications for soil structure and water retention capacity. The moisture content of the soil varied significantly among treatments, with FYM + BC + VC treatment showing the highest moisture content (42.15%) followed by ST (44.97%) and VC (43.21%). Conversely, the control treatment exhibited the lowest moisture content (36.42%). This indicates that organic amendments, particularly a combination of FYM, BC, and VC, can significantly improve soil moisture retention, which is crucial for plant growth and drought resistance. The finding is in accordance with the work of Mishra et al. (2020). Bulk density, an indicator of soil compaction, was notably lower in treatments involving organic amendments compared to the control and RDF treatments. Among the organic amendments, BC and FYM + BC + VC treatments exhibited the lowest bulk density, suggesting improved soil structure and porosity. This was further supported by higher pore space percentages observed in these treatments, indicating better aeration and water infiltration capacities. The bulk density and pore space reported in this study are consistent with previous research findings (Rivenshield et al., 2007), which suggest that organic amendments positively influence to decrease bulk density and increase macroporosity in soils. Mechanical resistance, representing soil strength or compaction, showed considerable variation among treatments. BC treatment exhibited the lowest mechanical resistance (1.54 MPa), indicating softer and less compacted soil, while the control treatment showed the highest resistance (1.65 MPa). This suggests that organic amendments, particularly BC, can mitigate soil compaction and improve soil workability, facilitating root growth and nutrient uptake Sharifi et.al. (2011). Overall, the results demonstrate that organic amendments, especially a combination of FYM, BC, and VC, positively influence soil physical properties, enhancing moisture retention, reducing compaction, and improving soil structure and porosity. These findings underscore the importance of incorporating organic inputs practices in promoting sustainable soil management and enhancing sugarcane productivity that ultimately sequester more carbon from atmosphere.
Table 1
Effect of different organic and inorganic amendments on soil physical properties under sugarcane cultivation
Treatments | Sand (%) | Silt (%) | Clay (%) | Moisture content (%) | Bulk density (gcm− 3) | Pore Space (%) | Mechnical Resistance (Mpa) |
T1 | 31.83 | 54.75 | 13.42 | 36.42 | 1.37 | 45.42 | 1.65 |
T2 | 32.86 | 53.89 | 13.25 | 41.08 | 1.39 | 46.16 | 1.74 |
T3 | 33.13 | 53.61 | 13.26 | 43.92 | 1.32 | 45.65 | 1.54 |
T4 | 31.63 | 54.12 | 14.25 | 43.21 | 1.35 | 47.49 | 1.63 |
T5 | 32.16 | 55.69 | 12.15 | 39.56 | 1.36 | 46.25 | 1.59 |
T6 | 32.65 | 53.23 | 14.12 | 44.97 | 1.34 | 46.53 | 1.61 |
T7 | 31.73 | 53.83 | 14.44 | 42.15 | 1.28 | 45.13 | 1.52 |
T8 | 31.15 | 54.89 | 13.96 | 38.45 | 1.32 | 45.18 | 1.58 |
Mean Value | 32.14 | 54.25 | 13.60 | 41.22 | 1.34 | 45.97 | 1.61 |
SEm ± | 1.6 | 0.69 | 0.49 | 1.31 | 0.02 | 0.79 | 0.03 |
CD (P = 0.05) | 2.1 | 1.98 | 1.26 | 3.98 | 0.09 | 2.38 | 0.08 |
Note: T1: Control; T2: FYM @ 20 t ha-1; T3: BC @20 t ha-1; T4: VC @ 5.0 t/ha; T5: GM with mung; T6: ST @ 10 t ha-1; T7: FYM + BC + VC; T8: RDF. |
Chemical properties of rhizospheric soil under experimental field
Table 2 presents the soil chemical properties and the organic carbon (SOC) storage in rhizospheric soil of planted sugarcane under different treatments.
pH and Electrical Conductivity (EC)
The pH values of soil ranged from 8.14 to 8.59 across different treatments, indicating alkaline soil conditions. There were no significant differences in pH among treatments, suggesting that the application of organic amendments or RDF did not significantly alter soil acidity. Similarly, EC values varied slightly among treatments, reflecting variations in soil salinity levels. Overall, the soil remained within acceptable ranges for sugarcane cultivation. The optimal soil pH for sugarcane can range from slightly acidic to alkaline, depending on the specific conditions of the plantation. Organic matters help optimising the pH of soil making it suitable for uptake of nutrients, this matching with the work of Rusli et al. (2022).
