| Phosphorus enhances aluminium tolerance in both aluminium-tolerant and aluminium-sensitive wheat seedlings | Iqbal, MT | 2013 |
KeywordsAl × P interaction, apoplast aluminium, bulk soil pH, genotypic variation, rhizosphere pH AbstractSeedlings growing in acid soils suffer both phosphorus (P) deficiency and aluminium (Al) toxicity stresses. An experiment was conducted to study the effects of Al and P interaction on Al-tolerant (ET8) and Al-sensitive (ES8) wheat genotypes in an acid soil. This study aimed to determine the interactive effect of Al and P in soil and within plant tissue. Three Al levels (0, 50 and 150 mg aluminium chloride [AlCl3] kg−1 soil) and five P levels (0, 20, 40, 80 and 160 mg P kg−1) were used in this experiment. Bulk soil pH decreased with addition of AlCl3 to the soil. Bulk soil pH increased at 160 mg P kg−1 supply at three Al levels. Phosphorus supply reduced extractable Al in the soil in all Al treatments. Seedlings suffered more from Al toxicity in the absence of P supply. Increasing P supply resulted in increased seedling biomass under high Al toxicity. This high P ameliorated Al toxicity in the soil and may enhance ES8 growth under Al toxicity. The Al × P interaction affected the root and shoot P concentration in both genotypes and P supply had no effect on P translocation to the shoot. These results suggested that differential growth behaviour between ES8 and ET8 plays an important role in tolerance to Al toxicity irrespective of high P supply. It is concluded that the higher aluminium cation (Al3+) binding capacity in the root apoplast of ET8 seedlings contributes to its improved tolerance to Al toxicity compared to ES8 seedlings. AuthorsIqbal, MT Year Published2013 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2013.770929 This article contributed by:
|
| Principles of soil classification and the future of the South African system | van Huyssteen, CW | 2013 |
Keywordssoil classification, USDA Soil Taxonomy, World Reference Base AbstractHumans classify their environment to create order, make it understandable, aid recollection and to communicate. The nature of these classifications is not always understood, because they are learnt from an early age. Building on these principles provides a sound basis for any scientific classification. This paper explores these principles, those of the USDA Soil Taxonomy, the World Reference Base for soil resources, and the South African Soil Taxonomy. Knowledge should be ultimate aim of soil classification. A hierarchical system with four levels is proposed for the South African Soil Taxonomy. This can easily be achieved by adding a higher level, proposed to be called a Soil Group, to the current three levels (form, family, and phase). The South African Soil Taxonomy must guard against too many taxa, because humans have a limited ability to comprehend numerous taxa. The distinguishing criteria between taxa should be more clearly defined, while at the same time guarding against becoming too data hungry. The classification should not shy away from intergrades. The object being classified (soils) is a natural system and intergrades will necessarily occur. It is proposed that these should be classified as intergrades, rather than trying to artificially separate natural soil bodies. Authorsvan Huyssteen, CW, Le Roux, PAL and Turner, DP Year Published2013 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2013.771752 This article contributed by:
|
| Evaluation of electrical conductivity of the fertiliser solution on growth and flowering of a Cymbidium hybrid | Naik, SK | 2013 |
KeywordsCymbidium hybrid, electrical conductivity, flowering, nutrition AbstractThe effects of three fertiliser solutions (20:20:20, 15:5:25 and 12:30:10 NPK) with electrical conductivity (EC) of 1, 1.5 or 2 mS cm−1 on growth and flowering of Cymbidium ‘Sleeping Nymph’ were investigated over three years. One-year-old tissue-cultured propagules of ‘Sleeping Nymph’ were planted singly in plastic pots in a polyhouse. Plant height, leaf length, pseudobulb length and girth, and number of pseudobulbs per clump were highest in treatment T5 (20:20:20 NPK at 1.5 mS cm−1). The EC of the fertiliser solution had a significant influence on the number of spikes per plant, number of florets per spike, spike length and rachis length. The number of florets per spike and spike length were highest with fertiliser solution with an EC of 1.0 mS cm−1. The number of spikes per plant, florets per spike, spike length and rachis length (1.75, 11.25, 46.3 cm and 22 cm, respectively) were highest in treatment T4 (12:30:10 NPK at 1 mS cm−1). Plant nutrient content was highest with fertiliser solution with an EC of 2.0 mS cm−1. An EC of 0.8–1.0 mS cm−1 for the pour-through leachate from the growing medium was optimal for highest-quality flowering of the Cymbidium hybrid. AuthorsNaik, SK, Barman, D, Rampal and Medhi, RP Year Published2013 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2013.771753 This article contributed by:
|
| Effect of an organic plant fertiliser on the establishment of rooted cuttings of two species of Cyclopia (honeybush) | Mbangcolo, MM | 2013 |
