The purpose of this thesis is to design a computer model which compares three sprinkler irrigation systems---portable pipe with volume gun, traveller with volume gun and towable/non-towable centre pivot---for potato production. The model user is required to enter a set of basic data: crop and field conditions, irrigation technical parameters and basic economic data, following which the model establishes the preliminary irrigation system and a comparative investment analysis. The model was applied and tested on a potato farm situated in Notre-Dame-de-la-Paix (southwestern Quebec). Based on a 14-year climatic analysis, supplemental irrigation for a normal rainfall growing period (368 mm) was estimated at 250 mm. The application of the model indicates that for a normal rainfall period with an assumed yield increase of 25% over non-irrigated production, all three systems provide net profits (increases of 11% to 50%). However, when determining the Internal Rate of Return (IRR) on a 10-year period, the maximum rate attained by the more profitable systems---portable pipe and non-towable centre pivot (both with an electric pump)---was 14%, a rate inferior to the IRR for non-irrigated production (17%). The Net Present Value (NPV) analysis for the two most profitable irrigation systems provided a slightly higher NPV value for irrigated than for non-irrigated production ($10,942---irrigated vs $10,522---non-irrigated production). The payback period for those two irrigation systems was 7 years. Greater gains of irrigated over non-irrigated yields would be expected for a dry period because of low and unpredictable yields in non-irrigated conditions. A farmer planning to invest in an irrigation system must carefully investigate all technical and socio-economic aspects. The model presented gives the farmer a useful tool with which to do this.

