Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634998
D. Paterson, M. Laker
Opencast coal mining on the Highveld of Mpumalanga involves the disturbance of highly productive soils, which must then be rehabilitated on top of the mined spoil. Various problems in this process may occur, however, which may lead to water-logging, compaction and/or decreased soil volume. Ground penetrating radar (GPR) is a useful technique in the characterisation of the rehabilitated soil and in determining the depth contours of the spoil layer. Studies with GPR were conducted at three rehabilitated opencast coal mines. In most cases GPR was able to clearly detect the top of the spoil layer and thus identify the variations in soil depth covering the spoil. Three-dimensional imaging can be achieved by means of a grid system, thereby identifying basins which could cause waterlogging. Advantages in the use of GPR include its capacity for obtaining continuous imagery and penetration to greater depths than is possible by soil augering. Time, manpower and financial savings can be achieved, increasing the pote...
{"title":"Using Ground Penetrating Radar to investigate spoil layers in rehabilitated minesoils","authors":"D. Paterson, M. Laker","doi":"10.1080/02571862.1999.10634998","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634998","url":null,"abstract":"Opencast coal mining on the Highveld of Mpumalanga involves the disturbance of highly productive soils, which must then be rehabilitated on top of the mined spoil. Various problems in this process may occur, however, which may lead to water-logging, compaction and/or decreased soil volume. Ground penetrating radar (GPR) is a useful technique in the characterisation of the rehabilitated soil and in determining the depth contours of the spoil layer. Studies with GPR were conducted at three rehabilitated opencast coal mines. In most cases GPR was able to clearly detect the top of the spoil layer and thus identify the variations in soil depth covering the spoil. Three-dimensional imaging can be achieved by means of a grid system, thereby identifying basins which could cause waterlogging. Advantages in the use of GPR include its capacity for obtaining continuous imagery and penetration to greater depths than is possible by soil augering. Time, manpower and financial savings can be achieved, increasing the pote...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"6 1","pages":"131-134"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80296970","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 : 1999-01-01DOI: 10.1080/02571862.1999.10635001
A. J. Tarimo, F. Blarney
Two experiments were carried out to study groundnut (Arachis hypogaea L.) response to thinning time and intensity after anthesis at Redland Bay Farm, Southeast Queensland, Australia, during 1987/88 (Experiment 1) and 1989/90 (Experiment 2). Six cultivars were included in Experiment 1: Improved Virginia Bunch (IVB), NC7, Q18801 (Virginia type), TMV-2, McCubbin and Red Spanish (Spanish type); and two cultivars in Experiment 2: IVB and Red Spanish. These were thinned to 0 (control) or 50% at 42 or 91 days after planting (DAP) in Experiment 1; and 0 (control), 33, 50, 66 or 75% at 42 DAP in Experiment 2. Treatments were laid out in a randomized complete block design (RCBD) with three replications in both seasons. A 50% thinning at 42 DAP reduced intercepted photosynthetically active radiation but fadiation use efficiency, crop growth rate and total dry mass increased in all cultivars by maturity. A 50% thinning at 91 DAP significantly reduced groundnut production. Also, a thinning intensity of >66% reduced gr...
