**2. Agriculture practices which involve CS**

to its advantages of helping in agricultural sustainability CC mitigation [1]. The CS potential of agroforestry systems is estimated between 12 and 228 Mg ha−1. So, based on the Earth's total suitable area for crop production, which is 585–1215 × 10<sup>6</sup> ha, a total of 1.1–2.2 Pg C can be sequestered in the agricultural soils in the next 50 years [2]. Overall, the agriculture sector has a great potential for CS in the soil as well as in crop plants. Changes in agricultural practice and managements can also result in enhanced CS in them. It is presumed that if we change the management practice, it will result in decreased crop yields but the net C flux can be greater

**Sr. No. Term Definition Reference**

stored in the sinks like ocean, forest and crops, soils and geologic

perennial trees and shrubs are grown in combination with agricultural

plastic sheets which are spread around plants to secure them from excessive evaporation, cold stress and promoting SOM contents in

It is the combination of strategies which links soil, crop and weather factors and irrigation for ideal nutrient use efficiency to crops.

and sequestered in soils and can also be obtained by pyrolysis

[11]

[12]

[13]

[14]

[15]

[16]

[17]

[18]

[19]

[20]

[21]

[23]

[24]

[25]

1 Carbon sequestration It is the processes by which C is removed from the atmosphere and

2 Agroforestry It is a combination of two words, agriculture and forestry in which

3 Mulching It is a detached vegetation covering wheat straw, compost or may be

4 Crop residues Detached vegetative parts of crop plants that are intentionally left to

5 Crop rotation It is the systematic planting of different crops in a specific order for several years in the same agricultural field.

7 Zero tillage A tillage system in which soil disturbances through ploughing is not

8 Conservation tillage If we leave crop residues of previous crop on fields to improve SOM, reducing soil erosion and runoff.

10 Cover crops Crop which is grown for the benefit of the soil rather than the crop

11 Compost Material which largely consists of decayed organic matter and is used

14 Animal manure Animals excreta collected from livestock farms and barnyards used to

15 Peat moss It is also called bog moss or sphagnum moss, a plant very rich in organic matter and used to enhance SOM.

for fertilizing and conditioning of agricultural soil.

12 Cropping intensity It is the fraction of the cultivated area that is harvested. [22] 13 Bagasse It is a dry pulp like material which is left when we extract juice from

9 Biochar It is carbonized biomass obtained from sustainable sources

decay in agricultural fields after crop harvesting.

formations.

crops.

soil.

being done.

synthetically.

sugar cane.

**Table 1.** Some terms used in the chapter and their definitions.

enrich the soil.

yield.

6 Nutrient

management

18 Carbon Capture, Utilization and Sequestration

Agricultural practices help in sequestering C in soils such as zero or reduced tillage, crop residue incorporation in fields, nutrient management, preventing OM loss, supplying nutrients and maintaining soil microbes, soil erosion control, vegetation or revegetation, cover cropping, green manuring, crop rotations, agro-forestry, soil rehabilitation, reclamation and use of salt-affected soils for forest plantations and crop production.

#### **2.1. Zero tillage and conservation agriculture**

Zero tillage is the type of conservation agriculture which does not disturb the soil comprising minimum soil disturbance, crop residues, cover crops and their diversification; this is also promoted for reducing soil disturbance and improving SOM and its sustainability as well as it also mitigates the CC through CS up to 0.16–0.49 Mg C ha−1 yr−1. Increase in SOC concentration from CA induces improvement in the soil's physical and chemical attributes which ultimately contribute to increase the sustainability and CC mitigation through CS [26]. In Brazil, the government is trying to increase the agricultural area under zero tillage from 32 to 40 million ha by 2020 to mitigate C emissions. It was calculated that average annual CS is 1.61–1.48 Mg C ha−1 yr−1 in Brazil for the 8 years from 2003 to 2011. So, converting 8 million ha of cropland to zero tillage can sequester an estimated soil C storage of about 8 Tg C yr−1 in 10–15 years [27].

