With a rapidly growing world population and increased threats of climate change, Sub-Saharan Africa is most at risk for lower crop yields and facing hunger. Within Sub-Saharan Africa, Senegal has some of the highest levels of anemia and micronutrient deficiencies among women and children. Mungbean [Vigna radiata (L.) R. Wilczek] is a pulse crop that has recently been successfully introduced in Senegal to diversify a primarily cereal-based diet consisting of millet, maize, and rice. The potential for mungbean to be harvested as a leafy green as well as a pulse could allow for a more balanced and nutrient-rich diet. This diversification could help combat micronutrient deficiencies while earlier harvest of the leaves could help alleviate the pressures of the "hunger season." To understand the effects of leaf harvest on mungbean grain yield, yield components, and nutrition, a field trial was conducted in Blacksburg, Virginia for three consecutive years from 2020 to 2022. In a split-plot design, four frequencies of leaf harvest (0x, 1x, 2x, and 3x) on seven accessions of mungbean were tested in triplicate. The objective of this experiment was to determine if mungbean can be used as a dual-purpose crop as a leafy green vegetable without decreasing grain yield in Senegal. It was found that mungbeans could undergo up to two leaf harvest of immature leaves without reducing yield, total dry matter (TDM), or yield components. The harvested leaves were also found to be highly nutritious with 22.0% protein, 12.3% fiber and 8.5% ash with no significant differences between leaf harvest treatments. These results indicate that mungbean can be used as a dual-purpose crop for harvest as leafy greens and pulse in Senegal. Further, mungbeans were studied as a viable crop in southside Virginia. The objective was to evaluate the efficacy of mungbeans as an alternative crop to tobacco farmers in Virginia. Field trials were conducted on farmers' fields and at Virginia Tech's Southern Piedmont Agricultural Research and Extension Center in 2021 and 2022. A split-plot experimental design was used with early and late planting dates in the beginning and end of June as the whole plots and two commercially-available cultivars, Berken and OK 2000, as the sub-plots. Due to highly variable rain patterns in 2021 and 2022, as well as differing management practices, there were no consistent effects of genotype or planting date on yield, plant height, pods per plant, seeds per pod, or seed size. Yield ranged from 0.19 MT ha-1 to 1.18 MT ha-1 with an average yield of 0.84 MT ha-1 in 2021 and 0.38 MT ha-1 in 2022. Though there was variation in yield, across planting dates, cultivars, locations, and years, the highest yield was higher than global averages. It was concluded that while there is great potential with the growing mungbean market, more studies of breeding and supply chain issues and development of a production guide are needed for mungbean to be successful in Virginia. A final study compared soybean, edamame, and mungbean nutritional components and volatiles, two characteristics of importance to breeding objectives and food processing regarding plant alternative proteins. It was found that mungbean had significantly less protein (21.1%) than soy (36.2%) and edamame (38.3%). Mungbean also had lower fat (0.769%) compared to soy (13.5%) and edamame (14.0%). Analysis of aromatic compounds revealed that soybean, edamame, and mungbean each had unique profiles that could be advantageous to the production of specific plant protein foods. Overall, these studies demonstrate the growing importance and potential of mungbean in both Senegal and in the United States. / Master of Science / With a rapidly growing world population and increased threats of climate change, Sub-Saharan Africa is most at risk for lower crop yields and facing hunger. Within Sub-Saharan Africa, Senegal has some of the highest levels of anemia and micronutrient deficiencies among women and children. Mungbean [Vigna radiata (L.) R. Wilczek] is a pulse crop that has recently been successfully introduced in Senegal to diversify a primarily cereal-based diet consisting of millet, maize, and rice. The potential for mungbean to be harvested as a leafy green as well as a pulse could allow for a more balanced and nutrient-rich diet. This diversification could help combat micronutrient deficiencies while earlier harvest of the leaves could help alleviate the pressures of the "hunger season." To understand the effects of leaf harvest on mungbean grain yield, yield components, and nutrition, a field trial was conducted in Blacksburg, Virginia for three consecutive years from 2020 to 2022. In a split-plot design, four frequencies of leaf harvest (0x, 1x, 2x, and 3x) on seven accessions of mungbean were tested in triplicate. The objective of this experiment was to determine if mungbean can be used as a dual-purpose crop as a leafy green vegetable without decreasing grain yield in Senegal. It was found that mungbeans could undergo up to two leaf harvest of immature leaves without reducing yield, total dry matter (TDM), or yield components. The harvested leaves were also found to be highly nutritious with 22.0% protein, 12.3% fiber and 8.5% ash with no significant differences between leaf harvest treatments. These results indicate that mungbean can be used as a dual-purpose crop for harvest as leafy greens and pulse in Senegal.

