Submitted in fulfillment of the requirements of the Master of Technology Degree in Information Technology, Durban University of Technology, Durban, South Africa, 2014. / This dissertation reports on the original study that applies the differential evolution algorithm to support farmers with optimal strategic decision making in the crop planning system. The analysis and modelling of crop planning decision making process are attractive for producing formalized knowledge on cropping plans and choices of farmers under uncertainty. The formalization of the decision making process is generally becoming a crucial focal point for developing decision support systems that go beyond the limitation of formerly developed prescriptive approaches. This dissertation makes a distinctive contribution to the development of a formalized methodology to study the decision making process in crop farming systems. The research reported in this dissertation formulates crop-mix planning problems by concurrently maximizing net profit and crop production, while minimizing the total land in hectare used to determine optimal cropping patterns. Different optimal crop-mix problems formulated in this research were solved using a mathematical methodology of generalized differential evolution 3 algorithm to obtain globally optimal solutions. The methodology of this research strikes a balance between mathematical formulations of crop planning problems and effective implementation of crop planning decision models. Simulation experiments were conducted using the non-dominated sorted genetic algorithm II to validate the performance of the generalized differential evolution 3 algorithm for solving optimal crop planning problems. The empirical results of this study generally indicate that generalized differential evolution 3 algorithm is a viable alternative for optimal crop-mix planning decision. Based on the performance of the generalized differential evolution 3 algorithm, the design of a decision support system was realized which promises to assist farmers and decision-makers within the agricultural sector to make optimal decisions pertaining to crop planning.

MSCAGR (Soil Science) / Department of Soil Science / Maize (Zea mays L.) is widely grown in the semi-arid regions of South Africa mainly for its grain that is used for direct human consumption, feed for animals and raw materials for the industries. The challenges of soil infertility, water supply, and availability of high yielding cultivars remain a major constraint for its production in this environment. These constraints are a major threat to sustainable crop production and food security. Maize/lablab Zea mays L.\ L. purpureus) intercropping system could thus become an option for food security among small scale maize producers in dry environments. Preliminary studies show the huge potential of maize/lablab intercropping in the semi-arid environments of the North-Eastern South Africa. Therefore, this study aimed to assess the effects of maize/lablab intercropping on soil water content, nitrogen dynamics and crop productivity based field experiments and crop simulation modeling using the model APSIM. The trials were conducted at two sites (Univen and Syferkuil) in Limpopo province, South Africa, for two seasons (2015/2016) and 2016/2017). The treatments consisted of; (i) sole maize (ii) sole lablab (iii) maize and lablab planted at the same time (Maize+lablab-ST) and (iv) maize with lablab planted 28 days after maize (Maize+lablab-28).The treatments were laid out in an RCBD replicated 4 times, with individual plots size measuring 4.5 m × 4 m (18 m2) and the layout of the field as consisting of 4 plots per block giving a total of 16 plots in 4 blocks. The following parameters were determined: soil water content, soil NO3--N and NH4+-N levels, dry matter and grain yield. The APSIM-model (version 7.7) was then used to simulate maize grain yield and dry matter production to assess risks associated with the production of maize/lablab intercropping. The results obtained from this study showed that maize/lablab intercropping had significant effects on measured parameters (grain, biomass yield soil water content, and N-minerals). Maize+lablab-28 produced 46 % higher grain yield than sole cropping (24%) and maize+lablab-ST) (30%). The results also showed variation in soil water content at different depths among the treatments. The soil water content was increased with depth. The intercropped plots and lablab sole had significantly higher soil water content than the sole maize. At all depths, the highest soil water content was obtained under sole lablab followed by maize+lablab-ST and maize+lablab-28. It was notable however that maize/lablab intercropping showed a higher NO3--N and NH4+-N levels at all depths. At both sites, the soil NO3--N showed a sharp drop at V7 sampling time. The results showed the benefits of intercropping in comparison to sole cropping as demonstrated by positive land equivalent ratios of >1 for both cropping systems in both years and sites. Modelling exercises showed that APSIM was able to simulate the results sufficiently. In the simulation experiment, a stronger negative effect of planting lablab with maize simultaneously was found. Hence, delayed planting of lablab should be a standard practice / NRF

