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Modelling the effects of maize/lablab intercropping on soil water content and nitrogen dynamics using APSIM-ModelRapholo, Seroto Edith January 2020 (has links)
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
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Agriculture biologique et qualité des eaux dans des aires d’alimentation de captage : diversité des postures techniques d’agriculteurs conventionnels et biologiques et pressions nitrate et pesticide induites / Organic farming and groundwater quality in water catchment areas : diversity of conventional and organic farmers’ conceptions and induced reduction of nitrate and pesticide leachingGratecap, Jean-Baptiste 15 December 2014 (has links)
Face à la pollution généralisée des masses d’eau souterraines par les nitrates et les pesticides, l’agriculture biologique (AB) est présentée comme un outil pertinent pour la reconquête de la qualité des eaux sur les aires d’alimentation de captage (AAC). Ce travail vise à mieux définir l’opportunité d’un développement de l’AB sur des zones à enjeu eau. L’objectif de la thèse est d’évaluer conjointement la faisabilité des conversions sur les exploitations de l’AAC et l’efficacité de ces conversions par rapport aux enjeux de reconquête de la qualité de l’eau.Etudier l’opportunité d’un développement de l’AB à l’échelle territoriale suppose d’instruire la diversité des exploitations et des profils d’agriculteurs sur la zone à enjeu eau. Pour être en mesure de tester l’opportunité des conversions, une méthode typologique permettant d’analyser conjointement la variabilité actuelle des pressions sur les zones à enjeu eau et la propension des agriculteurs conventionnels à la conversion est nécessaire.Pour produire cette typologie, nous avons développé une méthode innovante d’analyse compréhensive des pratiques, centrée sur les principes d’action à l’origine des systèmes de culture. Les principes d’action correspondent à des méta-raisonnements à l’origine de l’organisation concrète des pratiques agricoles sur le territoire d’exploitation. Par l’analyse conjointe du discours des agriculteurs et de la variabilité des règles de décision, nous avons élaboré des typologies basées sur les postures techniques des agriculteurs pour i) identifier des principes d’action associés aux pratiques à risque et ii) dégager des proximités éventuelles entre agriculteurs biologiques et agriculteurs conventionnels. La méthode a été testée sur deux territoires à enjeu eau en Rhône-Alpes, sur lesquels des entretiens semi-directifs ont été réalisés auprès d’exploitants conventionnels et biologiques.Cinq principes d’action génériques à l’origine de l’organisation de l’assolement et cinq principes d’action génériques à l’origine des pratiques culturales ont été dégagés. A partir des différents principes d’action, des typologies des postures techniques ont été produites sur les deux terrains. Les pressions à l’origine de la lixiviation des nitrates et des pesticides ont été évaluées et spatialisées via le recours à des indicateurs agro-environnementaux. Nous avons démontré que la variabilité forte des indicateurs et leur distribution spatiale sur les AAC étaient liées à la diversité des postures techniques entre agriculteurs.Nous avons comparé les principes d’action mobilisés par les agriculteurs conventionnels et les agriculteurs biologiques « références » présents sur les zones à enjeu eau. Par l’étude des spécificités des postures techniques en AB, trois critères de propension à la conversion ont été identifiés. Plusieurs degrés de propension à la conversion ont été dégagés parmi les agriculteurs conventionnels des deux territoires.L’analyse croisée des degrés de propension à la conversion et des différentiels de pressions entre systèmes conventionnels et biologiques nous a permis d’évaluer l’opportunité d’un développement de l’AB sur les deux territoires. Nos résultats ont mis en évidence des niveaux de pression limités quant à la lixiviation des nitrates sur les systèmes biologiques : un développement exhaustif de l’AB à l’échelle des deux AAC entrainerait potentiellement une réduction forte de la lixiviation des nitrates. Néanmoins, l’opportunité d’un tel développement doit être relativisée. Les agriculteurs présentant une propension réelle ou forte à la conversion sont minoritaires sur les AAC. Ensuite, le différentiel des pressions entre systèmes conventionnels et systèmes biologiques diminue à mesure que la propension à la conversion augmente. Pour envisager une diminution forte des pressions sur les zones à enjeu eau, la conversion devrait concerner des exploitants pour lesquels cette conversion est difficilement envisageable à moyen terme. / Many problems with nitrate and pesticide contamination from agriculture exist in European drinking water catchments. In France, a new mitigation approach aims at preventing water quality degradation in explicitly targeting agricultural non-point source pollutions associated with leaching of nitrates and pesticides. This work aims at assessing the opportunity to develop organic farming in water catchment areas in order to reduce nitrate