Soil Organic Carbon (SOC) and its Carbon Storage
The soil organic carbon content ranged from 0.47–0.67% across treatments, with the highest value observed in the sugarcane trash treatment and the lowest in the FYM + BC + VC treatment. However, when considering SOC storage, which takes into account soil depth and bulk density, the ST treatment exhibited the highest SOC storage (1376.85 t/ha), followed by VC (1174.50 t/ha) and RDF (1287.00 t/ha). Conversely, the FYM + BC + VC treatment showed the lowest SOC storage (902.40 t/ha). These results suggest that incorporating ST or VC can significantly enhance SOC storage, contributing to soil fertility and carbon sequestration. Soil organic carbon is affected directly by the farm management practices such as crop type, manure application, tillage intensities, irrigation efficiency, harvesting approaches and the life period of crop plants (West and Marland, 2002; Smith, 2004). It has been reported that soil texture particularly clay content have a key role in capability of soil carbon sequestration (Reeder and Schuman, 2002). This is consistent with the results reported by Ghanbarian et al. (2015) and Sadeghi and Raeini (2016). However, according to another research, soil bulk density and sand content had negative effects on soil carbon storage. This result is in accordance with the results of a study conducted by Suman et al. (2009) who reported that reduction in soil bulk density would lead to increase in SOC of sugarcane farms. It seems that the differences in chemical and physical properties of soil in different nutrient management as outlined above might have caused the considerable differences in soil organic carbon content.
Available macro and secondary nutrients
The availability of nutrients such as nitrogen (N), phosphorus (P), potassium (K), and sulphur (S) varied among treatments while there were no significant differences in available N among treatments, ST @ 10 t ha− 1 treatment exhibited significantly lower available phosphorus compared to other treatments.. The sugarcane trash treatment exhibited the highest levels of available N (284.36 kg/ha), available P (24.48kg/ha), available K (193.05 kg/ha), and available S (16.98 mg/kg), indicating efficient nutrient cycling and decomposition of organic matter. Conversely, the FYM + BC + VC treatment showed the lowest levels of available nutrients, suggesting potential limitations in nutrient release and availability. These findings highlight the importance of selecting appropriate organic amendments to meet the nutrient requirements of sugarcane crops. Conversely, RDF treatment showed the highest available phosphorus content. Available potassium content was highest in ST @ 10 t ha− 1 treatment, while available sulphur content showed no significant differences among treatments. Overall, the results demonstrate that organic amendments, particularly ST and VC, can positively influence soil chemical properties, enhance SOC storage, and improve nutrient availability. However, the effectiveness of organic amendments may vary depending on factors such as application rate, soil type, and environmental conditions.
Table 2
Effect of different organic and inorganic amendments on soil chemical properties and soil organic carbon storage of planted sugarcane field
Treatments | pH (1:2.5) | EC (dSm− 1) | SOC (%) | Soil organic carbon storage* (t/ha) | Available N (kg/ha) | Available P (kg/ha) | Available K (kg/ha) | Available S (mg/kg) |
T1 | 8.14 | 0.82 | 0.51 | 1025.51 | 254.18 | 22.04 | 139.62 | 15.69 |
T2 | 8.16 | 0.54 | 0.49 | 1021.65 | 219.32 | 19.15 | 120.59 | 14.38 |
T3 | 8.15 | 0.48 | 0.59 | 1168.20 | 228.04 | 23.23 | 151.62 | 15.29 |
T4 | 8.53 | 0.62 | 0.58 | 1174.50 | 284.36 | 22.98 | 152.38 | 16.49 |
T5 | 8.59 | 0.68 | 0.53 | 1081.20 | 235.42 | 24.48 | 123.69 | 16.98 |
T6 | 8.49 | 0.38 | 0.67 | 1376.85 | 168.52 | 21.14 | 172.32 | 16.42 |