The US Department of Energy has focused research efforts on developing switchgrass into a bioenergy feedstock, helping to offset the use of non-renewable fossil fuels and make the US more energy independent. Bacterial endophytes, which reside inside plant tissues, are proven to increase yield and stress resistance in a number of plants. The primary objective of this dissertation was to explore the use of endophytes to improve biomass yields of switchgrass on lands not suitable for food crops and better understand the underlying mechanisms of the plant-endophyte interaction. Integration of this research into K-12 STEM education to increase interest in plant sciences and create the next generation of scientists with the motivation to help solve the challenges facing society in the twenty first century was the objective of the outreach component of this project. Chapter one demonstrates the ability of Burkholderia phytofirmans strain PsJN to colonize switchgrass and promote plant growth under in vitro (approximately 50% higher), and growth chamber and greenhouse (48.6% higher biomass yields) conditions. The objectives of Chapter two were to determine stand establishment in the field with different nutrient levels. PsJN bacterization positively benefited growth and development of switchgrass seedlings in the field with both low and high nutrient content. Highly significant (p<0.001) stimulation of root and shoot growth, lateral root formation and number of tillers was recorded on soil with low fertility. PsJN bacterization also enhanced biomass accumulation during the two seasons of growth on both poor (p<0.001) and rich (p<0.05) soil, indicating the potential for the use of PsJN in a low-input switchgrass feedstock production system. Chapter three outlines differences in gene expression patterns upon bacterization, between the responsive cv. Alamo, and a non-responsive cv. Cave-in-Rock. Using EST microarrays and quantitative PCR up- and down-regulated genes were identified in both cultivars. One of the key genes identified was a member of the tau class, glutathione S-transferase (GST). GST enzymes are known to be involved in plants responses to stress. Using overexpression and knockout/knockdown techniques we demonstrated that GST is likely involved in the bacterization induced early plant growth promotion in switchgrass. Chapter four describes the potential for the utilization of beneficial bacterial endophytes capable of fixing atmospheric nitrogen in a free-living state in the development of low-input switchgrass feedstock production systems. Sphingomonas sp. strain NSL isolated from switchgrass tissue was able to grow on nitrogen free medium and stimulated growth of switchgrass cv. Alamo under nitrogen deficient conditions. The ability to fix atmospheric nitrogen was also moved to Burkholderia phytofirmans strain PsJN via horizontal gene transfer from the legume nodulating Burkholderia phymatum. The transformed PsJN was able to fix nitrogen and promote plant growth under nitrogen limited conditions. At every step of the research described in this dissertation efforts were made to include its elements into K-12 education. Chapter five describes four case studies aiming at the enhancement of youth interest in plant sciences in the socieoeconomically depressed areas of Southside Virginia. / Ph. D.

