Tlou Elizabeth Mogale

South Africa has emerged as Africa's largest soybean producer, with cultivated area increasing by approximately 55% between 2018 and 2025. Understanding how this rapid expansion is reshaping the country's landscape is critical for agricultural planning and conservation, particularly given the well-documented ecological costs of soybean expansion in South America. This study integrates 10 m soybean time-series maps (SoySA10), land cover products, and 24 spatial factors to identify land sources, key drivers, and potential areas for soybean expansion in South Africa. Different from South America, where new soybean was mainly converted from pastures on previously deforested land, 87.4% of newly cultivated soybean in South Africa originated from land that was already cropland in 1990 and 2020, with 97.3% grown in rotation with other crops. Cropland proportion (within a 1 km cell) and distance to storage facilities emerged as the two most important drivers nationally. Factor importance varied across provinces, reflecting contrasts between regions where large-scale farming dominates (Free State, North West, and Mpumalanga) and those where smallholder farming is more prevalent (KwaZulu-Natal and Limpopo). Potential future expansion is more likely around existing hotspots in Free State and North West, but with a shift from cropland to grassland-dominated areas and, in some provinces, towards protected areas or forests. Further expansion will require additional investment in storage and processing infrastructure. These findings can support spatial planning for infrastructure investment, cropland intensification, and ecosystem conservation in South Africa, and the analytical framework can be transferred to other emerging producing countries across the Global South.

Cropland degradation is a major environmental concern, with over 65% of arable land affected by soil erosion, declining organic matter, nutrient loss, and reduced biodiversity. Restoring croplands is therefore crucial for sustainable agricultural productivity and ecosystem functioning under increasing climate variability, especially in sub-Saharan Africa (SSA). This review aims to evaluate the effectiveness of agroforestry systems in restoring degraded croplands across SSA, with a focus on soil quality, crop productivity and erosion control. A comprehensive search was performed using Scopus, Web of Science, and Google Scholar, covering agroforestry studies published between 2010 and 2025. Findings from 62 studies were analysed to identify the drivers of cropland degradation, benefits, limitations, and future directions of agroforestry systems as a restoration strategy. The primary indicators of degradation include declining soil fertility, increased soil erosion, vegetation loss, continuous monocropping and shortened fallow periods. Studies have shown that agroforestry systems can improve soil moisture retention, carbon storage, nutrient cycling and crop productivity. Challenges such as high costs of establishing these systems, limited access to high-quality trees seedlings, labour requirements, and a lack of supportive policies and extension services prevent many farmers from adopting agroforestry practices. Therefore, scaling up agroforestry adoption through regionally tailored policies and long-term localized research experiments with proven benefits will be essential in restoring degraded croplands. It is recommended that agroforestry be integrated not only in the national development and climate adaptation discussions, but also in food system policies to provide an effective strategy to rebuild degraded croplands and create resilience throughout SSA.

An intercropping system is one of the traditional practices adopted under dry conditions due to its ability to utilize resources efficiently. There is limited information on water use efficiency (WUE) and water equivalent ratio (WER) of grain sorghum ( Sorghum bicolor )‐cowpea ( Vigna unguiculata ) intercrop grown in different agroecological regions of the semi‐arid Limpopo province of South Africa. A no‐tillage field experiment arranged in a randomized complete block design with four replications over two growing seasons, 2018/2019 and 2020/2021, in two distinct regions, Syferkuil and Ofcolaco of the province, was established to assess the water productivity of sorghum‐cowpea intercrop. Four grain sorghum cultivars, Enforcer, Avenger, NS5511, and Titans were intercropped with two different cowpea densities of 37,037 and 74,074 plants ha ⁻¹ . The results from Syferkuil revealed that for grain sorghum, the cultivars Enforcer and NS5511 exhibited higher crop WUE when grown with 37037 plants ha ⁻¹ compared to 74074 plants ha ⁻¹ density, resulting in approximately 31% and 8% increase, respectively. For cowpea, 74074 plants ha ⁻¹ density cowpea in an intercropping system resulted in higher crop WUE of 3.22 kg ha ⁻¹ mm ⁻¹ , 6.85 kg ha ⁻¹ mm ⁻¹ compared to 37037 plants ha ⁻¹ density, with 1.18 and 5.05 kg ha ⁻¹ mm ⁻¹ in 2018/2019 and 2020/2021 cropping seasons, respectively. Similar results were observed at Ofcolaco, where Enforcer intercropped with 74074 plants ha ⁻¹ density accumulated the highest crop WUE. For cowpea, high crop WUE was observed with the intercrop cowpea means of WUE of 9.61 kg ha ⁻¹ mm ⁻¹ and 3.57 kg ha ⁻¹ mm ⁻¹ under 37037 plants ha ⁻¹ and 74074 plants ha ⁻¹ , respectively. The intercropping system resulted in high water productivity compared to sole, as indicated by WER greater than 1.0 for all the treatments. Intercropping enforcer or ns5511 with 37037 plants ha ⁻¹ cowpea density maximized sorghum WUE, whereas high cowpea density maximized cowpea WUE. All intercrops treatments achieved WER of > 1.0, indicating a higher advantage over the sole system.

