Pub Date : 2021-08-08DOI: 10.1080/02571862.2021.1913767
Tebogo J Lebea, N. Jovanović, M. Kena, K. Ayisi, Wisani G Mushadu
Intensification of low-tech agricultural production is required in the Greater Giyani Municipality (Limpopo province, South Africa) to respond to changing climatic conditions, water scarcity and increased food demand of the local market. Two years of field experiments were conducted on two typical small-scale farms under real-world conditions. The objective was to test the response of locally available tomato (Lycopersicon esculentum Mill.) cultivars (Rodade, STAR 9006, Commander, HTX 14 and MFH) to two different irrigation strategies (full irrigation FI and deficit irrigation DI). While results showed high tomato yield variability (ranging between 9.2 t ha−1 and 59.7 t ha−1) depending on the farms, environmental conditions (heatwaves, diseases) and irrigation management, STAR 9006 appeared to be the best performing cultivar and HTX 14 the worst. Seasonal evapotranspiration under FI was between 400 and 620 mm depending on the length of the season and harvesting time. Crop water productivity was generally higher for DI than FI treatments. Deficit irrigation appeared to be feasible to reduce water use for some cultivars (eg cv. STAR 9006), however, an economic analysis should be conducted at specific sites/farms to determine the impacts of DI on farmers’ income as some yield losses can be expected during drought years.
大吉亚尼市(南非林波波省)需要加强低技术农业生产，以应对不断变化的气候条件、水资源短缺和当地市场粮食需求增加。在现实条件下，在两个典型的小规模农场进行了为期两年的田间试验。目的是测试当地番茄(Lycopersicon esculentum Mill.)品种(Rodade、STAR 9006、Commander、HTX 14和MFH)对两种不同灌溉策略(完全灌溉FI和亏缺灌溉DI)的反应。结果表明，根据不同的种植方式、环境条件(热浪、病害)和灌溉管理，番茄产量变异较大(在9.2 ~ 59.7 t ha - 1之间)，STAR 9006表现最好，htx14表现最差。FI下的季节蒸散量在400 ~ 620 mm之间，取决于季节长度和收获时间。DI处理的作物水分生产力普遍高于FI处理。亏缺灌溉似乎是可行的，以减少一些品种的用水量(如cv。STAR 9006)，但是，应在特定地点/农场进行经济分析，以确定DI对农民收入的影响，因为在干旱年份可能会出现一些产量损失。
{"title":"Response of tomato cultivars to irrigation management strategies employed by emerging farmers in the Greater Giyani Municipality","authors":"Tebogo J Lebea, N. Jovanović, M. Kena, K. Ayisi, Wisani G Mushadu","doi":"10.1080/02571862.2021.1913767","DOIUrl":"https://doi.org/10.1080/02571862.2021.1913767","url":null,"abstract":"Intensification of low-tech agricultural production is required in the Greater Giyani Municipality (Limpopo province, South Africa) to respond to changing climatic conditions, water scarcity and increased food demand of the local market. Two years of field experiments were conducted on two typical small-scale farms under real-world conditions. The objective was to test the response of locally available tomato (Lycopersicon esculentum Mill.) cultivars (Rodade, STAR 9006, Commander, HTX 14 and MFH) to two different irrigation strategies (full irrigation FI and deficit irrigation DI). While results showed high tomato yield variability (ranging between 9.2 t ha−1 and 59.7 t ha−1) depending on the farms, environmental conditions (heatwaves, diseases) and irrigation management, STAR 9006 appeared to be the best performing cultivar and HTX 14 the worst. Seasonal evapotranspiration under FI was between 400 and 620 mm depending on the length of the season and harvesting time. Crop water productivity was generally higher for DI than FI treatments. Deficit irrigation appeared to be feasible to reduce water use for some cultivars (eg cv. STAR 9006), however, an economic analysis should be conducted at specific sites/farms to determine the impacts of DI on farmers’ income as some yield losses can be expected during drought years.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"313 - 325"},"PeriodicalIF":0.9,"publicationDate":"2021-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48452124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-08DOI: 10.1080/02571862.2021.1930209
F. Müller
This study evaluated the impacts of pH on the germination and early seedling growth of Calobota sericea and Lessertia frutescens subsp. frutescens, two perennial legume species found in the semi-arid rangelands of South Africa. The results of this study revealed that L. frutescens had higher seed germination under more acidic conditions, while C. sericea had higher seed germination under alkaline conditions. Similarly, L. frutescens seedlings were found to be larger under more acidic conditions, while C. sericea seedlings were larger under more alkaline conditions. Both species were able to germinate under all of the pH treatments, suggesting that they are adapted to a wide range of pH conditions, at least at the germination and early seedling growth stage.
