Restoration of Soil Organic Carbon a Reliable Sustenance for a Healthy Ecosystem

Abstract

Agricultural sustainability is an indicator for economic prospect across the globe. The revolution of industrial development and the growth of annual crop to meet the need of increasing world population is a determining factor for SOC availability. Sustainability of agriculture is largely related to SOC and management practices. Agro-ecological stability is significant to soil type and fertility input. Organic matter is a combination of plant residue and/ or animal waste. This is capable of accumulating carbon and nitrogen in the soil. It retains water and support the buildup of organic carbon. It enhances the stability of SOC and crop yield. The use of organic matter is effective at stabilizing the microbial communities. Carbon sequestration is high with crops that have abundant residues. SOC can potentially mitigate climate change. It prevents the use of minimum and conventional tillage. Higher deposit of SOC is associated with crop yield. Perennial crop cultivation such as cup plant (Siliphium perforliatum. L.) can potentially sequestrate carbon into the soil than annual crop. SOC are often exhausted with the cultivation of annual crop such as maize. However, SOC can be retained by growing clover in between harvests and the next sowing. Mineral fertilizer can likewise accumulate SOC but not as efficient as the use organic manure and plant residue. Perennial crop was found useful at preventing environmental degradation and soil compaction. Consistent assessment of SOC is essential for continuous food production and plant growth. This can be achieved through a multidimensional software called multiple linear regression.

1. Introduction

Global warming is caused by the continuous increase in greenhouse gases in the earth’s atmospheric surface [1, 2]. 50% of the total global emission is from agricultural production [3]. Excessive application of inorganic fertilizer causes ammonia volatilization, soil nitrogen leaching, air pollution, and soil acidification [1, 4]. This is a result of a rapid increase in the global population. They suggest the need for the protection of soil quality to meet the food requirement of the increasing global population and societal development [5, 6]. Climate change significantly affects the atmospheric carbon pool and its availability in the soil for agricultural productivity [7]. The loss of soil organic carbon and land degradation is one of the major factors that affect the yield of existing farmland [3, 8]. Soil organic matter deposition is released from approximately two-third of CO₂ exchange between the terrestrial ecosystem and atmosphere [9, 10]. The most active part of the global carbon pool is soil farmland. Farmland soil enables global carbon and nitrogen cycling [4, 11]. Farmland is an important source and sinks of CO₂ for the farmland ecosystem. Agricultural farmland with decrease organic carbon has been proven to be unreliable [6, 12]. This has led to pressure in crop production through cropland management practices such as irrigation and fertilization [8, 13]. Organic matter plays a significant role in food production and agricultural land expansion. It is an environmental factor that determines sustainability and development [8, 13]. It is an indicator for factors such as water retention and nutrient availability [14]. It is a structural balance that promotes efficient drainage, aeration and minimizes loss of topsoil from erosion [6, 15]. It decreases reliance on external inputs such as fertilizer and irrigation [11, 16]. It is a stable and a last longing input that supports crop yield and sustainability [11, 16]. One of the major limitations to the availability of soil organic matter in the soil is the target method of prediction for a specific agricultural land and environmental development [17, 18]. Yield is often expected to increase per unit area with a certain measure of organic matter. But yardstick for determining organic matter is yet to be fully exploited [6, 19]. Several studies have been established in relationship with soil organic matter and yield [6, 19]. It was also found that a concrete agreement among researchers is yet to be reached. For instance, a decrease [20], an increase [21], and no change were recorded in some research findings [11]. Variation in result findings may be due to management, climate change, and soil type [11, 20, 21]. Likewise, a global understanding of soil organic with yield is heterogeneous [11, 20, 21]. This suggests the need to test and understand the effect of soil organic matter and carbon in agriculture and its environment [11, 20, 21]. This paperwork investigates the impact of organic carbon and its relevance in agricultural sustainability and development.

