| Water retentivity of some South African soils in relation to particle size criteria and bulk density | Hutson, J. L. | 1986 |
KeywordsBulk density, hydrology, matric potential, particle size, water retentivity AbstractRetentivity data for 409 South African soils were obtained from several sources. Water retained at matric potential values of 0, −1, −3, −10, −30, −100, −500 and −1500 kPa was determined from the retentivity curve for each soil core. Retentivity at each matric potential value was related to clay, silt, (or clay plus silt), fine sand and bulk density using multiple regression analysis. For the combined data, R2 values ranged from 0,59 at −3 kPa to 0,86 at −1500 kPa. Using data from a single source, R2 values ranged from 0,55 at −1 kPa to 0,93 at - 50 kPa. AuthorsHutson, J. L. Year Published1986 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1986.10634212 This article contributed by:
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| Water balance simulation of a peach orchard using the SWB model | Jovanovic, N. Z. | 2003 |
KeywordsIrrigation scheduling, modelling, peach AbstractSoil Water Balance (SWB) is a user-friendly irrigation scheduling model developed to estimate water use for a wide range of crops. The FAO crop factor option within this model allows one to determine daily irrigation requirements from daily weather data as long as suitable crop parameters are available. The parameters required are the basal crop coefficient, root depth and plant height for the relevant growth stage (i.e. initial, development, mid- and late) and the length of each growth stage as well as a stress day index, the leaf water potential at maximum transpiration and the maximum transpiration rate. Data gained from trees planted in a lysimeter trial in South Africa have been used to develop these parameters for a deciduous peach tree crop (Prunus persica cv. Transvalia). These parameter values differed for first leaf and second leaf trees. The determined values gave very good estimates of water usage when applied in field trials. Evidence is presented to highlight the 2-D variation in the components of the soil water balance of a micro-irrigated hedgerow orchard and suggestions are made as to how these variations should be handled. AuthorsJovanovic, N. Z., Annandale, J. G. and du Sautoy, N. Year Published2003 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2003.10634930 This article contributed by:
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| Water and nutrient retention by Aquasoil® and Stockosorb® polymers | Ghebru, M. G. | 2007 |
KeywordsAmmonium, growth medium, nitrate, polymer, water AbstractWater retention and hydration rate of Aquasoil and Stockosorb polymers, the effects of these polymers on the water, ammonium and nitrate retention of a pine bark growth medium and the response of the polymers to fertilizer solutions were investigated. Aquasoil retained 129 g of distilled water g−1 of polymer, whereas Stockosorb retained 216 g−1 of polymer. Both polymers reached their maximum capacity in about one hour. The polymers when combined with 1 or 2 g 500 g−1 of pine bark, improved the water retention capacity of the growth medium. However, longer time was required in the growth medium for the polymers to reach maximum capacity than in the distilled water. All polymer-amended pine bark media retained more ammonium, compared to non-amended media. The 2 g polymer treatment retained greater amounts of NO3 than the lower rates. Retention of water by the Aquasoil® and Stockosorb® polymers was reduced to 88% and 86% of capacity compared to distilled water, whereas fertilizer solution reduced water retention to 53% and 42% of capacity. Soaking in distilled or tap water improved water retention of the polymers over fertilizer solutions. AuthorsGhebru, M. G., du Toit, E. S. and Steyn, J. M. Year Published2007 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2007.10634778 This article contributed by:
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| Voorspelling van nitraatbeweging in 'n fynsandleemgrond gedurende die braakperiode met die Burnsmodel | Haumann, E. J. | 1989 |
KeywordsBurns model, fallow period, fine sandy loam soil, nitrate movement Abstract'n Eenvoudige model wat deur Burns (1974) ontwikkel is vir die voorspelling van nitraatbeweging in sandtot sandleemgronde is getoets. Verskillende nitraatverspreidingspatrone is in 'n fynsandleemgrond van 1,5-m diepte tot stand gebring waarna water met mikrobesproeiing toegedien is om nitraatbeweging te induseer. 'n Redelike goeie ooreenkoms is tussen die gemete en voorspelde nitraatinhoude van nege proefpersele tot op 'n diepte van 1,2 m verkry. Alhoewel geen betekenisvolle verskille tussen die gemete en die voorspelde waardes gevind is nie, was laasgenoemde meestal effens hoër as eersgenoemde. Die model kan met redelike vertraue gebruik word om nitraatbeweging gedurende die braakperiode in 'n fynsandleemgrond te voorspel deur van maklik bekombare grondparameters gebruik te maak. AuthorsHaumann, E. J. and Du Preez, C. C. Year Published1989 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1989.10634511 This article contributed by:
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| Voorspelling van die aanpassingsvermoë van koringkultivars gebaseer op daglengte- en vernalisasiereaksie | Joubert, G. D. | 1985 |
KeywordsCold requirement, photoperiod, vernalization, wheat AbstractDie koue- en daglengtereaksies van koringkultivars in groeikaste is ondersoek as aanduiding van die produksiegebiede waar die betrokke kultivars sal aanpas. Die resultate toon dat die 24 koringkultivars wat ondersoek is, uiteenlopende koue- en daglengtereaksies vertoon. Klassifikasie van die kultivars op grond van hierdie inligting het goed ooreengestem met die nasionale kultivar-aanbevelings wat grootliks op die opbrengsprestasie In kultivarveldproewe gebaseer is. S.-Afr. Tydskr. Plant Grond 1985, 2: 120–122 AuthorsJoubert, G. D. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634150 This article contributed by:
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| Verwantskap tussen organiese materiaalinhoud van sekere onversteurde bogronde, grondeienskappe en klimaatsdata in Suid-Afrika | du Toit, M. E. | 1993 |
KeywordsAridity index, clay content, organic carbon, rainfall, temperature, total nitrogen AbstractDie doel met die ondersoek was om vas te stel of die organiese materiaalinhoud van onversteurde ortiese A-horisonte, wat deur rooi apedale, geelbruin apedale en sagte plintiese B-horisonte onderlê word, vanaf beskikbare of maklik meetbare grondeienskappe en klimaatsdata bereken kan word. Onversteurde ortiese bogronde (0–200 mm) is by 41 lokaliteite, wat verspreid in die somerreënvalgebied voorkom (25°—30°S en 24°—30E), gemonster. Die gronde se organiese koolstof- en totale stikstofinhoude, wat tiperende parameters van organiese materiaal is, is met grondeienskappe soos pH, katioonuitruilkapasiteit en deeltjiegrootte- verspreiding asook met klimaatsdata soos gemiddelde jaarlikse reenval, temperatuur en ariditeitsindeks gekorreleer. Statisties betekenisvolle verwantskappe tussen die organiese materiaalinhoud van die gronde en die fynslik-plus-klei-inhoud daarvan (organiese C: r= 0.91 en totale N: r= 0.91), die