{"title":"Contrasting effects of soil pH on seed germination and early seedling growth of Calobota sericea and Lessertia frutescens subs. frutescens","authors":"F. Müller","doi":"10.1080/02571862.2021.1930209","DOIUrl":"https://doi.org/10.1080/02571862.2021.1930209","url":null,"abstract":"This study evaluated the impacts of pH on the germination and early seedling growth of Calobota sericea and Lessertia frutescens subsp. frutescens, two perennial legume species found in the semi-arid rangelands of South Africa. The results of this study revealed that L. frutescens had higher seed germination under more acidic conditions, while C. sericea had higher seed germination under alkaline conditions. Similarly, L. frutescens seedlings were found to be larger under more acidic conditions, while C. sericea seedlings were larger under more alkaline conditions. Both species were able to germinate under all of the pH treatments, suggesting that they are adapted to a wide range of pH conditions, at least at the germination and early seedling growth stage.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"343 - 345"},"PeriodicalIF":0.9,"publicationDate":"2021-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46304643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-08DOI: 10.1080/02571862.2021.1913249
L. van Straaten, CF Wessels, G. Ceronio, C. du Preez
The grain yield and quality of maize is often negatively influenced by zinc (Zn) deficiencies during early growth and development. Application of Zn to soil is therefore a necessity, especially when it is sandy. Glasshouse experiments were carried out to test the effects of Zn sources and application rates on plant-available Zn and on early growth and development of maize grown in a sandy soil. Soil Zn concentration was increased most by ZnSO4 and least by ZnO. The Na2EDTA method was superior to four other methods in extracting soil Zn. For most plant parameters that were measured (leaf number, stem thickness, plant height, photosynthesis rate, leaf area, dry mass, root length and root mass) ZnEDTA was the most effective chelated source, followed by ZnHEDTA, ZnDTPA or ZnEDDHA. Regarding inorganic sources ZnSO4 was superior, followed by ZnCO3, ZnCl2 and ZnO. As a group the inorganic sources performed more poorly than the chelated sources. These rankings differed in terms of Zn concentration and uptake by the plants. The results must be verified in field trials that last for several years accommodating a wider range of climate and soil conditions to develop reliable Zn fertilisation guidelines for maize cultivated on sandy soils.
{"title":"Early growth and development of maize on sandy soils fertilised with zinc sources at different application rates","authors":"L. van Straaten, CF Wessels, G. Ceronio, C. du Preez","doi":"10.1080/02571862.2021.1913249","DOIUrl":"https://doi.org/10.1080/02571862.2021.1913249","url":null,"abstract":"The grain yield and quality of maize is often negatively influenced by zinc (Zn) deficiencies during early growth and development. Application of Zn to soil is therefore a necessity, especially when it is sandy. Glasshouse experiments were carried out to test the effects of Zn sources and application rates on plant-available Zn and on early growth and development of maize grown in a sandy soil. Soil Zn concentration was increased most by ZnSO4 and least by ZnO. The Na2EDTA method was superior to four other methods in extracting soil Zn. For most plant parameters that were measured (leaf number, stem thickness, plant height, photosynthesis rate, leaf area, dry mass, root length and root mass) ZnEDTA was the most effective chelated source, followed by ZnHEDTA, ZnDTPA or ZnEDDHA. Regarding inorganic sources ZnSO4 was superior, followed by ZnCO3, ZnCl2 and ZnO. As a group the inorganic sources performed more poorly than the chelated sources. These rankings differed in terms of Zn concentration and uptake by the plants. The results must be verified in field trials that last for several years accommodating a wider range of climate and soil conditions to develop reliable Zn fertilisation guidelines for maize cultivated on sandy soils.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"304 - 312"},"PeriodicalIF":0.9,"publicationDate":"2021-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49461719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-08DOI: 10.1080/02571862.2021.1925761
Phomolo Maphothoma, R. Kleynhans, G. Prinsloo, S. Mokgehle, Ian du Plooy, H. Araya
African ginger (Siphonochilus aethiopicus) is in high demand for medicinal use. The plant does not multiply after being harvested, as it is destroyed in the process. The species is now facing extinction as a result of over harvesting. In order to mitigate this threat, cultivation of the species has become priority. The objective of this study was to determine the growth and yield parameters of S. aethiopicus in relation to organic fertiliser treatments. The parameters were evaluated in response to three organic fertiliser applications (0, 100 and 200 kg N ha−1) and three rhizome sizes, namely small (10–20 g), medium (20–40 g) and large (> 40 g). The combination of a fertiliser application of 100 kg N ha−1 and large rhizomes provided the best results, with maxima for rhizome yield (7 t ha−1) and root yield (6 t ha−1). Small and medium rhizomes had a significantly lower yield than large rhizomes at all nitrogen levels. The different fertiliser applications were associated with significant variation in leaf chlorophyll content. It is concluded that the application of 100 kg N ha−1 and planting of large rhizomes would result in the best yield for African ginger’s commercial production.
