Reviving cropping land in Sub-saharan Africa: An in-depth review of the land recovery potential and strategies

J. Bio. & Env. Sci. 20 23 13 | Kalonga et al. REVIEW REVIEW REVIEW REVIEW PAPER PAPERPAPER PAPER OPEN ACCESS OPEN ACCESSOPEN ACCESS OPEN ACCESS Reviving cropping land in Sub-saharan Africa: An in-depth review of the land recovery potential and strategies Joseph Kalonga *1,4 , Kelvin Mtei 1 , Boniface Massawe 2 , Anthony Kimaro 3 1 Nelson Mandela African Institution of Science and Technology (NM - AIST), Arusha, Tanzania 2Sokoine University of Agriculture (SUA) Morogoro, Tanzania 3International Centre for Research in Agroforestry (ICRAF) World Agroforestry, Dar-es-Salaam, Tanzania 4University of Dar-es-Salaam (UDSM), Dar-es-Salaam, Tanzania Article published on September 08, 2023 Key words: Land degradation, Restoration , Biodiversity , Soil biotechnology, Ecological services Abstract Land degradation is a major challenge affecting the sustainability of agriculture and livestock production systems worldwide. Poor soil and water management practices coupled with unsustainable agricultural practices are known to accelerate land degradation. Globally, approximately 18.1 million km 2 of land is degraded, of which 62% is due to unsustainable use of the land and 38% is due to overgrazing. In SubSaharan Africa is 46% grassland, 12% cropland, and 26% forest land. This review found that SSA has a vast potential in restoring degraded land ranging from land degradation monitoring and evaluation, agricultural conservation techniques, soil biotechnology, and soil management techniques. The increasing land degradation problem in SSA is due to the ineffective utilization of soil conservation techniques. Effective utilization of land recovery potential and strategies in SSA for the aim of restoring degraded land in the region will play a large part in addressing the problem of land degradation which resulted in food insecurity in the SSA. This review recommends the following: the creation of participatory policies that allow governments to work successfully with local farmers to manage the soil sustainably using soil restoration and conservation technologies, making better and more effective use of the large informational resources from previously completed soil conservation and restoration based projects, continued funding of agricultural research to encourage the creation of technology that will restore degradation land and increase yields using sustainable land management practices, and need for the agent action to transform existing conventional agriculture into agricultural practices which ensure sustainability. * Corresponding Author: Joseph Kalonga  [email protected] Journal of Biodiversity and Environmental Sciences (JBES) ISSN: 2220-6663 (Print) 2222-3045 (Online) Vol. 23, No. 3, p. 13-33, 2023 http://www.innspub.net J. Bio. & Env. Sci. 20 23 14 | Kalonga et al. Introduction Land degradation is a major threat to the sustainability of agriculture and animal production systems around the world (Wynants et al., 2019). Land degradation is influenced by poor soil and water management practices coupled with unsustainable agriculture (Chalise et al., 2019). Land degradation is associated with a deterioration in the biological, chemical, and physical quality of soil, which affects the soil's capacity to deliver ecological services (Chabay, 2018; Tsatskin, 2021). In Sub-Saharan Africa approximately 65% of the total land is degraded (SSA) (Vlek et al., 2008), which affects social-environmental systems, hydrological cycle, and biochemical processes (Fernando et al., 2018). Due to its detrimental effects on agriculture, the environment, and food security, land degradation is a persistent problem throughout the world. Globally, approximately 18.1 million km 2 of land is degraded of which 62% is due to unsustainable use of the land and 38% is due to overgrazing (Hamdy & Aly, 2014; Toor et al., 2020). Generally, land degradation typically affects 20% of arable land, 30% of forests, and 10% of grazing area, which affects approximately 1.5 billion people (Pimentel, 2006). A study done by Reich et al., (2001) in Africa reported that 22% and 25% of the land was disposed off to wind and water erosion respectively. Desertification affects up to 65% of the agricultural land on the African continent and about 39% of the continent overall (Hossain et al., 2020). In Sub-Saharan Africa degraded land accounts for 46% of grassland, 12% of cropland, and 26% of forest land (Gebreselassie et al., 2015). Bindraban et al., (2012) and (Muoni et al., 2019) found that 30% of the cropping land in SSA is degraded by soil erosion, nutrient mining, deforestation, and overgrazing. It costs around 300 billion USD a year to manage land degradation in agricultural and pasture land due to changes in land use, land cover, and other factors (Braun et al., 2013). The largest percentage (22%) of the total global cost of land degradation is covered by SSA. Farmers pay about 46% of the cost of land degradation brought on by Land Use Land Cover Changes, which is equivalent to 78% of the total cost of land degradation in the globe. Ecosystem consumers who do not use farms, like those who pay a high price for food crops, pay the remaining 54% (Nkonya et al., 2015). This further demonstrates that, although having a significantly bigger impact on impoverished land users, land degradation is a global issue. Acting to stop land deterioration has tremendous benefits and is substantially less expensive than doing nothing. According to (Braun et al., 2013), investing one dollar in restoring damaged land often yields five dollars in return. This offers a compelling reason to take action to stop land deterioration. Unsustainable agricultural intensification has been cited as a major cause of land degradation that affects the soil health ecosystem, its ability to provide ecological services and decrease crop productivity. Due to agricultural intensification, each year about 24 million tonnes of topsoil are lost because of soil erosion. The projection shows that this may lead to 50 million people shifting from their current residence in the next 10 years (UNCCD, 2017). Hence, sustainable land management and restoration strategies can reduce and restore degraded land in the region. The main factors contributing to land degradation in the SSA include water erosion, salinization, loss of soil organic carbon, removal of vegetation, extinction of species, and settlement expansion. An effective approach for reducing and restoring degraded cropland in the SSA is the implementation of soil conservation techniques and sustainable land management practices. This review paper intends to explore land restoration potentials and strategies in the region specifically focusing on sustainable and innovative approaches to restoring degraded land. Types and Causes of Land Degradation in SubSaharan Africa Types of land degradation Three types of land degradation exist in SSA; chemical, biological, and physical land degradation (Tully et al., 2015). The major common types of land degradation are physical