Six combinations of grazing, tillage, and herbicides were studied during 2 yr in a randomized block design to determine alfalfa (Medicago sativa) survival, corn (Zea mays) plant populations and corn growth in an alfalfa-corn rotation. Alfalfa was overseeded with rye (Secale cereale) in autumn prior to planting corn in spring of each year. Treatments were 1) non-grazed control with standard chemical treatments for no-till establishment of corn, 2) grazing alfalfa, then grazing rye until corn planting followed by dicamba application, 3) alfalfa grazing plus glyphosate prior to corn planting, 4) treatment 3 plus grazing prior to rye jointing, and 5) alfalfa grazing plus autumn application of glyphosate, 6) alfalfa grazing plus autumn disking (no herbicides). Grazing until corn planting decreased (P<0.05) alfalfa stands and rye biomass, but increased (P<0.05) corn plant populations and soil bulk density compared to shorter grazing periods. Grazing prior to rye jointing increased (P <0.05) soil bulk density and corn plant populations, and decreased (P<0.05) rye biomass compared to no spring grazing. Autumn disking decreased (P<0.05) bulk density, but generally provided less (P<0.05) control of alfalfa compared to autumn application of glyphosate. Autumn disking and glyphosate application (Trts. 5 and 6) increased (P<0.05) rye biomass compared to no autumn treatment (Trts. 3 and 4). Applying glyphosate prior to corn planting (Trts. 3 and 4) improved (P<0.05) corn populations and growth compared to autumn glyphosate or disking (Trts. 5 and 6) and was similar to conventional no-till establishment (Trt. 1). Herbicides were necessary to completely kill alfalfa, but grazing reduced TNC in alfalfa roots and alfalfa plant persistence. / Master of Science

Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The aim of this study was to determine the effect of a grass herbicide, a broadleaf herbicide with some grass control capabilities, method of tillage (tine and no-tillage) at planting of wheat as well as different medic cultivars on the regeneration, dry matter (OM) production and quality of a medic pasture. The trial was conducted at Langgewens experimental farm in the Swartland wheat producing area. Nine medic cultivars of three different species were evaluated after being sprayed with either haloxyfop-R-methyl (HAL) ester or imazamox (IMI) and subjected to either a tine tillage or a no tillage treatment at planting of wheat. Soil samples were taken during January 2000 to determine the size of the medic and weed seedbank as well as the degree of dormancy in the medic seeds, while OM samples were taken throughout the growing season to determine the OM production of the different medic cultivars and weed species. OM samples taken during October 1998 on the same pasture, were used to determine the crude protein (CP) and neutral detergent fibre (NOF) content of the pasture. The samples were subjected to in vitro digestion and the digestibility of pasture CP (OCP), NOF(ONOF) and DM (DOM)were determined. Results showed that seedling establishment differed between cultivars used, herbicide treatments applied as well as the crop stage in the rotation. The cultivars produced more seedlings where IMI was applied compared to HAL as well as where the area consisted of two year pasture compared to one year pasture (1998) and one year wheat (1999). After a year of pasture and a year of wheat, cultivars Sephi and Paraggio produced the most seedlings, while Caliph and Orion produced the least. Caliph however, showed a very high degree of seed dormancy while Orion's low seedling establishment was due to its sensitivity to the IMI herbicide used. Little difference was found between the nine cultivars early in the season (July - August) with regard to cumulative OM production, except for Orion, whose growth was severely damaged by the IMI treatment. At the end of the growing season (October), the cultivar Caliph's cumulative OM production (2010.1 kg/ha) was significantly higher than all the other cultivars, except for Parabinga (1053. 