Pub Date : 2022-10-20DOI: 10.1080/02571862.2022.2125094
S. Magwaza, M. van der Laan, D. Marais
Wheat (Triticum aestivum L.) production is threatened by climate change and the decline in agricultural land available due to urbanisation, farmers switching to other crops, and environmental degradation. The aim of this study was to investigate the ecological intensification (EI) of irrigated wheat production in South Africa. Data from the long-term wheat trial at the University of Pretoria and an intensive growth analysis conducted in 2019 were used to calibrate and evaluate the APSIM model. Following adequate model performance, improved management scenarios including crop rotation, manure application, optimised inorganic nitrogen (N) fertiliser application rate, objectively scheduled irrigation, and a combination of all these improved management practices together, were tested. The adoption of all management practices simultaneously was shown to be the best practice, achieving an increase of 18% in yield and reducing deep drainage and N leaching by 31%. Whereas measured data indicated a decrease in soil organic matter (SOM) from 1.20% in 1950 to 0.58% in 2019, adopting EI measures could reduce the loss of SOM to only 0.68%. Farmers are encouraged to adopt one or more of these EI management practices as their site-specific situations allow.
{"title":"Long-term experimental data and crop modelling to inform the ecological intensification of irrigated wheat production in South Africa","authors":"S. Magwaza, M. van der Laan, D. Marais","doi":"10.1080/02571862.2022.2125094","DOIUrl":"https://doi.org/10.1080/02571862.2022.2125094","url":null,"abstract":"Wheat (Triticum aestivum L.) production is threatened by climate change and the decline in agricultural land available due to urbanisation, farmers switching to other crops, and environmental degradation. The aim of this study was to investigate the ecological intensification (EI) of irrigated wheat production in South Africa. Data from the long-term wheat trial at the University of Pretoria and an intensive growth analysis conducted in 2019 were used to calibrate and evaluate the APSIM model. Following adequate model performance, improved management scenarios including crop rotation, manure application, optimised inorganic nitrogen (N) fertiliser application rate, objectively scheduled irrigation, and a combination of all these improved management practices together, were tested. The adoption of all management practices simultaneously was shown to be the best practice, achieving an increase of 18% in yield and reducing deep drainage and N leaching by 31%. Whereas measured data indicated a decrease in soil organic matter (SOM) from 1.20% in 1950 to 0.58% in 2019, adopting EI measures could reduce the loss of SOM to only 0.68%. Farmers are encouraged to adopt one or more of these EI management practices as their site-specific situations allow.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46431586","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 : 2022-10-20DOI: 10.1080/02571862.2022.2132542
H. van Zyl, C. du Preez
Soil acidity can adversely affect wheat production in the eastern Free State, South Africa. Liming of the soils is therefore essential. The aim of this study was to establish whether extractable phosphorus (P), exchangeable calcium (Ca), magnesium (Mg) and potassium (K) concentrations and cation ratios remained within recommended ranges after liming. Incubation and field studies were done on soils of wheat fields at Kestell, Fouriesburg, Prinsloo and Melrose in the eastern Free State, South Africa. Lime was applied at different rates to induce soil acidity ranges for determination of Bray 1 extractable P and ammonium acetate (NH4OAc) exchangeable Ca, Mg and K concentrations. Cation ratios (Ca:Mg, Mg:K and (Ca + Mg):K) and effective cation exchange capacity (ECEC) were also calculated. Apart from the Prinsloo soil, liming decreased extractable P concentration only in the incubation study. In the incubation and field studies exchangeable Ca and Mg concentrations increased while exchangeable K concentration remained unchanged. Despite liming of the soils, exchangeable Ca and Mg concentrations at Kestell and Fouriesburg were still less than the required thresholds. The Ca:Mg ratio decreased at both sites while the Mg:K and (Ca + Mg):K ratios increased with liming. Liming increased ECEC of all soils at all four sites. Our results show that liming does not always result in the recommended cation levels required for soil fertility.