soil degradation in the form J. Bio. & Env. Sci. 20 23 15 | Kalonga et al. of water and wind erosion (Kiptoo & Mirzabaev, 2014). SSA has been observed to have a more serious problem with land degradation due to soil erosion than in nontropical places (Sanchez & Swarninathan, 2009). Several factors have been put forth as to why the tropics experience such high rates of soil erosion, including the harsh climate, high soil erosivity, the prevalence of extremely fragile soils, steep slopes, insufficient land management, and, primarily, resource-poor farmers who cannot afford to implement conservation measures (Kiage, 2013). However, during the 1980s and 1990s, the first narrative that was widely known by policymakers and development organizations operating in SSA was that severe land degradation in the form of soil erosion was caused by ineffective land management brought on by ignorance and a lack of education (Kimaru & Jama, 2006). Major causes of land degradation Land degradation has been caused by anthropogenic factors, natural factors, or a combination of both. Some of the anthropogenic factors that cause land degradation are deforestation, vegetation cover loss, inadequate land use policies, and insufficient soil conservation interventions. Deforestation is the extensive clearing of forests for agriculture, urbanization, or logging resulting in the removal of vegetation cover (Tsegaye et al., 2023). Forests protect the soil from erosion and help to stabilize it naturally. Deforestation disrupts this equilibrium and leaves the soil vulnerable to soil erosion, nutrient depletion, and reduced water-holding capacity (Mazi et al., 2022; Moisa et al., 2022). In addition to deforestation, other factors leading to loss of vegetation cover are overgrazing, unsustainable land use practices, and bush firing. Vegetation cover plays a significant role in reducing land degradation by acting as a physical barrier against water and wind forces. Insufficient vegetation cover accelerates soil erosion which leads to land degradation. Insufficient land use planning and implementation can also lead to land degradation. When land is utilized without taking into account its ecological capacities such as converting fragile ecosystems into agricultural land or urban areas, it accelerates soil erosion, lowers soil fertility, and interferes with the natural ecosystems that keep the soil healthy (Oliveira, 2018). The absence of effective soil conservation techniques aggravates land degradation. Without appropriate interventions like terracing, contour plowing, cover cropping, and erosion control structures, soil erosion intensifies, water runoff increases, and due to a loss of topsoil, soil fertility declines (Kumawat et al., 2020). Land degradation occurs through the interaction between human interaction and the biophysical environment. The process of soil erosion is greatly influenced by biophysical elements, such as the soil, climate, topography, and vegetation cover. For instance, the erodibility of soils is determined by the fundamental characteristics of soils, such as texture, structure, organic matter concentration, clay mineralogy, and water retention properties (Kiage, 2013). The rate of erosion is determined by topographic factors including slope steepness, length, and shape, whereas erosivity is influenced by rainfall features like intensity, amount, and frequency. Although these biophysical forces might interact to cause soil erosion, frequently need the involvement of human activities (Chalise et al., 2019). Land Degradation Assessment and Monitoring in SSA Decision-makers need to monitor and prepare mitigation strategies for sustainable land management practices, which require assessment and monitoring of land degradation (Tesfahunegn et al., 2011). More specifically, monitoring land degradation regularly allows decision-makers to understand the impact of land degradation and the effects of soil conservation techniques. To address this problem, effective techniques to evaluate and track land degradation are imperative for sustainability. Using this information, decision-makers set attainable management goals for example; to reach land degradation neutrality by 2030 as directed by the Sustainable Development Goal - SDG 15. Land degradation is often measured by evaluating the status and trends using the productivity of agricultural land. However, as variables other than J. Bio. & Env. Sci. 20 23 16 | Kalonga et al. land degradation such as climate phenomena, precipitation, pests, and diseases can also affect productivity, this method is considered biased and imprecise. Hence, researchers have developed several techniques to quantify and assess land degradation, including the use of remote sensing, expert/land manager knowledge, and field measurements and observations (Omuto et al., 2014). Land Degradation Surveillance Framework (LDSF) The LDSF is a geographically stratified, randomized sample technique that was developed to provide a landscape-level biophysical baseline and a framework for monitoring and evaluating land degradation processes and the effectiveness of restoration activities (Tor-gunnar et al., 2013). LDSF provides a biophysical assessment and monitoring of the process of land degradation as well as the success of shortand long-term rehabilitation measures. It can also be used as part of a monitoring approach to detect vegetation changes over time (Lohbeck et al., 2018). The technique typically produces maps of 16 indicators of land degradation, which help to evaluate the state of a landscape. The World Agroforestry (ICRAF) created the LDSF to meet the demand for uniform field techniques and indicator frameworks to evaluate land health in landscapes. The technique was effectively established during land degradation studies in the Lake Victoria basin of Kenya, Mali, Southern Africa, and Madagascar. The framework is currently being used in projects all over the tropics and includes more than 30,000 observations, making it one of the largest land health databases worldwide (Lohbeck et al., 2018). To map the soil functional parameters and land degradation risk at a geographical scale of 500 m Vågen et al., (2014) use data from 114 LDSF sites, which were collected between 2010 and 2013. As the foundation for focusing on sustainable land management techniques, Waswa et al. (2013) employ LDSF to assess the geographical and temporal patterns of indicators of land degradation. Kyei, (2020) uses the data collected using LDSF to complement qualitative data from farmers' perception of the study to assess the rate of land degradation in Kenya. In their study, Lohbeck et al., (2018) used LDSF to discover that, above-ground biomass has a positive effect on soil health in East Africa by raising SOC and lowering soil erosion. In their study carried out in Ethiopia, Vågen et al., (2013) integrated LDSF to produce predictive models and maps of several indicators of land health that could be used to develop management recommendations. Its cost-effectiveness and less time demand are among the potential benefits of incorporating LDSF in the monitoring