2. Carbon oxidation and deposition in the soil

Organic carbon is an important component of the soil that can stimulate functional compounds and enhances the performance of a microbial community [22, 23]. It provides lubrication and facilitates ease of energy transfer in an ecosystem [6, 8]. Cropping history and management on agricultural land are determining factors for net carbon sink or CO₂ availability in the soil [7, 23]. Arable crop production decline carbon stored between 40% - 60% through conventional tillage and planting activities [9, 24]. Though at some point depending on the soil type and climate change crop production may attain an equilibrium carbon [9, 24]. This attainment may vary with different agro-ecological zones or regions [25, 26]. Soil carbon accumulation largely depends on the rate at which biomass decomposes [12, 22]. This includes primary reduction of plant residues above ground; leaves, stems, and other tissues. Likewise, plant exudates and the below ground as well as the roots. The pool of carbon in the soil depends on the rate at which organic carbon is oxidized by microbes and invertebrates [12, 22]. Soil organic carbon can be categories into active, stable, and inert organic carbon pools; active organic carbon is closely related to the nutrient requirement supply into the soil [7, 27]. They are permeable and can efficiently build up organic matter [13]. This category comprises microbial biomass carbon, soluble organic, mineralisable carbon, and carbohydrate, stable organic carbon pools are dominated by carbohydrate and lipid. This pool is made of organic particles and carbohydrates [15, 22]. The release of nutrients in this case is relatively slow. In other words, the inert organic carbon pool deposition is very slow. It comprises lignin, hummus, polyphenol, and polysaccharide [15, 22]. More carbon will be available in the soil if organic carbon oxidation is low but with high oxidation, soil organic matter is used up than it is replaced by new biomass [2, 5]. A low oxidation rate increases the net sink of CO₂. However, in the soil where biomass deposition is stable, the net change in carbon will be stored is continually [2, 5]. The continuous application of biomass at a point attains maximum carbon saturation. Equilibrium change of CO₂ uptake into the atmosphere plays a significant role in net carbon sink in the soil [2, 5]. The quality of organic matter is affected by deposition. Microclimate and microorganisms play a major role in steady metabolization processes [20, 22, 27]. This regulates the extent to which chemical constituent is released into the soil. It was recorded that senesced leaves and stems with high carbon-nitrogen and corn stalks as well as the wood decomposes at a very low rate [28, 29]. Nevertheless, legumes and stems decompose more rapidly due to their low carbon-nitrogen and lignin content. The aggregate of oxygen supply to microbes in the soil may be restricted by tillage due to accelerated deposition by breaking apart the soil [15, 30]. This promotes rapid oxidation of carbon into the air. Plowing exposes the soil to direct insolation which may support rapid deposition [3, 31]. In this regard, CO₂ emission is remarkably high and profound. This affects the quantity and quality of organic matter in the microenvironment [11, 22]. The net annual flux of soil CO₂ year after year represents a change in organic soil carbon where erosion is put to control [14, 32]. Erosion prevents direct oxidation of carbon into CO₂ due to surface runoff, particles are washed into waterways to bury existing carbon [14, 32]. It slows its deposition due to accumulation in anaerobic sediments. In other words, a carbon sink may be achieved as a result of slow deposition on an eroded site [14, 32]. It was recorded that the sink capacity of eroded soil amounted to 26% in a finding [3, 14, 15]. Several chemicals used in agricultural land increase CO₂ in the air. Its impact on global warming is highly detrimental for instance 2.3 kg CO₂ per active ingredient (750 Ngm⁻¹) 4.5 kg CO₂ per kg of N methane (CH₄) are applied as fossil fuel to meet its temperature and pressure requirement [31, 33]. Also, lime (CaCO₃) and dolomite (CaMg (CO₃)₂) were applied to neutralize the effect of acid cation in the soil [2, 32]. The use of lime may be influential as an agent of weathering. Nitric acid produces nitrifying bacteria [1, 4]. This supports the breakdown of carbon in lime.

$${\mathrm{CaCO}}_3+{2\mathrm{H}\mathrm{N}\mathrm{O}}_3\to C{a}^{+}+{{2\mathrm{H}\mathrm{N}\mathrm{O}}_3}^{-}+{\mathrm{H}}_2\mathrm{O}+C{O}_2$$

But a weak carbonic acid from the root acid and microbial respiration transform lime into bicarbonate [1, 4].

$${\mathrm{CaCO}}_3+{\mathrm{H}}_2\mathrm{O}+C{O}_2\to Ca+{{2\mathrm{H}\mathrm{N}\mathrm{O}}_3}^{-}$$