{"title":"Impact of liming on extractable phosphorus, exchangeable base cations, and effective cation exchange capacity of eastern Free State soils","authors":"H. van Zyl, C. du Preez","doi":"10.1080/02571862.2022.2132542","DOIUrl":"https://doi.org/10.1080/02571862.2022.2132542","url":null,"abstract":"Soil acidity can adversely affect wheat production in the eastern Free State, South Africa. Liming of the soils is therefore essential. The aim of this study was to establish whether extractable phosphorus (P), exchangeable calcium (Ca), magnesium (Mg) and potassium (K) concentrations and cation ratios remained within recommended ranges after liming. Incubation and field studies were done on soils of wheat fields at Kestell, Fouriesburg, Prinsloo and Melrose in the eastern Free State, South Africa. Lime was applied at different rates to induce soil acidity ranges for determination of Bray 1 extractable P and ammonium acetate (NH4OAc) exchangeable Ca, Mg and K concentrations. Cation ratios (Ca:Mg, Mg:K and (Ca + Mg):K) and effective cation exchange capacity (ECEC) were also calculated. Apart from the Prinsloo soil, liming decreased extractable P concentration only in the incubation study. In the incubation and field studies exchangeable Ca and Mg concentrations increased while exchangeable K concentration remained unchanged. Despite liming of the soils, exchangeable Ca and Mg concentrations at Kestell and Fouriesburg were still less than the required thresholds. The Ca:Mg ratio decreased at both sites while the Mg:K and (Ca + Mg):K ratios increased with liming. Liming increased ECEC of all soils at all four sites. Our results show that liming does not always result in the recommended cation levels required for soil fertility.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44322268","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 : 2022-10-20DOI: 10.1080/02571862.2022.2121438
H. van Zyl, C. du Preez
Soil acidity hampers the sustainability of wheat production in the eastern Free State, South Africa. Specific guidelines for liming are needed by farmers and advisors to ameliorate this condition. In this study, soils from four representative wheat producing farms were used for incubation and field studies to generate data for the development of liming guidelines. The clay content of the soils ranged between 8 and 33%, with pH (KCl) values below 4.5 and percentage acid saturation (%AS) above 8. These parameters are regarded as thresholds for wheat cultivation. Liming of the topsoil (0–200 mm) at different rates increased pH (KCl) linearly and decreased %AS exponentially. Either the resulting pH (KCl) or %AS values can be used in the development of liming guidelines. Using these values, an equation was established that is suitable for the estimation of lime requirement of soil: y 8.320× 1 + 0.0459× 2 − 1.0370, R 2 = 0.86 where y is the lime requirement (tonnes ha−1), x 1 = ΔpH (KCl) and x 2 = clay content (%). This equation was also used to compile a look-up table from which the soils’ lime requirement can be derived. Farmers and advisors can improve liming strategies for wheat production by applying this information.
{"title":"Liming guidelines for soils under wheat cropping in the eastern Free State, South Africa","authors":"H. van Zyl, C. du Preez","doi":"10.1080/02571862.2022.2121438","DOIUrl":"https://doi.org/10.1080/02571862.2022.2121438","url":null,"abstract":"Soil acidity hampers the sustainability of wheat production in the eastern Free State, South Africa. Specific guidelines for liming are needed by farmers and advisors to ameliorate this condition. In this study, soils from four representative wheat producing farms were used for incubation and field studies to generate data for the development of liming guidelines. The clay content of the soils ranged between 8 and 33%, with pH (KCl) values below 4.5 and percentage acid saturation (%AS) above 8. These parameters are regarded as thresholds for wheat cultivation. Liming of the topsoil (0–200 mm) at different rates increased pH (KCl) linearly and decreased %AS exponentially. Either the resulting pH (KCl) or %AS values can be used in the development of liming guidelines. Using these values, an equation was established that is suitable for the estimation of lime requirement of soil: y 8.320× 1 + 0.0459× 2 − 1.0370, R 2 = 0.86 where y is the lime requirement (tonnes ha−1), x 1 = ΔpH (KCl) and x 2 = clay content (%). This equation was also used to compile a look-up table from which the soils’ lime requirement can be derived. Farmers and advisors can improve liming strategies for wheat production by applying this information.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48710942","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 : 2022-10-04DOI: 10.1080/02571862.2022.2107244