of land degradation and conservation strategies. Winowiecki et al., (2021) found that through the integration of LDSF and with the development of soil spectroscope and health observation data, it is possible to estimate and map Soil Organic Carbon (SOC) concentrations with high precision, this allows to pinpoint regions for restoration and monitor interventions over time. Regardless of the effectiveness and all the advantages of LDSF in monitoring and evaluation of land degradation, in SSA, particularly in East Africa LDSF has not been effectively utilized. Utilization of Geographical Information System (GIS) and Remote Sensing (RS) GIS and RS are now reported as making important contributions to natural resource management, including land degradation and soil erosion rate determination (Chiemela et al., 2018; Jiru, 2019). Due to the use of RS and GIS technologies, land degradation and its geographical distribution is now possible with reasonable costs and better accuracy across the greater parts of the regions (Reddy et al., 2018). It has been shown that the utilization of space borne multispectral data can be used to learn more about the characteristics, scope, distribution, and extent of degradation (Hank et al., 2019). Remote sensing-based assessments and monitoring of land degradation have several benefits, including consistent data, a source for spatially detailed data, and reporting that is nearly real-time (Reith et al., 2021). When ground data is paired with high- J. Bio. & Env. Sci. 20 23 17 | Kalonga et al. resolution remote sensing data, digital elevation models made from satellite data like that from Cartosat-1 and Cartosat-2, and Light Detection and Ranging (LiDAR), there is a great deal of promise for evaluating land degradation at local scales (Gianinetto, 2008). Through the integration of RS, GIS, and Revised Universal Soil Loss Equation (RUSLE), estimation of the amount of soil erosion loss on a cell-by-cell basis is achieved (Alexakis et al., 2013). Lu et al., (2004) showed that the use of geostatistical approaches to integrate ground dataset, thematic mapper (TM), and digital elevation model (DEM) data produces noticeably better results than using conventional methods to forecast soil erosion loss. RS data has been reportedly used as a potential tool for developing a cover management factor by using land cover classifications (Murambadoro, 2011), while GIS technologies might be utilized to integrate the RUSLE factors for the estimation of soil erosion (Kabanza et al., 2013). GIS capability becomes more useful when used with empirical and predictive models in the assessment of soil loss. Ganasri & Ramesh (2016) and Kunta (2009) studied the uses of GIS in estimating soil erosion and concluded that GIS held enormous promise for enhancing soil erosion estimation compared to methods that did not use GIS. Several remote sensing datasets have been used to measure and track soil erosion in sub-Saharan Africa, including satellite data with coarse, medium, and fine spatial and spectral resolutions as well as imagederived products like Digital Elevation Models (DEM) (Seutloali et al., 2018). For instance Taruvinga et al., (2008) in their study conducted in South Africa concluded that the Normalized Difference Vegetation Index (NVDI) and Transformed Soil Adjusted Vegetation Index (TSAVI) can successfully map continuous gullies with a moderate level of agreement when compared to traditional gully mapping method. Using slope classes and vegetation cover data produced from DEM and Landsat imagery, respectively, a study conducted in Tanzania by Vrieling et al., (2006) reliably identifies soil erosion risk quickly and accurately across vast special regions. Moreover, the study conducted by Panagos et al., (2014) in the European continent showed that the Moderate Resolution Imaging Spectroradiometer (MODIS) datasets, which are available for free, have the potential to be included in environmental models that deal with soil erosion. Additionally, they showed how MODISderived products enhance the spatial and temporal monitoring of biophysical features such as vegetation over vast geographic areas such as continents. RS and GIS technology give timely results in land degradation research as was evident in mapping degraded land in space and time with its distinct advantages of systematic, synoptic, fast, and repeating coverage (Metternicht & Zinck, 2003). The use of GIS and RS technology in managing degraded soils has been significantly expanded worldwide due to its quick development and its capabilities with new tools and software. According to studies, RS and GIS applications together have a lot of potential for assessing, mapping and monitoring land degradation over a wider region with less expense and more accuracy than would be achievable alone. Incorporation of emerging techniques such as GIS and remote sensing in the planning, and implementation of conservation strategies has many potential benefits including the identification of areas that are susceptible to soil erosion caused by land use land cover change. These techniques help to identify where conservation efforts and priorities should be focused (Ghosh et al., 2023). It can also be used to evaluate the extent of land degradation such as the rate of soil erosion, develop soil conservation strategies, estimate sediment yield, and design effective water management plans (Aouadj et al., 2023). Moreover, GIS and Remote Sensing can map soil nutrient levels and projections of crop yield which help farmers to optimize the use of agricultural inputs such as fertilizers and other inputs more efficiently. However, in Sub-Saharan Africa, their utilization in managing and restoring degraded land is still minimal. Techniques for Land Restoration in Sub-Saharan Africa Restoration of degraded land is a tendency to bring abandoned or previously degraded land back into J. Bio. & Env. Sci. 20 23 18 | Kalonga et al. useful or productive use and enhance the expansion of the productive area without compromising natural ecosystems (Chabay, 2018). Restoration of degraded land requires different methods depending on the agent of degradation, severity, and the aim of restoration (Stanturf et al., 2014). Restoration of degraded agricultural land can be done to increase productivity, enhance ecosystem services, or restore saline soil. Restoration techniques can be grouped into two categories: (i) agricultural conservation techniques and (ii) soil amendment techniques. Agricultural Conservation Techniques Conservation agriculture Conservation agriculture (CA) is a type of agricultural production system that is efficient in resources to ensure production intensification and crop yield improvement while enhancing natural resources through the improvement of soil nutrition and pest management. The main elements of CA for rainfed farming are reduced tillage, diversified crop rotation, soil cover, and soil moisture conservation, which when applied correctly result in enhanced soil health and contribute to crop yield sustainability (Shrestha et al., 2020). Tillage intensity reduction and residue