In Haryana, India, conventional and zero tillage techniques were tested for the efficiency of CS; results showed that nearly USD 97.5 ha−1 can be earned extra by adopting zero tillage as zero tillage reduces the tillage implement costs, labor and fuel costs by spending USD 76 ha−1 and 97.5 USD earnings show that shifting from conventional to zero tillage reduces cost and additionally, sequester C emission by 1.5 Mg C ha−1 season−1 [28, 29]. Zero tillage generates considerable benefits up to US D 97 ha−1; it also increases the crop yield by 5–7%, saving costs up to USD 52 ha−1 [30–32].

tillage and rotation studies were conducted. Conventional techniques and ZT were applied and C and N were determined from soils at depths of 0–2.5, 2.5–7.5, 7.5–15 and 15–30 cm. It was revealed that compared with CT, NT had greater organic C, N and SOM. Increases in

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21

Soils represent a C pool of approximately 1500 Gt. Any modification or change of land use or land management can induce variations in soil C stocks [42]. Intense cropping systems always cause depletion of SOM but applying crop residues, balanced fertilization with NPK and use of organic amendments can increase CS levels to 5–10Mgha−1yr.−1. As these amendments also

In agricultural systems, there is a need for the optimization of C and N by cropping intensity and system to sequester C in the form of SOM which, in addition, gives stable soil structure, more yield and economic benefits [44]. Here, one challenge is to analyze the mechanism, capacity and longevity of C stabilization in agricultural lands by cropping intensity and systems. It is estimated that across 10 cropping systems, annual soil CS rates range up to 0.56 Mg C ha−1 yr.−1 [45]. Continuous and intense crop production accumulates 10–17% more SOM and N [46]. Increases in CS in soil can be attained by improved soil fertility, extensive cropping systems with shifting cultivation cropped fallows and cover crops [47]. Tillage, land cover, nutrients and cropping system management can contribute in CS up to 30–105 million metric tons of C (MMTC) yr.−1. Cropping intensity and rotations have the potential to sequester 14–29 MMTC yr.−1. By adopting these strategies, biomass production is increased and so, the C usage in the plants is increased and more C is sequestered in the plant and soil. If nutrient inputs combined the above strategies, this CS amount can be doubled [48]. Increase in SOM can be seen under long-term maize-wheat-cowpea cropping system up to

Carbon concentration and SOM is increased by adding mulch, and crop residues are widely applied in the form of mulch for CS and crop protection against cold stress. Mulch can increase CS in agricultural soils up to 8–16 Mg ha−1 yr.−1 and additionally, the soil's physical and chemical properties are also improved. Total SOM by using mulch increased from 1.26 to 1.50% [50]. Mulch also plays a key role in supplying nutrients, playing a role in the C and N cycle and the sink of C. It can significantly increase SOM and CS in the topsoil layer of 0–5 cm. This variation in the CS is attributed to the mulch rates. As more is the mulch and time after applying mulch, more will be the CS rate. For example, there will be 41% more CS after

Crop residues and nutrients especially N help in sequestering C in soils up to 21.3%–32.5% and simultaneously improve soil quality and plant growth [53]. Total SOM stocks are improved

4 years of mulching and 52% more CS after 11 years of mulching [51, 52].

**2.6. Residues and nutrient management**

SOM were directly related to the tillage practice and N fertilizer application [41].

**2.4. Cropping system and intensity**

1.83 Tg C yr.−1 [49].

**2.5. Mulching**

contain 10.7–18% C in them, they also help in CS [43].

#### **2.2. Conservation tillage**

Soil organic matter (SOM) is considered as C pool as well as its source while it decomposes. It decomposes when conventional tillage (CoT) is done. To check the effectiveness of conservation tillage in SOM retention, three scenarios of conservation tillage in model were used, that is, 27%; the current usages are 57 and 76%. The SOM content for major field crops up to 30 cm was 5304–8654 Tg C with 1710–2831 Tg C at 0–8 cm depth and 1383–2240 Tg C at 8–15 cm depth [33]. Changes in the SOC are greatly influenced by long-term tillage practices. For example, soil from 0 to 60 cm after 25 years of CT showed 5% higher soil bulk density for conservation tillage as compared to CoT practices. Analysis also showed that CS and storage was significantly higher in CT soil than CoT. So, it was concluded that CT practices increased SOM and CS as compared to CoT [34, 35]. It is a fact that interest in C storage in soils has gained a lot of interest in the last few years, especially C with its potential to help alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. Several questions still exist about what management practices can optimize CS in the soil. Primary method is to conserve SOM by not ploughing. As in a study involving different tillage practices like CT, ZT, NT and CoT, it showed that CS throughout the profile was significantly affected by tillage practices. Conservation, ZT and NT showed that there is the greatest potential of CS while applying ZT, NT and CoT [36]. Conservation tillage is highly recommended in crop lands as a means of enhancing CS in these soils. Carbon sequestration can be increased by 3.15 ± 2.42 t ha−1 by adopting CT [37].