and pesticide leaching from root zone. The objective was to analyze both i) feasibility of conversions to organic farming on farms concerned by water preservation and ii) the potential impacts of these conversions in terms of nitrate and pesticide leaching reduction.To explore the potential contribution of organic farming in water catchment areas, we develop an innovative typology approach to characterize farmers’ conceptions and strategies related to cropping systems’ organization on the farm territory. Our method was tested in two French water catchment areas characterized by diversified production systems, where semi-structured interviews were carried out with conventional and organic farmers. Resulting typologies of farmers were used to assess leaching risks variability related with current cropping systems and to identify potential similarities between conventional and organic farmers’ conceptions. Nitrate and pesticide leaching risks for cropping systems were assessed and spatialized by using four agro-environmental indicators. Our results show major variations for all indicators at both study sites, for example N-surpluses which range from -105 to 192 kg N ha-1 year-1. These variations are deeply related with diversity of farmers’ conceptions summarized in typologies. To assess proximity of conventional farmers to organic farming, we used typologies to compare conceptions related to organization of cropping systems between conventional and organic farmers. By analyzing specificities of organic farmers’ conceptions, we determined three main criteria of proximity to organic farming; these criteria were then used to identify various degrees of proximity to organic farming among conventional farmers in the catchment areas.To assess potential contribution of organic farming to water preservation in catchment areas, we firstly compared nitrate leaching risks between conventional and organic cropping systems. Our results reveal low leaching risks from organic systems, characterized by reduced N-surpluses and lower bare soils frequencies in autumn. According to these results, massive development of organic farming should decrease nitrate leaching in our two water catchment areas. However, analysis of similarities between conventional and organic farmers’ conceptions shows that a majority of farmers are characterized by a low level of proximity to organic farming. Moreover, the farmers who show strongest similarities with organic farmers’ conceptions are already those with low leaching risks cropping systems. To significantly lower nitrate leaching risks, conversions should concern conventional farmers with low degree of proximity to organic farming.
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Farm planning for a typical crop-livestock integrated farm : an application of a mixed integer linear programming modelGhebretsadik, Amanuel Habte 12 1900 (has links)
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.
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Soil nitrogen dynamics and spring wheat (Triticum aestivum) production in different cropping systems in the SwartlandWessels, Pieter Gerhardus Wilhelmus 03 1900 (has links)
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.
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The design, implementation and assessing of an agroecological cropping system by rural KwaZulu-Natal households : its effect on their diet and food securityStrachan, Brian Douglas 04 1900 (has links)
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.
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Effet d'apport de matières organiques sur le contrôle biologique des nématodes parasites du bananier en Guadeloupe / Effects of organic material inputs on the biological control of banana parasitic nematodes in Guadeloupe (F.W.I.)Tabarant, Perrine 13 April 2011 (has links)
Aux Antilles, dans les plantations de bananes en monoculture mécanisée, l'un des principaux problèmes à résoudre est le contrôle des populations de nématodes phytoparasites. Dans cette thèse, les effets d'apports de différentes matières organiques (MO), brutes ou compostées, sur la régulation biologique des nématodes ont été étudiés, cet effet suppresseur ayant déjà été montré sur d'autres cultures. L'analyse de la littérature sur le sujet montre que les effets d'un apport de MO sur les populations de nématodes phytoparasites et sur leurs dégâts sont complexes et varient fortement en fonction de la nature biochimique du produit et de l'espèce de nématode. Ainsi, les matières organiques qui libèrent beaucoup d'azote minéral en se décomposant favorisent la croissance des racines, ce qui peut augmenter la ressource alimentaire des nématodes phytoparasites et/ou la tolérance des plantes à leurs attaques. La décomposition des matières apportées peut libérer des composés nématotoxiques. Enfin, l'apport de carbone peut entrainer une diversification des communautés de nématodes, une complexification des réseaux trophiques et, par la suite, favoriser la régulation biologique des nématodes phytoparasites par les espèces appartenant aux niveaux trophiques supérieurs et par la microflore. Nous