South African Journal of Plant and Soil最新文献

{"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":null,"pages":null},"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}

{"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":null,"pages":null},"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}

{"title":"Conservation Agriculture in rainfed annual crop production in South Africa","authors":"J. Strauss, Paul Swanepoel, M. Laker, Hj Smith","doi":"10.1080/02571862.2021.1891472","DOIUrl":"https://doi.org/10.1080/02571862.2021.1891472","url":null,"abstract":"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.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48057136","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}

{"title":"Challenges and opportunities for water conservation in irrigated agriculture in South Africa","authors":"W. D. de Clercq, M. de Witt, Giel Laker","doi":"10.1080/02571862.2021.1891475","DOIUrl":"https://doi.org/10.1080/02571862.2021.1891475","url":null,"abstract":"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.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2021.1891475","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45240278","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}

{"title":"Aligning Conservation Agriculture among various disciplines in South Africa","authors":"P. Swanepoel","doi":"10.1080/02571862.2021.1954249","DOIUrl":"https://doi.org/10.1080/02571862.2021.1954249","url":null,"abstract":"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.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47045680","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}

{"title":"Soil management for carbon sequestration","authors":"R. Lal","doi":"10.1080/02571862.2021.1891474","DOIUrl":"https://doi.org/10.1080/02571862.2021.1891474","url":null,"abstract":"An increase in atmospheric CO2 by ∼146% and global temperature by ∼1 °C since the year ca. 1750 has created an urgency to identify potential sinks for storage of excess CO2. The historic depletion of soil organic carbon (SOC) from agroecosystems is 135 petagrams of carbon (Pg C). Thus, soils of agroecosystems have a potential to sequester atmospheric CO2 and mitigate anthropogenic global warming. Of the total anthropogenic emissions of 11.3 Pg C in 2017, 4.1 Pg C (36.3%) was absorbed by land-based sinks. Hence, land-use and soil management systems that can create a positive soil/ecosystem carbon (C) budget have a potential to store C in soil. A positive soil C budget is created when input of biomass-C exceeds that of losses. Practices that can create a positive soil C budget in the surface layer (0–30 cm) are conservation agriculture, mulch farming, cover cropping, biochar and complex farming systems. Techniques to include SOC in the sub-soil (30–100 cm) are deep-rooted species and deep-burrowing earthworms. There exists a positive correlation between SOC concentration and aggregation, plant-available water capacity, nutrient retention, bulk density and porosity. Therefore, restoring the SOC stock of degraded soils is pertinent to advancing global food and climate security, allowing an agricultural solution to environmental issues.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2021.1891474","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42445300","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}

{"title":"Importance of detailed soil surveys for Conservation Agriculture","authors":"J. Schoeman, E. Verster, HB Booyens, M. du Plessis","doi":"10.1080/02571862.2021.1989506","DOIUrl":"https://doi.org/10.1080/02571862.2021.1989506","url":null,"abstract":"This paper explores the role that detailed soil surveys can play in Conservation Agriculture (CA). While it is widely acknowledged that CA practices have to be adapted to local conditions, it appears as if in-field physical soil and hydrological properties, the type of information gathered during detailed soil or soil-landform surveys, tend to be neglected. Aspects of soil-landform surveys relevant to CA are discussed, namely plough pan related compaction, soil surface crusting, the hydric properties of subsoils, toposequence effects on soil hydrology, in-field variation in soil texture and luvic properties and soil related features that may affect no-till planter operations. In addition soil-landform surveys can be used to plan crop rotation, crop sequencing and periodic ripping. The soil-landform map units can shed light on the suitability of existing field boundaries for CA. The point data can also be utilised to monitor changes in soil properties over time. Lastly, the suveys provide data and information that can be employed by equivalent management units elsewhere.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44457359","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}

