Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.1891474
R. Lal
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.
{"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":"38 1","pages":"231 - 237"},"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}
Pub Date : 2021-05-27DOI: 10.1080/02571862.2021.1989506
J. Schoeman, E. Verster, HB Booyens, M. du Plessis
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.
{"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":"38 1","pages":"258 - 263"},"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}
Pub Date : 2021-05-15DOI: 10.1080/02571862.2020.1813823
E. Hugo, M. Craven, A. A. Nel
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.
{"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":"38 1","pages":"264 - 275"},"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}
Pub Date : 2021-05-15DOI: 10.1080/02571862.2020.1797195
R. van Antwerpen, M. Laker, D. Beukes, J. Botha, A. Collett, M. du Plessis
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.
{"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":"38 1","pages":"202 - 216"},"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}
Pub Date : 2021-05-15DOI: 10.1080/02571862.2020.1836274
L. Muzangwa, P. Mnkeni, C. Chiduza
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.
{"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":"38 1","pages":"276 - 283"},"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}
Pub Date : 2021-03-15DOI: 10.1080/02571862.2021.1881633
C. V. van Huyssteen, NR Rantoa, C. du Preez
Soil classification aims to group similar soils to facilitate communication and management. Management of soil organic carbon is gaining international recognition in an attempt to manage atmospheric carbon in addressing global warming. This paper explored the soil morphological and analytical data from a land type survey of South Africa, as augmented by data from other soil surveys in the country, to establish if soil classification, especially the soil form, can indicate the expected soil organic carbon content and thus enable generalisations to be drawn. Average organic carbon in the diagnostic topsoil horizons followed a predictable pattern: organic O (9.51% OC) > humic A (3.69% OC) > melanic A (2.59% OC) > vertic A (1.49% OC) > orthic A (1.38% OC). However, the organic carbon content also differed within the same diagnostic horizon between different soil forms. These differences could largely be related to the nature of the overlying topsoil, where topsoils with higher organic carbon contents typically resulted in subsoils with higher organic carbon. The results presented here can thus be used to semi-quantitatively determine the organic carbon contents of selected soil forms.
{"title":"Organic carbon content in the diagnostic horizons and materials of South African soil forms","authors":"C. V. van Huyssteen, NR Rantoa, C. du Preez","doi":"10.1080/02571862.2021.1881633","DOIUrl":"https://doi.org/10.1080/02571862.2021.1881633","url":null,"abstract":"Soil classification aims to group similar soils to facilitate communication and management. Management of soil organic carbon is gaining international recognition in an attempt to manage atmospheric carbon in addressing global warming. This paper explored the soil morphological and analytical data from a land type survey of South Africa, as augmented by data from other soil surveys in the country, to establish if soil classification, especially the soil form, can indicate the expected soil organic carbon content and thus enable generalisations to be drawn. Average organic carbon in the diagnostic topsoil horizons followed a predictable pattern: organic O (9.51% OC) > humic A (3.69% OC) > melanic A (2.59% OC) > vertic A (1.49% OC) > orthic A (1.38% OC). However, the organic carbon content also differed within the same diagnostic horizon between different soil forms. These differences could largely be related to the nature of the overlying topsoil, where topsoils with higher organic carbon contents typically resulted in subsoils with higher organic carbon. The results presented here can thus be used to semi-quantitatively determine the organic carbon contents of selected soil forms.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"140 - 151"},"PeriodicalIF":0.9,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2021.1881633","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46038224","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 : 2021-03-15DOI: 10.1080/02571862.2021.1903106
Yared Semahegn, H. Shimelis, M. Laing, I. Mathew
Drought is a major cause of reduced yields in dryland wheat production. This study aimed to determine the combining ability effects of selected bread wheat genotypes (Triticum aestivum L.) for yield and yield-related traits. Eight parental lines were selected and crossed using a half-diallel mating design. The parents and 28 crosses were evaluated at two sites in Ethiopia, representing drought-stressed and non-stressed conditions, using a 6 x 6 simple lattice design. The parental line ETW17302 was the best general combiner for the growth indices: days to heading, days to maturity, grain-filling period, and 1 000-kernel weight, thereby enabling direct selection for improved grain yield under a drought-stressed condition. Parent ETW17377 could also be used for improving grain yield under a drought-stress condition owing to its positive and significant general combining ability effect on grain yield. The families ETW17302 × ETW17377, ETW17396 × ETW17374, and ETW17396 × ETW17385 were the best specific combiners for improving grain yield under the drought-stressed condition. The selected parents and families are desirable genetic resources to enhance yield and yield-related traits under both drought-stressed and non-stressed conditions.