Assignment (MSc) -- University of Stellenbosch, 2004. / ENGLISH ABSTRACT: In an integrated crop-livestock production farm, the profitability and sustainability of farm production is dependent on the crop rotation strategy applied. Crop rotations have historically been applied to maintain long-term profitability and sustainabiliry of farming production by exploiting the jointly beneficial interrelationships existing among different crop types and the animal production activity. Monocrop (specifically wheat) growers in the Swartland area of the Western Cape are struggling to maintain long-term profitability and sustainability of the crop production, challenging them to rethink about the introduction crop rotation in the production planning. By making proper assumptions, this paper develops a mixed integer linear programming model to suggest a decision planning for the farm planning problem faced by an integratedcrop- livestock production farmer. The mathematical model developed includes crop production, dairy production and wool sheep production activities, which permitted the consideration of five crop types within a crop rotation system. By assuming that a farmer uses a cycle of at most three years, the crop rotation model was incorporated in the composite mixed integer linear farm planning model. In order to demonstrate the application of the mathematical farm planning model formulated, a case study is presented. Relevant data from the Koeberg area of the Swartland region of the Western Cape was applied. For each planning period, the model assumed that the farm has the option of selecting from any of 15 cropping strategies. A land which is not allocated to any of the 15 crop rotation strategies due to risky production situation is left as grass land for roughage purposes of the animal production. Results of the mathematical model indicated that farm profit is dependent on the cropping strategy selected. Additionally, animal production level was also dependent on the crop strategy appl ied. Furthermore, study results suggest that the profit generated from the integrated crop-livestock farm production by adopting crop rotation was superior to profit generated 1'1'0111 the farm activities which are based on monocrop wheat strategy. Empirical results also indicated that the complex interrelationship involved in a mixed crop-livestock farm operation play a major role in determining optimal farm plans. This complex interrelationships favour the introduction of crop rotation in the crop production activities of the farm under investigation. Crop production risk is the major risk component of risk the farmer faces in the farm production. In this study, risk is incorporated in the mixed integer programrnmg farm planning model as a deviation from the expected values of an activity of returns. Model solution with risk indicated that crop rotation strategy and animal production level is sensitive to risk levels considered. The Results also showed that the incorporation of risk in the model greatly affects the level of acreage allocation, crop rotation and animal production level of the farm. Finally, to improve the profitability and sustainability of the farm activity, the study results suggest that the introduction of crop rotation which consist cereals, oil crops and leguminous forages is of paramount importance. Furthermore, the inclusion of forage crops such as medics in the integrated crop livestock production is beneficial for sustained profitability from year to year. / AFRIKAANSE OPSOMMING: Wisselbou is baie belangrik om volhoubare winsgewindheid te verseker in 'n geintegreerde lewendehawe I gewasverbouing boerdery in die Swartland gebied van Wes-Kaap. "n Monokultuur van veral koring produksie het ernstige problerne vir produsente veroorsaak. In hierdie studie word 'n gemengde heeltallige liniere prograrnmerings-model gebruik om te help met besluitneming in sulke boerderye.Die wiskundige model beskou die produksie van kontant- en voer-gewasse (5 verskillende soorte) asook suiwel- en wol/vleis-produksie (beeste en skape) .Daar word aanvaar dat die boer "n siklus van hoogstens 3 jaar in die wisselbou rotasie model gebruik .. 'n Gevallestudie word gedoen met behulp van toepaslike data van 'n plaas in die Koeberg gebied. Die model aanvaar dat die produsent 'n keuse het uit 16 wisselbou strategic .Resultate toon dat winsgewindheid afhanklik is van die strategie gekies en dat wisselbou beter resultate lewer as in die geval van "n monokultuur.Dit wys ook dat die wisselwerking tussen diereproduksie en gewasproduksie baie belangrik is in die keuse van 'n optimale strategie. Die risiko in gewasverbouing is die belangrikste risiko factor vir die produsent.In hierdie studie word risiko ook ingesluit in die gemengde heeltallige model, naamlik as 'n afwyking van die verwagte opbrengs-waardes .Die model toon duidelik dat gewasproduksie en lewendehawe-produksie baie sensitief is ten opsigte van die gekose risiko vlak. Die studie toon ook dat 'n wisselbou program wat die produksie van graan (veral koring) .oliesade asook voere insluit belangrik is vir volhoubare winsgewindheid Die insluiting van klawers (bv "medics") is veral belangrik hier.

Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Protein and oilseed production in the winter rainfall region of South Africa (primarily the Southern and Western Cape) is well below the potential for the area. One possible method of increasing production is to convince producers that the inclusion of protein and oilseed rotational crops will enhance the sustainability of wheat production systems. A project to investigate, quantify and elucidate the effect of canola (Brassica napus), lupins (Lupinus angustifolius) and medics (Medicago spp.) on subsequent wheat (Triticum aestivum) production as well as their influence on soil fertility in respect to nitrogen was initiated in 1999. The long- term rotational crop system experiment on Langgewens experimental farm near Malmesbury, provided the infrastructure for the project. During the 1999 and 2000 wheat-growing seasons, 50m2 plots were demarcated in wheat fields where wheat, lupins, canola or medics were produced in 1998 and 1999 respectively. Each plot was cleared of all vegetation and received no fertilizer N. In these fallow plots, soil samples were collected at three to four week intervals and the available nitrate-N and ammonium-N content of the topsoil (0-15cm depth) and the subsoil (15-30cm depth) were determined. Additional soil samples were also taken from the topsoil on 09/03/2000 after a summer fallow period. These samples were taken on plots that were subjected to a wheat crop in 1999, but were preceded by either wheat, canola, lupins or medics in 1998. The soil samples were then subjected to a 60-day incubation period at 15°C while being maintained at 75% of their water holding capacity. Mineral N was determined after 0, 3, 7, 15, 30, 45 and 60 days of incubation. Large variation in the nitrogen contents observed made it difficult to always obtain significant differences. The results of the soil investigations however indicate that the inclusion of lupins and medics in wheat cropping systems in the Swartland could help to limit the decline of mineral N in the soil profile, experienced within a growing season. This will therefore enable farmers to reduce fertilizer inputs without facing soil mineral N depletion. Plant samples were also collected from wheat plots during the 1999 growing season on three occasions (23/06/99 (growth stage 5), 5/08/99 (growth stage 15), 14/09/99 (growth stage 23)). Plots were selected to represent the same treatments as in the soil sampling procedure during the growing season of 1999 as described above. Plant and tiller numbers of a 0.25m2 sub sample from each plot were counted and leaf area was determined, whereafter the dry material was weighed. The percentage nitrogen content in the leaves and stems were subsequently determined using Near Infra-Red Spectroscopy. In terms of vegetative growth, little difference was observed. A significant increase in nitrogen content of wheat plants growing in plots where wheat and canala were grown in 1998 was observed in the second plant sampling (growth stage 15) and this was attributed to higher nitrogen topdressing. However, on the third sampling date on 14/9/1999 (growth stage 23), the difference was no longer evident. The most important conclusion to make from this study, is that farmers can probably save on fertilizer inputs when including lupins and medics in their wheat production systems, without risking poorer wheat growth. At growth stage 28, a 0.25m2 sub sample of wheat plants was removed at a randomly chosen point in each of the plots described above. Ears and grains were subsequently counted. The wheat remaining on the plots were then harvested at the end of October 1999 using a plot combine. Subsequently the yield, hectolitre mass, thousand grain mass and % crude protein was determined from samples of harvested grain from each plot. The % flour and % bran extraction were then determined whereafter the % flour protein was determined. Micro bread loafs were baked to estimate the loaf volume. Flour and dough properties were also tested using the Falling Number System, mixograph and alveograph. Wheat in cropping systems consisting of legume phases such as lupins and medics, required less nitrogen fertilizer application to achieve statistically the same yield, flour and dough properties. These crop rotations can therefore be considered as more ecologically sustainable and economically viable for the Swartland. This study was aimed at determining the effect of different crop rotations on soil fertility, and because clear soil