#### **2.3. Nutrient management**

Agricultural soils can be a sink for atmospheric C concentrations by CS. It is accomplished by the formation of SOM or humus which is limited by the availability of nutrients such as nitrogen (N). Optimization of N can be a good mean for CS. Practices that enhance N in soil are no or reduced tillage and increased crop intensity. Nitrogen additions are important for increasing biomass yield and hence crop residues' decomposition in soil which increases SOM concentration. Practices like CT and increased cropping intensity and crop rotations yield more quantity of crop residues, increasing N availability and CS. Croplands have the potential of sequestering C from 8 to 298 Tg C yr.−1 [38]. Soil organic matter and N are directly influenced by tillage, residue return and N fertilization management practices [39], and that is why, intensive use of N fertilizers is employed to achieve higher economic value of highgrain yields and is generally perceived to bring about CS and by increasing the inputs of crop residues [40]. To determine the effects of N, tillage and crop rotation on SOM, long-term tillage and rotation studies were conducted. Conventional techniques and ZT were applied and C and N were determined from soils at depths of 0–2.5, 2.5–7.5, 7.5–15 and 15–30 cm. It was revealed that compared with CT, NT had greater organic C, N and SOM. Increases in SOM were directly related to the tillage practice and N fertilizer application [41].

#### **2.4. Cropping system and intensity**

In Haryana, India, conventional and zero tillage techniques were tested for the efficiency of CS; results showed that nearly USD 97.5 ha−1 can be earned extra by adopting zero tillage as zero tillage reduces the tillage implement costs, labor and fuel costs by spending USD 76 ha−1 and 97.5 USD earnings show that shifting from conventional to zero tillage reduces cost and additionally, sequester C emission by 1.5 Mg C ha−1 season−1 [28, 29]. Zero tillage generates considerable benefits up to US D 97 ha−1; it also increases the crop yield by 5–7%, saving costs

Soil organic matter (SOM) is considered as C pool as well as its source while it decomposes. It decomposes when conventional tillage (CoT) is done. To check the effectiveness of conservation tillage in SOM retention, three scenarios of conservation tillage in model were used, that is, 27%; the current usages are 57 and 76%. The SOM content for major field crops up to 30 cm was 5304–8654 Tg C with 1710–2831 Tg C at 0–8 cm depth and 1383–2240 Tg C at 8–15 cm depth [33]. Changes in the SOC are greatly influenced by long-term tillage practices. For example, soil from 0 to 60 cm after 25 years of CT showed 5% higher soil bulk density for conservation tillage as compared to CoT practices. Analysis also showed that CS and storage was significantly higher in CT soil than CoT. So, it was concluded that CT practices increased SOM and CS as compared to CoT [34, 35]. It is a fact that interest in C storage in soils has gained a lot of interest in the last few years, especially C with its potential to help alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. Several questions still exist about what management practices can optimize CS in the soil. Primary method is to conserve SOM by not ploughing. As in a study involving different tillage practices like CT, ZT, NT and CoT, it showed that CS throughout the profile was significantly affected by tillage practices. Conservation, ZT and NT showed that there is the greatest potential of CS while applying ZT, NT and CoT [36]. Conservation tillage is highly recommended in crop lands as a means of enhancing CS in these soils. Carbon sequestration

Agricultural soils can be a sink for atmospheric C concentrations by CS. It is accomplished by the formation of SOM or humus which is limited by the availability of nutrients such as nitrogen (N). Optimization of N can be a good mean for CS. Practices that enhance N in soil are no or reduced tillage and increased crop intensity. Nitrogen additions are important for increasing biomass yield and hence crop residues' decomposition in soil which increases SOM concentration. Practices like CT and increased cropping intensity and crop rotations yield more quantity of crop residues, increasing N availability and CS. Croplands have the potential of sequestering C from 8 to 298 Tg C yr.−1 [38]. Soil organic matter and N are directly influenced by tillage, residue return and N fertilization management practices [39], and that is why, intensive use of N fertilizers is employed to achieve higher economic value of highgrain yields and is generally perceived to bring about CS and by increasing the inputs of crop residues [40]. To determine the effects of N, tillage and crop rotation on SOM, long-term

up to USD 52 ha−1 [30–32].