avons, par une étude fine de la structure des communautés de nématodes et le suivi de la croissance des jeunes plants de bananier, cherché à évaluer l'induction de la régulation biologique des nématodes parasites du bananier dans une sole bananière par un apport de MO, au moyen de deux expérimentations en pots conduites pendant 13 semaines. Les MO testées étaient quatre MO brutes et quatre MO compostées. L'expérience sur les MO brutes a montré que trois des quatre MO (bagasse, écumes de sucrerie et déchets verts) ont entrainé une diminution des populations de nématodes parasites dans les racines du bananier, l'intensité de cette régulation dépendant de l'espèce. En revanche, le quatrième type de MO, des boues de station d'épuration, n'a pas permis de diminuer la pression parasitaire. Les différences de croissance des systèmes racinaires n'ont pas été un facteur explicatif des régulations observées et les meilleures conditions de croissance observées n'ont pas réduit les impacts des nématodes phytoparasites sur les racines. Seules les écumes de sucrerie ont entrainé un impact positif global sur la plante, en diminuant la pression parasitaire tout en augmentant sa croissance. La bagasse et les déchets verts, principalement composés de lignines et de cellulose, ont entrainé une modification significative de la structure des communautés de nématodes, avec un fort accroissement des populations de nématodes fongivores et, avec la bagasse, de nématodes carnivores. L'expérience en pot sur les MO compostées a montré que les trois composts commerciaux produits par SITA VERDE (Biogwa, Ecogwa B, Ecogwa D) et l'amendement organique commercial Vegethumus (de Phallipou-Frayssinet) avaient engendré une diminution du parasitisme et que ce contrôle dépendait de l'espèce de nématodes phytoparasites. Dans cet essai, le contrôle des nématodes parasites du bananier est apparu lié à la biomasse racinaire totale des bananiers. L'apport des composts Ecogwa D et Vegethumus a augmenté la taille des populations de nématodes microbivores, mais seul Vegethumus a accru la voie de décomposition fongique. [...] Suite et fin du résumé dans la thèse. / In French West Indies, banana crops are generally managed as an intensive mechanized monoculture, and one of main problems to solve is the control of plant-parasitic nematodes. In this study, the effects of the input of different organic materials, gross or composted, on the biological control of nematodes were investigated. The analyze of the literature showed that the effects of an organic material input on plant-parasitic nematode populations and on their damage on the plant are complex and vary highly according to the biochemical characteristics of the products and the plant-parasitic nematode species. Thus, organic materials that release great amounts of mineral nitrogen during their decomposition promote root growth, which increases the feeding resource for plant-parasitic nematodes and/or plant tolerance to their attacks. Organic material decomposition can also release nematotoxic chemical compounds. Lastly, carbon input can lead to nematode community diversification, soil food web complexification, and, as a result, favoring the biological control of plant-parasitic nematodes by top predators or microflora. We evaluated the induction of the biological control of banana parasitic nematodes by an organic input, using soil nematofauna analyses and measuring the growth of young banana plants. We thus conducted two pot experimentations during 13 weeks. The organic materials tested were four raw and four composted organic materials that were locally available. The raw organic materials trial showed that three amongst the four amendments (sugarcane bagasse, sugarcane refinery sludge and plant residues) led to a decrease of parasitic nematode populations within banana roots, the control efficiency depending on nematode species. In contrast, the fourth type of organic material, sewage sludge, did not induce the decrease of the parasitic pressure. Changes in root growth were not an explanatory factor and the better soil conditions for plant growth did not reduce the impact of plant-parasitic nematode. Only sugarcane refinery sludge engendered overall positive effect on the banana plant, decreasing parasitic pressure and enhancing plant growth. Sugarcane bagasse and plant residues, mainly composed of lignins and cellulose, led to significant changes in nematode community structure, increasing fungivorous nematode populations and, only after bagasse supply, those of carnivorous nematodes. The compost trial showedndment that the three commercial composts produced by SITA Verde (Biogwa, Ecogwa B, Ecogwa D) and the commercial organic amendment Vegethumus (Phallipou-Frayssinet) induced a decrease of plant-parasitic nematode populations and that this control depended on banana parasitic nematode species. In this trial, the control of banana parasitic nematodes was linked to overall biomass of banana root system. The input of Ecogwa D and Vegethumus composts boosted microbivorous nematode populations, but only Vegethumus favored the fungal decomposition pathway. Last and final summary in the thesis.