4 kg/ha). Oifferent pasture samples, of which the botanical composition was known, was analysed for CP, NOF, OOM, OCP and ONOF. There was no significant difference in pasture composition during 1998 but variation in the pasture composition did however cause the IMI treatment, compared to the HAL treatment, to have a lower ONOFand OOMcontent. A modelling procedure was used to predict the pasture quality parameters (CP, NOF, OOM,OCP and ONOF) from the pasture composition (medic hay, medic pods, grassy and broadleaf weeds). This prediction of CP, NOF, OOM, ONOF and OCP from the pasture components had a relative low accuracy (49 -74.1 %) and a further refinement of this model for possible use on farms in order to improve grazing management and animal production is advised. In conclusion it could be said that broadleaf weed control caused a definite increase in medic seed and OMproduction, but Orion should not be used with an IMI herbicide. All the cultivars, except for Orion, produced enough seedlings up to the second year to ensure sustainability of the medic pasture. All the cultivars, except for Orion, produced a sufficient amount of OM early in the growing season. Caliph however, produced by far the most OM later in the growing season. A reduction of broadleaf weeds and medic pods will increase the digestibility of NOFand OMand therefore increase the quality of the pasture. Pods however are an important part of summer forage and the aim should therefore rather be to reduce the number of broadleaf weeds in the pasture. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van 'n gras en breëblaar onkruiddoder (wat sekere grasse beheer), metode van bewerking tydens die saai van koring asook nege verskillende medic kultivars op die regenerasie, droë materiaal produksie en kwaliteit van medic weidings te bepaal. Die proef is gedoen op Langgewens proefplaas wat geleë is in die Swartland koring produserende gebied. Nege medic kultivars is geëvalueer nadat die weiding met of haloxyfop-R-metiel ester (HAL) of imazamox (IMI) onkruiddoders gespuit is en onderwerp is aan of 'n vlak tand of geen bewerking tydens die saai van koring. Grondmonsters is geneem in Januarie 2000 om die grootte van die medic en onkruid saadbank asook om die graad van dormansie in die verskillende medic kultivars se sade te bepaal. Droë materiaal monsters is gedurende die 2000 groeiseisoen geneem om die droë materiaal produksie van die verskillende medic kultivars asook onkruid spesies te bepaal. Droë materiaal monsters is gedurende Oktober 1998 geneem en gebruik om die ruproteïn (CP) en neutraaloplosbare vesel (NDF) inhoud van die weiding te bepaal. Die monsters is in vitro verteer en die verteerbaarheid van CP (OCP), NDF (ONOF) en droë materiaal (DOM) is bepaal. Resultate wys dat saailing vestiging verskil tussen die verskillende kultivars wat gebruik is, verskillende onkruiddoder behandelings asook die stadium van die weidings/koring. Die kultivars het meer geproduseer waar die weiding met IMI behandel is in vergelyking met waar HAL toegedien is, asook waar koring nog nie gesaai is nie. Na 'n jaar van weiding en 'n jaar van koring, het die kultivars Sephi en Paraggio die meeste saailinge, en Caliph en Orion die minste saailinge gehad. Caliph het egter 'n hoë graad van dormansie in sy saad getoon, terwyl die swak vestiging van Orion die gevolg is van die kultivar se hoë sensitiwiteit teenoor IMI. Min verskil is gevind tussen die nege kultivars, vroeg in die groei seisoen (Julie - Augustus), wat kumulatiewe droë materiaal produksie betref, behalwe vir Orion wat erg beskadig is deur die IMI behandeling. Aan die einde van die groeiseisoen (Oktober 2000) was die kumulatiewe droë materiaal produksie van die kultivar Caliph (2010.1 kg/ha) betekenisvol hoër as al die ander kultivars behalwe vir Parabinga (1053.4 kg/ha). Weidingsmonsters, waarvan die botaniese samestelling bekend was, is ontleed vir CP, NDF, DDM, DCP en DNDF. Daar is geen betekenisvolle verskille gevind in die botaniese samestelling van die weidingmonsters geneem in 1998 nie,maar die variasie in botaniese samestelling het veroorsaak dat IMI in vergelyking met HAL 'n laer DNDF and DDM inhoud het. 