Dissolution of lime by strong acid generates a large amount of CO₂ into the air but weak acid support carbon sinks into the soil [15, 34]. It was revealed in research that sequestration of lime carbon depends on nitric or carbonic acid [24, 35]. CO₂ may largely be neutralized for agricultural lime [3, 36]. The growth of biomass both above and below ground represents CO₂ sink as carbon is captured in perennial vegetative growth [2, 37]. Perennial crops increase carbon sequestration due to persistent land cover [2, 37]. In this case, soil carbon is continually stored in the soil [37]. Perennial crop accumulates more carbon than annual crops [31]. Land cover prolong carbon stored in the soil. However, soil biomass is often accomplished by reducing the soil deposition rate. It increases soil organic carbon [38, 39]. Carbon sequestration is high with crops that have abundant residue [6, 11]. Soil carbon can be enhanced through corn rotation. The use of corn-soybean rotation was found to be effective than corn rotation [12, 16]. The biochemical complexity of carbon residue input in the soil is a result of land cover. This helps build soil carbon [12, 16]. The no-till practice performs the function of deepening carbon into the soil. It increases the storage at the surface layer. Soil carbon content is ample evidence for no-till gain [8, 9]. More so, agricultural CO₂ could be derived from energy input and soil amendment [25, 35]. Most cropping systems are not effective at retaining carbon as exogenous input such as manure, biochar, or sewage sludge [11, 33]. In other words, the native ecosystem is preferred at storing carbon to the use of the organic supplement [2, 25]. It is better concluded that permanent no-till mitigation is by far sustainable at retaining carbon in the soil [20, 40].

3. Climate change and its influence on environmental balance

Climate change is an environmental behavior that characterizes the amount of water availability or dryness in a particular area. It is proportionate to land utility and nutrient availability [24, 25]. A land cover with the forest is significant to accumulating carbon and nitrogen in the soil [16, 27]. In other words, land use and evacuation of forests for buildings are inversely proportional to the balance of greenhouse gas emissions for the atmosphere [24, 26, 35]. This involves activities such as tractor pass on the land, burning of trees, and continuous harvest. This change is substantial to agricultural development and food availability [6, 7, 19]. In recent findings, it was hypothesized that soil depth of 30 cm is rich in carbon than the entire atmosphere. The carbon sink in the ocean is though relatively higher than the amount in the soil [1, 8]. However, soil and forest vegetation play a major role in carbon storage [2, 36, 38]. The global average temperature has risen nearly twice as much as high as the land surface air temperature [34]. Climate change has been noted to harm food security and the terrestrial ecosystem since the pre-industrial revolution [6, 7, 19]. This change was observed between 1850 and 1900 and 2006–2015. The land surface air temperature was found to have increased by 1.53°C and the global mean surface temperature (GMST) by 0.87°C ‘[34]. This frequent rise in temperature was recorded in the Mediterranean, West Asia, South America, Africa, and North-East Asia [34]. This global change has resulted in vegetation browning than greening in many regions [2, 6, 7]. This is associated with dust storms, evapotranspiration, and decrease precipitation coupled with human activities [14, 28, 29]. This has drastically affected sustainability and development [24, 25]. In the last two decades, it was discovered that continuous rise in average temperature and reduction in the amount of rainfall might create a need for irrigation and poor agricultural output [8, 41]. More so, the success of agricultural output depends on the plant and animal cycle [12, 35]. Global warming may cause a polar shift in the climatic zone in the middle of the equator [1, 2]. The global warmth may result in high latitude. The regions with high latitude suffer drought, wildfire, and pest outbreaks [1, 2]. These regions have been depicted with global warmth of 1.5°C – 3.0°C. This warmth can be ascribed to permafrost degradation, poor agricultural output, and minimal carbon sink [2, 17]. This resulted in soil compaction and dryness [9]. It destabilizes the structural relevance of the soil, poor water retention, and plant growth [24, 40]. The nutritional quality of crops is lowered with increased atmospheric CO₂ [5, 9]. Presently, over 7.6% rise in global crop and economic model of cereal due to climate change predict higher food price, food insecurity, and hunger in 2050 [25, 26]. In this case, food stability is disrupted due to extreme weather conditions [24, 25]. This climate influence on seasonal changes may affect plant blossoming before their pollinators such as insects, birds, etc. are hatched [20, 26]. This may invariably result in flower loss and poor fruit formation [20, 26]. Soil health and agricultural management are hinged on meeting food production for the increasing world populationFigure 1 [16].

Figure 1.

Global warming and environmental changes sourced from [14].

