Unlocking the Carbon Sequestration Potential of Horticultural Crops

Abstract

As the world grapples with the escalating threat of global warming, exploring sustainable agricultural practices has become imperative. Carbon sequestration is one such efficient method to mitigate carbon emissions and reduce global warming. Among the numerous sequestration options, terrestrial methods, notably via horticultural crops, have enormous potential. Horticultural crops, which encompass a diverse array of fruits, vegetables, plantations, and ornamental plants, offer a unique chance to sequester a considerable amount of atmospheric carbon dioxide. In particular, perennial horticultural systems provide numerous benefits over annual crops, such as increased productivity, reduced water and input requirements, and higher economic returns via carbon credits. However, the transition from annual to perennial crops presents logistical and financial challenges. The carbon sequestration capacity of plantations and horticulture crops is larger, at 16.4 Gt C, compared to the agroforestry system, which is at 6.3 Gt C. In order to fully use this capacity, it is essential to employ effective carbon management systems. These methods include growing higher biomass, recycling agricultural waste, employing animal manure, switching to perennial crops, adopting crop rotation, and encouraging agroforestry systems. Although there are advantages, substantial initial investments and continuous management are required to ensure effectiveness, and these demands might hinder widespread acceptance. This review emphasizes the critical role of horticulture systems in improving soil carbon levels, soil organic matter dynamics, different forms of carbon, and their overall potential for carbon sequestration. By unlocking the potential of horticultural crops to sequester carbon, we can help minimize atmospheric carbon dioxide levels, lessen the impact of climate change, and ensure nutritional security and economic benefits.

1. Introduction

In the light of a changing climate and a growing population, ensuring food security is a topic of global discussion. The global population is projected to reach nine billion by the end of 2050, and therefore increasing agricultural productivity is the need of the hour. In the face of more pressing environmental issues, the need to address climate change has sparked a search for novel ways to mitigate its consequences [1]. Climate-smart agriculture is one such method of increasing production sustainably. It also aims to lessen agriculture’s contribution to climate change through reducing greenhouse gas (GHG) emissions and increasing carbon sequestration [2]. Increased emissions of GHGs from different sources (Figure 1) are one of the main causes of global warming. The increase in atmospheric carbon dioxide (CO₂), from 280 ppm in the pre-industrial period to 310 ppm in 2010 (39% enrichment), as well as other GHGs like nitrous oxide and methane, has changed the mean precipitation and temperature [3]. It has been said that CO₂ concentrations by the year 2100 must be limited to below 441 ppm through the sequestration of carbon in soils and other inland aquatic and terrestrial ecosystems [4]. The act of capturing atmospheric CO₂ by plants via photosynthesis and storing it as carbon in soil and biomass is known as carbon sequestration [5]. This helps to reverse soil fertility loss, limit atmospheric GHG concentration, and also decrease the climate change impact on agricultural ecosystems [6].

While research has mostly focused on the significant carbon-absorbing capacity of forests and seas, the potential of horticulture crops to act as formidable carbon sinks has astonishingly remained overlooked [7]. Horticultural crops, which include a wide range of plant species grown for fruits, vegetables, and decorative uses, have long been praised for their benefits to subsistence, nutrition, and visual aesthetics. Horticultural crops are more profitable than field crops and are expected to cover roughly millions of acres of cultivable wastelands. It is estimated that producing roughly 2.2 metric tonnes of wood is required to sequester one tonne of carbon in the atmosphere [8]. Perennial fruit trees, plantation crops, etc., have 25–100 times higher biomass of carbon compared to agricultural lands. However, their latent capacity to actively contribute to the reduction of atmospheric CO₂ has significant ramifications for environmentally friendly farming practices and sustainable development. These plants have the innate capacity to absorb CO₂ from the atmosphere and convert it into organic matter via the complex process of photosynthesis, providing a powerful mechanism for curbing the global climate change effects [9].

We performed a bibliometric analysis using data sourced from Scopus and executed a network visualization through the VOS viewer. We retrieved approximately 43 documents from the Scopus database using the keywords “carbon AND sequestration AND horticulture AND crops”. We conducted a co-occurrence analysis, using all key words as the unit of analysis. We chose two as the minimum number of key word occurrences. Out of 580 keywords, 107 met the threshold. All 107 keywords have substantial connectivity (Figure 2). These terms exhibit significant interconnectedness, indicating a closely linked multidisciplinary approach to understanding and improving carbon sequestration in horticulture systems. This integrated network symbolizes a cohesive research community committed to common goals and the advancement of knowledge in this crucial area of environmental science. We also conducted a citation analysis, using the authors as the unit of analysis. We chose twenty-five as the maximum number of authors per document. We set a minimum of one document and citation for each author. Out of 221 authors, only 194 authors met the threshold. Figure 3 represents the largest set of connections among the 28 authors.

The goal of this in-depth review article is to highlight the unrealized potential of horticulture crops as important agents in carbon sequestration and to provide insight on the complex aspects that contribute to their effectiveness as carbon sinks. By delving into the diverse mechanisms of carbon assimilation and storage inherent to different types of horticultural crops, we endeavor to unravel the complex interplay between various environmental nuances and management intricacies that govern these processes [10]. This review also goes into detail about the other benefits of carbon storage, such as improving soil health, increasing biodiversity, and making agroecosystems more resistant to climate change.

Understanding the unique dynamics of carbon sequestration inherent to horticultural crops could lead to the incorporation of these crops into frameworks for sustainable land management, for the creation of creative agroforestry models, and the development of climate-responsive strategies meant to meet global emission reduction targets [11]. This review article aspires to raise awareness among a diverse audience made up of academics, cultivators, policymakers, and stakeholders by synthesizing a sizable compendium of available research that includes empirical studies and illustrative case analyses. By providing a deeper understanding of the latent capacity within horticultural crops, we hope to reveal novel avenues that transform conventional agriculture into a potent vanguard against climate change. By unlocking this potential, we may uncover new avenues for transforming agriculture into a powerful ally in the race to mitigate the effects of rising greenhouse gas concentrations and achieve a more sustainable and resilient future for generations to come.