fertility trends take time to form, this study was probably too short to obtain fully significant differences. / AFRIKAANSE OPSOMMING: Proteïen- en oliesaad produksie in die winter reënval streek van Suid Afrika (hoofsaaklik die Suid- en Weskaap) is ver benede die potensiaal vir die streek. Een moontlike manier om die produksie hiervan te verhoog is om produsente in hierdie streek te oortuig dat die insluiting van proteten en oliesaad gewasse die volhoubaarheid van koring verbouingstelsels sal verhoog. Na aanleiding hiervan, is In projek in 1999 van stapel gestuur om die effek van canola (Brassica napus), lupiene (Lupinus angustifolius) en medies (Medicago spp.) op daaropvolgende koring (Triticum aestivum) produksie, asook die invloed daarvan op grondvrugbaarheid in terme van stikstofinhoud, te ondersoek. Die langtermyn wisselbouproef op Langgewens proefplaas naby Malmesbury, het as infrastruktuur vir die ondersoek gedien. Gedurende die 1999 en 2000 koring groeiseisoene is 50m2 plotte in koringkampe gekies waarop koring, canola, lupiene en medies geproduseer is in onderskeidelik 1998 en 1999. Hierdie plotte is skoon gehou van plantegroei en het ook geen stikstof in kunsmisvorm gekry nie. Met drie tot vier week intervalle is grondmonsters op hierdie plotte versamel in die bogrond (0-15cm diep) en ondergrond (15-30cm diep), waarna die beskikbare nitraat-N en ammonium-N konsentrasie bepaal is. Adissionele grondmonsters van die bogrond is ook geneem op 9/03/2000 na In somer braak periode. Hierdie monsters was geneem op persele wat blootgestel was aan In koringproduksie in 1999, maar voorafgegaan is deur koring, canola, lupiene en medies in 1998. Hierdie monsters is dan vir 60 dae geïnkubeer teen 15°C en 75% van die grond se water houvermoeë. Minerale N inhoud bepalings is gedoen na 0, 3, 7, 15, 30, 45 en 60 dae van inkubasie. Groot variasie in die minerale stikstof inhoud, het die verkryging van herkenbare tendense en konstante statistiese verskille belemmer. Die resultate wat verkry is dui egter dat die insluiting van lupiene en medies in koring produksie stelsels in die Swartland, hoër minerale N vlakke in die grond handhaaf en dit kan boere gevolglik in staat stelom kunsmis insette te besnoei sonder dat grondvrugbaarheid verswak. Op 23/06/99 (groeistadium 5), 5/08/99 (groeistadium 15) en 14/09/99 (groeistadium 23) is plantmonsters versamel van koringpersele. Hierdie persele is gekies om die behandelings van die grondmonsterontledings soos hierbo beskryf, te verteenwoordig. Plante en halms van 'n 0.25m2 area uit die persele is getel en die blaaroppervlaktes is bepaal, waarna die droëmateriaal massa van die area bepaal is. Die persentasie stikstofinhoud van die blare en stingels was daarna bepaal. In terme van vegetatiewe groei was daar nie groot verskille te bespeur nie. Betekenisvolle hoër stikstof inhoud van koringblare in plotte waar daar in die vorige jaar canola en koring verbou was, is in die tweede planttrekking (groeistadium 15) gevind en dit is toegeskryf aan die hoër stikstof kopbemesting wat daardie behandelings ontvang het. Teen die derde monsterneming op 14/09l99 (groeistadium 23), was hierdie verskille nie meer in die ontledingsdata te sien nie. Die afleiding wat van hierdie studie gemaak is, is dat boere moontlik stikstofbemesting kan verminder as hulle lupiene en medies in hulle koring produksiestelsels inbring, sonder om die risiko van swakker groei te verhoog. Op 20/10/99 (groeistadium 28) is 0.25m2 plante van elke koringperseel verwyder waarna die are en die korrels getel is. Die koring wat nog op die persele was is teen die einde van Oktober 1999 met 'n perseelstropertjie geoes. Opbrengs, hektoliter massa, duidendkorrel massa en % ru-proteïene is daarna bepaal. Volgende is die % meel en % semel ekstraksie bepaal waarna die % meelproteïene bepaal is. Mikro broodjies is ook gebak om die broodvolume te bepaal. Meel en deeg eienskappe is ook getoets met die Falling Number System, mixogram en alveogram. Koring in produksiestelsels met peulplant fases (lupien en medies in hierdie geval), het minder N toediening nodig gehad om statisties dieselfde opbrengs, meel- en deeg eienskappe te verkry. Lupien en medic gebaseerde wisselbou praktyke in die Swartland kan gevolglik as meer ekologies volhoubaar en ekonomies haalbaar bestempelword. Hierdie studie het gepoog om die invloed van wisselbou op grondvrugbaarheid te ondersoek. Sodanige veranderings neem egter tyd en daarom is dit waarskynlik nog te gou om werklike grondvrugbaarheids verskille waar te neem.