KeywordsCutting position, Cyclopia genistoides, Cyclopia intermedia, Nitrosol®, root growth, shoot growth AbstractThe effect of different application rates of an organic plant fertiliser (Nitrosol®) on the establishment and early growth of rooted cuttings of Cyclopia (Fabaceae) species was evaluated. Rooted terminal and subterminal cuttings of C. intermedia and C. genistoides were transplanted into pots (576 cm3) and treated with Nitrosol® fertiliser at application rates of 0 (control), 1.67 and 3.33 ml Nitrosol® l-1 water. To enhance the formation of nodules the cuttings were inoculated with symbiotic Rhizobium bacteria. The different species differ in their response to the fertiliser treatment, with C. genistoides showing a larger response than C. intermedia, especially at the higher application rate of 3.33 ml Nitrosol® l-1 water. This study therefore suggests that Nitrosol® fertiliser applications can be recommended to enhance the establishment of rooted cuttings of Cyclopia species, but optimum application rates may differ between species. Although a significant specie × cutting position interaction was shown with regard to plant height and number of shoots per plant, cutting position in general did not have an effect on the establisbment of the species used in this study. AuthorsMbangcolo, MM, Reinten, EY and Agenbag, GA Year Published2013 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2013.775368 This article contributed by:
|
| Comparison of medium-term organic and inorganic fertiliser application on leaf nutrient concentration and yield of maize in rural agriculture in the Mbizana area, Eastern Cape province, South Africa | Beukes, DJ | 2013 |
Keywordschicken manure, nutrient uptake, soil fertility, yield AbstractA five-year study was conducted in the Mbizana area, Eastern Cape province, to assess the seasonal and medium term effects of chicken manure and inorganic fertiliser application to an acid clay loam topsoil on nutrient element uptake and yield of maize in a field trial under dryland. Treatments consisted of a once-off application of three levels of dolomitic lime, annual application of two levels of inorganic fertiliser, and three levels of chicken manure. A no-till practice with hand planting and fertiliser application was used. Leaf and soil sampling, as well as harvesting were performed and analyses done. Chicken manure application induced similar maize leaf macro- and micro-nutrient concentrations to the recommended inorganic fertiliser (Frec) level and, in general, significantly higher values than the traditional fertiliser level (Ftrad). Augmenting chicken manure with inorganic nitrogen led to significant increases in leaf nitrogen and phosphorus levels. Grain yields under chicken manure were similar to those under Frec, but far superior to those under Ftrad. It is concluded that under acid soil conditions the improvement of soil fertility, either by organic or inorganic fertiliser application, can result in maize grain yields of about 3 Mg ha-1 under the prevailing rainfall conditions. AuthorsBeukes, DJ, Fyfield, TP, Jezile, GG and Mapumulo, TC Year Published2013 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2013.777131 This article contributed by:
|
| Soil colour variation between topsoil and subsoil horizons in a plinthic catena on the Mpumalanga Highveld, South Africa | van der Waals, JH | 2013 |
KeywordsE horizon, Munsell value, orthic A horizon, red apedal B horizon, yellow-brown apedal B horizon AbstractThe South African plinthic catena is characterised by a grading of soils from red through yellow to grey (bleached) soils down a slope. The colour sequence is ascribed to different Fe-minerals stable at increasing degrees of wetness. Soil survey data (422 points) was obtained from three soil surveys on the Mpumalanga Highveld. For each survey point, the topsoil and subsoil horizon Munsell® colour was determined. The data was compared for topsoil horizons overlying different subsoil horizons. A distinct trend was observed in that orthic A horizons overlying yellow-brown apedal B horizons exhibited a marked lighter colour (similar to E horizons) compared to the underlying B-horizon as well as orthic A horizons overlying red apedal B horizons. This implied that topsoil colour is not indicative of subsoil horizon colour – especially in soils of the Avalon, Clovelly, Glencoe and Pinedene forms. The lighter-coloured A horizons also exhibited a marked lower clay content compared to the underlying B horizon. The lighter-coloured A horizons on high chroma B horizons have major implications for the conceptual classification of the soils as well as description of hillslope hydrology and mapping of soils from aerial photographs and satellite images. Authorsvan der Waals, JH Year Published2013 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2013.777132 This article contributed by:
|
| Winter cover crops effects on soil strength, infiltration and water retention in a sandy loam Oakleaf soil in Eastern Cape, South Africa | Mupambwa, HA | 2012 |