2. Soil Organic Carbon and Its Dynamics

A soil system is a complex and dynamic ecosystem that sustains vital biological functions and facilitates the cycling of important nutrients required for life on land [12]. Soils play a crucial role in regulating climate by acting as substantial carbon sinks, effectively absorbing and storing atmospheric CO₂ [13,14]. The quantity of organic carbon sequestered in soils is around 1550 Gt, representing approximately 73% of the estimated 2110 Gt of organic carbon present in the biosphere [15]. Soil organic carbon (SOC) is a crucial element of land-based ecosystems, with a significant impact on soil fertility, structure, and overall ecosystem health. It serves as a reservoir for carbon within the Earth’s carbon cycle and is vital in preventing climate change. About 70% of the carbon on land is found in SOC, which is more than twice as much as the 760 Gt of carbon in the atmosphere [16]. Together, the management (carbon input) and environmental changes (climatic condition, soil qualities) affect the SOC pool to control the SOC dynamics across time and place [17,18]. Ecosystem functions heavily depend on the dynamics of SOC, which include its deposition, turnover, and accumulation [19]. Precipitation and temperature are the primary influential elements that determine the dynamics of soil carbon and contribute significantly to the release of CO₂ into the atmosphere during global warming. The climatic conditions and environment of a specific location determine the properties of litters and crop residues [19]. The quantity and quality (proximate and ultimate constituents) of litter and crop residues directly influence the carbon balance in the soil. Moreover, the quality and quantity of leftovers play a crucial role in shaping the microbial community structure at that specific location. This occurs because microbes utilize this litter as a source of nourishment, thus affecting the distribution of soil organic carbon throughout the area [20]. Soil conditions, such as geochemistry and physical structure, directly affect the stability of SOC through physico-chemical barriers. SOCs can prevent the breakdown of soil aggregates by occulting them or adsorbing to mineral surfaces. The protective efficacy of different soils varies considerably based on their soil type and physico-chemical conditions. The microbial activities involved in decomposition are influenced by the physical and chemical traits of the soil. Microbial decomposition processes would differ greatly between soils even with equal climate and C inputs due to differing enzyme activity and community structure. Hence, the following strategies have been followed including manuring and fertilizing, management of crop residue, conventional tillage, farmyard manure application, cover cropping, rotational grazing, and perennial cropping systems to enhance the capture of carbon and its storage in soil [6].

3. Carbon Capture and Sequestration: Mechanisms and Factors Affecting

3.1. Mechanism of Carbon Capture and Sequestration

Atmospheric CO₂ concentrations can be reduced by sequestering them in the terrestrial carbon pool through a process called carbon sequestration (Figure 4) [21,22]. Sequestrations may be categorized into different types depending on the location of the sequestration. The oceanic pool has 38,000 Pg of carbon, the geologic pool contains 5000 Pg of carbon, the soil C pool contains 2500 Pg of carbon, the atmospheric pool contains 760 Pg of carbon, and the biotic pool contains 560 Pg of carbon. In addition, the soil carbon pool is significant from the perspective of agriculture [23]. According to the IPCC, agricultural soils can sequester up to 1.2 billion metric tonnes of carbon every year. As one-third of the world’s arable land is devoted to agriculture, it is projected that agricultural land could absorb at least 10 percent of the annual carbon emissions (8–10 Gt) [24]. It is projected that land used for agriculture can sequester up to 66% of historical carbon loss if it is managed effectively [25]. Thus, planting trees and perennial crops on arable land is a very effective approach to increasing SOC [26]. Perennial crops provide continuous vegetation cover, leading to year-round photosynthesis. This, in turn, enhances the production of biomass, which remains on the site and contributes to the accumulation of SOC. Moreover, it remains on the land for more than a year, minimising tillage practices and soil disturbances. In addition, therefore, there is a higher capacity to preserve or store SOC compared to annual crops. In addition to the potential advantages for soil health and the reduction of GHG emissions, perennial crops can store biomass and may be used as a substitute for fossil fuels in energy production [27].

In this context, not only horticulture crops but also any crop sequesters atmospheric carbon by the following methods: (i) Plants capture CO₂ from the atmosphere on their leaves through photosynthesis, convert it into carbohydrates [28], and transform it into biomass. This is considered both above-ground biomass carbon and below-ground biomass carbon. (ii) The sequestered carbon in plants reaches the ground as a litter undergoes decomposition and humification by soil microbes, which contribute a certain amount of carbon to the soil, particularly compounds rich in lignin, which persist as a more recalcitrant fraction, contributing to soil organic carbon accumulation while the remaining carbon is released as CO₂ through microbial respiration (Figure 5). Estimates imply that around 60–70% of the carbon present in plant residues may be converted into CO₂ within a year [29]. The speed of the decomposition process is determined by its C/N ratio. The study by Rahn and Lilly White revealed that vegetable crops have more nitrogen (N) than cereals [30]. As a result, vegetable crops have a narrower carbon-to-nitrogen (C/N) ratio, ranging from 9 to 24, while wheat has a C/N ratio of 58. The humification rate of crop residues with a low C: N ratio was higher than that of residues with a high C:N ratio [31], and the wider C/N ratio may result in immobilization. However, perennial crops, such as fruit trees, can absorb and retain around 0.5 to 2.5 metric tonnes of CO₂ per hectare annually [32]. An analysis of metadata on changes in SOC under perennial crops revealed a 20% increase in SOC at a depth of 0–30 cm (equivalent to a gain of 6.0 ± 4.6 Mg/ha) and a total 10% increase across the entire 0–100 cm soil profile (equivalent to 5.7 ± 10.9 Mg/ha) [33]. The second input of SOC is root exudates. Plants release organic compounds, known as root exudates, into the soil. These exudates include sugars, amino acids, and other complex compounds that fuel microbial activity. In return, these microbes facilitate nutrient uptake by plants. Some of the exudates contribute to SOM, enriching the carbon content in the rhizosphere—the region around plant roots. This distribution of carbon belowground increases the soil’s capacity for long-term carbon storage [34]. Mycorrhizal fungi form symbiotic associations with plant roots, enhancing nutrient uptake and aiding in carbon sequestration. These fungi extend their hyphal networks into the soil, accessing nutrients and minerals beyond the plant’s reach. In exchange, they receive carbon compounds from the plant through root exudates [35]. This mutualistic relationship not only supports plant growth but also contributes to the accumulation of SOC.

3.2. Influencing Factors for Soil Organic Carbon Sequestration

Soil carbon sequestration plays a crucial role in reducing the impact of climate change, improving soil fertility, and supporting sustainable agricultural practices. A number of factors affect the soil’s ability to store carbon, such as soil characteristics, land management techniques, climatic conditions, and kinds of vegetation (

Table 1. Factors influencing soil carbon sequestration.