Thesis(MPhil)--Stellenbosch University, 2014 / ENGLISH ABSTRACT: This thesis documents a Participatory Action Research (PAR) project conducted from 2011 to 2013 in a rural communal area in southern KwaZulu-Natal, South Africa. The area is a microcosm of the global environmental and socio-economic polycrisis; with adult unemployment at 50 percent, 73 percent female-headed households, heavy dependence on government social grants and a food system reliant on purchased food. Eight, mainly female-headed households (the co-researchers), assisted by the student researcher, implemented and assessed a cropping system, designed on agroecological principles, on their abandoned garden plots. The objective was to grow culturally acceptable food crops to supplement their household diets and positively affect their food security. The student researcher provided the necessary infrastructure, including goat-proof plot fences, hand tools, a grain hammermill, seed, and fertiliser. The literature review, which also used early 1900’s photographs and contemporary isiZulu language as evidence, revealed the agroecological basis of pre-colonial agriculture. However, colonial and apartheid influences destroyed this knowledge base. The cropping system design utilized practices from this pre-colonial era combined with current agroecological techniques. The agroecological techniques employed on the plots included non-inversion tillage of planting pits using garden forks, precision placement of phosphate fertiliser and animal manures, open pollinated seeds, east-west orientated strip cropping, soil surface mulches, crop rotations including legumes and the use of chickens to control pests. Dryland crops included maize, beans, sweet potatoes, and butternuts, with small trial vegetable patches on some plots. The research identified a method to calculate the planting frequency of these vegetables to ensure a constant annual supply, however further research is needed. The dryland crops supplemented household diets between harvests. The formation of structured groups amongst the households proved vital to the success of the cropping system, providing mutual labour assistance, shared decision-making, building knowledge and moral support. The importance of dialogue and trust, reinforced by the student researcher’s ability to communicate in isiZulu with the co-researchers, formed the basis of both the PAR, and Focus Group Discussions(FGD), used to qualitative assess the cropping system. During these, the households reported a good understanding of the agroecological principles of the cropping system, a willingness to continue with it post research, and positive benefits, including better health, and money saved on food purchases, redirected to improve their asset base. The World Food Programme (2008) Food Consumption Score Analysis Method (FCS), modified to show the percentage contribution of homegrown food to the FCS, provided the quantitative assessment of the cropping system. The FCS scores rose during the research, with homegrown food contributing over a third of the FCS at times. The co-researchers suggested instituting group ‘stokvels’1to finance inputs and maintain infrastructure post research. The financial implications of these ‘stokvels’ was calculated. Due to the initial success of the PAR, the research recommends a method to extend the cropping system to more households, utilizing state finance to provide the infrastructure, and the co-researchers imparting technical knowledge through farmer-to-farmer extension. / AFRIKAANSE OPSOMMING: In hierdie tesis word verslag gedoen van ’n deelnemende aksienavorsingsprojek wat van 2011 tot 2013 in ’n landelike dorpsgebied in die suide van