Nevertheless, an unprecedented rate of land and freshwater adaptive use for agriculture has been estimated to be 70% [25, 26, 35]. This is a result of global population growth and change in per capita consumption of food, fiber, timbre, and energy release [6, 7, 19]. This global population change has contributed to net GHG emissions, loss of natural ecosystems, and declining biodiversity [2, 7]. Likewise, more than 25 – 30% of food produced is wasted due to climate change [2, 7]. These challenges are aggravated in frost and ice-dominated regions [21, 42]. More so, an area not covered with ice is influenced by human activities [21, 42]. Moreover, due to fossil fuel extinction and greenhouse gas emission, there is an increasing need to replace fossil fuel with biofuel and other plant-based products [40, 41]. Furthermore, erosion is an important determinant of landform and nutrient availability [3, 15]. Intense rainfall, drought, heat loss, heat waves, and a storm cause agricultural land degradation, nutrient loss, plant breakage, stunted growth and total wilting, and perhaps rises in sea level, particularly in the coastal area [3, 43]. Climate change may produce a significant loss in agriculture output by 2050 if measures are not drawn or put in place [25, 26, 35]. Moreover, in some regions of the world climate change is linked to the availability of carbon dioxide and methane in the soil [2, 7]. The permafrost and melt of ice are common in the arboreal region. In this region, an increased temperature causes permafrost to melt [14, 15, 41]. This change over a period trapped organic matter into the frozen which after some time cause a disintegration [3, 43, 44]. Despite the continuous change of climate across the globe, ecosystem and soil quality can be restored by removing carbon dioxide from the atmosphere [1, 38]. According to findings, more than 63 billion tonnes of carbon are removed from the soil [1, 38]. The health of the soil is improved by storing carbon underground [2, 37]. The growth of the plant and natural storage of carbon in the soil serves as a defense against climate change [22, 23]. Green space in the cities such as floods and heatwaves is cost-effective protection [25, 26, 35]. They perform the function of flood elimination and storage of excess water [14]. They cool down heat waves due to water accumulation in the soil [14]. They provide a healthy ecosystem during drought through a gradual release of water stored underground [11, 14, 38]. The availability of carbon in the soil can be maintained by converting arable land to grassland [7, 22, 23]. The growth of clover in between harvests and sowing the next crop [8]. This mitigation practice prevents erosion wash. It improves fertility and crop development [12]. Other adaptive measures to fight desertification and land degradation include reduced deforestation, ecosystem conservation, reduced food loss, and waste [3, 15, 30]. The conservation of high carbon ecosystems such as peatland, wetland, rangeland is linked with effective management practice [1, 2]. In addition, carbon sequestration in the soil or vegetation can be maintained by afforestation, reforestation, and agroforestry [12, 29]. The removal of the wood product from the forest restricts carbon in the soil [12, 29]. Peatland is efficient at striking a balance between vegetation and carbon reservoir [22]. This is achieved with the annual removal of CO₂ from the atmosphere when the carbon sink declines towards zero [1]. This is the point where saturation measure is reached between vegetation and carbon reservoir [3, 15]. Management practices such as flood, drought, fire, or pest outbreaks may be hindered by mitigation practice if future management plans are considered [8, 40].

4. Carbon sequestration and sustainable practice

Perennial energy crop serves as a feedstock for agricultural biogas are agro-ecological sustainable [9, 14, 29]. They prevent environmental degradation such as erosion and soil compaction. They provide lower methane yield [1, 9, 24]. They reduce management effort and cost fertilization. They create a balance in groundwater quality and greenhouse gas emission [5, 9]. This perennial energy crop includes pliscanthus Miscanthus gigateus, cup plant Siliphium perforliatum. L, wheatgrass Agropyron elongatum [14, 37]. Research findings indicate that these perennial energy crops are potentially useful in carbon sequestration [35, 37]. They prevent the use of minimum and conventional tillage which support one or two pass tractors on agricultural land [12, 26]. It retains organic matter in the below and above plants since soil organisms are active and efficient [23, 39]. This practice enhances the formation of complex humid compounds which over time may increase soil organic matter [33, 40]. Some research findings reveal that perennial crops are efficient than annual energy crops such as maize and wheat [6, 11, 19]. Their impact on climate with regards to soil organic matter and greenhouse gas emissions is not beneficial as a perennial energy plant [24, 45]. It was also found that perennial energy crop increases soil organic carbon and nitrogen [29, 37]. Higher microbial biomass and better-developed soil fractal aggregation. it provides a stable organic matter [45]. An experiment was conducted on the distribution and drive of soil organic matter under perennial energy crops. It was found that carbon concentration in the soil cultivated with perennial energy crops was a significantly higher fraction [24, 29]. A significant difference was observed in the perennial crop. Perennial crop such as cup plant and giant-knot weed has higher carbon concentration [24, 29]. It was also found that perennial crop cultivation resulted in higher SOC and elevated bulk density than maize and wheat [24, 29]. It was also recorded that the microbial activities in the soil for the perennial crop were continually [22, 23]. The highest and lowest microbial activities were obtained in the perennial crop than in an annual crop [22, 23]. 1,4 β glucobiosidae shows a positive output with soil organic matter. A consistent increase was observed plot cultivated with perennial energy crops [24, 29]. It was also recorded that the aboveground production depends on the cultivated species. The vegetation period plays a significant role in pre-harvest [22, 45]. This may result in light intensity and internal nutrient distribution for young shoots and roots [24, 29].