{"title":"Physiological response of groundnut (Arachis hypogaea L.) to thinning time and intensity after anthesis","authors":"A. J. Tarimo, F. Blarney","doi":"10.1080/02571862.1999.10635001","DOIUrl":"https://doi.org/10.1080/02571862.1999.10635001","url":null,"abstract":"Two experiments were carried out to study groundnut (Arachis hypogaea L.) response to thinning time and intensity after anthesis at Redland Bay Farm, Southeast Queensland, Australia, during 1987/88 (Experiment 1) and 1989/90 (Experiment 2). Six cultivars were included in Experiment 1: Improved Virginia Bunch (IVB), NC7, Q18801 (Virginia type), TMV-2, McCubbin and Red Spanish (Spanish type); and two cultivars in Experiment 2: IVB and Red Spanish. These were thinned to 0 (control) or 50% at 42 or 91 days after planting (DAP) in Experiment 1; and 0 (control), 33, 50, 66 or 75% at 42 DAP in Experiment 2. Treatments were laid out in a randomized complete block design (RCBD) with three replications in both seasons. A 50% thinning at 42 DAP reduced intercepted photosynthetically active radiation but fadiation use efficiency, crop growth rate and total dry mass increased in all cultivars by maturity. A 50% thinning at 91 DAP significantly reduced groundnut production. Also, a thinning intensity of >66% reduced gr...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"133 1","pages":"148-152"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86728665","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 : 1999-01-01DOI: 10.1080/02571862.1999.10634849
A. Nel, H. Loubser, P. Hammes
Voor die olie van sonneblomsaad (Helianthus annuus L.) uitgepers word, word dit ontdop om onder andere die kwaliteit van die oliekoek so hoog moontlik te kry. Dopbaarheid, of die gemak van ontdopping, het 'n positiewe verwantskap met saadgrootte. Aangesien saadmonsters 'n samestelling van verskillende saadgroottes is en elk moontlik 'n unieke dopperverstelling vereis, bestaan die moontlikheid dat indien elke grootteklas teen sy unieke optimale dopperspoed gedop word, die effektiwiteit van die verwerkingsproses verbeter kan word. Vier saadmonsters is in grootteklasse van 3.5 mm geskei. Die drie grootteklasse en 'n ongesifte monster is teen 'n voorafbepaalde optimale dopperspoed ontdop en elk is in 'n fyn-, kernryke en dopryke fraksie geskei en geweeg. Die persentasie dop wat verwyder is (die dopbaarheid), is bereken en die olie- en proteieninhoud van die kernryke fraksies is bepaal. Die gedopte en ongedopte monsters is vergelyk deur middel van die Student-t-toets met kontraste. Saadbron het...
{"title":"Die sif van sonneblomsaad vir die verbetering van olie- en proteienherwinning","authors":"A. Nel, H. Loubser, P. Hammes","doi":"10.1080/02571862.1999.10634849","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634849","url":null,"abstract":"Voor die olie van sonneblomsaad (Helianthus annuus L.) uitgepers word, word dit ontdop om onder andere die kwaliteit van die oliekoek so hoog moontlik te kry. Dopbaarheid, of die gemak van ontdopping, het 'n positiewe verwantskap met saadgrootte. Aangesien saadmonsters 'n samestelling van verskillende saadgroottes is en elk moontlik 'n unieke dopperverstelling vereis, bestaan die moontlikheid dat indien elke grootteklas teen sy unieke optimale dopperspoed gedop word, die effektiwiteit van die verwerkingsproses verbeter kan word. Vier saadmonsters is in grootteklasse van 3.5 mm geskei. Die drie grootteklasse en 'n ongesifte monster is teen 'n voorafbepaalde optimale dopperspoed ontdop en elk is in 'n fyn-, kernryke en dopryke fraksie geskei en geweeg. Die persentasie dop wat verwyder is (die dopbaarheid), is bereken en die olie- en proteieninhoud van die kernryke fraksies is bepaal. Die gedopte en ongedopte monsters is vergelyk deur middel van die Student-t-toets met kontraste. Saadbron het...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"11 1","pages":"69-73"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72875123","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 : 1999-01-01DOI: 10.1080/02571862.1999.10635009
J. P. Human
Runner plants of three strawberry cultivars, ‘Selekta’, ‘Tiobelle’ and ‘Tioga’, each with three crown diameter classes, were planted using one, two or three runner plants per planting hole. This was done in order to determine whether yield reductions stemming from the use of small runner plants (crown diameter 10 mm and crown diameter 5–10 mm runners of ‘Selekta’ and ‘Tiobelle’ gave similar yields. ‘Tioga’ crown diameter <10 mm runner plants yielded better than crown diameter <5 mm plants. Increasing the number of plants per hole resulted in a mean fruit size decrease of 8.9. These results indicate that the use of more than one runner plant of small crown diameter per planting hole may result in improved yields, but not economic returns with existing price structure of runner plants. Nurseries should, ther...
