Grondversuring en bekalking van Oos-Vrystaatse gronde onder droëlandkoring
| dc.contributor.advisor | Du Preez, C. C. | |
| dc.contributor.advisor | Kilian, W. H. | |
| dc.contributor.author | Van Zyl, Hendrik Johannnes Jakobus | |
| dc.date.accessioned | 2017-10-23T10:44:32Z | |
| dc.date.available | 2017-10-23T10:44:32Z | |
| dc.date.issued | 2003-04 | |
| dc.description.abstract | English: The value of liming of agricultural land has been demonstrated all over the world during the past century. Therefore liming as an agro-economical practice has been adopted widely by farmers with a beneficial impact on sustainable crop production for future generations. However, soil acidity is still a common yield limiting factor for a variety of crops in the Free State, Mpumalanga, KwaZulu-Natal and parts of the Western Cape. Due to above mentioned reasons incubation and field experiments were conducted over several years to quantify the following after liming of various Eastern Free State soils. Firstly, the changes in soil acidity parameters and secondly, the growth and development of wheat cultivars that differ in tolerance to aluminium (AI). Over time liming increased the pH(KCI) and decreased the percentage acid saturation (%AS) significantly in the top- (0-200mm) and subsoil (200-400mm) of all the localities. In the topsoils a good correlation was obtained between pH(KCI) and %AS. An increase in pH(KCI) of 0.1 will more or less be concomitant with a decrease of 5.5 in %AS. The amount of lime needed to raise the pH(KCI) or to lower the %AS up to a specific level, differed between the localities because of buffer capacity. Since pH(KCI) showed a better correlation with lime than %AS, it was decide to use pH(KCI) as parameter to develop a model with which the lime requirement of a soil can be calculated: Y=8.3240X1-O.0459X2-1.0370, where Y=lime requirement (ton ha"), X1=~pH(KCI and X2=clay content (%) At all localities the good AI-tolerant cultivar gave significant higher yields than the medium and poor AI-tolerant cultivars. When no lime was applied on the unlimed soils the good AI-tolerant cultivar produced economical yields, which was not the case with the medium and paar AI-tolerant cultivars. The medium and poor Al-tolerant cultivars responded therefore very well to liming with yield increases up to 90%. The good, medium and poor Al-tolerant cultivars showed a yield decrease of 15% at an %AS of 30, 10 and 8, respectively. Considering that %AS correlated better with yield than pH(KCI), liming to the required %AS of a cultivar is a possibility. Differences in AI-tolerance between cultivars resulted in that the optimum economic lime levels differ between cultivars. The optimum lime level of the cultivar with good AI-tolerance was the lowest, followed by the medium and paar AI-tolerant cultivars. Liming of acid soil has become an expensive practice for farmers, which led to the adoption of planting AI-tolerant cultivars to bridge the soil acidity problem. During this process soils has slowly started to deteriorate with an accompanying lost of yield and income per hectare. The results of this study clearly indicate the economical value of liming acid soils for wheat production. | en_ZA |
| dc.description.abstract | Afrikaans: Die waarde van bekalking op landbougronde is wêreldwyd bevestig gedurende die afgelope eeu. Daarom word bekalking as 'n agro-ekonomiese praktyk wyd deur boere aanvaar, met In voordelige impak op volhoubare gewasproduksie vir die volgende generasie. Ten spyte van bogenoemde, is grondsuurheid nog 'n algemene opbrengsbeperkende faktor vir verskeie gewasse in die Vrystaat, Mpumalanga, Kwa-Zulu Natal en gedeeltes van die Wes-Kaap. Weens bogenoemde redes is inkubasie- en veldproewe oor 'n aantal jare gedoen om die volgende te kwantifiseer na bekalking van verskeie Oos- Vrystaatse gronde: Eerstens, die verandering in grondsuurheidsparameters en tweedens, die groei en ontwikkeling van koringcultivars wat verskil in verdraagsaamheid teenoor aluminium (AI). Bekalking het oor tyd die pH(KCI) betekenisvol verhoog en die persentasie suurversadiging (%SV) betekenisvol verlaag in die bo- (0-200 mm) en ondergrond (200-400mm) van al die lokaliteite. In die bogronde is daar 'n goeie korrelasie tussen pH(KCI) en %SV gekry. 'n Styging in pH(KCI) van 0.1 sal min of meer gepaard gaan met 'n daling van 5.5 in %SV. Die hoeveelheid kalk wat nodig was om die pH(KCI) te verhoog of die %SV te verlaag tot by 'n spesifieke vlak, het egter verskil tussen die verskillende lokaliteite, as gevolg van bufferkapasiteit. Aangesien pH(KCI) beter gekorreleer het met bekalking as %SV, is pH(KCI) as parameter gebruik vir die ontwikkeling van 'n model waarmee die kalkbehoefte van 'n grond bereken kan word: Y=8.3240X1- 0.0459X2-1.0370, waar Y=kalkbehoefte (ton ha"), X1=L\pH(KCI) en X2=kleiinhoud (%). By al die lokaliteite het die goeie AI-verdraagsame cultivar betekenisvol hoër opbrengste as die medium en swak AI-verdraagsame cultivars gegee, wanneer geen kalk toegedien is nie. Op die onbekalkte gronde het die goeie AI-verdraagsame cultivar 'n ekonomiese opbrengs gegee, wat nie die geval met die medium en swak AI-verdraagsame cultivars was nie. Die medium en swak AI-verdraagsame cultivars het dus goed op bekalking gereageer met opbrengsverhogings van tot 90%. Die goeie, medium en swak AIverdraagsame cultivars het 'n opbrengsafname van 15% getoon by %SVvlakke van onderskeidelik 3D, 10 en 8. Aangesien %SV beter as pH(KCI) met opbrengs gekorreleer het, kan daar dus moontlik bekalk word tot by die vereiste %SV van 'n cultivar. Verskille in AI-verdraagsaamheid tussen cultivars bring egter mee dat die optimum ekonomiese kalkpeil tussen cultivars sal verskil. Die optimum kalkpeil van die cultivar met goeie AI-verdraagsaamheid was die laagste, gevolg deur die medium en swak AI-verdraagsame cultivars. Bekalking van suurgronde het 'n duur praktyk geword vir boere, wat gelei het tot die plant van AI-verdraagsame cultivars om die grondsuurheidsprobleem te oorbrug. Gedurende die periode het die gronde stadig agteruit gegaan, met 'n verlies aan opbrengs en inkomste per hektaar. Die resultate van die studie dui duidelik die ekonomiese waarde van bekalking vir koringproduksie aan. | af |
| dc.description.sponsorship | Omnia Kunsmis Beperk | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/7334 | |
| dc.language.iso | af | af |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Aluminium tolerance | en_ZA |
| dc.subject | Grain quality | en_ZA |
| dc.subject | Grain yield | en_ZA |
| dc.subject | Lime requirement, | en_ZA |
| dc.subject | Nutrient uptake | en_ZA |
| dc.subject | Wheat cultivars | en_ZA |
| dc.subject | Liming of soils -- South Africa -- Eastern Free State | en_ZA |
| dc.subject | Soil acidity -- South Africa -- Eastern Free State | en_ZA |
| dc.subject | Wheat -- South Africa -- Eastern Free State | en_ZA |
| dc.subject | Dissertation (M.Sc.Agric. (Soil, Crop and Climate Sciences))--University of the Free State, 2003 | en_ZA |
| dc.title | Grondversuring en bekalking van Oos-Vrystaatse gronde onder droëlandkoring | af |
| dc.type | Dissertation | en_ZA |