retention are crucial CA components, but in smallscale farming systems in developing countries where crop leftovers can also be used as fodder and fuel wood, recycling or adding organic matter from outside sources may be an alternative. Many researchers have reported a positive contribution of CA on soil quality in Sub-Saharan Africa. The benefits of CA on soil quality vary from increasing productivity to improving soil organic carbon (SOC), infiltration, and soil moisture. An increase in crop yield was the major benefit of CA reported, according to Thierfelder et al.,( 2013) yield gains of 5 t/ha and 1 t/ha on maize and cowpea respectively were recorded after CA was applied in Zimbabwe and Zambia were recorded, taking into account that the average maize yield has been constant for the past two decades at roughly 0.89 t/ha. This milestone has been contributed by benefits contributed by different components of CA. The application of mulching on CA covers the soil surface as a result it protects the soil from erosion. According to Mugandani & Mwadzingeni, (2021), CA reduces soil erosion and surface runoff by 90% and 67%, respectively. Apart from protection from surface erosion, soil cover will also regulate soil temperature, control weeds and increase organic matter in the soil after decomposing. According to research on the physical and biological features of soils in Zambia, directly seeded CA systems exhibited more stable soil aggregates (41%-45%) than the conventional method (24%) (Thierfelder et al., 2017). Because of these improvements in soil qualities and nutrient availability, CA has the potential to reduce external fertilizer inputs like fertilizers and pesticides, which over time may have negative consequences for the ecosystem and soil health. Apart from soil health, another potential benefit of CA practice such as reduced tillage and direct sowing is to reduce soil compaction which improves soil structure and nutrient uptake in degraded soils of SSA. In the areas with high soil erosion, CA may have the potential to plan and implement conservation and restoration efforts for degraded land in SSA due to its minimum soil disturbances which reduces the runoff and sediments yield. CA may also be potential in areas with low organic matter content due to its ability to increase soil organic matter through its practices of incorporation crop residues in the soil (Page et al., 2020). Agroforestry Agroforestry refers to the practice of purposely using woody perennials (trees, shrubs, palms, bamboo, etc.) on the same land management units as crops and/or animals, in some kind of spatial arrangement or temporal sequence. Various elements in agroforestry systems interact in a way that is both ecological and profitable. Another definition of agroforestry is a dynamic, ecology-based system for managing natural resources that, by incorporating trees into farms and agricultural landscapes, diversifies and sustains production for greater social, economic, and environmental advantages for all land users (FAO, 2015). The capacity of agroforestry to improve soil quality has long been considered a key advantage J. Bio. & Env. Sci. 20 23 19 | Kalonga et al. since it emerged as a scientifically accepted discipline and practice (Dollinger & Jose, 2018). For decades, both in the tropics and temperate areas of the world, agroforestry practices have been promoted for their proven advantages in enhancing not only soil quality but also other ecosystem services (Jose, 2009). There are several agroforestry systems for recovering and enhancing soil health while simultaneously fulfilling the demands of poor resource farmers (Viswanath & Lubina, 2018). To counteract soil erosion and promote soil fertility, trees add nitrogen through nitrogen fixation, stabilize the soil, and be utilized in contour farming, and strip cropping. Trees planted in windbreaks and shelterbelts can help to prevent soil erosion (Misebo, 2018). To improve soil organic matter and nutritional status, Trees can be planted using enhanced fallow and alley cropping techniques, and the branches can be cut and used as mulch. However, by blocking the flow channel, an agroforestry system may also decrease runoff and reduce its ability to transfer soil (Kuyah et al., 2019). Agroforestry can increase soil fertility, protect biodiversity, increase carbon sequestration, and help with climate change adaptation and mitigation. According to Gupta, (2020) some agroforestry trees, including the Leucaena, Acacia and Alnus species, may fix up to 400-500 kg, 270 kg, and 100-300 kg of nitrogen per hectare per year, respectively. Furthermore, the annual major nutrients contributed by different agroforestry tree species range from 33.7 to 398 kg ha -1 year -1 N, 2 to 19.3 kg ha -1 year -1 P, 20 to211 kg ha -1 year -1 K, 14 to 98 kg ha -1 year -1 Ca and 5 to 17 kg ha -1 year -1 Mg (Dagar et al., 2020). For instance, agroforestry in Ethiopia boosted infiltration and decreased surface runoff by as much as 81% (Nyong & Martin, 2019). A review of African studies found that in around 60% of situations when the interaction between agroforestry and the environment was examined, trees enhanced the provision of ecosystem services (mainly at the field scale) (Rosenstock et al., 2019). Agroforestry has been shown to increase crop yield. For instance, a Zambian study found that growing maize in an agroforestry system surrounded by covers of Faidherbia albida trees resulted in yield increases of 88-190%. Results also indicate that contour hedges have reduced runoff by nearly 70% and that soils are better preserved with tree hedges than in untreated terraces (ICRAF, 2010). Agroforestry has numerous potential benefits at once, including restoring ecosystems and preserving biodiversity while also supplying food and income, as compared with other restoration strategies. Agroforestry can be used in improving soil fertility of degraded land through the practice of green manuring where leaves and tree branches are left to decompose in the soil. This practice improves soil structure, soil aeration, and soil nutrient content. Agroforestry can be used for water conservation in soils with low water holding capacity, Besides its multiple benefits its adoption is still low in SSA due to many reasons including high initial investment costs and delay or long-term return (Mwase et al., 2015). To support sustainable land productivity, enhance biodiversity, and improve ecosystem services at the plot and landscape scales, effective agroforestry systems must be developed. This now calls for researchers to investigate the affordable and efficient agroforestry system for restoring SSA-degraded land. Cover cropping Cover crops (CCs) are any live ground cover that grows to protect the soil, seed, and enhance the soil between periods of normal crop growth or between trees in orchards and vines in vineyards (Fageria et al., 2005). These plants are often known as "green manure crops." Cover cropping is the process of planting crops to cover the soil's surface to reduce wind and water erosion (Saturday, 2018). CCs can be any plants but