{"title":"Effect of number of plants per plant hole and of runner plant crown diameter on strawberry yield and fruit mass","authors":"J. P. Human","doi":"10.1080/02571862.1999.10635009","DOIUrl":"https://doi.org/10.1080/02571862.1999.10635009","url":null,"abstract":"Runner plants of three strawberry cultivars, ‘Selekta’, ‘Tiobelle’ and ‘Tioga’, each with three crown diameter classes, were planted using one, two or three runner plants per planting hole. This was done in order to determine whether yield reductions stemming from the use of small runner plants (crown diameter 10 mm and crown diameter 5–10 mm runners of ‘Selekta’ and ‘Tiobelle’ gave similar yields. ‘Tioga’ crown diameter <10 mm runner plants yielded better than crown diameter <5 mm plants. Increasing the number of plants per hole resulted in a mean fruit size decrease of 8.9. These results indicate that the use of more than one runner plant of small crown diameter per planting hole may result in improved yields, but not economic returns with existing price structure of runner plants. Nurseries should, ther...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"326 1","pages":"189-191"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75072245","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 : 1999-01-01DOI: 10.1080/02571862.1999.10634842
P. L. Campbell, D. Naudé, R. L. Kluge
Four integrated control strategies were developed for wattle that could not be removed for utilization. In the first two strategies, a combination of mechanical and/or chemical control methods either reduced the wood biomass in situ (fell, stack and burn) or retained the wood biomass above the soil surface (control of standing trees). Follow-up control involved a combination of chemical control and burning high fuel loads of sown pastures species. For the third strategy, dense infestations were contained and prevented from encroaching into neighbouring veld (grasslands). These infestations were controlled once sufficient funds became available, or converted to wood lots and shelter belts. The fourth strategy describes control of dense seedling regeneration promoted by uncontrolled fire, and the calculation of a reserve ‘fire fund’. A customized management plan was developed for a particular property that assigned these six integrated control strategies to infestations in different situations. Prioritizing...
{"title":"Development of integrated control strategies for wattle. II. Control of unwanted wattle","authors":"P. L. Campbell, D. Naudé, R. L. Kluge","doi":"10.1080/02571862.1999.10634842","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634842","url":null,"abstract":"Four integrated control strategies were developed for wattle that could not be removed for utilization. In the first two strategies, a combination of mechanical and/or chemical control methods either reduced the wood biomass in situ (fell, stack and burn) or retained the wood biomass above the soil surface (control of standing trees). Follow-up control involved a combination of chemical control and burning high fuel loads of sown pastures species. For the third strategy, dense infestations were contained and prevented from encroaching into neighbouring veld (grasslands). These infestations were controlled once sufficient funds became available, or converted to wood lots and shelter belts. The fourth strategy describes control of dense seedling regeneration promoted by uncontrolled fire, and the calculation of a reserve ‘fire fund’. A customized management plan was developed for a particular property that assigned these six integrated control strategies to infestations in different situations. Prioritizing...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"20 1","pages":"31-37"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74341245","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 : 1999-01-01DOI: 10.1080/02571862.1999.10635006
J. Pretorius, D. Nieuwoudt, D. Eksteen
By omitting N and K either separately or in combination from the rooting medium, a nutrient stress condition was created with the aim of ascertaining whether sucrose synthesis or its translocation was linked to nutrient availability (N, K) in young maize plants. Sucrose and glucose levels as well as SPS activity measured over a six-week growth period showed no significant differences in leaves between the control and both the N- and K- stressed plants. Subsequently, the two top leaves of four-week old control and stressed plants were pulselabelled with [U-14C]-glucose for 24 hours and the translocation of radioactivity to stems and roots measured. K-stressed plants translocated less than 40 of the absorbed radioactivity from the leaves to the stems and roots and also tended to translocate more sucrose to the roots while much less was off-loaded in the storage tissue of the stems. Translocation of sucrose as well as radioactivity from leaves to stems and roots in N-stressed plants paralleled that of contro...