Factor	Percentage Contribution	Description	References
A. Soil Properties (30%)
Soil Texture	15%	Clay-rich soils can sequester carbon by protecting organic materials from degradation.	[37]
Soil Structure		Well-aggregated soils facilitate organic matter-stabilizing microenvironments.	[38]
Soil pH	5%	Optimal pH (6–7) promotes microbial activity and nutrient availability, improving sequestration.	[39]
Soil Moisture	10%	Moist soil is necessary for plant development and microbial activity, which add carbon and stabilize soil.	[40]
Soil Temperature		Moderate temperatures enhance microbial activity and carbon stabilization, whereas severe temperatures hinder both.	[41]
B. Land Management Practices (40%)
Tillage Practices	10%	Conservation tillage increases soil carbon by 57% over conventional tillage.	[42]
Crop Rotation and Diversification	10%	Cover crop rotations boost soil organic carbon by 20% over monocultures.	[43]
Organic Amendments	10%	By adding organic matter like compost and manure, soil carbon content increases. Organic additives boost soil carbon reserves over time.	[44]
Agroforestry	10%	Adding trees to agricultural areas increases biomass and soil carbon sequestration. Agroforestry systems can store 1.5 Mg C ha⁻1 yr⁻1.	[45]
Perennial Cropping Systems		Deep root systems help perennial crops like switchgrass and miscanthus store soil carbon. Perennial crops trap carbon well on marginal landscapes.	[46]
C. Climate Conditions (20%)
Temperature and Precipitation	15%	Climate substantially impacts soil carbon sequestration. Warm, wet temperatures boost plant production and soil carbon.	[47]
Extreme Weather Events	5%	Droughts, floods, and storms damage soil structure, vegetation, and erosion, reducing soil carbon sequestration.	[48]
D. Vegetation Types (10%)
Grasslands	4%	Grasslands are significant carbon sinks due to their extensive root systems and continuous ground cover.	[49]
Forests	4%	Forest biomass and soil store much of carbon. Forest soils may store up to 2.0 Mg C ha⁻1 yr⁻1, depending on species mix, age, and management approaches.	[50]
Wetlands	2%	The slow decomposition, makes wetlands one of the best carbon sequestration habitats. Wetlands, such as peatlands, trap up to 5.5 Mg C each year.	[51]

). Quantifying the exact proportion of each component that influences soil carbon sequestration is difficult because of the intricate interplay between these factors and the diversity across diverse ecosystems and management approaches (Figure 6) [36].

4. Why Horticultural Crops for Carbon Sequestration?

Approximately 120 gigatons (Gt) of carbon are fixed annually by photosynthesis in plants worldwide, with horticulture crops making a major contribution. Perennial fruit trees, plants, gardens, etc., contain 25–100 times more carbon in their biomass than agricultural fields. Therefore, unoccupied and wastelands might be assigned to permanent horticulture systems rather than agricultural or agroforestry crops [52]. There are important reasons for considering the horticulture area as a prime source to sequester carbon and offset GHGs emission [53]. They are the following:

(i) Perennial Growth: Many horticultural crops are perennial, meaning they live for multiple years. This extended growth period allows them to accumulate more biomass and contribute more organic matter to the soil over time, increasing carbon sequestration potential [54]. The biomass carbon content in these crops generally falls within the range of 40–50% of their dry weight. For example, an apple orchard covering one hectare may normally capture around 20–30 tonnes of CO₂ annually, while a tomato field of the same size can sequester around 10–15 tonnes.

(ii) Root Structure: Compared to annual crops, the root systems of horticultural plants are often more widespread and penetrating. These deeper roots can store carbon deeper in the soil, reducing its vulnerability to rapid decomposition [55].

(iii) Continuous Ground Cover: This is maintained by perennial horticulture crops, which lower soil erosion and avoiding carbon loss from the topsoil. It also helps maintain soil structure and organic matter content.

(iv) Reduced Tillage: Many horticultural systems use reduced or no-till practices, which minimize soil disturbance and carbon loss through oxidation. Reduced tillage also promotes the accumulation of organic matter, fostering a healthier soil ecosystem.

(v) Diverse Cropping Systems: Horticultural systems often involve a diverse range of plant species and crop rotations. This diversity enhances soil health by supporting a variety of soil microorganisms that contribute to organic matter decomposition and carbon storage.

(vi) Organic Matter Inputs: The organic matter content of soil may be increased by horticultural practices such as the use of cover crops, organic mulches, and compost. This organic matter serves as a carbon source and contributes to long-term carbon sequestration.

(vii) Agroforestry and Orchards: Some horticultural systems, like agroforestry and orchards, involve planting trees alongside crops. Due to their vast biomass and extensive roots, trees are very adept at carbon sequestration [56]. Agroforestry systems have the capacity to capture and store 3–5 tonnes of carbon dioxide per hectare year, which is much more than the amount sequestered by monoculture systems.

(viii) Urban and Peri-urban Settings: Horticultural practices are often integrated into urban and peri-urban areas, where they can convert unused spaces into carbon sinks. Urban agriculture contributes to carbon sequestration, improves air quality, and enhances local food security.

(ix) Longer Harvest Cycles: Horticultural crops typically have longer harvest cycles compared to annual crops. This means that the fields are disturbed less frequently, reducing carbon loss from the soil.

(x) Soil Health Benefits: Horticultural practices that focus on soil health management also improve carbon sequestration. Healthy soils with good structure and microbial diversity enhance carbon storage capacity [57].

These points are important for tropical nations with extensive deforested and degraded soil suitable for the growth of perennial horticultural crops.

5. Carbon Stock Measurement in Horticultural System

The suggested method for quantifying the sequestration of carbon in horticulture gardens is to monitor both the orchard and the baseline using permanent sample sites. A well-established statistical approach is utilized to determine the sample design and needed intensity for a particular degree of accuracy. For larger regions, random subsamples of the permanent sampling units may be taken annually. Imaging and remote sensing-based techniques are used for mega orchards. A horticulture project, for accounting the carbon sequestration, involves the measurement of four pools: living aboveground biomass, living belowground biomass, soil carbon, and necromass (Figure 7) [53].

In the carbon market, not all of these are likely to be acknowledged as sources of sequestration, and not all pools must be assessed with the same degree of accuracy or regularity over the orchard’s life. To establish a baseline, all relevant carbon pools should be assessed in the first inventory. However, for further monitoring based on project type, only the chosen pools must be measured [58]. Hamburg provided the degree of accuracy at which each pool could be measured economically [59].