5. Digestate a better stimulant for agricultural production

Change in the agro-ecological landscape is a serious challenge. This change was observed in humans, society, and the soil ecosystem [25, 26, 35]. This change brought uncertainty to the soil–plant atmospheric system and variation in the environment. This has resulted in continuous depletion of SOM with ease [12, 13]. Similarly, in an agricultural market survey conducted in Europe. It was discovered that after 1990 a negative phenomenon was recorded in agricultural production [12, 30]. The practice of crop rotation was reduced. Increasing demand for staple food brought a cut down in forage crops by 35% [6, 25]. The production of cereal was increased by 54% and rapeseed by 343% [5, 46]. Likewise, a cut down was documented in animal husbandry by 50% [5, 9, 46]. This was identified as a depleting factor for soil organic matter [5, 9, 46]. The use of mineral fertilizer, organic waste, and manure was found useful but digestate was twice richer compare to other forms of manure [3, 15, 30]. Digestate is made of plants with a large amount of N and P. It is a by-product biogas plant that is capable of providing a high yield of spring crop [3, 15, 30]. It is an excellent fertilizer that can enhance the biological properties of the soil. It is widely used in Europe [2, 17, 30]. Digestate average dry matter content ranges between 1.5% and 46%. Digestate is primarily effective at building up the biological quality of the soil [30]. It can efficiently increase the nutrient quality of the topsoil. It plays a significant role in the carbon pool. SOC content initiates positive or neutral ions with the application of digestate [45, 47]. The amount of organic matter applied to determine the SOC content. The higher the digestate, the larger the SOC vice versa [24, 35]. It was reported that larger particles have a positive influence on SOC content than fine particles [30]. The use of animal droppings as the organic compound was significant [12, 40]. Continuous application of digestate creates a better environment for the decomposition of organic matter. It was also recorded that soil with low quality may prevent the decomposition of organic matter [22, 23, 45]. Accurate dosage of fertilizer and accelerated biological processes in the soil enhance productivity [22, 45, 47]. A decrease in pH and soil sorption complex saturation was found to be an attribute of digestate [30]. This may be due to hydrogen and aluminum ion replacement. A significant reduction was recorded in soil acidification with the application of digestate [3, 15, 30]. The agricultural intensive area was typically high in biological activity. This is significant with soil depth [13, 16, 40]. SOC sequestration is high with the regular application of organic manure. It was recorded that a significant amount of 10 t ha⁻¹ of organic manure can increase the SOC stock by 5.5% in 100 years [30, 34, 48]. The use of mineral fertilizer and farmyard manure was also significant to the soil to increasing soil fertility, SOC, and nutrient content [13, 16, 40]. It provides stable nutrients and decreases soil acidity. It was observed that regular application of organic manure provides long-term stable yield and as well improves the quality of the soil [13, 16, 40]. It was found that the use of organic manure and straw is highly valuable to the soil ecosystem [3, 8, 17]. Sufficient application of digestate to the soil can positively influence SOM and SOC content without other manure [15, 30]. Long-term application of digestate maintains SOC content. Postharvest reduces such as straw provide an additional source of organic carbon [4, 24, 30]. A decrease in SOC was recorded in an intensive permanent grassland but SOC and SOM were higher in permanent grassland compare to arable land Figure 2 [29, 37].

Figure 2.

Digestate production and organic carbon sourced from [49].