T7 | 8.16 | 0.62 | 0.47 | 902.40 | 238.26 | 18.98 | 152.18 | 15.93 |
T8 | 8.43 | 0.73 | 0.65 | 1287.00 | 258.04 | 21.09 | 193.05 | 13.04 |
Mean Value | 8.33 | 0.61 | 0.56 | 1129.66 | 235.77 | 21.63 | 150.68 | 15.53 |
SEm ± | 0.06 | 0.02 | 0.05 | 39.51 | 9.4 | 0.97 | 5.79 | 0.63 |
CD (P = 0.05) | 0.21 | 0.08 | 0.16 | 138.9 | 28.20 | 2.92 | 17.93 | 1.97 |
*Soil organic carbon storage (t/ha) = 1 ha× soil depth (m) × soil bulk density (g/cm3) ×SOC (%) |
Carbon Sequestration in Different Cane Parts
The plant sequestered carbon (kg ha− 1) content in different plant parts of planted sugarcane under various treatments is summarized in Table 3. The below-ground carbon storage, primarily in roots, ranged from 586.45 to 668.74 kg ha− 1 across treatments. The highest below-ground carbon storage was observed in the FYM @ 20 t ha− 1 treatment, while the control treatment exhibited the lowest storage. Treatments involving organic amendments generally showed higher below-ground carbon storage compared to the control and RDF treatments. The above-ground carbon storage, including stems and leaves, ranged from 398.77 to 422.77 kg ha− 1 for stems and 779.14 to 872.15 kg ha− 1 for leaves across treatments. The highest above-ground carbon storage in stems was observed in the ST @ 10 t ha− 1 treatment, while the highest storage in leaves was observed in the BC @ 20 t ha− 1 treatment. Again, treatments involving organic amendments generally showed higher above-ground carbon storage compared to the control and RDF treatments. The results of this study also indicated that sugarcane leaves and roots had higher carbon storage than shoots (Tables 3). Several studies have found that perennial plants with woody organs had higher potential to reserve the organic carbon compared to annual plants (Ghanbarian et al., 2015). Overall, 1291.82 kg ha− 1 (66%)) carbon storage belonged to the aboveground plant organs of T6 and 668.74 kg ha− 1 belonged to the roots of sugarcane of T2 showing that the considerable carbon storage capability of sugarcane. The total stored carbon above ground, comprising stems and leaves, ranged from 1201.91 to 1291.82 kg ha− 1 across treatments. The highest total stored carbon above ground was observed in the ST @ 10 t ha− 1 treatment. Additionally, the total stored carbon (combining below-ground and above-ground carbon) ranged from 1774.11 to 1947.19 kg ha− 1, with the highest value observed in the ST @ 10 t ha− 1 treatment. The carbon sequestration values reported in this study align with previous research findings (Gao et al., 2007), which suggest that organic amendments positively influence carbon storage in agricultural systems. Overall, the results indicate that treatments involving organic amendments contribute to higher carbon sequestration in both below-ground and above-ground cane parts compared to conventional treatments. This highlights the importance of organic farming practices in enhancing carbon sequestration potential in sugarcane cultivation, which can contribute to mitigating climate change impacts. However, further research is needed to assess the long-term effects of these treatments on carbon sequestration and soil health.
Table 3
Effect of different organic and inorganic amendments on plant sequestered carbon (kg ha− 1) in different parts of planted sugarcane
Treatments | Stored carbon (kg ha− 1) |
below ground | above ground | Total stored carbon above ground | Total stored carbon (kg ha− 1) |
Roots | Stems | Leaves | stem + leaf | Root + Stem + Leaf |
T1 | 586.45 | 403.12 | 784.54 | 1187.66 | 1774.11 |
T2 | 668.74 | 420.12 | 785.48 | 1205.6 | 1874.34 |
T3 | 598.12 | 398.77 | 872.15 | 1270.92 | 1869.04 |
T4 | 645.31 | 405.87 | 862.31 | 1268.18 | 1913.49 |
T5 | 616.69 | 422.77 | 779.14 | 1201.91 | 1818.60 |
T6 | 655.37 | 414.74 | 877.08 | 1291.82 | 1947.19 |
T7 | 596.53 | 419.64 | 867.14 | 1286.78 | 1883.31 |
T8 | 606.61 | 412.15 | 792.15 | 1204.3 | 1810.91 |