mostly are legumes or nonlegumes/grass. Crop production is increased by CCs through enhancing the physical, chemical, and biological characteristics of the soil. Many studies have reported the potential of cover crops on soil qualities (Coombs et al., 2017). CCs regulate soil heat and temperature hence creating a favorable environment for the microorganisms. J. Bio. & Env. Sci. 20 23 20 | Kalonga et al. When fallen leaves are decomposed, become sources of organic matter in the soil. CCs help to store moisture, reduce evaporation from the soil surface, reduce the kinetic energy of raindrops on the ground, and increase the amount of soil moisture (Sharma et al., 2018). Additionally, CCs reduce soil erosion caused by wind and water, as well as particulate matter emissions brought on by wind and machinery. According to Kaspar & Singer, (2015) soils planted with rye and oats as CCs showed a 54 and 89% decrease in rill erosion after 3 years (Kaspar & Singer, 2015). Other studies have found that CCs increase water infiltration by up to 629%, increase macropores by around 33%, and reduce soil bulk density by roughly 4% when compared to soil without CCs. According to reports, these changes could result in a 96% decrease in soil loss. (Haruna et al., 2020). Wet aggregate stability, macroporosity, and water infiltration are all improved by an average of 16%, 16%, and 62%, respectively, by CCs, which also reduce penetration resistance (compaction indicator) by an average of 5% (Blanco-Canqui & Ruis, 2020). According to Brennan & Acosta-Martinez, (2017) research, the soil food web has improved as microbial biomass carbon has increased from 40 mg kg1 to 200250 mg kg1. Other researchers reported an increase of SOC by 15.6 - 17.9g kg −1 (Adetunji et al., 2020). Furthermore, perennial legumes, such as those used as legume cover crops, can produce up to 10 t ha -1 of dry matter and fix up to 120kg N ha -1 annually (Agegnehu & Amede, 2017). CCs are one of the important strategies for improving soil fertility in cropping land, but their impact on restoring degraded land when combined with other techniques such as physical structures is still not well documented. Therefore, much more research must be done to determine how CCs and physical structures work together to improve the health of degraded land in SSA. Crop rotation Crop rotation is a practice that involves growing a range of unrelated crops in the same place over multiple seasons to gain benefits such as reducing the spread of disease and pests that appear when one species is constantly cultivated (Rechcigl, 2018). By balancing the nutrient demands of various crops, crop rotation prevents the loss of soil nutrients. Crop rotation has a long-standing component of replacing nitrogen with the use of green manure and legumes planted after cereals and other crops. By alternating shallowand deep-rooted crops, crop rotation can help improve soil fertility and structure. A three-year study in Ethiopia on the interaction of crop rotation and manure application interventions improved the maximum average bulk density (BD), pH, cation exchange capacity (CEC), organic carbon (OC), total nitrogen (TN), available phosphorus (AP), and exchangeable potassium (EK) contents of the experimental soils, respectively, by 22.63%, 17.87%, 66.82%, and 88.89%, 150.00%, 88.87%, and 44.12%, compared to the baseline state of the soil's qualities before the experiment began (Alemayehu et al., 2020). On the other hand, research done by Njaimwe, (2010) in South Africa reported yield increases of 13 and 29% for 2 years of soybeans-maize and 3 years of maize - dry bean - wheat rotations, respectively. There are many potential benefits of incorporating crop rotation in soil conservation and restoration of degraded land in SSA these include improved soil fertility. Through crop rotation, specific demand for certain nutrients is rotated, hence reducing the possibility of depletion of specific nutrients in the soil. Not only that but also different crops take up different nutrients from the soil this is important for the soil to balance its nutrients for plant growth (Li et al., 2023). Reduced soil erosion is another potential benefit of incorporating crop rotation in soil conservation and restoration. Through crop rotation, the soil is provided with year-round soil cover which reduces the likelihood of soil erosion. Crops have different root systems which helps them to hold the soil and reduce soil erosion through runoff. Moreover, crop rotation increases soil organic matter, and through increased soil organic matter, soil structure and nutrition of soil microorganisms will be improved which is important for soil health and nutrient cycling. J. Bio. & Env. Sci. 20 23 21 | Kalonga et al. Organic Agriculture for Land Restoration Organic agriculture is a method of farming that avoids the use of chemicals like synthetic fertilizers and pesticides, as well as genetically modified organisms (GMOs) and a variety of other synthetic food additives (Topwal et al., 2018). The evolution of organic farming may be dated to the 1920s to 1930s in North Europe, primarily in Germany and the United Kingdom. It is now widely practiced around the world (Nielsen, 2019). Organic farming has evolved into a comprehensive strategy to combat contaminated food production, health security, biodiversity loss, interrupted soil nutrient cycles, polluted soil, and degraded agricultural land (Skoufogianni et al., 2016). The use of organic inputs, which do not deplete soil nutrients, the encouragement of soil microbial growth, and the management of soil from texture to ecosystem are today's organic farming ethics (Lal, 2015). Organic farming relies on many farming systems that take full use of ecological cycles to protect soil fertility. The use of green manure cover crops, polyculture, intercropping, crop rotation, and mulching are all part of organic farming techniques that increase soil fertility (Kumar et al., 2020). Although soil properties are typically site-specific, several scholars have demonstrated that organic farming outperforms conventional farming in terms of both biophysical (such as SOM, stored nutrients) and biological (such as biodiversity) factors in maintaining or enhancing soil quality (Niemiec et al., 2020; Zandi & Basu, 2016). It has also been suggested that combining organic and mineral fertilizers could be a viable strategy for addressing soil fertility reduction in SSA (Agegnehu & Amede, 2017). When a reference is made to Europe and the United States, a significant increase in SOM content as well as better biochemical performance indicators, there is no doubt that the adoption of organic farming would greatly reduce agricultural land degradation in SSA. Organic farming also dramatically reduces soil erosion by up to four times (Novara et al., 2019). In organic farming, techniques to reduce N loss such as manure application and conservation agriculture and increase N absorption efficiency are frequently employed, and many investigations show that organic farming reduces N loss through leaching and enhances N uptake efficiency (Dahlin et