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MEASURING SOIL NITROUS OXIDE EMISSIONS BY USING A NOVEL OPEN PATH SCANNING TECHNIQUECheng-Hsien Lin (5929973) 02 August 2019 (has links)
A
better way to improve understanding and quantification of nitrous oxide (N<sub>2</sub>O)
emitted from intensive maize cropping systems is to develop an advanced emissions
measurement method This study developed an open path (OP) method to measure N<sub>2</sub>O
emissions from four adjacent maize plots managed by tillage practices of no-till
(NT) and chisel plow (ChP), and different nitrogen (N) treatments from 2014 to
2016. Anhydrous ammonia (220 kg NH<sub>3</sub>-N ha<sup>-1</sup>) was applied in once or equally split (full vs.
split rate) and applied in different timing (Fall vs. Spring). The spring N
application occurred either before planting (pre-plant) or in season (side-dress).
Emissions measurements were conducted by using
the OP method (the scanning OP Fourier transform infrared spectrometry (OP-FTIR)
+ the gas point-sampling system + a backward Lagrangian stochastic (bLS)
dispersion model) and static closed chamber methods. The performance and
feasibility of the OP measurements were
assessed by a sensitivity analysis, starting with errors associated with the
OP-FTIR for calculating N<sub>2</sub>O concentrations, and then errors
associated with the bLS model for
estimating N<sub>2</sub>O emissions. The quantification of N<sub>2</sub>O
concentrations using the OP-FTIR spectrum was influenced by ambient humidity,
temperature, and the path length between a spectrometer and a retro-reflector.
The optimal quantitative method mitigated these ambient interference effects on
N<sub>2</sub>O quantification. The averaged bias of the calculated N<sub>2</sub>O
concentrations from the spectra acquired from wide ranges of humidity (0.5 – 2.0
% water vapor content), temperature (10 – 35 °C), and path length (100 – 135
meters) was 1.4 %. The precision of the OP-FTIR N<sub>2</sub>O concentrations
was 5.4 part
per billion<sup> </sup>(3σ) in a stationary flow condition for a 30-minute averaging period. The emissions
measurement from multiple sources showed that the field of interest was likely
interfered by adjacent fields. Fields with low emission rates were more sensitive
to the adjacent fields with high emissions, resulting in substantial biases and
uncertainties. The minimum detection limit of the N<sub>2</sub>O emission rates
was 1.2 µg m<sup>-2</sup> s<sup>-1</sup> (MDL; 3σ). The OP measurements showed
that the NT practice potentially reduced N<sub>2</sub>O emission compared with ChP. Under the long-term NT treatments, the
split-N rate application (110 kg NH<sub>3</sub>-N ha<sup>-1</sup> in the fall
and spring) resulted in lower N<sub>2</sub>O emissions than the full
application (220 kg NH<sub>3</sub>-N ha<sup>-1</sup> in the fall). The management
of NT coupled with split-N rate application minimized N<sub>2</sub>O emissions among
treatments in this study, resulting in N<sub>2</sub>O-N losses of 3.8, 13.2,
and 6.6 N kg ha<sup>-1</sup> over 9-, 35-, and 20-days after the spring NH<sub>3</sub>
application in 2014, 2015, and 2016, respectively. The spring pre-plant N
application in 2015 also resulted in higher N<sub>2</sub>O emissions than the
spring side-dress application in 2016, and the increased N<sub>2</sub>O-N loss
was corresponding to lower N recovery efficiency in 2015 measurements. A
comparison of chamber and OP measurements showed that soil N<sub>2</sub>O
emissions were likely underestimated by 10x without considering the
wind-induced effect on gas transport at the ground-atmospheric interface. This
study showed that the OP method provides a great
opportunity to study agricultural N<sub>2</sub>O emissions as well as management optimization for the sustainability
of the agroecosystems.