Keywordslupin, oats, plant available water, vetch, water infiltration rate AbstractThere is substantial evidence that cover crops increase soil fertility and plant nutrition but the few studies concerning soil physical properties are conflicting. This study determined the effects of monocultures of vetch (Vicia dasycarpa L.), lupin (Lupinus angustifolius L.), oats (Avena sativa L.) and bicultures of oats and vetch and a weedy fallow on the strength and water conservation properties of a hardsetting Oakleaf soil. Oats monoculture lowered the soil strength by 48.5%, whilst vetch and lupin increased soil strength by 43% and 31%, respectively, relative to the control. Bicultures decreased soil strength as the proportion of oats increased. Oats monoculture increased cumulative water infiltration relative to the control. Bicultures increased the water final infiltration rate by 105–163% compared to the control. Plant available water increased by 24–28% compared to the weedy fallow under monocultures. However, no significant differences were observed on plant available water after two rotations with bicultures compared to the weedy fallow. We concluded that oats monoculture reduced the strength and improved water conservation properties of the hardsetting soil but vetch and lupin monoculture worsened the deleterious effects of the hardsetting phenomenon. AuthorsMupambwa, HA and Wakindiki, IIC Year Published2012 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2012.722697 This article contributed by:
|
| Carbon stocks in fynbos, pastures and vineyards on the Agulhas Plain, South Africa: a preliminary assessment | Mills, AJ | 2012 |
Keywordsaboveground biomass, agriculture, carbon sequestration, land conversion, land use, soil carbon AbstractLarge tracts of fynbos on the Agulhas Plain are being converted to agriculture. Carbon (C) stocks in fynbos, pastures and vineyards were measured in this preliminary study to determine whether conservation of fynbos results in greater C storage relative to agricultural land uses. Fynbos had greater aboveground C than pastures (12.7 ± 1.7 vs 0.8 ± 0.3 t C ha−1), greater root C than pastures and vineyards (13.0 ± 11.7, 4.9 ± 1.4 and 0.2 ± 0.2 t C ha−1, respectively), less soil organic C than pastures (1.26 ± 0.14 vs 2.06 ± 0.22%) and less total soil C than pastures (66.7 ± 7.2 vs 99.2 ± 10.9 t C ha−1). The results indicate that conversion of fynbos into pastures is unlikely to result in a net loss of C stocks because reductions in aboveground biomass, litter and root C are recovered through gains in soil C. Conversion of fynbos into vineyards is likely to result in a net loss of approximately 23 t C ha−1 in aboveground and root biomass. AuthorsMills, AJ, Birch, SC, Stephenson, JD and Bailey, RV Year Published2012 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2012.730636 This article contributed by:
|
| Winter cover crops and fertiliser effects on the weed seed bank in a low-input maize-based conservation agriculture system | Dube, E | 2012 |
Keywordsgrazing vetch, mulch effects, oat, problematic weeds AbstractThis study investigated the effects of grazing vetch (Vicia dasycarpa L.) and oat (Avena sativa L.) cover crops and fertiliser on the seed bank of some problematic weeds in a maize-based conservation agriculture system. Soil sampling for seed bank analysis was carried out at the 0–5 and 5–20 cm depths after four years of rotations. The winter cover crops reduced the seed-bank density of Digitaria sanguinalis (L.) Scop., Eleusine indica (L.) Gaertn., Amaranthus retroflexus L. and Datura stramonium L. in the 0–5 cm depth by 30–70%. Vetch was more effective on depleting the D. sanguinalis seed bank than oat. Fertiliser application reduced the A. retroflexus seed bank by 41.6% in the weedy fallow, but had no significant effect in plots grown to the cover crops. The winter cover crops did not significantly affect seed-bank weed species diversity. AuthorsDube, E, Chiduza, C, Muchaonyerwa, P, Fanadzo, M and Mthoko, TS Year Published2012 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2012.730637 This article contributed by:
|
| Effects of liming and inorganic fertiliser application on soil properties and maize growth and yield in rural agriculture in the Mbizana area, Eastern Cape province, South Africa | Beukes, DJ | 2012 |
Keywordsamelioration, infertility, maize yield, nutrient efficiency, soil acidity AbstractA five-year study was conducted to assess the seasonal and medium-term effects of liming and fertilisation of an acid clay loam topsoil on soil properties and on the growth and yield of maize under dry land. Treatments consisted of a control, a once-off application of three levels of dolomitic lime, annual application of two levels of inorganic fertiliser, and three levels of chicken manure. A no-till practice was used with hand planting and fertiliser application. Leaf and soil sampling, as well as harvesting, were performed and analyses done. Soil extractable acidity, acid saturation and leaf Mn and K were reduced significantly, whereas soil pH, soil and leaf P, Ca and Mg increased significantly with an increase in lime application. Liming had no clear effect on soil K, maize leaf N, Cu, Fe and Zn, or on maize grain yield. The higher commercial fertiliser level significantly increased soil P, K and Ca, as well as leaf N, P, K, Cu, Mn and grain yield, compared to the traditional level. These results emphasise the longevity of liming application and that low soil fertility, followed by soil acidity, are the primary factors limiting soil productivity in the study area. AuthorsBeukes, DJ, Fyfield, TP, Jezile, GG and Mapumulo, TC Year Published2012 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2012.740506 This article contributed by:
|