5.1. Aboveground Biomass (AGB)

There are various conventional, well-established techniques for measuring aboveground carbon biomass in forests; the same could be used in horticultural crops. Calculating the aboveground biomass involves multiplying the biomass volume by the wood density, which includes all live biomass above the soil [60]. Based on the height and diameter, the volume can be determined:

AGB (g) = volume of biomass (cm³) × wood density (g/cm³).

5.2. Belowground Biomass (BGB)

Live roots make up the below-ground biomass, with the exception of fine roots with a diameter of less than 2 mm [61]. With 40% of the overall biomass, this pool is the most significant [62]. The root-to-shoot ratio of 0.26 is multiplied by the aboveground biomass to calculate the belowground biomass [60]:

BGB (t/ha) = 0.26 × aboveground biomass.

5.3. Soil Carbon

The major sources of soil carbon include the decomposition of crop residues, microbial activity, and root exudates. Even though measuring soil carbon directly is a costly endeavor, particularly due to the very strong influence that soil characteristics have on the dynamics of carbon, Hamburg suggested that it is possible to measure soil carbon to an admissible accuracy level for the purposes of biological mitigation projects if a few generalized principles are utilized [59]. It was his recommendation that the measurement of soil carbon be carried out to a depth of at least one meter, and that measurements of bulk density and soil carbon be performed from the same soil sample. For the project with a non-decreasing effect of the soil carbon, it is suggested that after the establishment of the baseline, there is no need to measure the soil carbon. Literature is available that provides estimates of soil oxidation rates for a variety of land use patterns [58]. Reforestation initiatives on degraded or agricultural land are likely to result in an increase in the amount of carbon found in the soil. It has been found that the project developer does not need to measure this pool when the marginal cost of measuring it exceeds the marginal benefits of carbon credits. Alternative groups to slash and burn (ASB) have stated that most of the sequestration capacity in tropical areas is aboveground rather than in the soil. In the tree-based system that was being planted to replace the damaged pastures, it was discovered that time-averaged carbon stock went up by 50 metric tonnes/ha in 20 years, while carbon stock in the soil increased by 5 to 15 metric tonnes per hectare [63,64]. Modelling may enhance monitoring procedures [58]. These are notably used to anticipate the gradual changes in the carbon pools in the soil. Wise and Cacho provide a demonstration of this method [65]:

Soil Carbon Stock (C/ha) = Total Soil Organic Carbon (%) × Bulk Density (Mg/m³) × Depth of the soil (cm).

5.4. Necromass

Necromass pools contain carbon from decaying plants, such as dead branches, leaves, and trees. Since the losses from decomposition occurring in the soil balance the yearly intake of leaf litter, it is not necessary to include them in the calculation of the necromass pool. Instead, the net impact is taken into account when calculating the soil pool [59]. The kind of plantations and the history of disturbance have a significant impact on the amount of necromass. Accurately estimating this component takes time and is quite uncertain. When we are certain that it will not go down as a result of the project, this component may be neglected [59]. A key carbon pool that should be monitored is dead wood, both standing and lying [58]. Since the techniques for this component have been proven, only the live biomass has to be measured.

5.5. Constrains for Measuring Carbon Stock

The measurement of carbon sequestration in different horticulture crops, such as fruits, vegetables, and plantation crops, is difficult because of their varied properties. Accurately evaluating the amount of biomass above the ground in fruit trees and plantation crops is challenging due to their diverse shapes and sizes. This assessment requires the complete harvesting of trees and the measurement of different parts. Additionally, measuring the biomass below the ground is laborious, time-consuming, resource-intensive, and expensive due to the presence of deep root systems. In contrast, vegetable crops, which have shorter lifespans and smaller root systems, provide a simpler method for estimating above-ground biomass [66]. Therefore, it is challenging to establish a uniform method of measuring that can be used for all types of crops. Similarly, the evaluation of soil carbon sequestration faces constraints caused by variables such as soil types, agricultural techniques, and weather patterns. As well, the rates at which organic matter and necromass break down vary greatly across different crop species, which makes estimating the carbon pool more challenging. The presence of different soil types and changes in carbon levels over time make it even more complex, requiring thorough sampling and sophisticated modelling to provide accurate results. The intersection of these factors increases costs, workforce requirements, and the challenge of accurately measuring carbon sequestration in multiple horticulture systems [67].

6. Prospects and Potential of the Cropping System for Sequestration of Carbon

The cropland’s significant capacity for carbon sequestration offers an effective method for lowering atmospheric CO₂ levels. However, this strategy is built on the cropping system, which is described as the operating system for producers to follow in their methods of crop production. A farming system that includes a lot of biomass, or organic carbon, in the soil is appropriate for carbon sequestration [68]. The amount of crop residue that is either integrated into the soil or left on the soil surface (0–15 cm) represents the rate of organic carbon there [69]. Thus, it is necessary to enhance the input of plant biomass residues in order to promote carbon sequestration. The accumulation of biomass could be strengthened by enhancing the cultivation intensity, intercropping, cover cropping, and reducing the fallow period of the land. The restoration of biomass to the soil may be enhanced by eliminating the winter or summer fallow and keeping a rich plant cover on the soil’s surface, which also minimizes SOC loss [70].

6.1. Crop Rotation

When legumes and non-legumes are rotated, crop rotation promotes soil carbon sequestration and biomass output. Growing legumes may cut down on the usage of chemical fertilizers, which cuts back on the use of fossil fuels to make fertilizers [71]. In contrast, the production of biomass could decrease in the absence of a suitable crop rotation due to an increase in weed, insect, and disease infestations. Another effective method for increasing carbon sequestration and biomass production is to reduce bare land and increase cropping intensity. Additionally, increasing crop intensity may slow down the oxidation and mineralization of SOC as well as the rate of organic matter breakdown [72].