{"title":"Sucrose synthesis and translocation in Zea mays L. during early growth, when subjected to N and K deficiency","authors":"J. Pretorius, D. Nieuwoudt, D. Eksteen","doi":"10.1080/02571862.1999.10635006","DOIUrl":"https://doi.org/10.1080/02571862.1999.10635006","url":null,"abstract":"By omitting N and K either separately or in combination from the rooting medium, a nutrient stress condition was created with the aim of ascertaining whether sucrose synthesis or its translocation was linked to nutrient availability (N, K) in young maize plants. Sucrose and glucose levels as well as SPS activity measured over a six-week growth period showed no significant differences in leaves between the control and both the N- and K- stressed plants. Subsequently, the two top leaves of four-week old control and stressed plants were pulselabelled with [U-14C]-glucose for 24 hours and the translocation of radioactivity to stems and roots measured. K-stressed plants translocated less than 40 of the absorbed radioactivity from the leaves to the stems and roots and also tended to translocate more sucrose to the roots while much less was off-loaded in the storage tissue of the stems. Translocation of sucrose as well as radioactivity from leaves to stems and roots in N-stressed plants paralleled that of contro...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"211 1","pages":"173-179"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75586466","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 : 1999-01-01DOI: 10.1080/02571862.1999.10634852
K. F. Lawrance, M. Prinsloo, W. Berry
The effect of four tillage systems on grain yield of maize, incidence of diseases and production costs was investigated for a Hutton soil in the Natal Midlands from 1982 to 1995. The four tillage systems were no-till (NT), reduced tillage (R, T and R2 T) and conventional tillage (CT). Mean grain yields were not significantly affected by tillage system. Compared with the other systems, NT negatively affected final plant densities, by about 2000 plants ha1. The incidence of ear rot caused by Stenocarpella spp. was not significantly affected by tillage systems, although NT resulted in reduced ear rot incidence in seven out of 13 years. Spraying fungicide for control of grey leaf spot (Cercospora zeae-maydis) improved yields over 100% for NT and in reduced tillage systems during a wet season, compared to 80% increase with CT. During a drier season spraying had no significant effect on grey leaf spot. In the long term, NT was economically more profitable and less risky than the CT system.
{"title":"Long and short term effects of tillage systems on grain yield, the incidence of diseases and production costs for maize","authors":"K. F. Lawrance, M. Prinsloo, W. Berry","doi":"10.1080/02571862.1999.10634852","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634852","url":null,"abstract":"The effect of four tillage systems on grain yield of maize, incidence of diseases and production costs was investigated for a Hutton soil in the Natal Midlands from 1982 to 1995. The four tillage systems were no-till (NT), reduced tillage (R, T and R2 T) and conventional tillage (CT). Mean grain yields were not significantly affected by tillage system. Compared with the other systems, NT negatively affected final plant densities, by about 2000 plants ha1. The incidence of ear rot caused by Stenocarpella spp. was not significantly affected by tillage systems, although NT resulted in reduced ear rot incidence in seven out of 13 years. Spraying fungicide for control of grey leaf spot (Cercospora zeae-maydis) improved yields over 100% for NT and in reduced tillage systems during a wet season, compared to 80% increase with CT. During a drier season spraying had no significant effect on grey leaf spot. In the long term, NT was economically more profitable and less risky than the CT system.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"46 1","pages":"85-91"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73424820","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 : 1999-01-01DOI: 10.1080/02571862.1999.10635010
A. D. Lange, M. Labuschagne
Analysis of variance, correlation analysis and principal factor analysis were applied to data for 23 sensory and physico-chemical traits measured on five cultivars of small white canning beans (Phaseolus vulgaris L.) planted at five localities in the 1995–96 season. Trait expression was strongly influenced by genotype × environment interactions, with the exception of the processed bean colour and the subjective evaluations of colour and splits. Non-significant main effects and interactions of processed colour showed that since small white beans are canned in tomato sauce in South Africa, colour analysis could be excluded from the canning quality evaluations. The principal factor analysis identified seven different factors. They were seed size, dry colour, processed colour, visual appearance, texture, water absorption and the red colour of the processed beans. Four different factors remained after exclusion of the colour of the dry and processed beans. They were seed size, water absorption, visual appearan...