Mycorrhizae utilization is an integral part of the strategy for adapting to climate change in semi-arid regions. A controlled experiment was conducted at the University of Limpopo, South Africa, to determine the effects of arbuscular mycorrhiza fungi (AMF) and soil type on crop growth and root colonization of Jew’s mallow. Treatments comprised two levels of mycorrhiza (with and without), two soil sources (Ofcolaco and Syferkuil), and three Jew’s mallow cultivars (“Amugbadu”, “Oniyaya”, and a landrace). The results revealed that the Amugbadu cultivar produced the highest Mycorrhizal growth response (MGR) in Syferkuil soil, whereas the Oniyaya cultivar was the highest in Ofcolaco soil. MGR in Ofcolaco soil was six times higher than in Syferkuil soil. AMF-inoculated Amugbadu consistently resulted in the highest crop growth rate (CGR) in Ofcolaco soil. The inoculated landrace was superior in CGR, compared to the uninoculated landrace in Syferkuil soil. Approximately 71.23–75.86% of the Jew’s mallow roots were colonized by AMF in both soil sources, with inoculated “Amugbadu” producing the highest root colonization. The landrace root colonization was inferior in both soil sources. Our results indicate that incorporating AMF in Jew’s mallow could improve root colonization, growth rate, and productivity in the semi-arid regions of South Africa, depending on soil type.

Mycorrhizae utilization is an integral part of adaptation strategy to climate change in semiarid regions. A controlled experiment was conducted at the University of Limpopo, South Africa, to determine the effects of arbuscular mycorrhiza fungi (AMF) and soil type on crop growth and root colonization of Jew’s mallow. Treatments comprised two levels of mycorrhiza (with and without), two soil sources (Ofcolaco and Syferkuil), and three Jew’s mallow cultivars ("Amugbadu", "Oniyaya", and a Landrace). The results revealed that the Amugbadu cultivar produced the highest Mycorrhizal growth response (MGR) in Syferkuil soil, whereas Oniyaya cultivar was the highest in Ofcolaco soil. MGR in Ofcolaco soil was six times higher than in Syferkuil soil. AMF-inoculated Amugbadu consistently resulted in the highest crop growth rate (CGR) in Ofcolaco soil. Inoculated Landrace was superior in CGR, compared to uninoculated Landrace in Syferkuil soil. Approximately 71.23-75.86% of the Jew’s mallow roots were colonized by AMF in both soil sources, with inoculated ʺAmugbaduʺ producing the highest root colonization. The landrace root colonization was inferior in both soil sources. Our results indicate that incorporating AMF in Jew’s mallow could improve root coloni-zation, growth rate, and productivity in the semi-arid regions of South Africa, depending on soil type.