Jacobus FN Smith, A. Hardie
Previous research on the effect of soil liming on rooibos tea growth was limited to short-term greenhouse trials. This is the first long-term field study to investigate the effect of lime application on rooibos tea production. Micro-fine and class A calcitic lime with similar levels of purity were applied at rates of 0, 0.5, 1.0, 2.0 and 5.0 tonnes ha−1 to a depth of 15 cm on an acid (pHKCl 4.4), sandy soil in Clanwilliam, prior to planting. Soil pH and electrical conductivity (EC), rooibos mortality and yields were then measured over a period of 4 years. Foliar nutrients were determined in Year 4. Micro-fine lime resulted in significantly higher soil pH values (0.5 pH units) than class A lime. Both limes achieved maximum soil pH and EC values in Year 2, but these values declined significantly in Years 3 and 4. This is most likely due to leaching and exhaustion of the most soluble lime fractions. Although micro-fine lime had positive effects on foliar nitrogen and calcium concentrations and bush survival, liming appeared to have a negative effect on rooibos tea yields. Yields tended to decline with increasing lime application rate. Thus, it appears that under the Clanwilliam field conditions in the present study, liming is unnecessary.
{"title":"Long-term effects of micro-fine and class A calcitic lime application rates on soil acidity and rooibos tea yields under Clanwilliam field conditions","authors":"Jacobus FN Smith, A. Hardie","doi":"10.1080/02571862.2022.2107244","DOIUrl":"https://doi.org/10.1080/02571862.2022.2107244","url":null,"abstract":"Previous research on the effect of soil liming on rooibos tea growth was limited to short-term greenhouse trials. This is the first long-term field study to investigate the effect of lime application on rooibos tea production. Micro-fine and class A calcitic lime with similar levels of purity were applied at rates of 0, 0.5, 1.0, 2.0 and 5.0 tonnes ha−1 to a depth of 15 cm on an acid (pHKCl 4.4), sandy soil in Clanwilliam, prior to planting. Soil pH and electrical conductivity (EC), rooibos mortality and yields were then measured over a period of 4 years. Foliar nutrients were determined in Year 4. Micro-fine lime resulted in significantly higher soil pH values (0.5 pH units) than class A lime. Both limes achieved maximum soil pH and EC values in Year 2, but these values declined significantly in Years 3 and 4. This is most likely due to leaching and exhaustion of the most soluble lime fractions. Although micro-fine lime had positive effects on foliar nitrogen and calcium concentrations and bush survival, liming appeared to have a negative effect on rooibos tea yields. Yields tended to decline with increasing lime application rate. Thus, it appears that under the Clanwilliam field conditions in the present study, liming is unnecessary.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48795199","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 : 2022-10-04DOI: 10.1080/02571862.2022.2092659
NZ Sosibo, E. Dube, P. Muchaonyerwa, TJ Tsilo
While conservation agriculture (CA) has largely been successful in many areas, some reports suggest that certain farmers have not realised the benefits they had hoped for, especially in Africa. The benefits of CA could depend on the cropping sequences involved. This study determined the short-term effects of wheat (Triticum aestivum L.)/ maize (Zea mays L.) and wheat/ soybean (Glycine max L.) cropping sequences on fractions of soil organic carbon (SOC), inorganic phosphorus and other soil quality parameters in the 0–200 and 200–400 mm depths on CA farms. Water-soluble carbon (C) and available phosphorus (P) (NaHCO3 Pi) were significantly higher and NaOH I Pi was lower in maize/wheat than in soybean/wheat sequences. SOC, extractable P, and NaHCO3 Pi were significantly higher in the 0–200 mm than in the 200–400 mm depth. Extractable P correlated positively with particulate organic carbon (OC) fractions under both sequences. In addition, soil pH, exchangeable potassium (K), calcium (Ca), magnesium (Mg) and cation exchange capacity (CEC) were significantly higher while acid saturation and Ca:Mg was lower in maize/wheat than in soybean/wheat sequences. The findings imply that short-term cropping sequences do not affect SOC sequestration but a wheat crop preceded by maize could benefit from higher soil pH and labile C fractions making P more available, with the additional benefit of available K in these CA systems.