干旱是旱地小麦产量下降的主要原因。本研究旨在确定选定的面包小麦基因型（小麦）对产量和产量相关性状的配合力效应。选择8个亲本系，采用半双列杂交设计进行杂交。在埃塞俄比亚的两个地点对亲本和28个杂交种进行了评估，分别代表干旱胁迫和非胁迫条件，采用6 x 6的简单晶格设计。亲本系ETW17302是生长指数（抽穗天数、成熟天数、灌浆期和1000粒重）的最佳组合，从而能够在干旱胁迫条件下直接选择提高粮食产量。亲本ETW17377在干旱胁迫条件下也可用于提高粮食产量，因为其对粮食产量的总体配合力效应是积极而显著的。在干旱胁迫条件下，ETW17302×ETW17377、ETW17396×ETW1737 4和ETW17396ETW17385是提高粮食产量的最佳组合。所选择的亲本和家庭是在干旱胁迫和非胁迫条件下提高产量和产量相关性状的理想遗传资源。
{"title":"Combining ability of bread wheat genotypes for yield and yield-related traits under drought-stressed and non-stressed conditions","authors":"Yared Semahegn, H. Shimelis, M. Laing, I. Mathew","doi":"10.1080/02571862.2021.1903106","DOIUrl":"https://doi.org/10.1080/02571862.2021.1903106","url":null,"abstract":"Drought is a major cause of reduced yields in dryland wheat production. This study aimed to determine the combining ability effects of selected bread wheat genotypes (Triticum aestivum L.) for yield and yield-related traits. Eight parental lines were selected and crossed using a half-diallel mating design. The parents and 28 crosses were evaluated at two sites in Ethiopia, representing drought-stressed and non-stressed conditions, using a 6 x 6 simple lattice design. The parental line ETW17302 was the best general combiner for the growth indices: days to heading, days to maturity, grain-filling period, and 1 000-kernel weight, thereby enabling direct selection for improved grain yield under a drought-stressed condition. Parent ETW17377 could also be used for improving grain yield under a drought-stress condition owing to its positive and significant general combining ability effect on grain yield. The families ETW17302 × ETW17377, ETW17396 × ETW17374, and ETW17396 × ETW17385 were the best specific combiners for improving grain yield under the drought-stressed condition. The selected parents and families are desirable genetic resources to enhance yield and yield-related traits under both drought-stressed and non-stressed conditions.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"171 - 179"},"PeriodicalIF":0.9,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2021.1903106","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45234169","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 : 2021-03-15DOI: 10.1080/02571862.2021.1888391
V. Mathinya, J. Barnard, Z. Bello, E. van der Watt
Premiums are offered for high quality grain, but producers of malting barley are often confronted with marginal soils and water scarcity. Irrigation water quality is often low, primarily due to high salt loads. This study determined the effect of irrigation water salinity (ECi) on grain quality characteristics of malt barley evaluated in a lysimeter-based trial over two seasons. The trial involved five ECi levels (1. 5, 4. 5, 6, 9 and 12 dS m−1), and two different soil types (Bainsvlei and Clovelly). Grain yields, 1 000 seed mass (TSM, g), germination characteristics, and crude proteins (CP) were determined. Salinity levels of greater than 6 dS m−1 decreased TSM but had no significant effect on germination characteristics, while CP content of the grains significantly increased above the required range (between 9% and 11.5%) for malting. Increasing ECi reduced malt extract potential for all treatments, most noticeably at 9 and 12 ECi dS m−1. There were significant relationships between salinity and germinative characteristics as well as the malt extract proxy (germination index). The study shows that premium quality barley grain cannot be produced when salinity exceeds 6 dS m−1 and that the Clovelly soil would be a better fit for producing barley irrigated with saline water.