Agricultural nonpoint source nutrient pollution is the leading cause of water quality impairment in the Chesapeake Bay. Agroforestry, the integration of trees with crops or livestock production, or both, achieves production and conservation objectives on a single plot of land. Agroforestry is recognized by the Chesapeake Bay Program's strategy as a means of reducing nonpoint source pollution to improve water quality in the Bay. Despite this, agroforestry adoption remains limited and agroforestry is not recognized in Virginia's water quality trading program. To understand the potential of agroforestry nutrient credit trading, I studied the prospects of agroforestry from both a social and biophysical perspective. First, I surveyed 1,436 randomly selected landowners in four 5th level watersheds of the Chesapeake Bay in Virginia for a mixed-methods analysis of agroforestry adoption interest. Second, I used the Chesapeake Bay Assessment Scenario Tool to analyze the water quality implications of intermediate forest conversion scenarios on four initial agricultural land uses on respondent properties. From these studies, I recommend landowner characteristics, concerns, and objectives concerning agroforestry need to shape research and outreach messaging. Furthermore, agroforestry practices has potential to significantly reduce nonpoint source nutrient pollution in a manner that preserves agricultural production, but the terrestrial nutrient dynamics of agroforestry will need to be better captured in modeling to aid in the design of these systems and to generate adequate and fair crediting standards. / Master of Science / Pollution from farming is one of the largest threats to the health of the Chesapeake Bay. Retiring farmland is one method of reducing pollution. Water quality trading is a new strategy to encourage farmers to retire farmland. As part of this strategy, regulated polluters, such as a property developer, can offset their pollution by paying farmers to retire farmland and plant trees. Agroforestry practices involve the production of trees with crops or livestock on the same piece of land. These integrated systems could reduce pollution to the Bay while allowing farmers to continue farming, but few farmers have been willing to adopt these practices. Additionally, although agroforestry is recognized as part of a larger strategy to clean up the Bay, currently it is not recognized by Virginia's water quality trading program. To understand how agroforestry and water quality trading could help restore the bay, we asked farmers about their interest in agroforestry and used a computer program to estimate how increasing tree coverage on farms could reduce pollution to the Bay. We found that agroforestry could reduce a significant amount of pollution, while allowing farmers to continue farming to some degree. Though, knowledge of how agroforestry reduces pollution and technology that can assist in the design of these systems will need to advance for two reason. First, technology based on a better understanding of how agroforestry reduces pollution will allow us to properly credit farmers for adopting agroforestry. Second, it will assist in designing these systems. Outreach, research, and development of agroforestry should be informed by landowner perceptions, concerns, and objectives.

Achieving food security in Bangladesh remains an arduous task, as the country struggles with several challenges. These challenges include the effects of climate change, occurrence of natural disasters, lack of proper access to credit facilities, and the anthropogenic modification of the agricultural landscape. The vulnerability of agricultural practice in the northern regions to drought, flood, and riverbank erosion, as well as the increased occurrence of coastal surges, waterlogging, cyclones, coastal floods, shrimp aquaculture and soil salinity in the southwestern region, poses a major threat to Bangladesh’s attainment of food security. In this context, we analyze the anthropogenic factors such as land use and land covers change, waterlogging, soil salinity and agriculture credit facilities which combinedly affecting the food security in the southwestern and northern regions of Bangladesh. Findings revealed that in the southwestern regions agricultural lands have decreased because of an increase in shrimp farming. Waterlogging and soil salinity are increasing due to increased shrimp farms also for poor drainage infrastructure and human modification. In our studied three interior coastal districts agricultural land in 2011 was 19,657.12 acres, 12,750.14 acres and 38,774.70 acres which changed to 12,668.70 acres (-36%), 7,151.27 acres (-44%) and 32,809.30 acres (-16%) in 2021. By utilizing CMIP5 data and RCP 4.5 scenarios, we also projected temperature and precipitation in the northern and southwestern regions for the years 2030, 2040, 2050, and 2060 the results indicated substantial variations between pre- and post-monsoon temperatures, with projected maximum, minimum, and mean temperature differences of > 5°C, < 3°C, and < 4°C, respectively. Structural equation modeling reveals that shrimp farming has a significant negative impact on farmers' income and dietary habits. Land use and land cover analyses in the exposed coastal area indicate that agricultural land has decreased by 321.83 km2 over more than thirty years. Structural equation modeling also revealed that agricultural credit influences the food security of marginal farmers. Our study serves as a guide for policymakers in Bangladesh and other developing countries, providing insights into the implementation of effective and sustainable agriculture and climate policies to address the constraints and challenges associated with food security.