虽然保护性农业在许多领域基本上取得了成功，但一些报告表明，某些农民没有实现他们所希望的好处，尤其是在非洲。CA的好处可能取决于所涉及的种植顺序。本研究确定了小麦（Triticum aestivum L.）/玉米（Zea mays L.）和小麦/大豆（Glycine max L.）种植顺序对土壤有机碳（SOC）、无机磷和其他土壤质量参数在0–200和200–400范围内的短期影响 CA农场的深度为mm。玉米/小麦序列的水溶性碳（C）和有效磷（P）（NaHCO3 Pi）显著高于大豆/小麦序列，而NaOH I Pi低于大豆/小麦。SOC、可提取P和NaHCO3 Pi在0–200 mm mm深度。在两个序列下，可提取P与颗粒有机碳（OC）组分呈正相关。此外，玉米/小麦序列的土壤pH、交换性钾（K）、钙（Ca）、镁（Mg）和阳离子交换容量（CEC）显著高于大豆/小麦序列，而酸饱和度和Ca:Mg则低于大豆/小麦。研究结果表明，短期种植顺序不会影响SOC固存，但玉米之前的小麦作物可能受益于更高的土壤pH值和不稳定的C组分，使P更有效，在这些CA系统中，有效K也有额外的好处。
{"title":"Influence of cropping sequences on labile carbon and phosphorus fractions in a wheat-based conservation agriculture system","authors":"NZ Sosibo, E. Dube, P. Muchaonyerwa, TJ Tsilo","doi":"10.1080/02571862.2022.2092659","DOIUrl":"https://doi.org/10.1080/02571862.2022.2092659","url":null,"abstract":"While conservation agriculture (CA) has largely been successful in many areas, some reports suggest that certain farmers have not realised the benefits they had hoped for, especially in Africa. The benefits of CA could depend on the cropping sequences involved. This study determined the short-term effects of wheat (Triticum aestivum L.)/ maize (Zea mays L.) and wheat/ soybean (Glycine max L.) cropping sequences on fractions of soil organic carbon (SOC), inorganic phosphorus and other soil quality parameters in the 0–200 and 200–400 mm depths on CA farms. Water-soluble carbon (C) and available phosphorus (P) (NaHCO3 Pi) were significantly higher and NaOH I Pi was lower in maize/wheat than in soybean/wheat sequences. SOC, extractable P, and NaHCO3 Pi were significantly higher in the 0–200 mm than in the 200–400 mm depth. Extractable P correlated positively with particulate organic carbon (OC) fractions under both sequences. In addition, soil pH, exchangeable potassium (K), calcium (Ca), magnesium (Mg) and cation exchange capacity (CEC) were significantly higher while acid saturation and Ca:Mg was lower in maize/wheat than in soybean/wheat sequences. The findings imply that short-term cropping sequences do not affect SOC sequestration but a wheat crop preceded by maize could benefit from higher soil pH and labile C fractions making P more available, with the additional benefit of available K in these CA systems.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46016703","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 : 2022-10-04DOI: 10.1080/02571862.2022.2104945
M. Mabika, N. Mapope, CC Chinheya, E. Ngadze, E. Carstens
Pests associated with the fruit pathway are the determining factor in market access negotiations. Unconfirmed records of the occurrence and distribution of a pest in a country can lead to disputes. A report published in 1980 indicated that Monilinia fructicola is present in Zimbabwe and therefore hindering both market access and negotiations for access to new export markets for fresh stone fruit. To confirm this report, as stone fruit exports are an important foreign exchange earner for Zimbabwe, detection surveys were conducted in 2019 in the stone fruit production areas. The identities of fungal isolates were verified by using morphological and molecular characterisation. None of the fungal isolates tested positive for Monilinia species. This study confirmed that M. fructicola is not present in Zimbabwe and that stone fruit rot in Zimbabwe is not caused by Monilinia species. Therefore, the status of M. fructicola in Zimbabwe can be reported as: ‘Absent: pest records invalid’.