al., 2005; Farzadfar et al., 2021). According to Bai et al., (2018), The type and quantity of applied organic matter affect SOM's contribution to soil sustainability. Adding compost, farmyard manure, and slurry to the top 10 cm of soil raised SOM by 37%, 23%, and 21%, respectively. For every 1% increase in SOM concentration, estimations show that the soil may hold 10-11 liters of plant-available water per hectare of soil at a depth of 30 cm (Libohova et al., 2018). Organic fertilizers are mostly made up of farmyard manure, green manure, and composts. For instance, Quinton & Tyrrel, (2006) reported that manure reduces surface runoff by 70-90% and soil loss by 8095%. SSA being among regions with high livestock density Otte et al., (2019) the option of manure application to restore degraded agricultural lands would be easily encouraged. Organic farming can result in soil erosion rates that are 30-140 percent lower as compared to conventional farming (Kumawat et al., 2018). Microbes easily colonize organic additions, which improves other soil qualities while maintaining fertility stability. To continually release nutrients for plant and microbial growth, a balanced ratio of microbial biomass and activity is required. Organic farming contributes to soil fertility stabilization by boosting nitrogen fixation, lowering nutrient leaching, improving SOM, and soil cover, and improving soil structure (Asoegwu et al., 2020; Avasthe & Babu, 2017). According to certain research, organic farming is typically associated with a significantly higher level of biological activity, which includes bacteria, fungi, springtails, mites, and earthworms (Purohit, 2020). Biodynamic and organic management significantly improved soil ecological performance in the long term. According to studies, microbial biomass and activity increase under organic farming leading to increased root length of crops of up to 40% compared J. Bio. & Env. Sci. 20 23 28 | Kalonga et al. Kiptoo KO, Mirzabaev A. 2014. Economics of land degradation in Eastern Africa. University of Bonn, Center for Development Research (ZEF), Bonn This, ZEF Working Paper Series, No. 128. Kumar S, Meena RS, Datta R, Verma SK. 2020. Carbon and Nitrogen Cycling in Soil. In Carbon and Nitrogen Cycling in Soil (Issue August 2019). https://doi.org/10.1007/978-981-13-7264-3 Kumawat A, Yadav D, Kala Samadharmam Rashmi I. 2018. Soil and Water Conservation Measures for Agricultural Sustainability. Intechopen 25(4), e275-e281. http://dx.doi.org /10.5772/intechopen.92895 Kumawat A, Yadav D, Rashmi KSI. 2020. Soil and Water Conservation Measures for Agricultural Sustainability. Soil Moisture Importance 23. https://doi.org/10.5772/intechopen.92895 Kunta K. 2009. Effects of Geographic Information Quality on Soil Erosion Prediction (Issue May). Kuyah S, Whitney CW, Jonsson M, Sileshi GW, Öborn I, Muthuri CW, Luedeling E, Whitney CW, Jonsson M. 2019. Agroforestry delivers a win-win solution for ecosystem services in sub-Saharan Africa. A meta-analysis. Kyei E. 2020. Using the Land Degradation Surveillance Framework ( LDSF ) and Farmers ’ Perceptions to assess how land degradation has changed over nine years in the Sasumua catchment, Kenya. September 2017. https://doi.org/10.13140 /RG.2.2.27462.83527 Lal R. 2015. Restoring soil quality to mitigate soil degradation. Sustainability (Switzerland) 7(5), 58755895. https://doi.org/10.3390/su7055875 Ledo A, Smith P, Zerihun A, Whitaker J, Luis J, Qin VZ, Mcnamara NP, Zinn YL, Llorente M, Liebig M, Kuhnert M, Dondini M, Don A. 2020. Changes in soil organic carbon under perennial crops. March 1-11. https://doi.org/10.1111/gcb.15120 Li C, Shi W, Huang M. 2023. Effects of Crop Rotation and Topography on Soil Erosion and Nutrient Loss under Natural Rainfall Conditions on the Chinese Loess Plateau. Land 12(2). https:// doi.org /10.3390/land12020265 Libohova Z, Seybold C, Wysocki D, Wills S, Schoeneberger P, Williams C, Lindbo D, Stott D, Owens PR. 2018. Reevaluating the effects of soil organic matter and other properties on available water-holding capacity using the National Cooperative Soil Survey Characterization Database. Journal of Soil and Water Conservation 73(4), 411421. https://doi.org/10.2489/jswc.73.4.411 Lohbeck M, Winowiecki L, Aynekulu E, Okia C, Vågen TG. 2018. Trait-based approaches for guiding the restoration of degraded agricultural landscapes in East Africa. Journal of Applied Ecology 55(1), 59-68. https://doi.org/10.1111/1365-2664. Lu D, Li G, Valladares GS, Batistella M. 2004. Mapping soil erosion risk in Rondônia, Brazilian Amazonia: Using RUSLE, remote sensing and GIS. Land Degradation and Development 15(5), 499-512. https://doi.org/10.1002/ldr.634 Mazi M El, Hmamouchi M, Saber E, Bouchantouf Soumaya Houari A. 2022. Deforestation effects on soil properties and erosion : a case study in the central Rif, Morocco. Eurasian Journal of Soil Science 11(4), 275-283. https://doi.org /10.18393/ejss.1098600 Mcgowan AR, Nicoloso RS, Diop HE, Roozeboom KL, Rice CW. 2019. Soil Organic Carbon, Aggregation, and Microbial Community Structure in Annual and Perennial Biofuel Crops. Agronomy Journal 111(1), 128-142. https://doi.org /10.2134/agronj2018.04.0284 Meena VS, Mishra PK, Bisht JK, Pattanayak A. 2017. Agriculturally important microbes for sustainable agriculture. In Agriculturally Important Microbes for Sustainable Agriculture (Vol. 2, Issue January). https://doi.org/10.1007/978-981-10 J. Bio. & Env. Sci. 20 23 29 | Kalonga et al. Metternicht GI, Zinck JA. 2003. Remote sensing of soil salinity : potentials and constraints 85, 1-20. https://doi.org/10.1016/S0034-4257(02)00188-8 Misebo AM. 2018. The Role of Agronomic Practices on Soil and Water Conservation in Ethiopia; Implication for Climate Change Adaptation: A Review. Journal of Agricultural Science 10(6), 227. Mishra J, Prakash J, Arora NK. 2016. Role of Beneficial Soil Microbes in Sustainable Agriculture and Environmental Management. Climate Change and Environmental Sustainability 4(2), 137. https://doi.org/10.5958/2320-642x.2016.00015.6 Moisa MB, Dejene IN, Hirko O, Gemeda DO. 2022. Impact of deforestation on soil erosion in the highland areas of western Ethiopia using geospatial techniques : a case study of the Upper Anger watershed. Asia-Pacific Journal of Regional Science, April. https://doi.org/10.1007/s41685-022-00238-7 Molnar TJ, Kahn PC, Ford TM, Funk CJ, Funk CR. 2013. Tree crops, permanent agriculture: Concepts from the past for a sustainable future. Resources 2(4), 457-488. https://doi.org/10.3390 Mugandani R, Mwadzingeni L. 2021. Contribution of Conservation Agriculture to Soil Security 1-11. Muoni T, Koomson E, Öborn I, Marohn C, Watson CA, Bergkvist G, Barnes A, Cadisch G, Duncan A. 2019. Reducing soil erosion in smallholder farming systems in East Africa through the introduction of different crop types. Experimental Agriculture. https://doi.org/10.1017 /S00144797 0 Murambadoro D. 2011. ` Multi-Scale Analysis of Urban Wetland Changes Using Satellite Remote Sensing Techniques (Issue Turnbull 1986). Mwase W, Sefasi A, Njoloma J, Nyoka BI, Manduwa D, Nyaika J. 2015. Factors Affecting Adoption of Agroforestry and Evergreen Agriculture in Southern Africa. Environment and Natural Resources Research 5(2). https://doi.org/ 10.5539 Nalivata P, Kibunja C, Mutegi JK, Tetteh FM. 2017. 