Mean Value | 621.73 | 412.15 | 827.50 | 1239.65 | 1861.37 |
SEm ± | 17.29 | 7.97 | 24.61 | 26.31 | 49.51 |
CD (P = 0.05) | 53.82 | 23.78 | 73.63 | 84.23 | 163.32 |
Correlation coefficients among different soil properties and SOC
Table 4 displays correlation coefficients among different soil properties and the Soil Organic Carbon (SOC %) in the given dataset. Correlation coefficients range from − 1 to 1, where − 1 indicates a strong negative correlation, 1 indicates a strong positive correlation, and 0 suggests no correlation. Sand (%) and SOC (%): The correlation coefficient between sand content and SOC% is -0.03448, indicating a very weak negative correlation. This suggests that there is little to no relationship between the sand content in the soil and the percentage of soil organic carbon Arunrat et al. (2020). Silt (%) and SOC (%): The correlation coefficient between silt content and SOC% is -0.19752, indicating a weak negative correlation. There is a slight tendency for higher silt content to be associated with lower SOC% (Matus, 2021). Clay (%) and SOC (%): The correlation coefficient between clay content and SOC% is 0.243831, indicating a weak positive correlation. This suggests that higher clay content in the soil may be associated with a slightly higher percentage of SOC. Moisture (%) and SOC (%): The correlation coefficient between soil moisture and SOC% is 0.332486, indicating a moderate positive correlation. This suggests that as soil moisture increases, there may be a tendency for higher SOC%. Bulk Density (gcm− 3) and SOC (%): The correlation coefficient between bulk density and SOC% is -0.13615, indicating a weak negative correlation. There is a slight tendency for higher bulk density to be associated with lower SOC%. Pore Space (%) and SOC (%): The correlation coefficient between pore space and SOC% is 0.225035, indicating a weak positive correlation. This suggests that higher pore space in the soil may be associated with a slightly higher percentage of Soil Organic Carbon. Mechanical Resistance (Mpa) and SOC (%): The correlation coefficient between mechanical resistance and SOC% is -0.19117, indicating a weak negative correlation. There is a slight tendency for higher mechanical resistance to be associated with lower SOC%. pH and SOC (%): The correlation coefficient between pH and SOC% is 0.535278, indicating a moderate positive correlation. This suggests that higher pH levels in the soil may be associated with a higher percentage of SOC. EC (dSm− 1) and SOC (%): The correlation coefficient between electrical conductivity (EC) and SOC% is -0.37008, indicating a moderate negative correlation. This suggests that higher electrical conductivity may be associated with lower SOC%. In summary, while some correlations are weak, the results suggest that soil properties such as clay content, soil moisture, pH, and electrical conductivity may have some influence on the percentage of SOC in the given dataset.
Table 4: Correlation coefficients among different soil properties and SOC%
|
Sand
(%)
|
Silt
(%)
|
Clay
(%)
|
Moisture
(%)
|
Bulk density
(gcm-3)
|
Pore Space
(%)
|
Mechnical
Resistance
(Mpa)
|
pH
(1:2.5)
|
EC
(dSm-1)
|
SOC
(%)
|
Sand (%)
|
1
|
|
|
|
|
|
|
|
|
|
Silt (%)
|
-0.50443
|
1
|
|
|
|
|
|
|
|
|
Clay (%)
|
-0.3725
|
-0.61342
|
1
|
|
|
|
|
|
|
|
Moisture (%)
|
0.522121
|
-0.77546
|
0.355895
|
1
|
|
|
|
|
|
|
Bulk density (gcm-3)
|
0.28321
|
0.25712
|
-0.53539
|
-0.31101
|
1
|
|
|
|
|
|
Pore Space (%)
|
0.165652
|
-0.14636
|
0.005791
|
0.478477
|
0.448434
|
1
|
|
|
|
|
Mechnical Resistance
(Mpa)
|
0.206593
|
0.013519
|
-0.20349
|
-0.23237
|
0.900452
|
0.387794
|
1
|
|
|
|
pH (1:2.5)
|
-0.30522
|
0.36479
|
-0.11291
|
0.144917
|
0.101304
|
0.601097
|
-0.06322
|
1
|
|
|
EC (dSm-1)
|
-0.72655
|
0.78556
|
-0.17978
|
-0.91598
|
0.115572
|
-0.36154
|
0.039509
|
-0.0564
|
1
|
|
SOC (%)
|
-0.03448
|
-0.19752
|
0.243831
|
0.332486
|
-0.13615
|
0.225035
|
-0.19117
|
0.535278
|
-0.37008
|
1
|