{"title":"Monilinia fructicola is not the causal agent of stone fruit rot in Zimbabwe","authors":"M. Mabika, N. Mapope, CC Chinheya, E. Ngadze, E. Carstens","doi":"10.1080/02571862.2022.2104945","DOIUrl":"https://doi.org/10.1080/02571862.2022.2104945","url":null,"abstract":"Pests associated with the fruit pathway are the determining factor in market access negotiations. Unconfirmed records of the occurrence and distribution of a pest in a country can lead to disputes. A report published in 1980 indicated that Monilinia fructicola is present in Zimbabwe and therefore hindering both market access and negotiations for access to new export markets for fresh stone fruit. To confirm this report, as stone fruit exports are an important foreign exchange earner for Zimbabwe, detection surveys were conducted in 2019 in the stone fruit production areas. The identities of fungal isolates were verified by using morphological and molecular characterisation. None of the fungal isolates tested positive for Monilinia species. This study confirmed that M. fructicola is not present in Zimbabwe and that stone fruit rot in Zimbabwe is not caused by Monilinia species. Therefore, the status of M. fructicola in Zimbabwe can be reported as: ‘Absent: pest records invalid’.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49665458","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 : 2022-10-04DOI: 10.1080/02571862.2022.2104946
Z. A. Belay, N. E. Nyamende, O. J. Caleb
Cold plasma technology has been used within the food industry for surface decontamination. Therefore, this study investigated the efficacy of low-pressure cold plasma (CP) treatment to decontaminate sodium alginate-coated and packaged ‘Monterey’ strawberries. Cold plasma treatment was carried out at 80 kV for 5 min. After treatments, samples were stored at 5 °C for six days, and samples were taken at regular intervals for microbial and visual quality analysis. Results obtained showed that coated strawberries without CP treatment packed in clamshell trays had a better visual appearance than the other treatments and control at the end of storage. Application of sodium alginate coating and CP treatment on strawberries resulted in ≈2 Log reduction in yeast and mould counts at the end of storage in comparison to the control (p < 0.05).
{"title":"Impact of cold plasma-mediated treatment on coated and packaged ‘Monterey’ strawberries during cold storage","authors":"Z. A. Belay, N. E. Nyamende, O. J. Caleb","doi":"10.1080/02571862.2022.2104946","DOIUrl":"https://doi.org/10.1080/02571862.2022.2104946","url":null,"abstract":"Cold plasma technology has been used within the food industry for surface decontamination. Therefore, this study investigated the efficacy of low-pressure cold plasma (CP) treatment to decontaminate sodium alginate-coated and packaged ‘Monterey’ strawberries. Cold plasma treatment was carried out at 80 kV for 5 min. After treatments, samples were stored at 5 °C for six days, and samples were taken at regular intervals for microbial and visual quality analysis. Results obtained showed that coated strawberries without CP treatment packed in clamshell trays had a better visual appearance than the other treatments and control at the end of storage. Application of sodium alginate coating and CP treatment on strawberries resulted in ≈2 Log reduction in yeast and mould counts at the end of storage in comparison to the control (p < 0.05).","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45676559","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 : 2022-10-04DOI: 10.1080/02571862.2022.2103192
S. Laurie, WM Mphela
In South Africa, the processing of sweet potatoes has a high potential for economic gain, therefore, chips were prepared from six sweet potato cultivars with varying flesh colours for consumer preference evaluation. Scoring was based on colour, crispness, taste and overall ranking by four groups of a total of 159 people at distinct locations. Instrumental assessment included colour measurement of chips, and dry mass and total carotenoid content of fresh roots. Analysis of variance, principal component analysis and Pearson correlation analysis were performed. Significant differences were found in taste/flavour, crispness and overall consumer ranking as well as for all instrumental measurements among chips made from the different cultivars. Orange-fleshed cultivars Bophelo, W-119 and Beauregard had values of 108.27, 112.37 and 113.33 µg/g for total carotenoids, respectively. The six cultivars were grouped into three clusters based on overall consumer rating, crispness, carotenoid content, colour a*, taste/flavour, oxidation and dry mass, colour L* and appearance. The results indicate that cultivars Beauregard and Bophelo can be recommended for making fried chips for South African consumers.