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Cultiver Miscanthus x giganteus en parcelles agricoles : du diagnostic agro-environnemental à la conception-évaluation ex ante de systèmes de culture à vocation énergétique / Cropping Miscanthus x giganteus in commercial fields : from agro-environmental diagnostic to ex ante design and assessment of energy oriented cropping systemsLesur, Claire 21 December 2012 (has links)
Second-generation biofuels could provide renewable energy while reducing the globaleconomy dependence on oil and mitigating climate change. However, their greenhouse gasemission balances, as well as their energy and environmental balances, are discussed,especially when they are produced from agricultural feedstock. The use of agriculturalfeedstock for energy purposes also raises the issue of competition with food production. Inthis context, this work contributes to the assessment of the sustainability of Miscanthus xgiganteus, a perennial C4 crop candidate to the production of second-generation ethanol. Theobjectives of this work are (i) to achieve a multicriteria evaluation of cropping systems basedon M. Giganteus using data collected in farmers’ fields and (ii) to compare these croppingsystems with cropping systems including other resources Agricultural candidates for biofuelproduction. The main contributions of this work are (i) the study of the variability of yieldsand winter nitrate losses in a network of commercial fields located in Burgundy (France), (ii)the characterization by modeling of M. giganteus long-term yield evolution and (iii) theintegration of these findings in a process of cropping systems design and assessment aimingat comparing M. giganteus with other feedstock candidate to the production of bioethanol.The study of M. giganteus in farmers’ fields shows that the high variability of yields andnitrate losses is linked to (i) crop age, (ii) soil type and (iii) the type of field (i.e. culturalhistory, size, shape, and environment). Contrasting yield scenarios, built by combining datacollected in commercial fields with a long-term yield evolution model, show that thesensitivity of assessment results regarding yields depends on the assessment field. Theinsertion of M. giganteus in a cropping system can significantly improve the greenhouse gasemission balance as well as the environmental balance, compared with a cropping systembased on a short cropping sequence. Economic results depend strongly on M. giganteus yield.Other agricultural feedstocks are also interesting, especially on soils where the yield potentialof M. giganteus is low: this is particularly the case of alfalfa stems, which can be used forsecond-generation ethanol production. / Second-generation biofuels could provide renewable energy while reducing the globaleconomy dependence on oil and mitigating climate change. However, their greenhouse gasemission balances, as well as their energy and environmental balances, are discussed,especially when they are produced from agricultural feedstock. The use of agriculturalfeedstock for energy purposes also raises the issue of competition with food production. Inthis context, this work contributes to the assessment of the sustainability of Miscanthus xgiganteus, a perennial C4 crop candidate to the production of second-generation ethanol. Theobjectives of this work are (i) to achieve a multicriteria evaluation of cropping systems basedon M. Giganteus using data collected in farmers’ fields and (ii) to compare these croppingsystems with cropping systems including other resources Agricultural candidates for biofuelproduction. The main contributions of this work are (i) the study of the variability of yieldsand winter nitrate losses in a network of commercial fields located in Burgundy (France), (ii)the characterization by modeling of M. giganteus long-term yield evolution and (iii) theintegration of these findings in a process of cropping systems design and assessment aimingat comparing M. giganteus with other feedstock candidate to the production of bioethanol.The study of M. giganteus in farmers’ fields shows that the high variability of yields andnitrate losses is linked to (i) crop age, (ii) soil type and (iii) the type of field (i.e. culturalhistory, size, shape, and environment). Contrasting yield scenarios, built by combining datacollected in commercial fields with a long-term yield evolution model, show that thesensitivity of assessment results regarding yields depends on the assessment field. Theinsertion of M. giganteus in a cropping system can significantly improve the greenhouse gasemission balance as well as the environmental balance, compared with a cropping systembased on a short cropping sequence. Economic results depend strongly on M. giganteus yield.Other agricultural feedstocks are also interesting, especially on soils where the yield potentialof M. giganteus is low: this is particularly the case of alfalfa stems, which can be used forsecond-generation ethanol production.
