Database of African Theses and Dissertations including Research (DATAD-R)

Radiation and water utilisation efficiency by mono-culture and inter-crop to suit small-scale irrigation farming

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dc.contributor De Jager, J. M.
dc.contributor Van Rensburg, L. D.
dc.creator Mukhala, Elijah
dc.date 2018-05-30T08:54:52Z
dc.date 2018-05-30T08:54:52Z
dc.date 1998-12
dc.date.accessioned 2018-06-24T05:30:02Z
dc.date.available 2018-06-24T05:30:02Z
dc.identifier http://hdl.handle.net/11660/8353
dc.identifier.uri http://hdl.handle.net/11660/8353
dc.description English: For small-scale irrigation farming systems to be sustainable, knowledge of the nature of these systems, their marketing constraints, labour limitations, crop, soil properties, water and climate, are just some of the aspects which need to be taken into consideration. In the light of this background a research project was started to identify the problems experienced by small-scale farmers using Participatory Rural Appraisal (PRA) approach. The PRA findings were that traditional farming practices were being neglected and that an effort needs to be made towards supplementing and encouraging small-scale irrigation farming practices. Social infrastructure, credit facilities, relevant extension and information services were not sufficient. There was lack of market incentives, market information and co-ordination in production among farmers. Lack of storage and transport facilities exacerbated this situation. Some of the agronomic problems identified with the PRA approach were later investigated through field experimentation. at the experimental site of the Agrometeorology Department (University of the Orange Free State). Production systems practised by small-scale farmers should be geared for optimum use of natural resources. Inter-crop maize/beans yielded more energy and nutrient content per hectare in most cases. The number of cobs per plant decreased with increase in plant density and a similar trend was observed in the weight of maize cobs per plant. There was no significant difference in cob number and weight per plant between inter and mono-cropping systems. Seasonal changes in the photosynthetic active radiation interception for the three inter-cropping plant densities followed the pattern of canopy development. The mean radiation use efficiency for inter-crop was 0.07 - 0.17 9 MJ-1 higher than mono-crop maize which was 1.13 - 1.42 g MJ-1. Dry matter production of inter-crop beans was lower in comparison with mono-crop beans and the reduction in inter-crop beans dry matter increased as the maize plant density increased. This was attributed to a reduction in radiation availability. Comparisons of water use at the end of the growing season indicated that mean measured cumulative water use in inter-crop maize/beans and monocrop maize were in the same order. With regard to full and supplementary irrigation, it was found that full irrigation used 100 mm more water than supplementary irrigation. A comparison of the mean water use in mono-crop maize and mono-crop beans showed statistically that mono-crop maize used more water than mono-crop beans. Comparison of water use efficiencies of inter-crop maize/beans with mono-crop maize and beans, revealed that inter-crop maize/beans produced the nutrients per hectare per millimetre (mm) of water more efficiently than mono-crop maize and mono-crop beans. Comparison of water use efficiencies for full and supplementary irrigation levels showed that supplementary irrigation was more efficient. The Putu and BEWAB models were found to be suitably accurate and user friendly for the purpose of decision support for planning small-scale irrigation farming. Putu was found to simulate both mono-crop and inter-crop maize biomass reasonably accurately. With regard to soil water content, Putu approximated the measured soil water content quite accurately in the high plant densities of intercrops and mono-crops while further work needs to be done on low and medium plant densities especially during the early growth stages of the crop. BEWAB predicted the crop water use very well with accuracy better than 80% and it was concluded that the model may be used to schedule irrigation for small-scale farmers with reasonable reliability. Putu and BEWAB can now be used for decision support .