{"title":"Consumer acceptability of fried chips made from South African sweet potato cultivars","authors":"S. Laurie, WM Mphela","doi":"10.1080/02571862.2022.2103192","DOIUrl":"https://doi.org/10.1080/02571862.2022.2103192","url":null,"abstract":"In South Africa, the processing of sweet potatoes has a high potential for economic gain, therefore, chips were prepared from six sweet potato cultivars with varying flesh colours for consumer preference evaluation. Scoring was based on colour, crispness, taste and overall ranking by four groups of a total of 159 people at distinct locations. Instrumental assessment included colour measurement of chips, and dry mass and total carotenoid content of fresh roots. Analysis of variance, principal component analysis and Pearson correlation analysis were performed. Significant differences were found in taste/flavour, crispness and overall consumer ranking as well as for all instrumental measurements among chips made from the different cultivars. Orange-fleshed cultivars Bophelo, W-119 and Beauregard had values of 108.27, 112.37 and 113.33 µg/g for total carotenoids, respectively. The six cultivars were grouped into three clusters based on overall consumer rating, crispness, carotenoid content, colour a*, taste/flavour, oxidation and dry mass, colour L* and appearance. The results indicate that cultivars Beauregard and Bophelo can be recommended for making fried chips for South African consumers.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47939258","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 : 2022-09-30DOI: 10.1080/02571862.2022.2079741
Trevan Flynn, Liesl Wiese, Andrei Rozanov
The change from grasslands and natural shrubs to afforested arable land has a major impact on soil organic carbon (SOC) stocks. Grasslands are known to be SOC sinks as seen in the Chernozems of North America, Eurasia and South Africa. However, determining the SOC stocks of soils can be financially costly as each location must be sampled in depth increments. This study aimed to estimate the SOC stocks for the Mvoti catchment (30° 48′ E and 29° 18′ S) in Kwa-Zulu Natal, South Africa by developing depth functions on a limited number of soil samples and expanding these functions to known land-uses and soil types. The results showed that splines captured the short-term vertical distribution of SOC better than exponential decay functions, which has major implications on arable lands. Long-term forest plantations showed a positive correlation with SOC stocks (32.7 kg m−2), while annual crop cultivation (27.0 kg m−2) showed a negative correlation when compared to natural grasslands (28.8 kg m−2). The Cubist algorithm predicted the total SOC stock of the catchment area at between 12 248 and 17 624 Mg depending on the depth function used. Soils with yellow-brown subsoils tend to have higher SOC stocks and the lowest degree of uncertainty.