20 Carbon Capture, Utilization and Sequestration

**2.2. Conservation tillage**

**2.3. Nutrient management**

can be increased by 3.15 ± 2.42 t ha−1 by adopting CT [37].

Soils represent a C pool of approximately 1500 Gt. Any modification or change of land use or land management can induce variations in soil C stocks [42]. Intense cropping systems always cause depletion of SOM but applying crop residues, balanced fertilization with NPK and use of organic amendments can increase CS levels to 5–10Mgha−1yr.−1. As these amendments also contain 10.7–18% C in them, they also help in CS [43].

In agricultural systems, there is a need for the optimization of C and N by cropping intensity and system to sequester C in the form of SOM which, in addition, gives stable soil structure, more yield and economic benefits [44]. Here, one challenge is to analyze the mechanism, capacity and longevity of C stabilization in agricultural lands by cropping intensity and systems. It is estimated that across 10 cropping systems, annual soil CS rates range up to 0.56 Mg C ha−1 yr.−1 [45]. Continuous and intense crop production accumulates 10–17% more SOM and N [46]. Increases in CS in soil can be attained by improved soil fertility, extensive cropping systems with shifting cultivation cropped fallows and cover crops [47]. Tillage, land cover, nutrients and cropping system management can contribute in CS up to 30–105 million metric tons of C (MMTC) yr.−1. Cropping intensity and rotations have the potential to sequester 14–29 MMTC yr.−1. By adopting these strategies, biomass production is increased and so, the C usage in the plants is increased and more C is sequestered in the plant and soil. If nutrient inputs combined the above strategies, this CS amount can be doubled [48]. Increase in SOM can be seen under long-term maize-wheat-cowpea cropping system up to 1.83 Tg C yr.−1 [49].

#### **2.5. Mulching**

Carbon concentration and SOM is increased by adding mulch, and crop residues are widely applied in the form of mulch for CS and crop protection against cold stress. Mulch can increase CS in agricultural soils up to 8–16 Mg ha−1 yr.−1 and additionally, the soil's physical and chemical properties are also improved. Total SOM by using mulch increased from 1.26 to 1.50% [50]. Mulch also plays a key role in supplying nutrients, playing a role in the C and N cycle and the sink of C. It can significantly increase SOM and CS in the topsoil layer of 0–5 cm. This variation in the CS is attributed to the mulch rates. As more is the mulch and time after applying mulch, more will be the CS rate. For example, there will be 41% more CS after 4 years of mulching and 52% more CS after 11 years of mulching [51, 52].

#### **2.6. Residues and nutrient management**

Crop residues and nutrients especially N help in sequestering C in soils up to 21.3%–32.5% and simultaneously improve soil quality and plant growth [53]. Total SOM stocks are improved by crop residues which suggests the substitution of SOM by fresh SOC derived from crop residues from 3.5 to 5.5 Mg C ha−1 [54]. The use of crop residue as a source of CS and keeping the soil in good quality helps in nutrient management and conservation. In the USA, a total of 367 × 10<sup>6</sup> Mg year−1 crop residues from 9 cereal crops, 450 × 10<sup>6</sup> Mg year−1 for 14 cereals and legumes and 488 × 10<sup>6</sup> Mg year−1 for 21 crops are produced. The amount of total crop residue production in the world is 2802 × 10<sup>6</sup> Mg year−1 from cereal crops and 3758 × 10<sup>6</sup> Mg year−1 from 27 food crops which can sequester 40–60% of total agricultural C emissions through their incorporation in the fields [55].

**3. Organic amendments**

of 1.0–1.4 Mg ha−1 yr.−1 [74].

the soil CS in organic farming system [78].