6.2. Intercropping

Crop productivity could be increased in intercropping due to the higher utilization efficiency of sunlight with the spatial distribution of different plant architectures. The system of intercropping involves mixed cropping, relay intercropping, row intercropping, and strip intercropping which depend chiefly on various crop characteristics in crop goals and spatial distribution [73]. For instance, growing sorghum or corn in a row with vine crops like sweet potatoes or climbing beans might increase the output of the vine crops since the vines can climb on the other plants to benefit from sunshine and space. The former crop produces an optimum yield compared to the latter. Intercropping cluster bean in elephant foot yam improved carbon accumulation by 54.40% compared to monocropping elephant foot yam [74]. Legumes increase the amount of labile carbon in the soil organic carbon pool when grown in intercropping [75]. A strip cropping system is preferred for the convenient harvest of several crops, especially when combine harvester machines are used. Selection of varieties or crops with different maturity rates would help in staggered harvest.

In intercropping systems, a mixed cropping system is also an effective approach for optimizing the environment for optimum plant production by growing two or more plants in combination. Benefits of mixed cropping include balancing soil nutrient inputs and outputs, suppressing insects and weeds, resisting temperature extremes, controlling plant diseases, and increasing total productivity with the available resources [76]. Beans, maize, and cucurbits (pumpkin and squash) are typical examples of mixed cropping. These three crops are first planted in the same hole. The corn serves as a support for the beans to climb; the beans are nutrient-dense, which reduces the amount of nutrients taken up by the corn, and pumpkins or squash are grown in soil that keeps weeds out and reduces water loss. The capacity for biomass return and soil carbon sequestration may be seen when all these advantages are achieved, leading to optimum production with a commensurate amount of biomass both above and below ground. Such mixed cropping systems must be adjusted for modern agriculture in order to facilitate machine harvest and management simplicity. Relay intercropping is a cropping technique in which the second crop is sown into the first crop just before its harvest. This system has a time and spatial advantage for obtaining optimal yield and eliminating the period of fallow, which helps in soil conservation and decreases water evaporation loss. Relay cropping effectively covers the land while using natural resources, particularly soil and sunshine, to provide an economic yield and accumulate biomass [77].

6.3. Cover Cropping

Another very successful strategy for improving SOC carbon sequestration and storage is to use cover crops. Summer cover crops, such as velvet beans, sunn hemp, etc., are the predominant species planted in humid, hot summers to cover barren ground and preserve water and soil in tropical or subtropical areas [78]. The summer crops, especially the sunn hemp, produce 15 Mg ha⁻¹ of aboveground biomass, 3–5 Mg ha⁻¹ of belowground biomass, which in combination contribute around 8 Mg ha⁻¹ of the SOC within 3 months [79]. Thus, the cover cropping system offers a crucial tactic to improve carbon sequestration and combat climate change.

6.4. Companion Cropping

Companion cropping is often followed in the system of organic vegetable production. For example, the use of continuous beds of companion crops, which are cultivated alongside vegetables (cabbage, lettuce, etc.), has evolved under different natural situations and is seen as a potential substitute for the production of organic crops [80]. The companion crops also reduced the pest and weed impact of vegetable crops due to their biodiversity. Furthermore, companion crops provide several advantages to the vegetable crop; for example, the trapping effect of companion crops helps to get rid of pests and thus aids the plant in yielding more biomass.

6.5. Ratoon Cropping

The technique of ratoon cropping allows the crop to produce two or more extra harvests. The essential characteristics of a crop for ratoon cropping systems are early maturity, a strong root structure, and perennial nature. It has advantages for the production of crops and soil carbon sequestration. Ratoon crop also reduces the production cost as there is no separate land preparation and planting [81]. It makes effective use of the growing season, better utilization of sunlight energy, increases yield with higher biomass, prevents water and soil erosion, uses less fertilizer and irrigation water, prevents leaching of nutrients, and is more economically productive compared to conventional systems of cropping. Okra is an ideal example of a ratoon vegetable in the tropics and subtropics, where ratooning can be carried out two or three times [82].

7. Carbon Sequestration Examples from Horticultural Crops

The sequestration potential of different horticulture crops varies in accordance with their biomass (Figure 8). Though measuring carbon is not much easier due to the involvement of complex variables (composition may vary due to soil type, microclimate, etc.), researchers have revealed some facts about horticultural crops (

Table 2. Carbon sequestration potential of various horticulture crops.