6. The impact of organic carbon on yield

According to research, it was found that the high yield of crops is a result of soil organic carbon. 2% soil organic carbon is critical to the threshold [23, 45]. A value below 2% may have a negative influence on the structural functionality and the asymptotic relationship that exist between soil organic carbon and yield [12, 20]. In other words, the critical threshold for productivity may not be relevant if there is sufficient mineral fertilizer to support crop production [3, 15, 43]. Mineral fertilizer was found to be effective at increasing maize yield [16, 21]. It was reported that mineral fertilizer increases SOC. It improves crop yield and promotes entire growth [2, 11, 31]. It was also found that long-term application of mineral fertilizer significantly increases the SOC content in the 0 – 20 cm soil layer [16, 27, 50]. However, the use of mineral fertilizer is not as effective as the use of straw on farmland [16, 17, 40]. It was discovered in an experiment that the use of straw provides a metabolic substrate for soil microorganisms. Soil porosity and water movement were influenced by straw input [3, 17, 30]. It was also recorded that the use of animal–plant residue increases the SOC content. Straw carbon transformation activates and enhances microbial communities such as bacteria, archaea, protozoa, fungi, and viruses [11, 12, 13]. These organisms distribute organic carbon in the complex terrestrial environment [6, 11, 33, 51]. Betaproteobacteria and Gammaproteobacteria were the main genera of Janthinobacterium, Massilia, Variovorax, Xanthomonas, and Pseudomonas in the early stage of carbon transformation of wheat straw [22, 45, 47]. A positive correlation was recorded relative to SOC to soil microbial structure and diversity. The quality and quantity of SOC are subjected to the metabolic action of the microorganism in the ecosystem [12, 17, 47]. The abundance and structure of microorganisms are generally considered to be essential for the fixation, transport, and accumulation of SOC [17, 22]. They are widely involved in soil processes and functions. Soil microorganisms are effective with the use of organic matter [5, 9]. It supports and shapes the global carbon cycle. It enhances the mechanism that increases SOC and limits the impact of climate change [2, 7, 37]. A limiting factor for straw application is moisture [17, 30]. In cold weather, the accumulation of straw in the soil does not easily decompose. Straw deposition in this case may result in phytotoxic [20, 21, 27]. The use of soil organic carbon is not sufficient enough to influence sustainable intensification to reduce the harm caused by inorganic fertilizer due to eutrophication and greenhouse gas emissions [17, 23, 41]. There is a positive relationship between soil organic carbon and yield starting from the 2% threshold [25, 45, 51]. It provides a reduction in nutrient runoff, drought resistance, and yield stability Figure 3 [22, 23, 45].

Figure 3.

Carbon pool and straw application sourced from [17].

In a finding, the cultivation of maize and wheat uses less than 2% soil organic carbon to area and harvest [2, 12]. It was also found that a continuous cropping system and grazing may result in carbon loss if not properly managed [1, 5, 9]. This practice in other words may improve the yield of maize and wheat due to a large amount of soil organic matter from animal waste [33, 39]. The reduction in nitrogen fertilizer plays a significant role in agricultural land and the ecosystem [16, 20]. It minimizes soil emission of nitrous, eutrophication of water, and efficiency of greenhouse gas [1, 4, 9, 44]. However, as much as soil organic matter is significant to providing nutrients to the soil. This cannot be a direct substitute for mineral fertilizer [16, 20, 40]. The efficiency of soil organic carbon varies between 0.5% and 2.0% to soil properties, climate, and the type of input applied at a point in time [8, 51]. The agricultural input differs in its potential. This efficiency ranges from farmyard manure to sewage sludge to mineral fertilization [13, 20, 27]. It was however concluded that soil organic matter and nutrient provision from agricultural input may be cut down the use of nitrogen fertilizer as input to a large extent [1, 4, 9]. Higher soil organic carbon enhances N input to produce a high yield. Likewise, essential macro and micronutrients are provided through the application of higher levels of soil organic matter [13, 16, 40, 51]. This compensates for soil with limited soil organic carbon concentration [16, 40].