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Graduation date: 1992

Graduation date: 1995

Thesis (MBA)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: This study evaluates the use of information technology as a method to reduce production risk for irrigated potatoes. Risk in agriculture is discussed under climatic, market or price and production related risk. Production related risk covers the disciplines of planting, irrigation, fertilisation, disease and pest control as well as harvesting. It is in the above mentioned disciplines that information technology could possible be applied to reduce production risk in irrigated potatoes. The nature of this study can therefor be described as the investigation of the economic justification of information technology as a method to reduce production risk in irrigated potatoes. A brief introduction to put potato production in world and South African context into perspective, is provided. In South African context the importance and position of potato production relative to other crops is discussed. To better understand the economic conditions, under which potatoes are produced in South Africa, a financial breakdown of production cost for irrigated potatoes over regions is given. It is important to understand the economics of potato production before a proper assessment of thepossible benefits of information technology can be made. Various principles and instruments involved with information technology, as it applies to potato production under irrigation are also discussed. Irrigation scheduling as a discipline in which information technology can be applied, is also discussed. It is important to understand that irrigation scheduling can be based on two underlying principles, i.e. atmospheric modelling and soil moisture measurement. Various examples of measurement instruments are discussed. Climatic based disease modelling and petiole sampling as a method to determine nutritional status in the potato plant, was also discussed. A brief discussion of computerised agriculture management software was included to conclude the discussion on the principles and instruments available for information technology in irrigated potato production. The use of fertiliser scheduling, irrigation scheduling and climatic modelling to reduce fungal diseases in potatoes, as information technology methods, are explained in greater detail. It is shown that recommended levels for various nutrients do exist and that petiole analysis as a method to determine these levels at various growth stages, can be applied successfully. It is further argued that with various methods of irrigation scheduling, proper decision making about the amount and timing of irrigation needed, can be possible. The Plant-Plus system as a method to better control Late Blight on potatoes, is discussed. The results obtained through a commercial trial proves the validity of climatic modelling as a method of information technology to reduce production risk on potatoes, specifically the risk associated with Late Blight. The existence of and results obtained through the equipment and methods previuosly mentioned, raises the question of the economic viability of information technology at farm level. To investigate the perception of growers with regard to the applicability of information technology to reduce production risk and their readiness to adopt such . -- technology, a questionnaire was sent to 40 commercial potato growers throughout South Africa. Growers were tested on their perception with regard to the use of information technology on aspects such as financial management, irrigation scheduling, fertilisation, climatic measurement for fungal modelling as well as a profile analysis of the grower. The results of the survey are tabulated and analysed. Growers were on average positive about the value of information technology and indicated that under certain conditions, they were prepared to implement such technology. Margins in commercial potato production are under severe pressure and are in fact shrinking. Case studies presented in this investigation and results from the pilot survey indicate that the use of information technology is not only important for the reduction of risk in potato production but also imperative for sustainable and profitable potato production. It can therefore be concluded that, based on the results obtained in the pilot questionnaire, a statistical valid sample would probably support the findings in the pilot study. The pilot study indicated that reliable, affordable and practical information technology, as it has been presented in this investigation, does have a place in modern day irrigated potato production. / AFRIKAANSE OPSOMMING: Hierdie studie evalueer die gebruik van informasie tegnologie as 'n metode om produksie risiko in die verbouing van aartappels onder besproeiing, te verminder. Risiko in landbou word onder klimatologiese, mark of prys en produksie verwante risiko bespreek. Produksie verwante risiko kan weer onderverdeel word in risiko wat verband hou met plant of vestiging, besproeiing, bemesting, plaag en pes beheer asook oes. Dit is dan in die bogenoemde dissiplines waar informasie tegnologie moontlik aangewend kan word om produksie verwante risiko te verminder. Die kern van hierdie ondersoek kan gevolglik saamgevat word as 'n ondersoek na die ekonomiese regverdigbaarheid van informasie tegnologie as 'n metode om produksierisiko in die verbouing van aartappels onder besproeiing, te verminder. Daar word kortliks verwys na aartappel verbouing in wêreld en Suid Afrikaanse konteks. In Suid Afrikaanse konteks is die relatiewe belangrikheid van aartappelverbouing in vergelyking met ander gewasse uitgelig. Ten einde 'n beter begrip vir die ekonomiese omstandighede waaronder aartappels in Suid Afrika verbou word, word 'n afbraak van produksiekoste oor streke verskaf Dit is belangrik om die ekonomie van aartappelproduksie te verstaan voordat 'n deeglike evaluering van die moontlike voordele wat informasie tegnologie kan inhou, onderneem kan word. Verskeie beginsels en instrumente in die aanwending van informasie tegnologie, soos van toepassing in die verbouing van aartappels onder besproeiing, word ook toegelig. Hieronder word besproeiingskedulering as 'n metode bespreek. Dit is verder belangrik om te besef dat besproeiingskedulering op hoofsaaklik twee beginsels berus naamlik atmosferiese modellering en fisiese grondvog meting. Verskeie voorbeelde van meetinstrumente word bespreek. Klimatologiese siektemodellering en petioolontledings as 'n metode om die voedingstatus van aartappelplante te bepaal, word ook bespreek. Die gebruik van bemestingskedulering, besproeiingskedulering en klimatologiese modellering vir die beheer van laatroes op aartappels, as metodes van informasie tegnologie, word in groter besonderhede toegelig. Daar is aangetoon dat aanbevole peile vir verskeie nutriënte bestaan. Deur die neem van gereelde petiool ontledings kan hierdie peile suksesvol gedurende die opeenvolgende fenologiese stadia van die aartappelplant, gehandhaaf word. Daar is verder aangevoer dat deur die gebruik van verskeie metodes van besproeiingskedulering, deeglike besluitneming rakende die hoeveelheid en tydsberekening van 'n besproeiing, moontlik is. Die Plant-Plus sisteem as 'n metode om laatroes op aartappels te beheer, is toegelig. Resultate behaal in 'n kommersiële aanplanting het die geldigheid van klimatologiese modellering as 'n metode om produksierisiko - veral die risiko geassosieer met laatroes - te verminder, onderskryf. Die bestaan van resultate en instrumente soos voorgehou in Hoofstukke 3 en 4, onderskryf of bevestig die vermoede dat informasie tegnologie wel aangewend kan word om produksierisiko in aartappelverbouing te verminder. Die vraag is egter of dit ekonomies op plaasvlak aangewend kan word. Ten einde die persepsie met betrekking tot - die toepaslikheid en gereedheid van produsente in dié verband te evalueer, is 'n loodsvraelys na 40 respondente, wat die kommersiële aartappelprodusente regdeur Suid Afrika verteenwoordig, gestuur. Respondente is ge-evalueer met betrekking tot hul persepsie rakende die gebruik van informasie tegnologie in die dissiplines van finansiële bestuur, besproeiingskedulering, nutriëntskedulering en klimatologiese modellering vir die beheer van laatroes. Respondente was oor die algemeen positief met betrekking tot die nut van informasie tegnologie en dat onder seker voorwaardes, hulle dit sal gebruik. Marges in kommersiële aartappelverbouing is onder ernstige druk en is inderdaad besig om te krimp. Gevallestudies wat in hierdie ondersoek voorgehou is, asook resultate verkry uit die vraelys, dui aan dat informasie tegnologie nie alleen belangrik is vir die vermindering van risiko in aartappelverbouing me, maar ook noodsaaklik IS vir volhoubare en winsgewende aartappelproduksie. Dit kan gevolglik gestel word dat resultate verkry uit die loodsvraelys, daarop mag dui dat 'n statisties verifieerbare steekproef moontlik kan uitwys dat betroubare, bekostigbare en praktiese informasie tegnologie, soos voorgehou in hierdie ondersoek, wel 'n bestaansreg in die moderne verbouing van aartappels onder besproeiing het.