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Breeding groundnut for resistance to rosette disease and its aphid vector, Aphis craccivora Koch in Malawi.Chintu, Justus M.M. 21 November 2013 (has links)
Groundnut (Arachis hypogaea L.) is one of the most important legume crops in Malawi.
However, production among smallholder farmers has declined in recent years. One of the
constraints affecting groundnut production is groundnut rosette disease (GRD). Therefore,
the main objective of this study was to develop appropriate groundnut cultivars that are
resistant to GRD, combined with other traits preferred by farmers, in order to improve
income and food security of smallholder farmers in Malawi and beyond. The specific aims
were; (i) to assess groundnut cropping systems used by smallholder farmers in Malawi, their
varietal preferences, and production challenges (ii) to assess the genetic diversity among
groundnut germplasm collected from ICRISAT, the Chitedze gene bank and farmers (iii) to
identify sources of resistance to GRD and to its aphid vector (iv) and to understand the type
of gene action governing GRD resistance, and to identify groundnut genotypes suitable for
use as parents in breeding for GRD resistance.
Assessment of groundnut cropping systems used by smallholder farmers, their varietal
preferences, and production challenges was done by using a field survey and participatory
rural appraisal (PRA) tools. The field survey was done in Lilongwe, Mchinji and Salima while
the PRA was done in Kasungu, Lilongwe, and Salima. The assessment of genetic diversity
among 106 groundnut genotypes collected from ICRISAT, Chitedze gene bank and farmers
was done using 19 SSR markers. High throughput DNA extraction was done followed by
polymerase chain reactions (PCR) after which the amplified products were analyzed.
Evaluation of genotypes to identify new sources of resistance to GRD and its aphid vector
was conducted under two test situations, one with high inoculum levels and one with low
inoculum levels. Under high inoculum level, the infector row technique developed by Bock
and Nigam (1990) which employs a susceptible variety as a disease spreader was used.
While under low inoculum level, an aphid resistant variety instead of the infector row was
used to control the aphids. Aphid resistance was studied under field and glasshouse
conditions. Plants were planted in rows and at 14 DAS, 2 aphids were place on each plant.
Aphid resistance was determined by observing the increase in number of the aphid
population on the test plants. Gene action governing inheritance of resistance to GRD was
studied under high disease pressure created by using viruliferous aphids. Parents and F2
generations and their reciprocals were used in the study. The trials were laid out in a
glasshouse and aphids were infested a week after germination and were killed after 7 days
using Dimethoate. Disease data was collected at 7, 14, 21 and 28 days after aphid
infestation.
The study on groundnut cropping systems, varietal preferences and production challenges
revealed that most farmers grew groundnut alongside maize (Zea mayis L.) and beans
(Phaseolus vulgaris L.) as food crops and tobacco (Nicotiana tabacum L.) and cotton
(Gossypium hirsutum L.) as cash crops. The most preferred groundnut varieties grown by
farmers were Chalimbana and CG 7. GRD was observed in half of the fields visited.
However, 98% of the farmers interviwed had experienced it in their fields at some point, and
63.3% of the farmers believed that GRD was a major problem. Other challenges noted by
farmers included lack of quality seed, poor extension support, lack of inputs, manipulation of
the markets by buyers, and the failure of groundnut crops to meet the high standards
required by the market. The examination of genetic diversity among 106 groundnut
genotypes revealed a total number of 316 alleles with a mean of 17 alleles per locus.
Polymorphic information content (PIC) and gene diversity values were high, which indicated
that genetic diversity among the groundnut genotypes was high. The analysis of molecular
variance indicated that 72.9% of the genetic variation observed in the genotypes was due to
the variation between individuals within rather than between specific population groups. The
evaluation of genotypes for resistance to GRD revealed five highly resistant genotypes
namely ICG 9449, ICG 14705, ICGV-SM 05701, MW 2672 and MW 2694. Farmer preferred
genotypes were rated as either moderately resistant or susceptible to GRD. Aphid resistance
was only recorded in ICG 12991. Yield and GRD incidence were negatively and moderately
correlated, which confirmed that GRD has the potential to reduce yield in groundnuts. The
highly resistant genotypes were also high yielding except for genotype ICG 9449. Farmer
preferred genotypes CG 7, Chalimbana and Tchayilosi, also gave above average yields,
despite high disease incidence levels, which showed that these genotypes have tolerance to
GRD. The study on gene action governing GRD resistance revealed information on
combining ability effects of GRD resistance. The diallel analysis showed that GCA, SCA,
reciprocal, maternal and non-maternal effects were all significant, which indicated that both
additive and non-additive gene effects played a role in governing GRD resistance. The
significance of SCA and reciprocal effects indicated that maternal parents played an
important role in the expression of GRD resistance. However, the additive effects were
predominant over non-additive gene effects. Four of the resistant genotypes, ICG 14705,
MW 2694, ICGV-SM 05701, and MW 2672, were the best combiners for GRD resistance.