{"title":"Weed species diversity and shifts in Conservation Agriculture-based crop rotation systems on the Highveld area of South Africa","authors":"E. Hugo, M. Craven, A. A. Nel","doi":"10.1080/02571862.2020.1813823","DOIUrl":"https://doi.org/10.1080/02571862.2020.1813823","url":null,"abstract":"The occurrence and infestation levels of weed species are known to vary greatly within Conservation Agriculture (CA) systems as weed species will react differently to different habitats. Two on-farm CA trial sites, near Buffelsvallei and Viljoenskroon respectively, were established during 2008/09. The objective of this study was to observe the species diversity and potential species shifts between conventional and CA based rotation systems. Monoculture maize (MM) under both conventional tillage (CT) and CA crop systems was accordingly evaluated against two-year and three-year rotation CA systems of maize with cowpea and sunflower respectively. Pearl millet was the third crop in the three-year rotation systems. Visual surveys of weed species were conducted annually at both trial sites and data for the 2012–2016 evaluation period presented regarding the weed spectrum observed. Weed spectrums differed significantly between the two localities, but weed species diversity remained constant across seasons. A weed species shift was recorded for the sandy loam soil where numbers of Commelina benghalensis L. increased rapidly after three years, whilst Crotalaria sphaerocarpa DC numbers more than doubled. New weed species, such as Helichrysum argyrosphaerum DC and Vernonia poskeana Vatke and Hildebr., also started to germinate at the sandy loam soil trial site.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2020.1813823","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49176616","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}

{"title":"Conservation Agriculture farming systems in rainfed annual crop production in South Africa","authors":"R. van Antwerpen, M. Laker, D. Beukes, J. Botha, A. Collett, M. du Plessis","doi":"10.1080/02571862.2020.1797195","DOIUrl":"https://doi.org/10.1080/02571862.2020.1797195","url":null,"abstract":"South Africa is, relative to the rest of the world, a water scarce country with a limited amount of arable land, especially land with a long-term sustainable agricultural production potential. Agriculture should therefore focus on the implementation of soil and water conservation systems. Soil conservation is administered in the South African legislation under the Conservation of Agricultural Resources Act 43 of 1983. The objective of this paper is to summarise Conservation Agriculture (CA) systems practiced in South Africa. These include measures to control wind and water erosion as well as soil compaction through implementation of rip on the row, vertical mulching, controlled traffic, crusting control, mulching, water harvesting and crop rotation. No-tillage is not in the scope of this paper, although aspects of reduced and minimum tillage are covered. Integrating these with existing farming systems could be complex and should be considered with great care. It is proposed that CA specialists should be trained to assist farmers in the selection, adoption and implementation of appropriate CA systems.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2020.1797195","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46512723","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}

{"title":"Soil C sequestration and CO2 fluxes under maize-based Conservation Agriculture systems in the Eastern Cape, South Africa","authors":"L. Muzangwa, P. Mnkeni, C. Chiduza","doi":"10.1080/02571862.2020.1836274","DOIUrl":"https://doi.org/10.1080/02571862.2020.1836274","url":null,"abstract":"Traditional farming methods deplete soil carbon and contribute to carbon dioxide (CO2) emissions. We investigated the effects of Conservation Agriculture principles on C sequestration and CO2 flux from two agroecological regions in the Eastern Cape province, South Africa, over five cropping seasons in the period 2012–2015. The field trials were laid in a split–split plot design. The main treatments were the tillage system, as conventional tillage or no-till. The sub-treatments were the crop rotation pattern: maize–fallow–maize (MFM); maize–fallow–soybean (MFS); maize– wheat–maize (MWM); or maize–wheat–soybean (MWS). Residue management after each crop in rotation was residue removal (R–) or residue retention (R+). The biomass and C-inputs by the crop rotations were both in the order: MWM > MWS > MFM > MFS. R+ resulted in greater levels of particulate organic matter (POM) than R–. The former was the only factor to significantly (p < 0.05) increase soil organic carbon (SOC) in the 0–5 cm depth layer at both sites after two years. CO2 flux under conventional tillage was 20% higher than with no-till. The CO2 fluxes were significantly influenced by air temperature (p < 0.001, r 2 = 0.41) and soil bulk density (p < 0.001, r 2 = 0.16). The results suggest that MWM or MWS crop rotation in conjunction with R+ under no-till offer the greatest potential for biomass and C-inputs, and consequently C sequestration, in sub-humid and semi-arid agroecological regions of South Africa.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2020.1836274","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48148493","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}