Thesis (MScAgric)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Thesis (MScAgric)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: In South Africa, sustainable land use and management is paramount as the country’s agricultural natural resources are diverse, complex and vulnerable to degradation. To realise sustainable agricultural production and development, an agro-ecosystem-specific approach entailing soil, water and nutrient conservation agricultural practices is imperative. Conservation Agriculture is one of the agricultural production method that can be employed to ameliorate and prevent the degradation of South Africa’s agricultural land. The major aim of this study was to investigate how the uptake and adoption of conservation agriculture is influenced by economic policies and instruments in South Africa. To achieve this, an interactive research approach was followed initially involving an extensive literature review before scientific and empirical analysis was conducted. Firstly it was noted in the study that currently there is not any specific policy for conservation agriculture that has been promulgated in South Africa, but however there are a number of policies (i.e. Climate change policy, Carbon Tax policy, Land Reform policy, Trade policy, Water policy, Food and nutritional security policy, NEMBA regulations, CRDP, CARA, Organic production policy, Policy on Agriculture in sustainable development and the Environmental policy) that have been drafted which have the potential to positively influence the uptake and adoption of conservation agriculture by farmers across all the farming typologies (i.e. small scale, emerging and commercial farmers). The afore-mentioned policies were described and analysed with the purpose of establishing how they affect conservation agriculture using analysis criteria adopted from the field of political sciences. Criteria of effectiveness, unintended effects, equity, cost, feasibility and acceptability were constantly employed. In this regard, all the policies were tested to see how they affect conservation agriculture and to check if there was any alignment and harmonisation within the policy environment. It was found in this study that an alignment of the aforementioned policies is imperative in order to make the policies politically and administratively feasible which will lead to the swift implementation and effectiveness of the policies in meeting their core objectives. On this basis, it was deduced that the aforementioned policy mix has the potential to advance the uptake and adoption of conservation agriculture to further contribute to an enhanced food security and a sustainable resource base in South Africa. The policy mix analysed in this study, is however under specific constraints. These were identified and subsequently recommendations were made to ameliorate these constraints, in order to make the policies align with each other and to maximise the contribution of the policies towards the advancement of conservation agriculture in South Africa. / AFRIKAANSE OPSOMMING: Volhoubare grondgebruik en bestuur is belangrik in Suid-Afrika as gevolg van diverse, komplekse en kwesbare natuurlike hulpbronne wat maklik degradeer. As gevolg hiervan moet volhoubare bewaringspraktyke gevolg word wat spesifiek is tot die grond, water en voedingswaarde kompleks van verskillende boerdery-omgewings gevolg word. In hierdie opsig is bewaringsboerdery een metode wat ontplooi kan word om grond-degradasie te voorkom. Die hoofdoel van hierdie studie was dus om te bepaal tot watter mate die aanvaarding van bewaringsboerdery praktyke deur ekonomiese beleid en -instrumente beïnvloed word. Hiervoor is ʼn interaktiewe benadering gevolg tussen ʼn uitgebreide literatuurstudie en ʼn wetenskaplike en empiriese analise. Die eerste belangrike bevinding is dat daar tans geen formele staatsbeleid oor bewaringsboerdery in Suid-Afrika bestaan nie, maar daar is wel verwante beleidsuitsprake (oor klimaatsverandering, die koolstof belasting, grondhervorming, internasionale handel, voedselen voedingsbeleid, NEMBA regulasies, CRDP, CARA, beleid oor organiese produksie, beleid oor volhoubare landbou-ontwikkeling en omgewingsbeleid) wat wel die aanvaarding van bewaringsboerdery praktyke kan versnel. Hierdie stel van beleidsuitsprake is beskryf en ontleed deur middel van ʼn analitiese raamwerk ontleen aan die politieke wetenskappe om hulle potensiële impak op bewaringsboerdery. Die spesifieke kriteria waarop gekonsentreer is sluit in doeltreffendheid, ongewensde gevolge, regverdigheid, koste, implementeerbaarheid en aanvaarbaarheid. Die doel van laasgenoemde was nie slegs om vas te stel hoe hulle bewaringsboerdery beïnvloed nie, maar ook of daar belyning bestaan tussen die verskillende beleidsuitsprake, omdat sulke belyning krities is tot suksesvolle implementering. Daar is dan bevind dat die huidige stel beleidsuitsprake wel die potensiaal het om by te dra tot die aanvaarding van bewaringsboerdery, en dus tot die volhoubare bestuur van Suid-Afrika se hulpbronne. Hierdie bestaande beleidsraamwerk word egter onderwerp aan spesifieke beperkings. Laasgenoemde is dan geïdentifiseer, en is aanbevelings gemaak om dié beperkings aan te spreek om sodoende beter belyning te kry en dus om hulle bydrae tot volhoubare boerdery te bevorder.