Generally, the study indicates that there is still a need to develop new varieties with
resistance to GRD having traits preferred by farmers to enhance adoption. There is also a
need for breeders to work with extension staff in promoting new varieties and also there is
need for extension staff to actively provide information to farmers on production and
marketing of groundnut. Groundnut is widely known to have a narrow genetic base which
has been a bottleneck to its improvement. However, the high genetic diversity observed in
this study provides a basis for selection of appropriate parental genotypes for breeding
programmes which can enhance further the broadening of the groundnut genetic base.
Identification of the genotypes with high resistance to GRD in this study provides an
opportunity to breed more GRD resistant materials. The observation that additive gene
effects are predominant in governing GRD resistance means that GRD resistant materials
can be improved by introgressing additive genes using recurrent selection breeding
procedures. There is also a need to employ molecular techniques which can help in
shortening the entire breeding process. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
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The applicability of the agricultural production systems simulator (APSIM) model to decision-making in small-scale, resource-constrained farming systems : a case study in the Lower Gweru Communal area, Zimbabwe.Masere, Tirivashe Phillip. January 2011 (has links)
Small-scale farmers rarely get enough yields to sustain themselves to the next harvest. Most of these farmers are located in marginal areas with poor soils and in semi-arid areas which receive little rainfall yet the farmers practice rainfed agriculture. A number of reasons can be attributed to the low yields characterizing these farms. Lack of relevant knowledge for decision-making and climate change are among the major reasons for poor yields. Whilst there is not much the small-scale farmers can do to influence climate, they can at least make informed decisions to improve their yields. The information necessary for agricultural decision-making include the climate forecast information and information about performance of new technologies be it fertilisers, varieties or other practices.
The study aimed to answer the primary research question: What is the applicability of the APSIM model in decision-making by small-scale resource constrained farmers? This question was supported by secondary research questions namely:
- How useful is the APSIM model in small-scale farmers' adaptation to future climate change?
- What are the current farming systems of Lower Gweru farmers with regards to maize production?
- What are farmers' perceptions of climate change and what changes have they noticed in the last 10 years?
- How do small-scale farmers make crop management decisions?
Data was gathered through five methods namely, Focus Group Discussions, resource allocation mapping technique, APSIM simulations, on-farm experimentation, and semi-structured interviews. Data was collected from a group of 30 small-scale farmers of Lower Gweru Communal area. The study concentrated on maize production due to the fact that it is the staple food and was grown by all farmers.
All the farmers perceived climate to be changing. The changes noted included late start of the rain season, early cessation of rain season and temperature extremes. The majority of farmers highlighted that they were using local indicators to make decisions about climate or to forecast the nature of the coming season before they were exposed to SCF and APSIM.
The data gathered from three selected resource allocation maps were used to run the APSIM model. For which farmers were convinced that the model was credible in yield prediction based on the simulated results which reasonably compared to observed yields. The what if questions raised by farmers during the discussions were also assessed and this further increased the farmers' confidence with the model, as they viewed it as a planning and guiding tool before one can actually commit resources. The semi-structured interviews showed that most farmers will continue to use the model outputs in their decision-making. The reasons being that it was a good planning and budgeting tool, it is cheaper and faster since one can assess a lot of options in a short time and would then decide on which options are viable in a given season. The few farmers who said they would not use the model or its outputs in decision-making cited reasons including lack of a computer to install the model and that it was complex for them. Semi-structured interviews confirmed the data collected in resource allocation mapping, focused group discussions and APSIM sessions. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
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