7. Organic nutrient composition and strawberry yield

The growth and yield of strawberries require macro and micronutrients. Nutrients are provided from the soil as integral support. It is a reservoir for water and nutrient retention. It is a support system for plant growth and root development [36, 52]. Good management practice and strategy for strawberry growth and yield involve the application of compost with synthetic nutrients as a substrate [28, 36, 52]. According to findings, the high growth performance of strawberry cultivars was a result of better nutrient uptake [2, 43]. This nutrient includes Bio plus compost (cocopeat 68.86%, peat moss 11.00%, and zeolite 9.00%, and perlite 11.00% [10]. This is a standardized organic compound used for vegetative growth in some parts of Europe [36]. This nutrient composition is beneficial to microbial development. It supports soil physiochemical properties, the decomposition of organic matter, reduction of eutrophication, and nutrient loss. This is due to organic stipulation and the gradual release of nutrients from this compound into the soil [43]. The nutrient in this organic compound contains a stable proportion of nitrogen and carbon ratio. This however suggests the presence of microbe, humic substances, and high cation exchange capacity [6, 7, 47]. This organic compound plays a significant role in root formation [7, 36, 42]. It is a fiber rich substance. It enhances soil structure [11, 31, 50]. The structural efficiency and stability of this compound lower the impact of global warming and provide the soil with a good carbon sink [31, 33, 51]. In other words, the growth of strawberry cultivar without adequate (NPK) nutrients may have a detrimental effect on vegetative growth [28, 39, 43]. The quality such as sweetness, firmness, and anthocyanin found in strawberries is a result of the optimal application of NPK [28, 39, 43]. The application of this organic compound enhances elongation, carbohydrate, and sugar synthesis [28, 39, 43]. The growth of strawberries using bio plus compost with synthetic nutrients and other growth media was tried in a greenhouse experiment [28, 39, 43]. Results obtained indicated that a significant increase was recorded in the vegetative growth and yield of strawberries compare to other growth media used in the experiment [28, 39, 43]. The increasing growth trend observed in vegetative and reproductive growth reflects a positive correlation with fruit set and the number of fruit per plant [28, 39, 43].

8. SOC determination and model application

The SOC behavior in the soil can be analyzed using different models [17, 18, 49]. The CENTURY soil organic matter model environment is a FORTRAN model. It is used in the plant–soil ecosystem. It is represented by C. It is a software design for nutrient dynamism in a different ecosystem. This includes grassland, forest, crop, and savannah [17, 18, 49]. The EPIC model establishes a relationship that exists between the soil and climate. It is a process-based model well-known. The Roth C-26.3 can be used to analyze soil type, temperature, moisture content, and plant cover on the turnover process. It can determine the turnover of organic carbon in non-waterlogged soil [17, 18, 49]. Some of the required parameters for analyzing SOM and SOC were weather, sowing procedures, plan of work on the different fields, fertilization etc. This information is based on different algorithms [17, 18, 49]. STIC model was also noted for a good approximation of water requirement. However, the use of multiple linear regression (MLR) was noted for its multidimensional functions [17, 18, 49]. MLR is capable of modeling soil properties after the application of organic manure. MLR can be used accomplished to the relationship between SOC stock and other soil properties in any region of the world. It can provide a relationship between liable C form, soil properties, and management practices. The use of MLR was found efficient and reliable [17, 18, 49].

9. Conclusions

Global warming is an atmospheric challenge that limit the efficiency of food production across the globe. It determines carbon sink its availability in the soil. Agricultural farmland is an important pool for carbon sink and deposit. Organic matter enhances water retention and nutrient built up in the soil. It cut down the input mineral fertilizer. It provides carbon stability and crop yield. Soil carbon accumulation largely depend on the rate at which biomass decomposes. Approximately 40% - 60% carbon are lost through conventional tillage. It regulates the extent to which chemical constituent is released into the soil. Plowing exposes the soil to direct insolation which may support rapid deposition. Erosion prevents direct oxidation of carbon into CO2. Carbon sequestration is high with crop that have abundant residue. The no-till practice perform the function of deepening carbon into the soil. A land cover with forest is significant to accumulating carbon and nitrogen in the soil. The nutritional quality of crop is lowered with increased atmospheric CO2. The growth of the plant and natural storage of carbon in the soil serves as defense against climate change. Peatland is capable of striking balance between vegetation and carbon reservoir. Perennial crop prevents environmental degradation such as erosion and soil compaction. Digestate is an excellent fertilizer that can enhance the biological properties of the soil. The higher digestate, the larger the SOC vice versa. Straw carbon transformation can activate microbial community such as bacteria, archaea, protozoa, fungus, and viruses. Multiple linear regression is a multidimensional software. It built a relationship between SOC stock and soil properties. Other software used for determining SOC are CENTURY soil organic matter model, EPIC model, Roth C-26.3 and the STIC model.