Crop	Crop Details	Above Ground Carbon	Below Ground Carbon	Total Carbon Sequestration	Carbon Stock	References
Fruit crops
Mango	Vol3.78 m3/ha	1.00 t/ha	0.26 t/ha	1.26 t/ha	-	[83]
	1908 trees	204.82 kg/tree	53.25 kg/tree	258.06 kg/tree	-	[84]
	764 trees	346 t/ha		346.04 t/ha	-	[85]
	6048 trees	44.73 t/ha	11.63 t/ha	56.36 t/ha	-	[86]
	-	22.70 Mg/ha	4.32 Mg/ha	27.02 Mg/ha	1.80 Mg/ha	[87]
	-	205.5 kg/tree	63.58 kg/tree	269.07 kg/tree	-	[88]
	-	555.6 kg/tree	180.25 kg/tree	733.025 kg/tree	110.88 mt	[89]
	10 year old	46.08 kg/tree	11.78 kg/tree	58.06 kg/tree	-	[90]
	15 year old	91.62 kg/tree	23.82 kg/tree	115.44 kg/tree	-
	113 trees	17.1 t/ha	4.5 t/ha	21.15 t/ha	4.5 t/ha	[91]
	14 years old	0.41 t/tree	0.09 t/tree	0.50 t/tree	0.59 t/tree	[92]
	15 years old	47.61 t/ha	7.17 t/ha	54.78 t/ha	-	[93]
Banana	25 trees	15.04 kg/tree	2.26 kg/tree	17.30 kg/tree	-	[94]
Citrus	492 trees	25.44 t/ha	20.68 t/ha	47.92 t/ha	-	[95]
	17 years old	149.53 kg/tree	36.72 kg/tree	186.25 kg/tree	-	[96]
Guava	-	6.33 t/ha	1.69 t/ha	8.02 t/ha	-	[97]
	10 years old	26.09 kg/tree	6.78 kg/tree	32.87 kg/tree	-	[98]
	15 years old	43.11 kg/tree	11.21 kg/tree	54.31 kg/tree	-
Grape	3077 vines	8.76 t/ha	1.92 t/ha	10.67 t/ha	-	[95]
	1631 vines	8.2 Mg/ha	4.1 Mg/ha	12.3 Mg/ha	-	[99]
Jack	0.35 m3/ha	0.09 t/ha	0.02 t/ha	0.11 t/ha	-	[83]
Jamun	5.96 m3/ha	1.74 t/ha	0.45 t/ha	2.19 t/ha	-	[83]
	10 years old	30.71 kg/tree	7.98 kg/tree	38.68 kg/tree	-	[98]
	15 years old	62.54 kg/tree	16.26 kg/tree	78.79 kg/tree	-
	73 trees	0.16 t/ha	0.03 t/ha	0.19 t/ha	-	[100]
Aonla	1130 trees	101.98 kg/tree	26.51 kg/tree	128.49 kg/tree	-	[84]
	25 years old	1.16 Q/tree	0.30 Q/tree	1.46 Q/tree	1.62 Q/tree	[101]
	191 trees	25.2 t/ha	6.75 t/ha	31.5 t/ha	5.1 t/ha	[91]
	19 trees	14.58 t/ha	2.19 t/ha	16.76 t/ha	-	[89]
	14 years old	0.65 t/ha	0.17 t/ha	0.39 t/ha	0.44 t/ha	[92]
	14 years old	8.98 t/ha	1.89 t/ha	10.88 t/ha	-	[102]
	-	0.21 t/tree	0.03 t/tree	0.25 t/tree	-	[103]
Ber	37 trees	0.36 t/ha	0.07 t/ha	0.43 t/ha		[100]
Date Palm	77 trees	14.33 Kg/tree	2.15 kg/tree	16.48		[89]
Wood Apple	10 years old	0.31 t/tree	0.08 t/tree	0.39 t/tree	0.44 t/tree	[92]
Rambutan	12 years old	13.4 t/ha	2.01 t/ha	15.41 t/ha	-	[93]
Custard Apple	0.24 m3/ha	0.05 t/ha	0.01 t/ha	0.07 t/ha	-	[83]
	1462 trees	35.95 t/ha	9.35 t/ha	45.30 t/ha	-	[84]
Apple	1250 trees	-	-	26.3 t/ha	-	[104]
	-	184.83 t/ha	46.20 t/ha	231.05 t/ha	126.20 t/ha	[105]
	2632 trees	7.65 t/ha	4.73 t/ha	12.91 t/ha	-	[95]
Plum	-	6.79 Mg/ha	1.06 Mg/ha	8.05 Mg/ha	1.61 Mg/ha	[87]
Kiwi	800 vines			19.6 t/ha	-	[104]
Litchi	-	0.52 Mg/ha	1.90 Mg/ha	8.42 Mg/ha	1.20 Mg/ha	[87]
	-	2.66 q/tree	0.41 q/tree	3.074 q/tree	1.13 q/tree	[106]
	14 years old	0.41 t/tree	0.09 t/tree	0.50 t/tree	0.59 t/tree	[92]
Vegetable Crops
Moringa	-	0.88 t/tree	0.12 t/tree	1.01 t/tree	-	[103]
	14 trees	0.626 t/tree	0.163 t/tree	0.789 t/tree	-	[107]
Flowering Trees
Scholars tree	308 trees	3496.10 kg	524.42 kg	4020.52 kg	-	[89]
	-	1.73 t/tree	0.26 t/tree	1.99 t/tree	-	[103]
Plumeria	222 trees	3339.43 kg	500.91 kg	3840.34 kg	-	[89]
May Flower	211 trees	3097.49 kg	464.63 kg	3562.11 kg	-	[89]
	-	0.13 t/tree	0.02 t/tree	0.15 t/tree	-	[103]
	13 trees	0.22 t/tree	0.06 t/tree	0.28 t/tree	-	[94]
Bottle bush	39 trees	586.78 kg	88.02 kg	674.80 kg	-	[94]
Cassia fistula	20 trees	301.77 kg	45.27 kg	347.04 kg	-	[94]
Pride of India	12 trees	179.40 kg	26.91 kg	206.31 kg	-	[94]
Copper pod	12 trees	108.87 kg	16.33 kg	125.20 kg	-	[94]
	-	0.23 t/tree	0.03 t/tree	0.26 t/tree	-	[103]
	17 trees	0.17 t/tree	0.04 t/tree	0.22 t/tree	-	[107]
Bauhinia	10 trees	149.40 kg	22.41 kg	171.81 kg	-	[94]
Butea	15 trees	0.06 kg	0.02 kg	0.08 kg	-	[94]
Plantation Crops
Coconut	50 years old	51.14 t/ha	47.06 t/ha	98.20 t/ha	-	[108]
	177 trees	143.01 kg/plant	-	103.2 t/ha	158.9 kg/plant	[98]
Nutmeg	135 trees	3.93 t/ha	-	2.16 t/ha	4.36 kg/plant	[98]
Rubber	47 years old	101.86 kg/plant	14.04 kg/plant	115.89 kg/plant	-	[109]
	15 years old	105.36 Mg/ha	19.66 Mg/ha	125.00 Mg/ha	-	[110]
	34 years old	61.57 Mg/ha	14.58 Mg/ha	76.15 Mg/ha	-	[111]
	17 years old	63.90 Mg/ha	13.10 Mg/ha	76.59 Mg/ha	-	[112]
Aercanut	-	12.02 kg/plant	2.98 kg/plant	15.34 kg/plant	-	[113]
Oil Palm	15 years old	56.66 t/ha	14.73 t/ha	71.39 t/ha	-	[114]
	8 years old	19.73 t/ha	5.13 t/ha	24.86 t/ha	-
	4 years old	2.23 t/ha	0.58 t/ha	2.81 t/ha	-

). A few examples are listed below:

7.1. Turfgrass

Turfgrass represents a chief part of urban horticulture, including golf courses and domestic lawns. Turfgrass develops thatch, roots, and shoot tissues as it grows, which allows it to store carbon. Depending on the species, grass may have either annual or perennial root systems [115]. The ageing root dies and sloughs off when the new ones are added, which in turn contributes to soil carbon accumulation. Through regular mowing, shoot systems are constantly recycled into the canopy. The layer of live and dead branches and roots that is found between the area of the soil’s surface and green plants is known as thatch [116]. Even though thatch is not a part of the SOM, its breakdown and incorporation into the soil by earthworms or cultivation tools, have an effect on the surface SOM level. Since turf is managed as a perennial and the sod that forms often stays in place for decades, the stored-up carbon is not subject to the same pressure to change that is put on agricultural land. The turfgrass potential to sequester carbon has been well demonstrated. Sixteen different golf area samples were collected with a varying range of ages (1.5–4.5 years) and different soil textures, ranging from sandy loam to clay loam. It was observed that the rate of carbon sequestration grew from 0.9 to 1.0 Mg carbon/ha/year for around 31 years before it levelled off. Added to this, it was found that fertilizers applied had no effect [117]. In parks with turfgrass varying in age from 3 to 24 years, Tocusend-Small and Crimczik evaluated the organic carbon in the soil under the grass and discovered that a total of 1.4 Mg carbon/ha/year was deposited [117]. The SOC sequestration rates were 0.32 to 1 tonne carbon/ha/year, according to Qian and co-workers [118]. Several studies addressed carbon sequestration by turfgrass; most of them had a similar range of SOC rates. Thus, turfgrass is a common feature of urban and suburban landscapes and has a large potential to help sequester carbon [119].