Few sectors of the economy are as influential to the environment and are as susceptible to the influence of environmental changes as agriculture. This dissertation contains three chapters that examine agriculture as the primary interface at which human and nature interact. Primarily, I explore how policy support for financial risk management tools can have substantial impact on agricultural production choices via moral hazard and selection problems. While mitigating agricultural production risk, these supports also impact the environment via induced change in production choices. This dissertation contributes to U.S. agriculture policy and pollution management literature and insurance literature on moral hazard and selection problems. By examining the case of Federal Crop Insurance Program in the United States, this dissertation explores input choice changes caused by changes in government support for crop insurance. I proposed theoretical mechanism through which increasing use of financial risk management strategy can influence input decisions with risk implications, and tested these theories empirically with county-level panel data. Empirical tests showed that there were substantial decreases in irrigation investment and fertilizer application due to crop insurance offering. Policy implications on water scarcity and non-point source pollution management and on federal support to crop insurance market are discussed.

No description available.

Thesis (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: This project aimed at enhancing the net benefit in production systems. It took a holistic approach to evaluate the potential interactions of herbaceous legumes in relation to weed dynamics, soil fertility and livestock management in the crop-livestock system in Nigeria. The project was carried out between 2000 and 2002 in two localities. These were the National Animal Production Research Institute (NAPRI) at Zaria in the northern Guinea savannah and the International Institute of Tropical Agriculture (IITA) at Ibadan in the derived savannah. The main experiment was carried out in the northern Guinea savannah, while the secondary experiments were simultaneously conducted in the derived savannah and the northern Guinea savannah. The experimental design for the three experiments reported in this thesis is a splitsplit plot, fitted into randomised complete block design (RCBD), with four replications. Main plot treatments were herbaceous legumes, namely Vigna unguiculata, Arachis hypogaea, Glycine max, Aeschynomene bistrix, Centrosema pascuorum, Stylosanthes guianensis and natural vegetation. Sub-plot treatments were management systems (1) M1, 'residues left in the field'; (2) M2, 'residues taken out of the field' and (3) M3, 'residues fed to livestock, manure/urine/refused feeds returned'. Sub-plot treatments were administered in a sequence following rotational fallows of herbaceous legumes and natural vegetation. However, plots in the secondary experiments were not subdivided before the cropping of maize in 2002, and for logistical reasons only two sub-plot treatments, M1and M2, are featured in this experiment. Herbaceous legumes were established at the start of the rainy season, approximately in June, in 2000, 2001 and 2002. All herbaceous legumes received single super phosphate (SSP) at 20kg ha" P20S at planting, while minimum hand weeding was done to maintain pure legume stands during the establishment phase. Forage biomass was higher in the derived savannah than in the northern Guinea savannah. Similarly, higher forage yields were observed after two consecutive years of legume fallow and natural vegetation, compared to the first year plots. Grain yield for Glycine max was consistently higher than for the other two grain legumes in 2001 and 2002. Chemical analysis of herbaceous legumes and natural vegetation showed that crude protein values ranged between 11.2% to 17.3% for legumes; that was significantly (p<0.05) higher than the 8.6% value found for natural