ariditeitsindeks van die lokaliteite (organiese C: r= 0.90 en totale N: r= 0.89) en die produkte van die ariditeitsindeks van die lokaliteite en die fynslik-plus-klei-inhoude van die gronde (organiese C: r = 0.94 en totale N: r= 0.95) is verkry. Uit die verwantskappe kan afgelei word dat die organiese materiaalinhoud laer is in warm, droër gebiede as in koeler, natter gebiede. In 'n gebied met dieselfde ariditeitsindeks, was die organiese materiaalinhoud direk eweredig aan die fynslik-plus-klei-inhoud. Die regréssievergelykings wat daargestel is, kan gebruik word om die organiese materiaalinhoud van sekere onversteurde ortiese bogronde in die ondersoekgebiedte raam. Authorsdu Toit, M. E. and Du Preez, C. C. Year Published1993 PublicationSouth African Journal of Plant and Soil Locations- Vryburg, South Africa (-26.3467, 24.8325)
- Vryburg, South Africa (-26.3236, 24.9231)
- Vryburg, South Africa (-26.3394, 24.8308)
- Vryburg, South Africa (-26.3033, 24.9619)
- Vryburg, South Africa (-26.3033, 24.95)
- Vryburg, South Africa (-26.3161, 24.9547)
- Virginia, South Africa (-28.2153, 24.9547)
- Viljoenskroon, South Africa (-27.245, 26.9667)
- Hennenman, South Africa (-27.8547, 26.9458)
- Hennenman, South Africa (-27.8442, 26.9667)
- Ottosdal, South Africa (-26.7767, 25.8717)
- Hennenman, South Africa (-27.8944, 26.9686)
- Tweespruit, South Africa (-29.2994, 27.0256)
- Tweespruit, South Africa (-29.3319, 27.0011)
- Tweespruit, South Africa (-29.2589, 27.0203)
- Tweespruit, South Africa (-29.2967, 27.0333)
- Tweespruit, South Africa (-29.2933, 27.0333)
- Harrismith, South Africa (-28.4333, 29.215)
- Harrismith, South Africa (-28.2458, 29.4083)
- Harrismith, South Africa (-28.4617, 29.1689)
- Harrismith, South Africa (-28.4422, 29.1636)
- Brandfort, South Africa (-28.9203, 26.1683)
- Boshof, South Africa (-28.4694, 25.3928)
- Hoopstad, South Africa (-27.8733, 25.8614)
- Wesselsbron, South Africa (-27.6306, 26.2208)
- Viljoenskroon, South Africa (-27.6306, 26.9489)
- Petrusburg, South Africa (-29.2606, 25.5147)
- Middelburg, South Africa (-25.9217, 29.5647)
- Bethal, South Africa (-26.375, 29.3333)
- Delmas, South Africa (-26.1486, 28.825)
- Morgenzon, South Africa (-26.7953, 29.6525)
- Warden, South Africa (-27.96, 29.0667)
- Warden, South Africa (-27.96, 29.0703)
- Warden, South Africa (-27.9833, 29.0881)
- Warden, South Africa (-27.9647, 29.0578)
- Bethlehem, South Africa (-28.2106, 28.2258)
- Bethlehem, South Africa (-28.125, 28.5611)
- Vryburg, Northwest (-26.95, 24.7333)
DOI10.1080/02571862.1993.10634665 This article contributed by:
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| Vergelyking van ammoniumsulfaat, kalksteenammo- niumnitraat en ureum onder besproeiingstoestande op twee gronde van die Vaalhartsbesproeiingskema | Snyman, P. J. | 1985 |
KeywordsIrrigation, leaching, N-carries, wheat AbstractOp 'n sandgrond met 9% klei in die B21-horison het ammoniumsulfaat hoër koringopbrengste gelewer as kalksteenammoniumnitraat en ureum. 'n Sandleemgrond met 20% klei in die B21-horison, het geen verskille tussen stikstofbronne getoon nie. Logingstudies in grondkolomme het aangetoon dat feitlik geen ammoniumstikstof uit laasgenoemde grond geloog word nie. Nitraatloging is aansienlik en baie hoër uit die sandgrond as uit die grond met meer klei. Omsetting van ammonium na nitraat is betreklik stadig in hierdie gronde, want 'n betekenisvolle vorming van nitraat het eers met die derde loging aan die lig gekom. Logingsverliese van stikstof was gevolglik baie kleiner in die geval van ammoniumsulfaat as vir ammoniumnitraat. S. Afr. Tydskr. Plant Grond 1985, 2: 175–178 AuthorsSnyman, P. J., Burger, R.