3 . Integrated Soil Fertility Management in SubSaharan Africa. August. https://doi.org/10.1079 /9781786392046.0025 Nath Yadav A. 2017. Plant Growth Promoting Bacteria: Biodiversity and Multifunctional Attributes for Sustainable Agriculture. Advances in Biotechnology & Microbiology 5(5). https://doi.org /10.19080/aibm.2017.05.555671 Nielsen KM. 2019. Organic Farming. In Encyclopedia of Ecology (pp. 550-558). Elsevier. https://doi.org/10.1016/B978-0-12-409548-9.10603Niemiec M, Chowaniak M, Sikora J, SzelagSikora A, Gródek-Szostak Z, Komorowska M. 2020. Selected properties of soils for long-term use in organic farming. Sustainability (Switzerland) 12(6), 1-10. https://doi.org/10.3390/su12062509 Njaimwe AN. 2010. Tillage and Crop Rotation Impacts on Soil Quality Parameters and Maize Yield in Zanyokwe Irrigation Scheme, South Africa (Issue December). University of Fort Hare, South Africa. Nkonya E, Mirzabaev A, von Braun J. 2015. Economics of land degradation and improvement - A global assessment for sustainable development. In Economics of Land Degradation and Improvement - A Global Assessment for Sustainable Development. https://doi.org/10.1007/978-3-319-19168-3 Novara A, Pulido M, Rodrigo-Comino J, Prima SDI, Smith P, Gristina L, Giménez-Morera A, Terol E, Salesa D, Keesstra S. 2019. Long-term organic farming on a citrus plantation results in soil organic carbon recovery. Geographical Research Letters 45(1), 271-286. https://doi.org/ 10.18172 Nyong PA, Martin NT. 2019. Enhancing agricultural sustainability and productivity under changing climate conditions through improved agroforestry practices in smallholder farming systems in Sub-Saharan Africa. African Journal of Agricultural Research 14(7), 379-388. https://doi.org /10.5897 J. Bio. & Env. Sci. 20 23 30 | Kalonga et al. Oliveira E. 2018. Can Strategic Spatial Planning Contribute to Land Degradation Reduction in Urban Regions ? State of the Art and Future Research. https://doi.org/10.3390/su10040949 Omuto CT, Balint Z, Alim MS. 2014. A Framework for National Assessment of Land Degradation In the Drylands : A Case Study Of Somalia 119(October 2011), 105-119. Otaiku AA, Soretire AA, Mmom PC. 2022. Biofertilizer Impacts on Soybean [Glycine max (L.)] Cultivation, Humid Tropics| Biological Nitrogen Fixation, Yield, Soil Health and Smart Agriculture Framework 9(1), 38-139. Otte J, Pica-Ciamarra U, Morzaria S. 2019. A comparative overview of the livestock-environment interactions in Asia and Sub-Saharan Africa. Frontiers in Veterinary Science 6(FEB). https:// doi.org/10.3389/fvets.2019.00037 Page KL, Dang YP, Dalal RC. 2020. The Ability of Conservation Agriculture to Conserve Soil Organic Carbon and the Subsequent Impact on Soil Physical, Chemical, and Biological Properties and Yield. Frontiers in Sustainable Food Systems 4(March), 117. https://doi.org/10.3389/fsufs.2020.00031 Panagos P, Karydas C, Borrelli P, Ballabio C, Meusburger K. 2014. Advances in soil erosion modeling through remote sensing data availability at European scale. Second International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2014) 9229(August 2014), 92290I. https://doi.org/10.1117/12.2066383 Pimentel D. 2006. Soil erosion: A food and environmental threat. Environment, Development and Sustainability 8(1), 119-137. https://doi.org /10.1007/s10668-005-1262-8 Pinto R, Brito LM, Coutinho J. 2017. Organic production of horticultural crops with green manure, composted farmyard manure and organic fertiliser. Biological Agriculture and Horticulture 33(4), 269284. https://doi.org/10.1080/01448 765.2017. 7521 Qiu Q, Bender SF, Mgelwa AS, Hu Y. 2022. Arbuscular mycorrhizal fungi mitigate soil nitrogen and phosphorus losses: A meta-analysis. Science of the Total Environment 807(October), 150857. https://doi.org/10.1016/j.scitotenv.2021.150857 Quinton JN, Tyrrel S. 2006. Effects of cattle manure on erosion rates and runoff water pollution by fecal coliforms. February. https://doi.org/ 10.1016 Rashid MI, Mujawar LH, Shahzad T, Almeelbi T, Ismail IMI, Oves M. 2016. Bacteria and fungi can contribute to nutrient bioavailability and aggregate formation in degraded soils. Microbiological Research 183, 26-41. https://doi.org /10.1016/j.micres.2015.11.007 Reddy GPO, Kumar N, Singh SK. 2018. Remote Sensing and GIS in Mapping and Monitoring of Land Degradation. 401-424. https://doi.org/10.1007/978-3-319-78711-4_20 Reich R, Eswaran H, Kapura S, Akca E. 2001. Land Degradation and Desertification in Desert Margins. Washington, D.C.: USDA Natural Resources Conservation Service. Reith J, Ghazaryan G, Muthoni F, Dubovyk O. 2021. Assessment of land degradation in semiarid Tanzania using multiscale remote sensing datasets to support sustainable development goal 15.3. Remote Sensing 13(9). https://doi.org/10.3390/rs13091754 Rosenstock TS, Dawson IK, Aynekulu E, Chomba S, Degrande A, Fornace K, Jamnadass R, Kimaro A, Kindt R, Lamanna C, Malesu M, Mausch K, McMullin S, Murage P, Namoi N, Njenga M, Nyoka I, Paez Valencia AM, Sola P, Steward P. 2019. A Planetary Health Perspective on Agroforestry in Sub-Saharan Africa. One Earth 1(3), 330-344. Sadeghi SH, Kheirfam H, Homaee M, Darki BZ, Vafakhah M. 2017. Improving runoff behavior resulting from direct inoculation of soil microorganisms. Soil and Tillage Research 171(March), 35-41. https://doi.org/10.1016/j.still.2017.04.007 J. Bio. & Env. Sci. 20 23 31 | Kalonga et al. Saggau P, Kuhwald M, Duttmann R. 2023. Catena Effects of contour farming and tillage practices on soil erosion processes in a hummocky watershed. A model-based case study highlighting the role of tramline tracks. Catena 228(March), 107126. https://doi.org/10.1016/j.catena.2023.107126 Sanchez PA, Swarninathan MS. 2009. Hunger in Africa: The link between unhealthy people and unhealthy soils. Science and Sustainable Food Security: Selected Papers of M S Swaminathan 365, 85-87. https://doi.org/10.1142/97898142 82116 Seneviratne G, Jayasekara APDA, De Silva MSDL, Abeysekera UP. 2011. Developed microbial biofilms can restore deteriorated conventional agricultural soils. Soil Biology and Biochemistry 43(5), 1059-1062. https://doi.org/10.1016 /j.soilbio. Seutloali KE, Dube T, Sibanda M. 2018. Developments in the remote sensing of soil erosion in the perspective of sub-Saharan Africa. Implications on future food security and biodiversity. Remote Sensing Applications: Society and Environment 9, 100-106. https://doi.org/10.1016/j.rsase.2017.12.002 Sher Y, Baker NR, Herman D, Fossum C, Hale L, Zhang X, Nuccio E, Saha M, Zhou J, PettRidge J, Firestone M. 2020. Microbial extracellular polysaccharide production and aggregate stability controlled by switchgrass (Panicum virgatum) root biomass and soil water potential. Soil Biology and Biochemistry, 143(August 2019), 107742. https://doi.org/10.1016 /j.soilbio.2020.107742 Shrestha J, Subedi S, Timsina K, Chaudhary A. 2020. Conservation agriculture as an approach towards sustainable crop production : A Review. Farming & Management 5(1). https://doi.org/ 10.31830 /2456-8724.2020.002 Singh JS, Gupta VK. 2016. Degraded land restoration in reinstating CH4 sink. Frontiers in Microbiology 7(JUN), 1-5. https://doi.org/10.3389 Skoufogianni E, Solomou A, Molla A, Martinos K. 2016. Organic Farming as an Essential Tool of the Multifunctional Agriculture. Organic FarmingA Promising Way of Food Production. https://doi.org/10.5772/61630 Smith DR, Owens PR, Leytem AB, Warnemuende EA. 2007. Nutrient losses from manure and fertilizer applications as impacted by time to first runoff event. Environmental Pollution 147, 131-137. https://doi.org/10.1016/j.envpol. 