'n Model is opgestel wat die weidingskomponente (medic hooi, medic peule, gras en breëblaar onkruide) gebruik om die kwaliteits parameters (CP, NDF, DDM, DCP en DNDF) van die weiding te skat. Hierdie skatting van CP, NDF, DDM, DCP en DNDF deur van die weidingskomponente gebruik te maak het 'n relatiewe lae akuraatheid gehad (49 -74.1 %) en verdere verfyning van hierdie model vir moontlike gebruik op plase, ten einde weidings bestuur en diere produksie te verbeter, word voorgestel. Die gevolgtrekking kan gemaak word dat breëblaar onkruidbeheer 'n definitiewe verbetering in die medic saailing en droë materiaal produksie van die medies te weeg gebring het, maar die kultivar Orion behoort nie saam met 'n IMI gebruik te word nie. AI die getoetste kultivars, behalwe Orion, het voldoende saad oorlewing vertoon tot en met die tweede jaar van die rotasie om lewensvatbaarheid van die sisteem te verseker en alle kultivars, behalwe Orion, het voldoende droë materiaal produseer vroeg in die groeiseisoen. Caliph het egter laat in die groeiseisoen by verre die meeste droë materiaal geproduseer. 'n Vermindering in die hoeveelheid breëblaar onkruide en peule in die weiding sal tot 'n verhoging in die verteerbaarheid van NDF en DM lei en dus 'n verhoging in die kwaliteit van die weiding tot gevolg hê. Peule is egter 'n belangrike bron van voedsel aan weidende diere gedurende droë somermaande en die verbetering van weidings moet eerder gedoen word deur te poog om breëblaar onkruide te beheer.

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This study was done during 2010 and 2011 as a component study within a long-term crop rotation/soil tillage trial that was started in 2007 at the Langgewens Research Farm near Moorreesburg in the Western Cape Province of South Africa. The aim of this study was to determine the effect of crop rotation and soil tillage on the soil moisture content, mineral-N levels of the soil, leaf area index, chlorophyll content of the flag leaf, biomass production, grain yield and grain quality of spring wheat (Triticum aestivum L). The experimental layout was a randomised complete block design with a split-plot treatment design replicated four times. Wheat monoculture (WWWW), lupin-wheatcanola- wheat (LWCW) and wheat-medic (McWMcW) crop rotation systems were included in this study and allocated to main plots. This study was confined to wheat after medic/clover, wheat after canola and wheat monoculture. Each main plot was subdivided into four sub-plots allocated to four tillage treatments namely: Zero-till (ZT) – soil left undisturbed until planting with a star-wheel planter No-till (NT) – soil left undisturbed until planting and then planted with a no-till planter Minimum-till (MT) – soil scarified March/April and then planted with a no-till planter Conventional-till (CT) – soil scarified March/April, then ploughed and planted with a no-till planter. Soil samples were collected every two weeks from just before planting until before harvest, from which gravimetric soil moisture and total mineral-N (NO3--N and NH4+-N) were determined. Plant samples were collected every four weeks until anthesis, starting four weeks after emergence. From these leaf area index and dry-matter production were determined. Chlorophyll content and light interception were measured at anthesis. At the end of the growing season the total biomass, grain yield and grain quality was determined. Crop rotations which included medics (McWMcW) or canola/lupins (LWCW) led to higher mineral-N content of the soil at the start of the 2011 growing season when compared to wheat monoculture, but did not have an effect on soil moisture. Conservation tillage (minimum- and no-till) practices resulted in higher soil moisture whilst conventional-till resulted in the highest mineral-N content for 2010. There was however no differences in mineral-N content between tillage methods for 2011, whilst soil moisture content was affected in the same way as the previous year. Both crop rotation and tillage influenced crop development and biomass production. In general, increased soil disturbance together with wheat after medics and wheat after canola resulted in better development of the wheat crop with regards to dry matter production