du T. and Laker, M. C. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634165 This article contributed by:
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| Veld compositional response to fertilization in the tall grassveld of Natal | le Roux, N. P. | 1986 |
KeywordsDetrended correspondence analysis, fertilization, grassveld, species composition AbstractThe plant species compositional response of veld at Ukulinga to application, over 30 years, of nitrogen, phosphate and lime is reported. Two types of nitrogen fertilizer were applied at four levels with and without phosphate, lime and lime + phosphate. Each treatment was replicated three times. Data on veld composition were obtained using a Levy bridge and observing 100 points per plot. The response of the veld to fertilization was examined using detrended correspondence analysis, providing simultaneously a samples and species ordination. The amount, but not the form, of nitrogen fertilizer strongly affected veld composition. Phosphate and lime had a lesser effect on veld compositon, but the presence of phosphate enhanced the effect of nitrogen on some grasses. S. Afr. J. Plant Soil 1986, 3: 1–10 Authorsle Roux, N. P. and Mentis, M. T. Year Published1986 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1986.10634177 This article contributed by:
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| Variations in floristic and palatability composition, yield of veld and of soil characteristics on a paddock scale | Barnes, D. L. | 1987 |
KeywordsGrazing capacity, line transects, spatial variation, weighted palatability composition AbstractFive parallel 900-m line-transects were laid out 100 m apart in relatively homogeneous veld. Floristic composition, yields of dry matter, soil forms and series, effective depth, clay content of the top and subsoil, and the pH of the topsoil were determined along the transects. The floristic data were subjected to multivariate classification and ordination analyses, but no meaningful discontinuities were found. Patterns of spatial variation in palatability composition, yield and in the relevant soil characteristics were established. Taking yield and palatability composition as the primary determinants of grazing capacity, it seems from the present and previous studies that spatial variations in one or both of these parameters in local veld are commonly so great that accurate determination of patterns of distribution of grazing capacity within farms is an unrealistic objective. It is suggested that in farm planning only broad assessment of grazing capacity within relatively homogeneous veld should be aimed at. Such assessments could subsequently be refined by monitoring the condition of the veld and stock, and by the use of grazing records. There was clearly no relation between soil characteristics and floristic composition, but, to a degree, it seems that clay content of the subsoil and pH of the topsoil were negatively related to yields of grass and to a limited extent, to yields of grass plus forbs. AuthorsBarnes, D. L., Kotzé, G. D., Beukes, B. H. and Kohlmeyer, C. Year Published1987 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1987.10634966 This article contributed by:
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| Variation of oil content and fatty acid composition in selected lines of vernonia (Vernonia galamensis variety ethiopica) | Labuschagne, M. T. | 2006 |
Keywordsfatty acids, oil content, Vernonia galamensis AbstractVernonia (Vernonia galamensis) is a new industrial crop that could offer a naturally epoxidized oil with great economic value. The oil content and fatty acid composition of 10 selected lines of V. galamensis variety ethiopica were analysed to study the variability among and within lines. Lines showed oil content varying from 24–29% and varying ranges of vernolic acid (7377%), linoleic acid (12–14%), oleic acid (3.5–5.5%), palmitic acid (2.4–2.9%) and stearic acid (2.3–2.8%). Entries collected from southern Ethiopia had higher oil content than those from eastern Ethiopia. Two accessions, Vge-10 with the highest contents of oil (29%) and vernolic acid (77%) and Vge-3 with the highest vernolic acid content (77%) were identified as promising parents for improving the quantity of oil and vernolic acid. AuthorsLabuschagne, M. T., Shimelis, H. A. and Hugo, A. Year Published2006 PublicationSouth African Journal of Plant and Soil Locations- Bedeno (9.1, 41.633)
- Melkabelo (9.2, 41.417)
- Harar Zuria (9.317, 42.117)
- Metta (9.417, 41.567)
- Gelemso (8.817, 40.517)
- Yirgalem (6.7, 38.35)
- Leku (6.867, 38.45)
- Awassa (6.867, 38.45)
- Areka (6.8, 37.717)
- Arsi-Negele (7.0, 38.583)
DOI10.1080/02571862.2006.10634732 This article contributed by:
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