{"title":"Genotype × environment interaction and principal factor analysis of seed characteristics related to canning quality of small white beans (Phaseolus vulgaris L.) in South Africa","authors":"A. D. Lange, M. Labuschagne","doi":"10.1080/02571862.1999.10635010","DOIUrl":"https://doi.org/10.1080/02571862.1999.10635010","url":null,"abstract":"Analysis of variance, correlation analysis and principal factor analysis were applied to data for 23 sensory and physico-chemical traits measured on five cultivars of small white canning beans (Phaseolus vulgaris L.) planted at five localities in the 1995–96 season. Trait expression was strongly influenced by genotype × environment interactions, with the exception of the processed bean colour and the subjective evaluations of colour and splits. Non-significant main effects and interactions of processed colour showed that since small white beans are canned in tomato sauce in South Africa, colour analysis could be excluded from the canning quality evaluations. The principal factor analysis identified seven different factors. They were seed size, dry colour, processed colour, visual appearance, texture, water absorption and the red colour of the processed beans. Four different factors remained after exclusion of the colour of the dry and processed beans. They were seed size, water absorption, visual appearan...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"9 1","pages":"192-196"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81705892","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 : 1999-01-01DOI: 10.1080/02571862.1999.10635013
H. D. Preez, A. Claassens
The changes in applied and residual phosphorus (P) were examined in Avalon and Clovelly soils under cultivation by using the P fractionation method of Hedley, Stewart and Chauhan (1982). Soil P was separated into six major fractions of which some fractions were subdivided into organic (Po) and inorganic (Pi) P forms: P extracted by an anion exchange resin (Resin-P); 0.5 M NaHCO3-P (NaHCO3-Pi and Po); 0.1 M NaOH (NaOH-l-Pi and Po); ultrasonication in 0.1 M NaOH at 75 watt (NaOH-ll-Pi and Po); 1.0 M HCI(HCI-Pi); and H2SO4 digestion and H2O2 oxidation, (H2SO4P). General trends in soil P were evident over 15 years of cultivation. Resin-P, NaHCO3-Pi, NaOH-l-Pi, NaOH-ll-Pi and HCl-Pi were reduced in the Avalon soil, while only the NaHCO3-Pi and NaOH-ll-Pi decreased in the Clovelly soil. It is hypothesised that NaOH-l-Pi, which showed the largest decrease, was mainly responsible for the replenishment of the labile P pool. In the Po fraction, NaHCO3-Po and NaOH-ll-Po decreased with time in the Avalon soil, in con...