and leaf area index. The positive effect of medic and canola rotations was also evident on chlorophyll content and light interception. Grain yield was positively influenced by wheat after medics and wheat after canola, with both systems out-yielding wheat monoculture in 2010 and 2011. Minimum- and no-till resulted in the highest grain yield in both years. Crop rotation and tillage practice showed no clear trends with regards to grain quality. This illustrated the important effect of environmental conditions during grain-filling. Environmental factors such as rainfall and temperature had significant effects in both years of the study, but the importance and advantages of crop rotation, especially with a legume crop such as medics included, was evident even though this component study was done early in terms of the long-term study. The positive effect of implementing conservation tillage practices such as minimum- and no-till were also clearly shown in results obtained throughout this experiment. / AFRIKAANSE OPSOMMING: Die studie is gedurende 2010 en 2011 uitgevoer as ‘n deelstudie van ‘n langtermyn grondbewerking- en wisselbouproef op die Langgewens proefplaas naby Moorreesburg in die Wes-Kaap Provinsie van Suid-Afrika. Die doel van hierdie studie was om die effek van grondbewerking en wisselbou op grondvog, minerale stikstof in die grond, blaaroppervlakindeks, chlorofilinhoud van die blare, graanopbrengs en -kwaliteit van lente koring (Triticum aestivum L) te kwantifiseer. Die eksperiment is uitgelê as ‘n volledig lukrake blokontwerp met ‘n verdeelde perseel ontwerp met vier herhalings. Wisselboustelsels wat aan hoofpersele toegeken is sluit koring monokultuur (WWWW), lupien-koring-kanola-koring (LWCW) en medic-koring (McWMcW) in. Grondbewerking is toegeken aan subpersele. Die grondbewerkingsbehandelings het ingeslui: Zero-bewerking (ZT) – die grond is onversteurd gelaat en koring is met ‘n sterwielplanter geplant, Geen-bewerking (NT) – die grond is onversteur gelaat tot en met planttyd waar koring met ‘n geenbewerking (no-till) planter geplant is, Minimum-bewerking (MT) – die grond is in Maart/April met ‘n tandimplement bewerk en met ‘n geen-bewerking planter geplant, Konvensionele-bewerking (CT) – die grond is in Maart/April met ‘n tandimplement bewerk die grond is in Maar/April geploeg met ‘n skaarploeg en met ‘n geenbewerking planter geplant. Grondmonsters is elke twee weke versamel van net voor plant tot net voor oes. Vanaf die versamelde monsters is die grondwaterinhoud grawimetries bepaal en ook die totale minerale stikstofinhoud (NO3--N en NH4+-N). Plantmonsters is vierweekliks versamel beginnende vier weke na opkoms tot en met antese. Blaaroppervlakindeks en biomassaproduksie is bepaal. Die chlorofilinhoud en ligonderskepping is tydens antese bepaal. Aan die einde van die groeiseisoen is totale biomassa, graan opbrengs asook graankwaliteit bepaal. Wisselboustelsels, wat medics (McWMcW) of kanola/lupine (LWCW) ingesluit het, het ‘n hoër minerale stikstofinhoud aan die begin van die 2011 groeiseisoen getoon. Wisselbou het egter geen effek op grondvog gehad nie. Minimum- en geenbewerking het ‘n hoër grondvoginhoud tot gevolg gehad, terwyl die persele onder konvensionele bewerking ‘n hoër minerale stikstof inhoud gehad het in 2010. In 2011 was daar geen verskille in die minerale stikstofinhoud tussen verskillende die bewerkingsmetodes nie en grondvog gedurende 2011 is op dieselfde wyse as in 2010 beïnvloed. Beide wisselbou en bewerkingsmetode het ‘n invloed gehad op gewasontwikkeling en biomassaproduksie. Die algemene tendens was dat, soos grondversteuring toegeneem het in die koring na medics en koring na kanola, het beter gewasontwikkeling plaasgeving met betrekking tot droëmassaproduksie en blaaroppervlakindeks. Die positiewe effek van wisselbou is ook waargeneem in die chlorofilinhoud van die blare en die ligonderskeppingspotensiaal van die blaredak. Graanopbrengs is positief beïnvloed deur die wisselboustelsel, met beide koring na medics en koring na kanola wat hoër graanopbrengste as koring monokultuur vir beide jare gelewer het. Die hoogste graanobrengs is ook gekry onder die minimumen