从草地和天然灌木到人工造林耕地的变化对土壤有机碳(SOC)储量有重要影响。在北美、欧亚大陆和南非的黑钙土中可以看到，草原是已知的碳汇。然而，确定土壤的有机碳储量在经济上是昂贵的，因为每个地点都必须以深度增量的方式采样。本研究旨在通过在有限数量的土壤样本上开发深度函数，并将这些函数扩展到已知的土地利用和土壤类型，估计南非夸祖鲁纳塔尔省Mvoti流域(东经30°48′和南纬29°18′)的有机碳储量。结果表明，样条曲线比指数衰减函数更能反映土壤有机碳的短期垂直分布，这对耕地土壤有机碳具有重要意义。长期人工林与土壤有机碳储量呈正相关(32.7 kg m−2)，而常年作物栽培与自然草地(28.8 kg m−2)呈负相关(27.0 kg m−2)。根据深度函数的不同，Cubist算法预测集水区SOC总储量在12 248 ~ 17 624 Mg之间。黄褐色底土的土壤有机碳储量较高，不确定度最低。
{"title":"Soil carbon stock assessment using depth and spatial models on afforested arable lands","authors":"Trevan Flynn, Liesl Wiese, Andrei Rozanov","doi":"10.1080/02571862.2022.2079741","DOIUrl":"https://doi.org/10.1080/02571862.2022.2079741","url":null,"abstract":"The change from grasslands and natural shrubs to afforested arable land has a major impact on soil organic carbon (SOC) stocks. Grasslands are known to be SOC sinks as seen in the Chernozems of North America, Eurasia and South Africa. However, determining the SOC stocks of soils can be financially costly as each location must be sampled in depth increments. This study aimed to estimate the SOC stocks for the Mvoti catchment (30° 48′ E and 29° 18′ S) in Kwa-Zulu Natal, South Africa by developing depth functions on a limited number of soil samples and expanding these functions to known land-uses and soil types. The results showed that splines captured the short-term vertical distribution of SOC better than exponential decay functions, which has major implications on arable lands. Long-term forest plantations showed a positive correlation with SOC stocks (32.7 kg m−2), while annual crop cultivation (27.0 kg m−2) showed a negative correlation when compared to natural grasslands (28.8 kg m−2). The Cubist algorithm predicted the total SOC stock of the catchment area at between 12 248 and 17 624 Mg depending on the depth function used. Soils with yellow-brown subsoils tend to have higher SOC stocks and the lowest degree of uncertainty.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48259820","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 : 2022-09-19DOI: 10.1080/02571862.2022.2086308
JR van der Nest, A. Hardie, J. Labuschagne, Paul Swanepoel
No-tillage systems and slow movement of surface-applied limestone can lead to stratification of soil acidity. Incorporation of lime by tilling soil is not preferred by producers following conservation agriculture practices. There is limited research on ways to facilitate lime movement without soil disturbance. This study aimed to determine the effects of form, fineness and calcium carbonate equivalent (CCE) of calcitic lime on its movement in soil with or without different soil disturbance actions and consequent effects on productivity of barley (Hordeum vulgare L.) and canola (Brassica napus L.). A field trial was established in the Western Cape province, South Africa. Ten treatments included a control, lime with different forms and fineness, and tillage practices. Due to the slow movement and reactivity of lime in soil, it was unlikely that growth responses from barley or canola would be detected within the first two years following liming. A once-off strategic tillage action promoted crop growth. This was attributed to deeper redistribution of lime in the soil (15–30 cm depth), among secondary agronomic responses to tillage. Strategic once-off tillage may address the stratification of both soil acidity and nutrients, such as calcium (Ca) and magnesium (Mg), and could be considered as an option to incorporate into management of no-tillage production systems.
{"title":"Effects of form, fineness and placement of lime with and without soil tillage on barley and canola growth and development","authors":"JR van der Nest, A. Hardie, J. Labuschagne, Paul Swanepoel","doi":"10.1080/02571862.2022.2086308","DOIUrl":"https://doi.org/10.1080/02571862.2022.2086308","url":null,"abstract":"No-tillage systems and slow movement of surface-applied limestone can lead to stratification of soil acidity. Incorporation of lime by tilling soil is not preferred by producers following conservation agriculture practices. There is limited research on ways to facilitate lime movement without soil disturbance. This study aimed to determine the effects of form, fineness and calcium carbonate equivalent (CCE) of calcitic lime on its movement in soil with or without different soil disturbance actions and consequent effects on productivity of barley (Hordeum vulgare L.) and canola (Brassica napus L.). A field trial was established in the Western Cape province, South Africa. Ten treatments included a control, lime with different forms and fineness, and tillage practices. Due to the slow movement and reactivity of lime in soil, it was unlikely that growth responses from barley or canola would be detected within the first two years following liming. A once-off strategic tillage action promoted crop growth. This was attributed to deeper redistribution of lime in the soil (15–30 cm depth), among secondary agronomic responses to tillage. Strategic once-off tillage may address the stratification of both soil acidity and nutrients, such as calcium (Ca) and magnesium (Mg), and could be considered as an option to incorporate into management of no-tillage production systems.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46138768","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}
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