采用Hedley, Stewart和Chauhan(1982)的P分选方法研究了Avalon和Clovelly土壤在耕作条件下的施磷和残磷变化。土壤磷分为6个主要组分，其中部分组分又分为有机磷(Po)和无机磷(Pi)形态:磷由阴离子交换树脂(resin -P)提取;0.5 M NaHCO3-P (NaHCO3-Pi和Po);0.1 M NaOH (NaOH-l- pi和Po);在0.75瓦的0.1 M NaOH (NaOH-l - pi和Po)中超声;1.0 M HCI(HCI- pi);H2SO4消解和H2O2氧化(H2SO4P)。在15年的栽培过程中，土壤磷的总体变化趋势很明显。树脂- p、NaHCO3-Pi、naoh - 1 - pi、naoh - 1 - pi和HCl-Pi在Avalon土壤中降低，而Clovelly土壤中只有NaHCO3-Pi和naoh - 1 - pi降低。假设减少幅度最大的NaOH-l-Pi主要负责补充活性磷库。在阿瓦隆土壤中，Po组分中NaHCO3-Po和naoh -l -Po随时间的增加而减少，且随时间的增加而减少。
{"title":"Changes in inorganic and organic Phosphorus in soil under maize (Zea mays) cultivation","authors":"H. D. Preez, A. Claassens","doi":"10.1080/02571862.1999.10635013","DOIUrl":"https://doi.org/10.1080/02571862.1999.10635013","url":null,"abstract":"The changes in applied and residual phosphorus (P) were examined in Avalon and Clovelly soils under cultivation by using the P fractionation method of Hedley, Stewart and Chauhan (1982). Soil P was separated into six major fractions of which some fractions were subdivided into organic (Po) and inorganic (Pi) P forms: P extracted by an anion exchange resin (Resin-P); 0.5 M NaHCO3-P (NaHCO3-Pi and Po); 0.1 M NaOH (NaOH-l-Pi and Po); ultrasonication in 0.1 M NaOH at 75 watt (NaOH-ll-Pi and Po); 1.0 M HCI(HCI-Pi); and H2SO4 digestion and H2O2 oxidation, (H2SO4P). General trends in soil P were evident over 15 years of cultivation. Resin-P, NaHCO3-Pi, NaOH-l-Pi, NaOH-ll-Pi and HCl-Pi were reduced in the Avalon soil, while only the NaHCO3-Pi and NaOH-ll-Pi decreased in the Clovelly soil. It is hypothesised that NaOH-l-Pi, which showed the largest decrease, was mainly responsible for the replenishment of the labile P pool. In the Po fraction, NaHCO3-Po and NaOH-ll-Po decreased with time in the Avalon soil, in con...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"41 1","pages":"207-213"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87719537","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 : 1999-01-01DOI: 10.1080/02571862.1999.10635008
J. Smit, B. D. Villiers, H. A. Smit
Herbicide mixtures are used to increase efficacy on broad-leaved as well as grass weeds and/or to reduce input costs. Components of mixtures may, however, induce antagonism. The aim of this study was to evaluate the efficacy of tralkoxydim (2-(1[etoxyimino)propyl]-3-hydroxy-5-(2,4,6-trimethylphenyl) cyclohex-2-enome) in combination with chlorsulfuron (2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazine2yl)amino]carbonyl]benzenes ulfonamide and tribenuron 2-[[[[(4-methoxy-6-methyl-1,3,5-triazine-2-yl)methylamino] carbonyl] amino]sulfonyl]benzoic acid on oats (Avena sativa L.) when applied as a tank mixture at different rates in a glasshouse. Significant differences were found between treatments, which indicated that antagonism occurs with the application of the above mentioned herbicides when applied as a tank mixture. Tralkoxydim at the registered rate (218 g a.i. ha-1) gave very good control on oats, which were not affected when chlorsulfuron (13.3 gai. ha-1) was added. Tribenuron on the other hand surely an...
混合除草剂用于提高对阔叶杂草和禾草杂草的防治效果和/或降低投入成本。然而，混合物的成分可能引起拮抗作用。本研究的目的是评价三烷基氧基(2-(1[乙氧基亚氨基)丙基]-3-羟基-5-(2,4,6-三甲基苯基)环己基-2-基因组)与氯磺隆(2-氯- n -[[(4-甲氧基-6-甲基-1,3,5-三嗪基)氨基]羰基]苯磺基]苯磺酰胺和三苯脲2-[[[[(4-甲氧基-6-甲基-1,3,5-三嗪基-2-基)甲氨基]羰基]氨基]磺基]苯甲酸在温室中以不同速率混合施用时对燕麦(Avena sativa L.)的效果。处理间差异显著，表明上述除草剂作为罐式混合物施用时发生拮抗作用。登记剂量(218 g a.i. ha-1)下的三甲氧苄啶对燕麦有很好的控制作用，氯磺隆(13.3 gai)对燕麦没有影响。添加了Ha-1。另一方面，三苯脲肯定会…
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