非洲生姜（Siphonchilus aethiopicus）在药用方面需求量很大。这种植物在收获后不会繁殖，因为它在这个过程中被破坏了。由于过度捕捞，该物种现在正面临灭绝。为了减轻这种威胁，培育该物种已成为当务之急。本研究的目的是确定与有机肥料处理相关的醚硫草的生长和产量参数。根据三种有机肥料（0、100和200 kg N ha−1）和三种根茎大小（即小根茎（10-20 g）、中根茎（20-40 g）和大根茎（>40 g））对参数进行了评估。施用100 kg N ha−1的化肥和大根状茎的组合效果最好，根状茎产量（7 t ha−1）和根产量（6 t ha−2）最高。在所有氮水平下，中小根状茎的产量都显著低于大根状茎。不同的施肥方式与叶片叶绿素含量的显著变化有关。结果表明，施用100kg N ha−1和种植大根状茎将为非洲生姜的商业生产带来最佳产量。
{"title":"Growth and yield of African ginger in response to application of organic fertiliser","authors":"Phomolo Maphothoma, R. Kleynhans, G. Prinsloo, S. Mokgehle, Ian du Plooy, H. Araya","doi":"10.1080/02571862.2021.1925761","DOIUrl":"https://doi.org/10.1080/02571862.2021.1925761","url":null,"abstract":"African ginger (Siphonochilus aethiopicus) is in high demand for medicinal use. The plant does not multiply after being harvested, as it is destroyed in the process. The species is now facing extinction as a result of over harvesting. In order to mitigate this threat, cultivation of the species has become priority. The objective of this study was to determine the growth and yield parameters of S. aethiopicus in relation to organic fertiliser treatments. The parameters were evaluated in response to three organic fertiliser applications (0, 100 and 200 kg N ha−1) and three rhizome sizes, namely small (10–20 g), medium (20–40 g) and large (> 40 g). The combination of a fertiliser application of 100 kg N ha−1 and large rhizomes provided the best results, with maxima for rhizome yield (7 t ha−1) and root yield (6 t ha−1). Small and medium rhizomes had a significantly lower yield than large rhizomes at all nitrogen levels. The different fertiliser applications were associated with significant variation in leaf chlorophyll content. It is concluded that the application of 100 kg N ha−1 and planting of large rhizomes would result in the best yield for African ginger’s commercial production.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"338 - 342"},"PeriodicalIF":0.9,"publicationDate":"2021-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44889439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.1979112
J. Strauss, Paul Swanepoel, H. Smith, EH Smit
Conservation Agriculture (CA) is a holistic farming system aimed at the conservation of natural resources by halting soil erosion and increasing biodiversity in cropping systems, while still effecting sustainable production. Conservation agriculture is based on three principles, namely minimum soil disturbance, diversity through crop rotation and permanent organic soil cover. The system has shown remarkable growth over the last few decades worldwide, as well as in South Africa. As there are numerous benefits, CA is viewed by many as the more sustainable alternative to conventional agricultural practice. A pragmatic approach, however, should be taken to combat the challenges associated with CA. This paper provides a brief explanation of the basic principles of CA, provides a brief history of the implementation of conservation agriculture in South Africa and provides a discussion of the benefits and challenges associated with the approach. This paper also serves as an introduction to a Special Issue on conservation agriculture in South Africa.