vegetation. Moreover, all herbaceous legumes and natural vegetation, except Arachis hypogaea, had dry matter digestibility values of more than 30%. Maize grain and stover yields on herbaceous legumes fallowed plots were evaluated and compared with those for natural vegetation. Results in 2001, i.e. after a one-year fallow with legumes, indicated that the dry matter of maize grain and stover yields in the Stylosanthes guianensis plots were higher among the forage legumes. Arachis hypogaea gave the highest grain and stover yields among the grain legumes in the northern Guinea savannah. Results in 2002, i.e. after a two-year fallow, also showed that the productivity of maize planted on Arachis hypogaea and Glycine max fallowed plots were consistently higher across the three management systems tested in the Centrosema pascuorum, Glycine max, Aeschynomene histrix, Vigna unguiculata and least weight gain was recorded for the natural vegetation. Objective functions in linear optimisation, or linear combinations in algebra, used to link dynamic processes in livestock production (Iiveweight gain) with the dynamic processes in soils (soil nitrogen), weeds (weed biomass), herbaceous legumes (legume biomass) and crop production (maize grain and stover yields) under varying management systems took the form: Management system 1, Y, = f (XI, Xz, x4); Yr= 0 Management system 2, Y, = f (x" x2); Yz = 0 Management system 3, Y, = f (XI, Xz, xl); Yz= f (XI, Xz, X4. x5) Where (1) (2) (3) Y1 = Crop in kg; Y2 = Livestock weight gain in kg; X1= Weed in kg; X2 = Soil N g kg-1; X3 = Livestock compost in kg; N= Herbaceous legumes in kg; X5 = Maize stover in kg, for the three management systems considered in this experiment. Deductions from these equations showed that Aeschynomene histrix performed better under M1, i.e. when legumes residues were left on the field. Natural vegetation performed better than the herbaceous legumes under M2, i.e. when legumes residues were exported out of the field. However, the presence of manure in M3 enhanced soil fertility in the system and improved the overall productivity across all the legumes and natural vegetation. Overall rankings, conducted by pooling all components in the system, indicated that Glycine max performed best among the legumes, followed by Stylosanthes guianensis and Arachis hypogaea, which ranked second and viithird respectively. In relation to the specific legume groups, Stylosanthes guianensis performed better than the other two forage legumes, while Glycine max also performed better than the other two grain legumes tested. We can see from these on-station research results that there are indications of positive opportunities for improving overall productivity and resources. This can be done through integrating and complementing crop and livestock production, to provide a sustainable intensification of agriculture. / AFRIKAANSE OPSOMMING: Die studie is uitgevoer om die potensiële wisselwerking van kruidagtige peulplante met onkruiddinamika, grondvrugbaarheid en veebestuur te evalueer. Die hoofeksperiment in die "Northern Guinea Savannah" is vanaf 2000 tot 2002 uitgevoer by die "National Animal Production Research Institute" (NAPRI) in Zaria, Nigerië. Die twee sekondêre eksperimente is gelyktydig in Zaria en by die "International Institute of Tropical Agriculture" (liTA) naby Ibadan in die "Derived Savannah" uitgevoer. Die eksperimentele ontwerp was 'n dubbel gesplete perseelontwerp gepas in 'n volledig ewekansige blokontwerp met vier herhalings. Die hoofkomponente was die kruidagtige peulplante naamlik: Vigna unguiculata, Arachis hypogaea, Glycine max, Aeschynomene histrix, Centrosema pascuorum, Stylosanthes guianensis en natuurlike plantegroei. Die gekose peulplante is potensieel aangepas vir uiteenlopende omgewings en word dikwels na verwys as "'n mandjie van opsies". Subperseel behandelings was (1) peulplant gevestig en gelaat op die land - M1; (2) peulplant gevestig, geoes en weggeneem uit die land M2 en (3) peulplant