{"title":"Response of malt barley grain quality characteristics to increasing irrigation water salinity","authors":"V. Mathinya, J. Barnard, Z. Bello, E. van der Watt","doi":"10.1080/02571862.2021.1888391","DOIUrl":"https://doi.org/10.1080/02571862.2021.1888391","url":null,"abstract":"Premiums are offered for high quality grain, but producers of malting barley are often confronted with marginal soils and water scarcity. Irrigation water quality is often low, primarily due to high salt loads. This study determined the effect of irrigation water salinity (ECi) on grain quality characteristics of malt barley evaluated in a lysimeter-based trial over two seasons. The trial involved five ECi levels (1. 5, 4. 5, 6, 9 and 12 dS m−1), and two different soil types (Bainsvlei and Clovelly). Grain yields, 1 000 seed mass (TSM, g), germination characteristics, and crude proteins (CP) were determined. Salinity levels of greater than 6 dS m−1 decreased TSM but had no significant effect on germination characteristics, while CP content of the grains significantly increased above the required range (between 9% and 11.5%) for malting. Increasing ECi reduced malt extract potential for all treatments, most noticeably at 9 and 12 ECi dS m−1. There were significant relationships between salinity and germinative characteristics as well as the malt extract proxy (germination index). The study shows that premium quality barley grain cannot be produced when salinity exceeds 6 dS m−1 and that the Clovelly soil would be a better fit for producing barley irrigated with saline water.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"159 - 170"},"PeriodicalIF":0.9,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2021.1888391","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44637642","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 : 2021-03-15DOI: 10.1080/02571862.2021.1879285
C. Nwigwe, A. Fossey, O. de Smidt
Hybrid vigour is exploited in Eucalyptus forestry through the production of interspecific hybrids. Hybrids are deployed via cuttings that often suffer from poor rooting. Rhizospheric microorganisms have been associated with rooting enhancement, therefore knowledge of the diversity of microorganism communities, and their abundance and changes over time could be of value in commercial forestry. This knowledge could be applied when sourcing and formulating combinations of useful rhizospheric microorganisms for the treatment of Eucalyptus hybrid cutting genotypes, specifically to improve rooting in the nursery for the establishment of clonal forests. Fatty acid methyl ester (FAME) profiles were prepared for 3-month-old and 5-year-old soil samples collected from rhizospheres of Eucalyptus grandis × Eucalyptus nitens clones to characterise microbial diversity. Saturated, monounsaturated and polyunsaturated fatty acids were present in both soil age groups, although in different proportions. Proportions of saturated fatty acids in the younger samples were greater than in the older samples, while proportions of unsaturated fatty acids were fewer in the younger samples. Palmitic (C16:0) and stearic (C18:0) acids were the most prevalent. Both Shannon’s and Simpson’s indices confirmed that younger soils were more diverse. The greater proportion of polyunsaturated fatty acids in older samples, especially linoleic, α-linolenic and γ-linolenic acids, suggests increasing establishment of fungi.