{"title":"A history of Conservation Agriculture in South Africa","authors":"J. Strauss, Paul Swanepoel, H. Smith, EH Smit","doi":"10.1080/02571862.2021.1979112","DOIUrl":"https://doi.org/10.1080/02571862.2021.1979112","url":null,"abstract":"Conservation Agriculture (CA) is a holistic farming system aimed at the conservation of natural resources by halting soil erosion and increasing biodiversity in cropping systems, while still effecting sustainable production. Conservation agriculture is based on three principles, namely minimum soil disturbance, diversity through crop rotation and permanent organic soil cover. The system has shown remarkable growth over the last few decades worldwide, as well as in South Africa. As there are numerous benefits, CA is viewed by many as the more sustainable alternative to conventional agricultural practice. A pragmatic approach, however, should be taken to combat the challenges associated with CA. This paper provides a brief explanation of the basic principles of CA, provides a brief history of the implementation of conservation agriculture in South Africa and provides a discussion of the benefits and challenges associated with the approach. This paper also serves as an introduction to a Special Issue on conservation agriculture in South Africa.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"196 - 201"},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48850163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.2003578
A. Franke
Conservation Agriculture (CA) as a pathway towards sustainable agriculture has gained a firm foothold in South Africa over the last decade, as is evident from reported adoption rates and the interest it attracts in farmers’ organisations and media. Globally, CA practices have been widely adopted in the Americas and Australia on large farms. The drivers of adoption and impacts of CA practices on sustainability indicators have been relatively well documented for these regions. Benefits from CA relate to ease of crop management, energy, cost and time savings, and soil and water conservation (Giller et al. 2015). In Africa, research on and promotion of CA practices have mostly taken place in smallholder environments with rather mixed results in terms of adoption and impacts on soil and water conservation, though there is emerging evidence that CA benefits farmers in regions that are prone to erratic rainfall (Stevenson et al. 2014). As the agricultural landscape in South Africa is highly diverse and rather different from the rest of the continent, the research experiences and lessons learned with CA in South Africa make up an interesting case study. South Africa harbours large-scale, technologically advanced crop farms that are often located in semi-arid regions with erratic rainfall. This suggests that the adoption of CA practices in South Africa, with all its adaptations to the farmers’ unique circumstances, can nevertheless be regarded as aligned with developments in Australia and the Americas. In addition, soil conservation approaches in South Africa are applied in systems other than rainfed annual crop production, such as irrigated cropping systems, orchards and mixed crop-livestock systems, in a flexible and non-dogmatic manner. Furthermore, South Africa harbours large numbers of mediumand small-scale crop farmers who are highly limited in their access to technologies and ability to apply technologies. Thus, the implementation of CA and related practices in South Africa occurs in diverse biophysical and socio-economic environments and in different types of production systems. This special issue aims to bring together available knowledge and experiences with CA in South Africa from different systems and disciplines. A CA workshop organised in Bloemfontein in 2019 was the starting point for the development of this special issue. In this issue, Swanepoel (2021) provides an integrated discussion of the various contributions leading to the development of a research agenda around the key themes of CA in South Africa and the question of how CA approaches can contribute to sustainable intensification. This is followed by focused contributions in the fields of annual crop production, orchards and vineyards, irrigated agriculture, soil fertility management, soil surveying and weed control. I would like to thank all the authors for their contributions to this special issue, and in particular Dr Cobus Botha, who has both coordinated it and served as a gues
保护农业(CA)作为通往可持续农业的途径，在过去十年中已经在南非获得了坚实的立足点，这一点从报告的采用率和农民组织和媒体对它的兴趣中可以明显看出。在全球范围内，CA做法已在美洲和澳大利亚的大型农场广泛采用。在这些地区，采用CA做法的驱动因素和对可持续性指标的影响已经有了相对较好的记录。CA的好处包括简化作物管理，节约能源、成本和时间，以及水土保持(Giller et al. 2015)。在非洲，对CA实践的研究和推广主要是在小农环境中进行的，在采用和对水土保持的影响方面，结果好坏参半，尽管有新证据表明CA有利于降雨不稳定地区的农民(Stevenson et al. 2014)。由于南非的农业景观高度多样化，与非洲大陆其他地区大不相同，因此南非CA的研究经验和教训构成了一个有趣的案例研究。南非拥有大规模、技术先进的农作物农场，这些农场通常位于降雨不稳定的半干旱地区。这表明，尽管南非采用了针对农民独特情况的CA实践，但可以被视为与澳大利亚和美洲的发展相一致。此外，南非的土壤保持办法以灵活和非教条的方式应用于除雨养年度作物生产以外的其他系统，例如灌溉种植系统、果园和混合作物-牲畜系统。此外，南非拥有大量的中小型作物农民，他们在获得技术和应用技术的能力方面非常有限。因此，南非在不同的生物物理和社会经济环境中以及在不同类型的生产系统中实施CA和相关做法。本期特刊旨在汇集来自不同系统和学科的南非CA的现有知识和经验。2019年在布隆方丹举办的CA研讨会是本期特刊发展的起点。在本期中，Swanepoel(2021)对各种贡献进行了综合讨论，这些贡献导致了围绕南非CA关键主题的研究议程的发展，以及CA方法如何促进可持续集约化的问题。其次是在年度作物生产、果园和葡萄园、灌溉农业、土壤肥力管理、土壤调查和杂草控制等领域作出重点贡献。我要感谢所有作者为本期特刊所做的贡献，特别是Cobus Botha博士，他协调了本期特刊并担任特邀编辑。