gevestig, geoes, vir vee gevoer, mis/urine/vermorste voer terug na die land - M3. Die dubbel gesplete perseel behandelings is toegedien in 'n sekere volgorde nadat die peulplant rusoes/braak toegepas is. In die eerste jaar is die kruidagtige peulplante geplant op die hoofperseel van 25m by Sam. In die tweede jaar is die hoofperseel verdeel in twee persele waar onderskeidelik peulplante en mielies gevestig is terwyl daar in die derde jaar 'n verdere verdeling was wat gelei het tot verskillende gewasrotasiestelsels, nl. Peulplant-peulplant-mielies, peulplant-mielies-peulplant en peulplant-mielies-mielies. Parameters wat insluit planthoogte, -wydte en persentasie grondbedekking van die kruidagtige peulplante is tweeweekliks gemeet op vier 1M2 persele wat ewekansig oor elke hoofperseel versprei is in beide gebiede waar die studie uitgevoer is. Resultate het getoon dat die kruidagtige peulplante wat getoets is potensiële kandidate is vir insluitings in gewas/weiding rotasiesteiseis. Alhoewel voerproduksie hoër was in die "derived savannah" as in die "northern Guinea savannah", het die prestasie van die peulplante in die noordelike savannah gevarieer met die gewasproduksiestelsels. Hoër opbrengste is gerealiseer na twee opeenvolgende jare van oesrus met peulplante vergeleke met die eerste jaar waar daar geen residuele effek van die peulplante was nie, en die laaste jaar wat deur 'n mielie-oes voorafgegaan is. Biomassa opbrengste na twee jaar van aanhoudende verbouiing was die hoogste vir S. guianensis en die laagste vir A. hypogea. Ruproteien inhoud van die kruidagtige peulplante het gewissel van 170 g kg-1 DM in A. hypogea tot 62.4 g kg-1 DM in A histrix. Graanproduksie deur G. max was deurlopend hoër in 2001 en 2002 vergeleke met die twee ander graanproduserende peulplante nl. V. unguiculata en A. hypogea. Die voerproduksie in 2002 was heelwat hoër as die vorige jaar. Rotasie effekte op mieliegraan en oesreste na peulplante is vergelyk oor die dubbel gesplete persele (areas met verskillende oesruslengtes) om die ximplikasies van hulle residuele effek op grondvrugbaarheid verbetering en onkruid dinamika te bepaal. Mielie-opbrengs na een jaar van rusoes toon hoër waardes op persele wat onder kruidagtige peulplante was vergeleke met natuurlike plantegroei. Net so was die opbrengs deurlopend hoër op persele waar daar graan peulplante was as waar daar voer peulplante was. Oor die algemeen was die waardes hoër vir G. max, gevolg deur A. hypogea, A. histrix, C. pascuorum, V. unguiculata, S. guianensis en die laagste vir natuurlike plantegroei. In terme van die bestuurstelsels, het persele wat kompos ontvang het (M3) beter as die ander twee bestuurstelsels presteer (2.6 Mg ha" mieliegraan). Produksie van mieliegraan en oesreste na twee opeenvolgende jare van mielieverbouing was die hoogste na G. max (7.2 Mg ha" mieliegraan), gevolg deur die A. histrix perseel en die laagste op S. guianensis persele. Algemene waarnemings oor die twee subpersele wat met mielies beplant was in 2002 het getoon dat mielies beter presteer het op persele wat twee opeenvolgende jare met peulplante beplant was. Onkruidsamestelling en verspreiding is in beide die peulplante en natuurlike plantegroei gemeet. Grond vir saadbankontledings is op diagonale transekte in 0.5m by 0.5m kwadrate gemonster. Grondmonsters is ge-analiseer vir pH, totale stikstof, organiese koolstof, fosfor, kalsium en magnesium. Hierdie parameters is gebruik in 'n meervoudige regressie ontleding om hulle effek op onkruidspesievoorkoms te bepaal. Onkruidgetalle in lande na In rusoes het In deurlopende hoër vlak van besmetting getoon op die natuurlike plantegroei persele as op die peulplant persele. Die prestasie in terme van onkruidonderdrukking was in dalende volgorde: S. guianensis, C. pascuorum, V. ungucuilata, G. max, A. hypogaea en A. histrix. Die onkruidsamestelling het verskilonder die verskillende behandelings en dit het ook met tyd verander in dieselfde behandelings. In Bykomende eksperiment met die peulplante is uitgevoer om