dc.description Afrikaans: Kennis oor die aard van kleinskaal besproeiingsboerderystelsels, die bemarkings- en arbeidsbeperkings daarbinne, grond- gewas en klimaatseienskappe asook waterhulpbronne is slegs 'n paar aspekte wat 'n rol speel om kleinskaal besproeiingsboerdery volhoubaar te maak. In die lig teen die agtergrond is In navorsingsprojek geloods waarin die probleme wat kleinskaal besproeiingsboere ondervind deur middel van 'n Deelnemende Landelike Evaluasie benadering (DLE) te identifiseer. Vogens die DLE-gebaseerde opname blyk dat die ontwikkeling van tradisionele boerderypraktyke totaal geignoreer en verwaarloos is en dat 'n poging aangend moet word om die boere en hul praktyke te onderskraag. Daar is verder bevind dat sosiale infrastrukture, krediet fasiliteite, toepaslike voorligting en inligtingsdienste onvoldoende is. Daar is 'n tekort aan bemarkingsaansporing, bemarkingsinligting asook 'n gebrek aan produksie koordinasie tussen boere geidentifiseer. Hierdie situasie is vererger weens 'n gebrek aan stoor- en vervoerfasiliteite. Sommige van die agronomiese probleme wat d.m.v. die DLE benadering geïdentifiseer is, is later in In veldproef op die proefterrein van Landbouweerkunde (Universiteit van die Oranje-Vrystaat) ondersoek. Produksiestelsels wat deur kleinskaal boere beoefen word, behoort gerat te wees om die natuurlike hulpbronne optimaal te benut. Vanuit die veldproewe was dit duidelik dat die mielielbone intergewasstelsel In hoër energie in voedingstofinhoud per hektaar gelewer het as waar die gewasse afsonderlik verbou is. Dit was veral van toepassing by die medium plantdigtheid (4.4 milieplante per m2 ) wat gevolglik aanbeveel word as riglynplantestand. Daar was geen betekenisvolle verskil in die getal mieliekoppe per plant asook die kopmassa per plant tussen die intergewas- en monogewasstelsel nie. Seisoenale veranderinge in die fotosintetiese aktiewe stralingsonderskepping by die drie intergewas plantdigthede, het dieselfde patroon as blaardakontwikkeling gevolg. Die gemiddelde stralingsverbruiksdoeltreffendheid van die intergewastelsel was 0.07 - 0.17 g MJ-1 hoër as die mielie monogewasstelsel wat tussen 1.13 en 1.42 g MJ-1 gewissel het. Die droëmateriaalproduksie van bone in die intergewasstelsel was deurgaans laer as bone in die monogewasstelsel. Die verskil het groter geword met 'n toename in plantdigtheid weens 'n vermindering in beskikbare straling. 'n Vergelyking van die waterverbruik tussen die mielie/bone intergewasstelsel met die mielie monbgewasstelsel, het aangedui dat dit in dieselfde orde was. Wat die vol- en aanvullende besproeiing betref is gevind dat die volbesproeiing 100 mm meer as die aanvullende besproeiing verbruik het. Die mielie monogewasstelsel het betekenisvol meer water as die bone monogewasstelsel verbruik. Vergelyking van die waterverbuiksdoeltreffendheid tussen die mielie/bone intergewas en die monogewasstelsels het aan die lig gebring dat die intergewasstelsel die voedingstowwe per hektaar per milimeter (mm) water meer doeltreffend as die mielie en bone monogewasstelsels verbruik het. Vergelyking van die waterverbruiksdoeltreffendheid tussen die vol- en aanvullende besproeiing het aangetoon dat die doeltreffendheid van die aanvullende besproeiing beter is as die volbesproeiing. Weens die akkuraatheid en verbruikersvriendelikheid van die Putu en BEWAB modelle is bevind dat die modelle aangewend kan word vir die beplanning van kleinskaal besproeiingsboerderystelsels. Daar is gevind dat Putu die biomassa akkuraat by mielies in beide 'n monogewas- en intergewasstelsel kan beraam. Wat die grondwaterinhoud betref het dit geblyk dat die Putu-model die grondwaterinhoud redelik akkuraat in die hoë plantdigtheid van die inter- en monogewasstelsel,beraam het. Verdere navorsing moet egter op die voorspelling van grondwaterinhoud in die lae en medium plantdigthede, veral in die vroeê groeistadiums van die gewas, gedoen word. Die BEWAB-model het die gewaswaterverbruik met 'n akkuraatheid van 80 % en hoër beraam. Hieruit kan afgelei word dat die model vir besproeiingsskedulering vir kleinskaal boere met redelike vertroue gebruik kan word. Putu en BEWAB kan nou gebruik word vir beplanningsdoeleindes
dc.description Foundation for Research and Development (FRD)
dc.language en
dc.publisher University of the Free State
dc.rights University of the Free State
dc.subject Irrigation farming -- South Africa -- Free State
dc.subject Intercropping -- South Africa -- Free State
dc.subject Crops and water -- South Africa -- Free State
dc.subject Thesis (Ph.D. (Agrometeorology))--University of the Free State, 1998
dc.title Radiation and water utilisation efficiency by mono-culture and inter-crop to suit small-scale irrigation farming
dc.type Thesis


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