The use of a starch-based superabsorbent polymer to support and optimise potato production in the sandy soils of the Sandveld production region in South Africa.

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dc.contributor.advisorSwanepoel, Pieter Andreasen_ZA
dc.contributor.advisorSteyn, Martinen_ZA
dc.contributor.advisorDenner, Freddieen_ZA
dc.contributor.authorSmit, Lomeen_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.en_ZA
dc.date.accessioned2023-03-05T18:47:39Z
dc.date.accessioned2023-05-18T07:17:17Z
dc.date.available2023-03-05T18:47:39Z
dc.date.available2023-05-18T07:17:17Z
dc.date.issued2023-03
dc.descriptionThesis (MScAgric)--Stellenbosch University, 2023. en_ZA
dc.description.abstractENGLISH ABSTRACT: Trends in agriculture are rapidly shifting towards more sustainable approaches. This is no different for the ecologically sensitive Sandveld region, where agricultural activities put pressure on the indigenous biodiversity and available resources. Potato production in the Sandveld region is highly reliant on groundwater resources for irrigation purposes, due to the low annual precipitation coupled with very high evaporative demands, especially in summer months. Additionally, potato crops are sensitive to water stress and the crop’s poorly developed rooting system is inefficient in extracting the already low plant available water in sandy soils. The aim of this study was to evaluate the potential of the biodegradable superabsorbent polymer, Zeba™, to support and improve potato production systems in semi-arid, drought prone areas. This study was approached by means of a field trial as well as a supplementary pot trial. In the field trial, four rates of Zeba™, were applied in- furrow at planting, and compared to a control. Soil water content measurements showed that the soil layers from the treatments contained more moisture than the control. Generally, increased potato tuber yield (P<0.05) was observed with increasing rates of Zeba™, except for the highest treatment rate, which had a similar yield as the control (P>0.05). The application of Zeba™ did not adversely affect the tuber quality. The increased tuber yields resulted in improved resource-use efficiencies. The water-use efficiencies, as well as nutrient-use efficiencies were either higher, or equivalent, to values reported for previous research in the area. Three application rates, similarly as three of the rates in the field trial but adjusted for a 15 cm pot, were compared to a control in a pot trial. The water holding capacity of the soil and polymer system was assessed one day, and three days after a weekly irrigation event. The trial was run over a twelve week period. The results showed that both the treatment rate and the time intervals had a significant influence on the water holding capacity of the soil. Similar to the findings of the field trial, the water holding capacity increased with an increase in product applied. The use of the superabsorbent polymer had a more pronounced effect on the water holding capacity as the soil dried out after the irrigation event, due to its superior ability to retain water compared to the large pores of sandy soils. In comparison to the control, the use of this product retained more water on the third day after irrigation than on the first day after irrigation. Although a decrease in water holding capacity was observed as the trial progressed, there was no clear indication that it was due to a reduction in the polymer's absorption ability from degradation. The decrease observed is ascribed to the increase in temperature, which led to a higher evaporation rate. Zeba™ successfully improved potato production in the Sandveld by increasing the water holding capacity of the sandy soils, leading to an increase in fresh tuber yield and improved resource use efficiencies. A treatment rate of 10 kg ha⁻¹ of Zeba™ is recommended as optimal to support and optimise potato production in the Sandveld region. This product could also be used to sustain production in other semi-arid regions and drought prone areas, with similar soil textures, when water stress limits production.