{"title":"Characterisation of Eucalyptus rhizospheric communities using fatty acid methyl ester (FAME) profile analysis","authors":"C. Nwigwe, A. Fossey, O. de Smidt","doi":"10.1080/02571862.2021.1879285","DOIUrl":"https://doi.org/10.1080/02571862.2021.1879285","url":null,"abstract":"Hybrid vigour is exploited in Eucalyptus forestry through the production of interspecific hybrids. Hybrids are deployed via cuttings that often suffer from poor rooting. Rhizospheric microorganisms have been associated with rooting enhancement, therefore knowledge of the diversity of microorganism communities, and their abundance and changes over time could be of value in commercial forestry. This knowledge could be applied when sourcing and formulating combinations of useful rhizospheric microorganisms for the treatment of Eucalyptus hybrid cutting genotypes, specifically to improve rooting in the nursery for the establishment of clonal forests. Fatty acid methyl ester (FAME) profiles were prepared for 3-month-old and 5-year-old soil samples collected from rhizospheres of Eucalyptus grandis × Eucalyptus nitens clones to characterise microbial diversity. Saturated, monounsaturated and polyunsaturated fatty acids were present in both soil age groups, although in different proportions. Proportions of saturated fatty acids in the younger samples were greater than in the older samples, while proportions of unsaturated fatty acids were fewer in the younger samples. Palmitic (C16:0) and stearic (C18:0) acids were the most prevalent. Both Shannon’s and Simpson’s indices confirmed that younger soils were more diverse. The greater proportion of polyunsaturated fatty acids in older samples, especially linoleic, α-linolenic and γ-linolenic acids, suggests increasing establishment of fungi.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"116 - 125"},"PeriodicalIF":0.9,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2021.1879285","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43367974","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 : 2021-03-15DOI: 10.1080/02571862.2020.1845831
J. Chipomho, C. Parwada, J. Rugare, S. Mabasa, R. Chikowo, A. Mashingaidze
Labour bottlenecks and multiple operations at the start of a cropping season often result in inadequate early weed control and subsequent poor crop performance. Therefore, there is a need to establish management practices that provide the best opportunities for the gains associated with weeding and nutrient management across farms. We investigated the influence of soil organic carbon (SOC), fertiliser management, and weeding regimes on weed dynamics and maize productivity on smallholder farms with contrasting SOC in eastern Zimbabwe. On each site, and for two seasons, a 2 × 5 factorial experiment laid in a randomised complete block design was used. Fertiliser management was NPK or NPK + cattle manure (CM); weeding regimes were herbicide + hoe weeding, hoe weeding thrice/twice/once, or weedy check. Principal component analysis was used to evaluate weed density. The grain yield of maize increased by 13% on the sites with higher SOC. Integrating NPK + CM increased weed density and maize grain yield by 1.32 and 1.46-times, respectively, compared with NPK application only. The increased maize yield from fertiliser-managed treatments occurred only in early frequently weeded treatments. However, fertiliser application had little effect when weeding was delayed, as maize yield instead declined by 40–80%. We concluded that higher SOC increased weed density and weed biomass. Smallholder farmers are encouraged to combine herbicide application combined with hoe-weeding options for sustainable maize production.
{"title":"Influence of soil organic carbon, fertiliser management, and weeding regime on weed dynamics and maize productivity on sandy soils in eastern Zimbabwe","authors":"J. Chipomho, C. Parwada, J. Rugare, S. Mabasa, R. Chikowo, A. Mashingaidze","doi":"10.1080/02571862.2020.1845831","DOIUrl":"https://doi.org/10.1080/02571862.2020.1845831","url":null,"abstract":"Labour bottlenecks and multiple operations at the start of a cropping season often result in inadequate early weed control and subsequent poor crop performance. Therefore, there is a need to establish management practices that provide the best opportunities for the gains associated with weeding and nutrient management across farms. We investigated the influence of soil organic carbon (SOC), fertiliser management, and weeding regimes on weed dynamics and maize productivity on smallholder farms with contrasting SOC in eastern Zimbabwe. On each site, and for two seasons, a 2 × 5 factorial experiment laid in a randomised complete block design was used. Fertiliser management was NPK or NPK + cattle manure (CM); weeding regimes were herbicide + hoe weeding, hoe weeding thrice/twice/once, or weedy check. Principal component analysis was used to evaluate weed density. The grain yield of maize increased by 13% on the sites with higher SOC. Integrating NPK + CM increased weed density and maize grain yield by 1.32 and 1.46-times, respectively, compared with NPK application only. The increased maize yield from fertiliser-managed treatments occurred only in early frequently weeded treatments. However, fertiliser application had little effect when weeding was delayed, as maize yield instead declined by 40–80%. We concluded that higher SOC increased weed density and weed biomass. Smallholder farmers are encouraged to combine herbicide application combined with hoe-weeding options for sustainable maize production.","PeriodicalId":21920,"journal":{"name":"South African Journal of Plant and Soil","volume":"38 1","pages":"81 - 92"},"PeriodicalIF":0.9,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/02571862.2020.1845831","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47107858","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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