KwaZulu-Natal, Suid-Afrika, uitgevoer is. Die gebied is ’n mikrokosmos van die wêreldwye omgewings- en sosio-ekonomiese polikrisis, met volwasse werkloosheid op 50%, 73% huishoudings met vroue aan die hoof, swaar afhanklikheid van die staat se maatskaplike toelae en ’n voedselstelsel wat van gekoopte kos afhanklik is. In die studie het agt huishoudings, wat hoofsaaklik vroue aan die hoof het (die medenavorsers), met behulp van die studentenavorser, ’n verbouingstelsel, wat op agro-ekologiese beginsels gegrond is, op hul verlate tuingrond geïmplementeer en geassesseer. Die doel was om kultureel aanvaarbare gewasse te verbou om hul huishoudelike dieet aan te vul en hul voedselsekerheid positief te beïnvloed. Die studentenavorser het die nodige infrastruktuur verskaf, met inbegrip van bokbestande omheining, handgereedskap, ’n graanhamermeul, saad en kunsmis. Die literatuurstudie, waarin foto’s uit die 1900’s en moderne Zoeloe as bewyse gebruik is, toon die agro-ekologiese grondslag van prekoloniale landbou. Koloniale en apartheidsinvloede het egter hierdie kennisbasis vernietig. Die verbouingstelselontwerp was gegrond op praktyke uit hierdie prekoloniale era gekombineer met moderne agro-ekologiese tegnieke. Hierdie tegnieke het ingesluit nie-inversie-grondbewerking van plantgate met gebruik van tuinvurke, presisieplasing van fosfaatkunsmis en dieremis, oop bestuifde sade, oos–wes-georiënteerde strookverbouing, grondoppervlak-deklae, wisselbou met onder andere peulgewasse en die gebruik van hoenders om peste te beheer. Droëland-gewasse het ingesluit mielies, bone, soetpatats en botterskorsies, met klein toetsgroenteakkers op sommige stukke grond. ’n Metode is in die navorsing geïdentifiseer om te bepaal hoe gereeld hierdie groente geplant moet word om ’n konstante jaarlikse voorraad te verseker. Verdere navorsing is egter nodig. Die droëland-gewasse het huishoudelike diëte tussen oeste aangevul. Die vorming van gestruktureerde groepe onder die huishoudings het noodsaaklik geblyk te wees vir die sukses van die verbouingstelsel, waardeur wedersydse hulp met arbeid, gedeelde besluitneming, die bou van kennis en morele ondersteuning gebied is. Die belangrikheid van dialoog en vertroue, wat versterk is deur die studentenavorser se vermoë om in Zoeloe met die medenavorsers te kommunikeer, het die grondslag gevorm van die deelnemende aksienavorsingsprojek asook die fokusgroeponderhoude, wat gebruik is om die verbouingstelsel kwalitatief te assesseer. In hierdie onderhoude het die huishoudings verslag gedoen van hul grondige begrip van die agro-ekologiese beginsels van die verbouingstelsel, hul gewilligheid om ná die navorsing daarmee voort te gaan, asook die voordele wat dit bied, soos beter gesondheid en geld wat op voedselaankope gespaar is, wat heraangewend is om hul batebasis te verbeter. Die Wêreldvoedingsprogram (2008) se Food Consumption Score- (FCS-)ontledingsmetode, wat aangepas is om die persentasie bydrae van selfgekweekte voedsel tot die FCS aan te toon, is gebruik vir die kwantitatiewe assessering van die verbouingstelsel. Die FCS-tellings het tydens die navorsing toegeneem, met selfgekweekte voedsel wat by tye tot meer as ’n derde tot die FCS bygedra het. Die medenavorsers het voorstel dat ’n stokvel gestig word om insette te finansier en die infrastruktuur ná die navorsing in stand te hou. Die finansiële implikasies van hierdie stokvel is bereken. Op grond van die aanvanklike sukses van die deelnemende aksienavorsingsprojek stel die navorser ’n metode voor om die verbouingstelsel na meer huishoudings uit te brei met behulp van staatsfinansiering om die infrastruktuur te verskaf asook die oordrag van die medenavorsers se tegniese kennis na ander boere.