7.2. Vegetable Crops

The majority of vegetable crop operations, including those that are produced on dry ground, under irrigation, or in arid conditions, discourage the use of conservation tillage due to diverse rotations and specialized management techniques in the field. There are, however, few research studies on using cover crops in vegetable cultivation to increase soil carbon storage [120]. Increasing crop frequency and using high residue crops are two management strategies that are recommended for vegetable systems to improve SOC. Alternately, soil tillage improves plant water usage efficiency, and the use of mulches may minimize soil carbon loss. Incorporation of legumes (cluster bean, cowpea, pea, French bean, lab-lab, etc.) can be effective for allocating a higher plant biomass carbon percentage to the belowground sequestration of soil carbon. Potadar and Patil observed that the carbon sequestration potential of moringa was about 117.44 kg/tree [121]. It was found that improved crop land practices could enhance the sequestration of SOC rates from 0.1 to 1 tonne of carbon per ha per year with diminishing accumulation rates as the soil approaches a new equilibrium. Vegetable biomass, including the leftover leaflet, can be converted into biochar and then incorporated into soils to retain carbon for a longer period of time.

7.3. Fruit Trees

Fruit trees are likely to display increased biomass production and photosynthetic rates regardless of soil moisture conditions. Consequently, the higher quantities of carbon are probably sequestered in woody trunks and fruit tree branches. Fruit-based systems are said to be self-sustainable as the solar energy could be harvested at various heights, allowing effective utilization of soil resources with increased cropping intensity [122]. The key components of this system are the main crop, intercrop, and filler crop, which are distributed throughout three different levels in the production system area. The fruit species of the main crop have an extensive canopy size with a prolonged juvenile and productive phase. The fruit species of filler crops are those with precocious and prolific bearers of short stature. They form the middle layer of the multitier system, where economic productivity is obtained. The lowermost layers of the multitier system are grown in the remaining free spaces. The prolific flowering and fruiting abilities of the trees enhance carbon removal from the environment, and the carbon is stored as cellulose in large quantities. Janiola and Marin estimated the carbon storage potential of santol (32 years old), mango (15 years old), and Rambutan (12 years old) at about 203.62, 122.34, and 112.17 t/ha, respectively [93]. The carbon storage in a nectarine orchard located in China varied from 13–15 tonnes of carbon per hectare [79]. The total carbon sequestered from the entire mango orchard in India was about 258.005 Mt of carbon [88].

7.4. Plantation Crops

On a broad scale, plantation crops are raised as perennials and are typically present in cropping systems as mixed species. In comparison to the monocropping system, this cropping method produces more biomass per unit area [123]. They act as the carbon pool that helps reduce global warming effects. Bhagya and Maheswarappa estimated that coconut alone sequestered carbon at about 51.14 t/ha [108]. Sonwa and his co-workers reported that the chocolate forest (cocoa trees) stores carbon at 243 Mg/ha in South Cameroon [124]. A study conducted in Brazil estimated that the carbon stock was about 79.3 Mg C/ha of a 15-year-old rubber plantation [110], and that for the cashew was estimated to be about 63.14 ± 3.78 to 84.84 ± 4.06 t carbon/ha [125]. Rakesh and his co-workers assessed the oil palm potential for carbon sequestration in the Coimbatore district of Tamil Nadu and found that carbon sequestration in trunk, root, and fronds was about 26.6, 6.93, and 2.1 t/ha of carbon in a 10-year-old oil palm plantation [114].

8. Challenges in Monitoring Carbon Sequestration

However, there are several opportunities to use the carbon stock and sequestration capacity in the soil of different ecosystems, but there are a number of obstacles to overcome [126] stated below to make it happen in practice:

(i) Measurement and Verification: It is challenging, costly, and time-consuming to measure the carbon stored in the soil. Due to sample mistakes, small-scale variability, and uncertainties in measurement and analysis, it is much more challenging to identify changes inside the 10% range [127]. The average yearly increase in soil carbon stock is just 0.25 to 1.0 tonne per hectare [60]. It is difficult to account for little changes in soil carbon at various scales due to challenges in methods, such as verification, sampling, monitoring, and depth. [128]. Even when these small changes (loss or gain) are detected, it is not very easy to link such changes in land use or management practices in a given context. The soil can only hold and store carbon for a limited amount of time before it reaches a steady state.

(ii) Carbon pools: In the context of soil carbon sequestration, carbon is partitioned into distinct pools, each characterized by varying residence times within the ecosystem, as outlined by Abdullahi and his co-workers [126]. The first pool is the passive, refractory, or recalcitrant pool, housing organic carbon with an extended residence duration spanning decades to even millennia. This carbon is notably resilient to decomposition due to its intricate molecular structure. Second, the active, fast, or labile pool contains carbon susceptible to swifter decomposition, resulting in a shorter residence span ranging from a mere day to a full year. This pool encompasses easily decomposable organic compounds, and its carbon turnover is largely influenced by microbial activity. Last, the stable, slow, or humus pool accommodates carbon that undergoes gradual decomposition, leading to a more prolonged turnover timeframe of one to ten years. This particular pool is enriched with partially decomposed organic materials, with humus being a significant component contributing to soil structure and nutrient retention. This segmentation of carbon into various pools with varied decomposition rates is crucial for understanding ecosystem carbon dynamics and developing methods to enhance carbon sequestration activities.

(iii) Permanence: Another problem with storing carbon in the soil is that it does not stay there forever. Carbon that has been stored in the soil can easily be released back into the air through mineralization or decomposition. This is the rationale for thinking of carbon sequestration as a temporary solution to reduce atmospheric carbon. Numerous land use, climate, and management variables influence the loss of carbon.