**3.2. Crop residues**

**3.3. Composting**

Animal manure is the source of C and the addition of animal manure to different crop fields has impacts on C contents [68]. Different researchers conducted the experiments in Germany to check the soil's C levels. The experiment showed that the annual application rate of 200 Mg ha−1 yr.−1 of manure to the crop field shows a high level of SOM with respect to adjacent fields [69]. Powlson reported that the mean annual SOC sequestration rates of three long-term (>49) years of manure applications ranged from 10 to 22 kg C ha−1 yr.−1 t

Enhancing Carbon Sequestration Using Organic Amendments and Agricultural Practices

http://dx.doi.org/10.5772/intechopen.79336

of dry solids, while SOC sequestration rates with shorter-term experiments (8–25 years of

solids [70]. The experiment was conducted to improve the soil quality and crop productivity. Improved soil properties refer to better C management. Animal manure also increases the salt concentration of the soil. The long-term application of manure increases the SOM significantly [71]. In another study, the farm yard manure was applied to the rice-wheat cropping system with NPK fertilizers and results showed significantly an increase in C sequestration in farm yard manure-applied plots than NPK-applied plots [72]. The same experiment was conducted on the maize-wheat cropping system, but in this experiment, the farm yard manure is applied with green manure and indicates that green manure sequesters more C [73]. It was also observed that the high application of N has the potential to sequester C almost at the rate

The researchers investigated that the annual production of crop residues is about 3.4 × 10<sup>9</sup> tones worldwide. If 15% of the total residue is applied to the soil, it will increase the C contents of soil. The crop residues are the remains of the agricultural crops. The intensive agriculture system increases the crop residue production significantly. This may increase the SOM and soil aggregation and hence C storage [75]. The degradation of crop residue depends upon its composition. For example, it is difficult for microorganisms to start the degradation of the substances which contain a high content of lignin. There three mechanisms, which are classified by different researchers based on the stabilization of SOM, include chemical, biochemical and physical stabilization [76]. Agricultural practices such as the addition of crop residues increase the SOM as well as nutrients contents in the soil by integrated nutrient management [77]. Most studies focus on the fact that the change of crop residue traits has positive effects of

Composting is the systematic and controlled breakdown of different types of organic matter including animal manure, woody material and other organic waste. The C content is available in the form of plant uptake in the composting. When the compost matures, 50% of C is available in the form of humic substances [79] and is thought to be more stable practically [80]. In the

farmyard manure, cattle slurry and boiler litter) were from 30 to 200 kg C ha−1 yr.−1 t

−1

23

−1 of dry

**3.1. Animal manure**

#### **2.7. Soil biota management**

Biological CS is accomplished by microbial activities. Mechanisms of CS by microbes need to be developed based on experiments and field investigations to predict the CS potential and C cycling under potential global change scenarios [56, 57]. Microbes improve the physical, chemical and biological soil properties in RT or NT areas. The evaluation of the soil microbial and biochemical environment greatly in these areas aids predictions of C availability in soil and plants to quantify CS. Where microbial communities are higher, C and N were 1.32–1.82 [58, 59]. Carbon sequestration was recorded higher up to 49.9 g C kg−1 in soils which were rich in soil microbes like fungi and soil bacteria [60].

#### **2.8. Cover crops**

The use of cover crops for the maintenance and restoration of SOM and soil productivity is a popular option [61]. Planting cover crops is a promising option to sequester C in cropping systems by the implementation of recommended management practices. The highest CS rate up to 5.3 t C ha−1 yr.−1 is observed by cover cropping of olive orchards, vineyards and almond orchards. Soil CS rate tends to be the highest during the first years after the change of the management and progressively attains equilibrium. Soil CS rates in cover cropping are much higher than that of fields with low or no cover cropping which suggests that the adoption of cover cropping is a sustainable and efficient measure to mitigate CC [62].

#### **2.9. Soil fertility management**

Rice-fallow-rice is one of the dominant cropping systems which has received attention to improve SOM by using organic amendments. Understanding the contributions of organic amendments in CS is important for the estimation of CS, their nutrient supply potential and their role in it. In different organic amendments, poultry manure is found to be more efficient in increasing C and other nutrients in soils and microbial activities which contribute to CS in the rice-rice cropping system [63, 64]. Raw adzuki bean (*Vigna angularis* (Willd.) Ohwi and Ohashi) and wheat (*Triticum aestivum* L.) straw residues can supply C into fields by 499 ± 119 kg C ha−1 [65]. The Mekong Delta, Vietnam, produces 21 Mt. of rough rice (*Oryza sativa* L.) and an estimated 24 Mt. of rice straw annually. The spread of these crop residues in this area can increase CS and SOM, significantly reducing GHG emissions [66]. Crop residue decomposition acceleration can enhance the SOM [67].