{"title":"Introduction to the Special Issue on Conservation Agriculture in South Africa","authors":"A. Franke","doi":"10.1080/02571862.2021.2003578","DOIUrl":"https://doi.org/10.1080/02571862.2021.2003578","url":null,"abstract":"Conservation Agriculture (CA) as a pathway towards sustainable agriculture has gained a firm foothold in South Africa over the last decade, as is evident from reported adoption rates and the interest it attracts in farmers’ organisations and media. Globally, CA practices have been widely adopted in the Americas and Australia on large farms. The drivers of adoption and impacts of CA practices on sustainability indicators have been relatively well documented for these regions. Benefits from CA relate to ease of crop management, energy, cost and time savings, and soil and water conservation (Giller et al. 2015). In Africa, research on and promotion of CA practices have mostly taken place in smallholder environments with rather mixed results in terms of adoption and impacts on soil and water conservation, though there is emerging evidence that CA benefits farmers in regions that are prone to erratic rainfall (Stevenson et al. 2014). As the agricultural landscape in South Africa is highly diverse and rather different from the rest of the continent, the research experiences and lessons learned with CA in South Africa make up an interesting case study. South Africa harbours large-scale, technologically advanced crop farms that are often located in semi-arid regions with erratic rainfall. This suggests that the adoption of CA practices in South Africa, with all its adaptations to the farmers’ unique circumstances, can nevertheless be regarded as aligned with developments in Australia and the Americas. In addition, soil conservation approaches in South Africa are applied in systems other than rainfed annual crop production, such as irrigated cropping systems, orchards and mixed crop-livestock systems, in a flexible and non-dogmatic manner. Furthermore, South Africa harbours large numbers of mediumand small-scale crop farmers who are highly limited in their access to technologies and ability to apply technologies. Thus, the implementation of CA and related practices in South Africa occurs in diverse biophysical and socio-economic environments and in different types of production systems. This special issue aims to bring together available knowledge and experiences with CA in South Africa from different systems and disciplines. A CA workshop organised in Bloemfontein in 2019 was the starting point for the development of this special issue. In this issue, Swanepoel (2021) provides an integrated discussion of the various contributions leading to the development of a research agenda around the key themes of CA in South Africa and the question of how CA approaches can contribute to sustainable intensification. This is followed by focused contributions in the fields of annual crop production, orchards and vineyards, irrigated agriculture, soil fertility management, soil surveying and weed control. I would like to thank all the authors for their contributions to this special issue, and in particular Dr Cobus Botha, who has both coordinated it and served as a gues","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"iii - iii"},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43071824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.1896039
G. Nortjé, M. Laker
Conservation Agriculture (CA) is an integrated approach that consists of a suite of practices, namely no-till farming, cover crops, and crop rotation that includes at least three crops. In the global context, CA is implemented widely in South America (Argentina and Brazil) and North America (United States and Canada), with smaller proportions in Australia and New Zealand. There is little implementation of CA elsewhere in the world mainly because of natural resource constraints. Benefits of the system include increases in soil organic matter and related increases in organic N in soils. Experimental results show extremely strong stratification of important plant nutrients, particularly P, K and Ca, at very shallow soil depths (<5 cm) under a no-tillage system due to their low mobility in soil. Results to date have demonstrated poor root development near the soil surface under the extreme conditions in the marginal cropping areas that dominate most of South Africa’s crop production areas. Plant nutrient uptake is thus much lower under no-till farming than under conventional tillage. Furthermore, scarce movement of lime was found under no-tillage, hampering amelioration of soil acidity. Research in South Africa has confirmed international data that indicate maize requires much higher N application under no-tillage than under conventional tillage.