2006 Stanturf JA, Palik BJ, Williams MI, Dumroese RK, Madsen P. 2014. Forest Restoration Paradigms. Journal of Sustainable Forestry 33. https://doi.org/10.1080/10549811.2014.884004 Taruvinga K, Kelly R, Price J. 2008. Gully mapping using remote sensing: Case study in KwaZulu-Natal, South Africa. Department of Geography and Environmental Management, MSc Thesis, 121. Tenge AJ, Okoba BO, Sterk G. 2011. Physical Effectiveness and Farmers’Preferences of Soil and Water Conservation in the East African Highlands in West Usambara. September 2016. https://www.researchgate.net/profile/Joseph-Hella/ publication/227626634_Social_and_economic_facto rs_affecting_the_adoption_of_soil_and_water_cons ervation_in_West_Usambara_highlands_Tanzania/l inks/5d6efd9d299bf16522f31094/Social-andeconomic-factors-affect Tesfahunegn BG, Tamene L, Vlek PLG. 2011. Geoderma Evaluation of soil quality identified by local farmers in Mai-Negus catchment, northern Ethiopia. Elsevier B.V 163, 209-218. https:// doi.org/10.1016/j.geoderma.2011.04.016 Teshome A, Rolker D, de Graaff J. 2013. Financial viability of soil and water conservation technologies in northwestern Ethiopian highlands. Applied Geography 37, 139-149. https://doi.org/ 10.1016 /j.apgeog.2012.11.007 J. Bio. & Env. Sci. 20 23 32 | Kalonga et al. Thierfelder C, Cheesman S, Rusinamhodzi L. 2013. Benefits and challenges of crop rotations in maize-based conservation agriculture (CA) cropping systems of southern Africa. International Journal of Agricultural Sustainability 11, 108-124. https:// doi.org /10.1080/14735903.2012.703894 Thierfelder C, Chivenge P, Mupangwa W, Rosenstock TS, Lamanna C, Eyre JX. 2017. How climate-smart is conservation agriculture (CA)? - its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa. Food Security 9, 537-560. https://doi.org /10.1007 Tilahun K, Desta G. 2021. Impact of Physical Soil and Water Conservation Measures on Soil Erosion Reduction and Associated Constraints in the Highland of Ethiopia. Journal of Soil and Water Science 5, 171-183. https://doi.org /10.36959 /442 Toor MD, Adnan M, Raza A, Ahmed R, Arshad A, Maqsood H, Abbas F, Mughees-ud-din M, Shehzad MH, Zafar MK. 2020. Land Degradation and its Management : A Review. International Journal of Environmental Sciences & Natural Resources Warming 25, 63-66. https://doi.org /10.19080/IJESNR.2020.25.556157 Topwal M, Agarawal S, Topwal CM. 2018. Organic farming: Benefits, climate challenges and food security. International Journal of Chemical Studies 6, 944-948. www.organic-world.net Tor-gunnar V, Norvin S, Ordonez J, Noel C, Ulloa I, Trujillo R, Norori R. 2013. Progress Update on the LDSF Field Surveys : Nicaragua Sentinel Landscape The Land Degradation Surveillance. Tsatskin A. 2021. Selim Kapur · Sabit Erşahin Editors Soil Security for Ecosystem Management Mediterranean Soil Ecosystems (Issue February). https://doi.org/10.1007/978-3-319-00699-4 Tsegaye NT, Negewo DA, Mitiku ST. 2023. East African Journal of Forestry & Agroforestry 6, 137-147. https://doi.org/10.37284/eajfa.6.1.1183 Tully K, Sullivan C, Weil R, Sanchez P. 2015. The State of Soil Degradation in Sub-Saharan Africa: Baselines, Trajectories, and Solutions 6523-6552. https://doi.org/10.3390/su7066523 UNCCD. 2017. United Nations Convention to Combat Desertification. 2017. The Global Land Outlook, first edition. Vågen TG, Winowiecki LA, Abegaz A, Hadgu KM. 2013. Landsat-based approaches for mapping of land degradation prevalence and soil functional properties in Ethiopia. Remote Sensing of Environment 134, 266-275. https://doi.org/ 10.1016 /j.rse.2013.03.006 Vågen TG, Winowiecki LA, Tondoh JE, Desta LT, Gumbricht T. 2014. Mapping of soil properties and land degradation risk in Africa using MODIS reflectance. Geoderma 263, 216-225. https:// doi.org/10.1016/j.geoderma.2015.06.023 Vanloqueren G, Baret PV. 2009. How agricultural research systems shape a technological regime that develops genetic engineering but locks out agroecological innovations. Research Policy 38, 971983. https://doi.org/10.1016/j.respol.2009.02.008 Viswanath S, Lubina PA. 2018. Traditional agroforestry systems. Agroforestry: Anecdotal to Modern Science, Vol II, 91-119. https://doi.org /10.1007/978-981-10-7650-3_3 Vlek PLG, Le QB, Tamene L. 2008. Land decline in Land-Rich Africa. Development, March. Vrieling A, Sterk G, Vigiak O. 2006. Spatial evaluation of soil erosion risk in the West Usambara Mountains, Tanzania. Land Degradation and Development 17, 301-319. https://doi.org /10.1002 Waswa BS, Vlek PLG, Tamene LD, Okoth P, Mbakaya D, Zingore S. 2013. Evaluating indicators of land degradation in smallholder farming systems of western Kenya. Geoderma 195-196, 192200. https://doi.org/10.1016/j.geoderma.2012.11.007 J. Bio. & Env. Sci. 20 23 33 | Kalonga et al. Weerasekara CS, Udawatta RP, Gantzer CJ, Kremer RJ, Jose S, Veum KS. 2017. Effects of Cover Crops on Soil Quality: Selected Chemical and Biological Parameters. Communications in Soil Science and Plant Analysis 48, 2074-2082. https://doi.org/10.1080/00103624.2017.1406103 Winowiecki LA, Bargués-tobella A, Mukuralinda A, Mujawamariya P. 2021. Assessing soil and land health across two landscapes in eastern Rwanda to inform restoration activities. 767-783. Wolka K, Mulder J, Biazin B. 2018. Effects of soil and water conservation techniques on crop yield, runoff and soil loss in Sub-Saharan Africa: A review. Agricultural Water Management 207, 67-79. https://doi.org/10.1016/j.agwat.2018.05.016 Wynants M, Kelly C, Mtei K, Munishi L, Patrick A, Rabinovich A, Nasseri M, Gilvear D, Roberts N, Boeckx P, Wilson G, Blake WH, Ndakidemi P. 2019. Drivers of increased soil erosion in East Africa’s agro-pastoral systems: changing interactions between the social, economic and natural domains. Regional Environmental Change 19, 1909-1921. https://doi.org/10.1007 /s10113-019-01520-9 Zaman S, Pramanick P, Mitra A. 2009. Chemical fertilizer. Dm. Zandi P, Basu SK. 2016. Organic Farming for Sustainable Agriculture 1, 71-87. http://dx.doi.org /10.1007/978-3-319-26803-3_3 Zingore S, Delve RJ, Nyamangara J, Giller KE. 2008. Multiple benefits of manure: The key to the maintenance of soil fertility and restoration of depleted sandy soils on African smallholder farms. Nutrient Cycling in Agroecosystems 80, 267-282. https://doi.org/10.1007/s10705-007-9142-2 Zingore S, Mutegi J, Agesa B, Tamene L, Kihara J. 2015. Soil Degradation in Sub-Saharan Africa and Crop Production Options for Soil Rehabilitation. Better Crops with Plant Food 99, 24-26.