hulle effek op inname en groei van skape, asook die effek op kompos wat gemaak is van vermorste materiaal en uitskeidings van die skape, te bepaal. Droë materiaal verteerbaarheid was hoog vir S guianensis, G. max en A. histrix terwyl die laagste syfer verkry is by A. hypogea (177.6 g kg-1 DM). Ramme wat met kruidagtige peulplante gevoer is het beter presteer as die wat met natuurlike plantegroei gevoer is. Ramme wat met A. hypogaea gevoer is, het In gemiddelde daaglikse toename (GOT) getoon van 85.7 g daq", gevolg deur S. guianensis, C. pascuorum, G. max, A. histrix, V. unguiculata en laaste natuurlike plantegroei. Bykomende ontledings was gemik daarop om objektiewe funksies af te lei om dinamiese prosesse in vee (massatoename) met dinamiese prosesse in grond (grond N), onkruid (onkruidmassa), kruidagtige peulplante (peulplantmassa) en mielies (mieliegraan en oesreste massas) onder verskillende bestuurstelsels te verbind. In In poging om objektiewe funksies xiivan die verskillende komponente van die studie te bepaal, is die volgende lineêre funksies vir die drie bestuurstelsels oorweeg nl. Bestuurstelsel1. Yl = f (Xl, xz, x.); Yz= 0 Bestuurstelsel 2, Yl = f (Xl, Xz); Yz= 0 Bestuurstelsel3, Yl = f (Xl, X2, Xl); Yz= f (Xl. Xz. x.. les) Waar (1) (2) (3) Y1 = Oesopbrengs in kg; Y2 = Daaglikse massatoename in kg; X1 = Onkruidmassa in kg; X2 = Grond N in g kg-1 ; X3 = Kompos in kg; X4 = Kruidagtige peulplante in kg; X5 = Mieliereste in kg. Onder bestuurstelsel 1, het A. histrix beter as die ander gewasse presteer, terwyl natuurlike veld beter presteer het onder bestuurstelsel 2. Dit is 'n aanduiding dat bestuurstelsel 2 nie volhoubaar is nie. Die derde bestuurstelsel verteenwoordig volle integrasie van gewas en vee produksiestelsels. Die teenwoordigheid van mis in die stelsel het grondvrugbaarheid verbeter en algemene produktiwiteit verbeter. Hierdie resultate dui aan dat daar geleenthede is om algemene produktiwiteit te verbeter deur integrasie en komplementering van gewas- en veeproduksiestelsels om volhoubare intensifikasie van landbou te bereik.

This study describes and analyses cattle management in Tlokweng Sub District. Two methods were used. The two are households' interviews and a system dynamics STELLA model called the Rain Land Cattle model, which was adapted from the 1990 Braat and Opschoor model. Ninety households, 61% of the 1991 households in the study area, were interviewed. All the households had arable fields and fifty nine percent had cattle. The Rain Land Cattle model uses 52 parameters to predict several cattle management factors, which include rainfall, stocking rate, total grazing area and livestock water availability. The model explored the use of parameters to relate water availability to grazing area and show the seasonality of the water source. Sixty two percent of the household had access to an ideal livestock water source. Cattle graze from the 5000 hectares of arable area for four months after harvesting. This seasonal grazing, optimises the uses of the grazing resource in the small sub - district. The model simulated a S and 20 percent permanent grazing land loss. Such a grazing land loss, increased the stocking rate, decreased the carrying capacity and cast doubt on sustainable cattle production. The model shows that the stocking rate is chronically greater than the carrying capacity. Most households acknowledged that there was land pressure due to the loss of grazing land. A drier climate scenario will lead to a loss of seasonal grazing, reduced livestock water, which will increase cattle emigration and cause cattle management problems. The model is exploratory; it needs to be validated. It is easily understood, adaptable to other communal areas, and identifies the most influential factors in cattle management. The livestock water parameters functioned reliably in the model. Based on the understanding of the cattle management derived from this study, more fenced grazing land is unlikely to improve the cattle management in the area.