{"title":"Soil fertility trends and management in Conservation Agriculture: a South African perspective","authors":"G. Nortjé, M. Laker","doi":"10.1080/02571862.2021.1896039","DOIUrl":"https://doi.org/10.1080/02571862.2021.1896039","url":null,"abstract":"Conservation Agriculture (CA) is an integrated approach that consists of a suite of practices, namely no-till farming, cover crops, and crop rotation that includes at least three crops. In the global context, CA is implemented widely in South America (Argentina and Brazil) and North America (United States and Canada), with smaller proportions in Australia and New Zealand. There is little implementation of CA elsewhere in the world mainly because of natural resource constraints. Benefits of the system include increases in soil organic matter and related increases in organic N in soils. Experimental results show extremely strong stratification of important plant nutrients, particularly P, K and Ca, at very shallow soil depths (<5 cm) under a no-tillage system due to their low mobility in soil. Results to date have demonstrated poor root development near the soil surface under the extreme conditions in the marginal cropping areas that dominate most of South Africa’s crop production areas. Plant nutrient uptake is thus much lower under no-till farming than under conventional tillage. Furthermore, scarce movement of lime was found under no-tillage, hampering amelioration of soil acidity. Research in South Africa has confirmed international data that indicate maize requires much higher N application under no-tillage than under conventional tillage.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"247 - 257"},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2021.1896039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42278993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.1891472
J. Strauss, Paul Swanepoel, M. Laker, Hj Smith
Pressures from population growth, changing diets and climate change are driving transformation of our global food production to ensure more efficient, reliable and sustainable production. In South Africa, arable land for crop production and permanent pastures accounts for 10–12% of the total land surface. South Africa is classified as semi-arid, with the average rainfall below the global average. Accordingly, dryland agriculture must identify and promote management systems with high water-use efficiency; this is crucial in a country with a debilitating water deficit. Climate change is expected to exacerbate climate variability in South Africa, and thus exert even more pressure on rainfed dryland production. Conservation Agriculture (CA) is a holistic set of principles aimed as a guide to sustainable, reliable and climate-smart farming practices. Although initially established as a guide for grain farmers, its principles are also applicable to other agricultural commodities. The three principles of CA have been extensively promoted, with successful adoption and adaptation in many countries. This review highlights the results of research to date and the challenges for practising rainfed conservation agriculture in South Africa.
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Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.1891475
W. D. de Clercq, M. de Witt, Giel Laker
This review provides a brief overview of problems in irrigated agriculture that have become more evident as a result of climate change. In most irrigated regions in South Africa, the demand for water is exceeding the supply, as surface water resources in most catchments are already fully or over-allocated. In a regional context, water suppliers should strive to optimally manage the quantity and quality of water distributed to farmers, while providing farmers with up-to-date water quantity and quality information for planning and management purposes. Recent prolonged droughts across most of South Africa have forced water users to review the efficiency of their farming systems. At the farm-scale, efficient irrigation is required by means of effective irrigation scheduling and implementation of appropriate irrigation technologies on suitable soils. The importance of soils information and land management is often underestimated, but these are key elements to successful conservation farming. Farmers should measure irrigation volume and demand, as well as irrigation and soil water quality during irrigation. The high cost of infrastructure changes is a major barrier to farmers becoming more efficient, while a lack of storage dams and the way that water is distributed in irrigation schemes also prevent farmers from being more efficient.
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Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.1954249
P. Swanepoel
In South Africa, the term Conservation Agriculture (CA) is often used to describe any soil conservation action rather than a combination of the three management principles that CA encompasses, namely minimum soil disturbance, using a diversity of crops in rotation or association, and protecting the soil with an organic soil cover. A workshop was held with delegates from tertiary institutions, research institutions, government and private companies, in January 2019, to share and exchange CA research experiences and lessons, and to identify research gaps in the field of CA in South Africa. By collating the information from the workshop, this article aims to align CA approaches among various disciplines in South Africa and to identify the inevitable challenges with CA and (mis-)perceptions of CA in South Africa. It was clear that CA is applicable to most farming systems, but is context specific. No specific CA practice can be recommended as a panacea to solve issues experienced in all systems. Adaptation and application of CA within different South African farming systems needs to be dealt with sensibly and realistically, in ways that are based on practical rather than purely theoretical considerations. It is important that CA is not advocated without taking sustainable intensification into account. Dealing with CA sensibly requires a multidisciplinary approach.
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