Understanding the carbon dioxide emission rates under different agricultural practices is a critical step in determining the role of agriculture in greenhouse gas emissions. One of the challenges in advocating for an intercropping system as a sustainable practice in the face of climate change is the lack of information on how much CO₂ is emitted by the system. A factorial randomized complete block design study was set up at two distinct agroecological locations (Syferkuil and Ofcolaco) in the Limpopo Province of South Africa to investigate carbon dynamics in sorghum-cowpea intercropping and sole cropping system over two seasons. Intercropping system emitted less CO₂ compared to sole cropping system. In 2018/19 at Syferkuil and 2020/21 at Ofcolaco, intercropping systems emitted 11 and 19 less CO₂, respectively, than sole cropping systems. In both agroecological regions, low cowpea density consistently resulted in higher CO₂ emissions than high density. During the 2018/19 cropping season, sorghum emitted more CO₂ of 5.87t·ha⁻¹ than cowpea with 5.14t·ha⁻¹ in a sole cropping system at Syferkuil. Cowpea, on the other hand, emitted more CO₂ of 6.5t·ha⁻¹ and 10.18t·ha⁻¹ than sorghum during the 2020/21 cropping season at Syferkuil and Ofcolaco, respectively. Furthermore, intercropping improved the carbon emission efficiency (CEE) of the individual crops in the system. The treatments used in the intercropping and sole cropping systems had a significant impact on the strength of the relationship between carbon stocks and CEE. Our results revealed that sorghum-cowpea intercropping system at a relatively higher cowpea density in a no-till system reduces the amount of CO₂ lost to the atmosphere. The system can thus, be promoted as one of the sustainable farming practices to reduce emissions and improve carbon storage in the soil.

Nitrogen (N) availability under no-till intercropping systems has not been widely investigated in diverse agro-ecological regions in Limpopo Province. Two seasons of rainfed experiments were conducted during 2018/19 and 2020/21 in a 2 × 4 × 2 factorial design to measure the biological nitrogen fixation (BNF) ability of cowpea in an intercropping system with four grain sorghum cultivars at two test locations, Ofcolaco and Syferkuil, of Limpopo Province using the natural abundance technique. The cowpea nitrogen isotope composition (δ ¹⁵N‰) ranged from 0.2 ‰ to 4‰ at Ofcolaco, whereas at Syferkuil, the range was 2 ‰ to 7 ‰. The N derived from air (Ndfa) was from 35% to 92% at Ofcolaco and 4% to 70% at Syferkuil during the two cropping seasons. The amount of N₂ fixed across locations and seasons ranged from 1 kg ha⁻¹ to 71 kg ha⁻¹. In the intercropping system, cowpea fixed more N at higher densities compared with lower densities at the two experimental sites. Biomass was significantly correlated with N accumulated by cowpea (r² > 0.9) at all locations and across seasons. N accumulated in sole cultures was 30% more at Ofcolaco and 36% more at Syferkuil compared with binary cultures. Furthermore, the treatment combination, cowpea density, as well as cropping system, significantly affected N fixation and accumulation. For high productivity, cowpea intercrop with grain sorghum cultivar Enforcer is recommended, as both crops complemented each other when intercropped. The research should investigate further the root distribution and biomass production of sorghum and cowpea, as well as their impact on N intake.

Climate change is severely disrupting ecosystem services and crop productivity, resulting in lower crop growth and yields. Studies have emphasized the importance of assessing conservation practices through crop modelling to improve cropland productivity. There is a lack of accurate information in the performance of conservation practices as well as data for improved crop modelling. No-tillage sorghum–cowpea intercrop experiments were established to assess the productivity of four sorghum cultivars and cowpea at two densities of 37,037 and 74,074 per plants and generate data for improved crop modelling. The leaf area index (LAI) varied in sorghum cultivars and cowpea densities during the two growing seasons. Cultivars Enforcer and NS5511 produced the highest grain yields of 4338 kg per ha and 2120 kg per ha, respectively, at Syferkuil. Ofcolaco’s Enforcer and Avenger were the highest yielding cultivars at Ofcolaco, with mean yields of 2625 kg per ha and 1191 kg per ha, respectively. At Syferkuil, cowpea yield was 93% and 77% more in sole compared to binary cultures during the growing seasons at Syferkuil. At Ofcolaco, sole yielded approximately 96% more grain than binary. The findings confirm that for the sorghum–cowpea intercrop to improve overall system productivity, cowpea density should be increased.