(iv) Separation: It is challenging to separate and isolate the diverse forms of carbon that are sequestered in the soil as a consequence of land use or management activities that occur naturally. According to the separation principle, management action or natural factors may stop carbon sequestration or greenhouse gas emissions. Therefore, techniques that can distinguish between carbon that is naturally sequestered and carbon that is trapped by human management are required [129].

9. Management Options in the Horticulture System for Increasing the Sequestration of Carbon

Orchard management methods vary by region, soil, culture, and society. Soil health management may enhance the development and production of horticultural plants, including annuals and perennials. There are three basic approaches for managing GHG reduction for enhancing SOC, including the following: (i) maintaining the existing SOC level; (ii) restoring the depleted SOC level; and (iii) enlarging the soil organic pool above its carrying capacity and magnitude. Management strategies for horticultural crops are instrumental in maximizing carbon sequestration potential and promoting sustainable land use. A comprehensive approach involves adopting strategies at various levels, ranging from land use planning to integrated farming systems, tillage practices, nutrient management, and pest control [130].

At the land use level, a strategic approach involves reclaiming culturable and degraded wastelands through the establishment of perennial horticultural crops such as mango, anona, amla, ber, litchi, apple, pomegranate, and peach. This choice of crops should be aligned with the climatic conditions of the region. To further enhance carbon sequestration, these horticultural systems can be integrated with erosion control measures, cover crops, and optimized fertilization. Water harvesting practices also play a pivotal role in providing necessary irrigation, while concurrently controlling pests and diseases [131].

Diversification within farming systems is a key management strategy. Monoculture should be minimized, and mixed orchards that incorporate a variety of crops, such as annona, ber, pomegranate, mango, amla, litchi, apple, guava, and pear, along with cover crops, should be encouraged. This approach not only enhances biodiversity but also reduces the need for excessive nutrient input and the control of diseases and pests. Additionally, mixed orchards engage farmers in diverse activities and provide insurance against crop failure within this diversified system. Tillage practices significantly impact carbon sequestration. Conservation tillage practices, such as reduced tillage and mulching, are effective in conserving soil health, organic carbon, and water resources. By minimizing soil disturbance, these practices contribute to improved carbon storage in the soil and promote sustainable agricultural systems [132].

Fertility maintenance is crucial for carbon sequestration in horticulture. A balanced use of organic manures and fertilizers, coupled with practices that enhance nutrient use efficiency, ensures optimal plant growth and carbon accumulation. Strategies like using cover crops to recycle nutrients, incorporating legumes, stimulation of earthworm activity, and utilization of beneficial microorganisms like biofertilizers and VAM fungi, contribute to the overall nutrient management approach. Incorporating biochar derived from pruned materials, crop residues, and other organic matter into the soil is an effective technique to store more carbon and enhance soil health [133]. This practice not only sequesters carbon but also enhances soil structure and fertility, thereby supporting sustainable horticultural systems. Pest management practices also play a pivotal role. Utilizing pesticides selectively to preserve natural enemies, adopting botanical agents when possible, and adhering to integrated pest management (IPM) principles help maintain a balanced ecosystem that supports horticultural productivity while minimizing environmental impacts. By integrating these strategies, horticultural systems can contribute significantly to carbon sequestration, sustainable agriculture, and environmental conservation [134].

10. Future Trust

The future of using the potential of horticulture crops for carbon sequestration lies in a broad range of key areas that span research, innovation, policy, and cooperation. These trust areas light the way forward as we stand at the confluence of agricultural sustainability and climate resilience. Adopting sustainable horticulture management strategies will be essential as we explore the intricacies of effective pest control, fertilization, and irrigation to maximize carbon storage. Agroforestry and intercropping designs combine crops and trees to weave complicated carbon-rich landscapes, while genetic and varietal research offers the potential of sculpting crops with raised biomass and robust root systems. The key to deeper carbon storage is improving soil health, which supports microbial diversity and nutrient availability. The digital domain beckons, where cutting-edge technologies and precise management strategies create data-driven carbon sequestration solutions. A tapestry of long-term monitoring and modelling efforts will chronicle our progress, with empirical insights guiding our course. Together, economic viability and policy advocacy will foster a sustainable equilibrium between economics and ecology. Through education and collaboration across disciplines, knowledge will transcend borders, empowering communities to become land custodians. The tapestry woven by these trust areas envelops us in a vision where horticultural landscapes not only flourish as bastions of biodiversity and food security, but also emerge as formidable allies in humanity’s voyage towards climate resilience.

11. Conclusions

Despite their significant capacity for carbon sequestration and climate change mitigation, horticultural crops have not fully utilized this potential. Perennial horticultural systems possess vast root structures, maintain continuous ground cover, and have long growth seasons, which provide notable benefits compared to annual crops. These systems have the ability to improve levels of SOC, with research showing a gradual rise of 20–50% in SOC over time as compared to annual systems. The enhancement is propelled by the process of photosynthesis, the release of substances from the roots known as root exudates, and the addition of organic materials. Utilizing methods such as crop rotation, intercropping, cover cropping, and companion planting may enhance plant material yield by 15–30% and enhance soil quality, resulting in a possible yearly increase in soil carbon storage of 2–5 tonnes of carbon per hectare. Improved monitoring techniques and models can help overcome the barriers associated with determining and verifying carbon sequestration, such as measurement complexity, carbon pool distinction, and permanence. Significant quantities of atmospheric CO₂ can be absorbed by horticultural crops; perennial systems have the capacity to sequester 4–7 tonnes of CO₂ per hectare annually. Agroforestry and sustainable land management combined with horticulture crops could improve the capacity for sequestering carbon by 10–20%. If horticultural crops were completely used worldwide, they have the potential to capture and store between 1.5 and 2 gigatons of CO₂ per year, making a substantial contribution to mitigating climate change. Emphasis should be placed on implementing sustainable horticulture management techniques, conducting genetic research to develop high-biomass crops, enhancing soil health, and adopting modern carbon management systems. Perennial fruit trees and plantation crops provide economic benefits by generating carbon credits, which have a potential worldwide worth in the billions of dollars. However, appropriate regulatory and policy measures are needed to be developed in the near future, especially with regards to residence time, monitoring, measuring, and carbon trading credits. By utilizing this untapped capacity, horticulture could serve as an effective resource for addressing climate change, fostering biodiversity, and attaining food security with potential carbon sequestration rates reaching up to 7–10 tonnes of CO₂ per hectare per year.