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Tendense in landbou is vinnig besig om na meer volhoubare benaderings te verskuif. Vir die ekologies sensitiewe Sandveldstreek, waar landbou-aktiwiteite tans druk op die inheemse biodiversiteit en die natuurlike hulpbronne plaas, is dit geensins anders nie. Aartappelproduksie in hierdie streek is baie afhanklik van grondwaterbronne vir besproeiingsdoeleindes. Dit is as gevolg van ‘n baie lae jaarlikse reënval en hoë verdamping, veral in die somermaande. Aartappels is ook uiters sensitief vir waterstres en hul vlak wortelstelsel is oneffektief in die opname van die reeds lae beskikbare grondwater in die sandgrond. Die doel van hierdie studie was om die potensiaal van die bioafbreekbare superabsorberende polimeer, Zeba™, te evalueer en om te bepaal of dit aartappelproduksie in droë streke kan ondersteun en optimaliseer. Hierdie studie is deur middel van 'n veldproef, sowel as 'n aanvullende potproef, uitgevoer. In die veldproef is vier Zeba™ behandelings met ‘n kontrole vergelyk. Grondwaterinhoudmetings het bepaal dat die grond waar die Zeba™, toegedien is, meer water as die kontrole bevat het. In die meeste van die Zeba™ behandelings was ‘n verhoging in opbrengs waargeneem (p < 0.05), behalwe vir die hoogste toedieningspeil wat ‘n soortgelyke opbrengs (p > 0.05) as die kontrole gehad het. Die toediening van Zeba™ het ook nie die kwaliteit van die aartappelknolle negatief beïnvloed nie. Die verhoging in opbrengste het die hulpbronverbruiksdoeltreffendheid verbeter. Die waterverbruiksdoeltreffendheid, asook die doeltreffendheid van die verbruik van voedingstowwe was óf hoër, óf soortgelyk aan die bevindinge van vorige studies in die area. Drie toedieningskoerse, soortgelyk aan dié van die veldproef, maar aangepas vir ‘n 15 cm pot, is met ‘n kontrole in die potproef vergelyk. Die waterhouvermoë van die grond en polimeersisteem was een dag, sowel as drie dae na besproeiings plaasgevind het, geassesseer. Die resultate het getoon dat beide die toedieningskoers en die tydsintervalle 'n beduidende invloed (p < 0.05) op die waterhouvermoë van die sandgrond gehad het. Soortgelyk aan die bevindinge van die veldproef, het die waterhouvermoë van die sandgrond met die toediening van Zeba™ verbeter. Die superabsorberende polimeer het veral ‘n beduidende effek op die waterhouvermoë gehad namate die grond uitgedroog het. Dit is omrede die polimeer ‘n beter vermoë het om die water te hou, as die groot porieë van sandgrond. Alhoewel 'n afname in waterhouvermoë waargeneem is namate die proef gevorder het, was daar geen duidelike aanduiding dat dit as gevolg was van ‘n afname in die polimeer se absorpsievermoë, wat ontstaan het as gevolg van die afbreek van die produk nie. Die afname wat waargeneem is word toegeskryf aan die toename in temperatuur, wat gelei het tot 'n hoër verdampingstempo. Zeba™ was suksesvol in die optimalisering van aartappelproduksie in die Sandveld, deurdat dit die waterhouvermoë van die sandgrond verbeter het wat tot verhoogde opbrengste en ‘n verbetering in hulpbrongebruiksdoeltreffendheid gelei het. ‘n Toedieningspeil van 10 kg Zeba™ ha⁻¹ word voorgestel as die optimale peil om aartappelproduksie in die Sandveldstreek te ondersteun en optimaliseer. Hierdie produk kan moontlik ook gebruik word in ander droë streke waar gronde met soortgelyke teksture aangetref word en waar produksie beperk word deur waterstres.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxi, 73 pages : illustrations (some color), mapsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/127345
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectStarch-based superabsorbent polymeren_ZA
dc.subject.lcshPotatoes -- Breeding -- South Africa -- Sandveld regionen_ZA
dc.subject.lcshSuperabsorbent polymer -- Biodegradationen_ZA
dc.subject.lcshPotatoes -- Production -- South Africa -- Sandveld regionen_ZA
dc.subject.lcshPotatoes -- Effect of stress onen_ZA
dc.subject.lcshGroundwater -- Measurement -- Mathematical modelsen_ZA
dc.subject.lcshSoils, Irrigated -- South Africa -- Sandveld regionen_ZA
dc.subject.nameUCTDen_ZA
dc.titleThe use of a starch-based superabsorbent polymer to support and optimise potato production in the sandy soils of the Sandveld production region in South Africa.en_ZA
dc.typeThesisen_ZA
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