geen-bewerkingsbehandelings vir 2010 en 2011. Wisselbou en bewerkingsmetodes het geen duidelike invloed op koringkwaliteit gehad nie. Dit is ‘n weerspieëling van die belangrike invloed van omgewingsfaktore gedurende die korrelvulstadium van koring. Omgewingsfaktore soos reënval en temperatuur het betekenisvolle effekte in beide jare van die studie gehad, maar die belang van ‘n wisselbou wat ‘n stikstofbinder soos medics insluit, was reeds in hierdie vroeë stadiums van die langtermynproef opvallend. Die positiewe effek van minimum- en geen-bewerking was ook duidelik sigbaar gedurende die verloop van die studie. / The Western Cape Agricultural Trust for the opportunity and the finances to do this study

Thesis (MScAgric)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The pressure on the world’s natural resources is increased by an expanding global population. The majority of the growth is expected to take place in Africa and Asia. This creates the need for sustainable agricultural practices. To sustain food security, the limited natural resources must be utilised efficiently to optimise agricultural productivity. Conservation agriculture (CA) is one of the most holistic sustainable agricultural practices yet. It reduces environmental degradation, and concurrently it could enhance farm profitability. The practice of CA is able to improve food security while sustaining the environment for the benefit of future generations of both consumers and producers. A large proportion of the commercial grain producers in the Western Cape have adopted CA to varying degrees. A purer form of CA practice is continually pursued to realise its full benefits. Adoption has taken place in the absence of any policy support framework directed to CA, and thus, has been market driven. The reasons for and rates of CA adoption in other regions of the world differed, but was mostly successful, which highlights the driving forces behind adoption of CA in the Middle Swartland. The physical/biological benefits of CA are well known. The financial implications of the various systems within CA, at farm-level are still unknown. This study implements trial data from Langgewens experimental farm to evaluate the financial implications of various farming systems over an extended period. Farm systems are complex, consisting of numerous interrelated components. A whole-farm budget model is developed within a systems approach to compare various farming systems designed within CA principles. A trustworthy whole-farm model providing an accurate representation of a real life farm requires insight across many scientific disciplines. Multidisciplinary group discussions are used to bridge the gap between scientific knowledge. To serve as a basis for comparison, the whole-farm model was based on a typical farm within the Middle Swartland relative homogeneous farming area. Trial data on crop rotations and tillage systems from Langgewens experimental farm served as starting point for the research. The data was fitted for use in financial analysis and as input to the typical farm model. A key role of the inter-disciplinary expert group was to ensure that data and the model design accurately reflect the underlying physical/biological processes of CA. The financial evaluation of the various farming systems showed that conventional agricultural practices of monoculture and deep tillage are financially unsustainable. Farming systems under conventional tillage returned negative net present values (NPV) and an internal rate of return on capital investment (IRR) lower than the real interest rate. This implies that investment in conventional tillage will ultimately lead to financial losses. The financial benefits of CA are directly related to improved soil health, lower weed and pest stress and improved yields. The CA farming systems were less susceptible to variations in external factors, highlighting the resilience of the system that incorporates crop rotation and no-till. The farming systems operated under conventional practices are expected to be unsustainable over a long-term period of 20 years. / AFRIKAANSE OPSOMMING: Opsomming Die druk op die aarde se natuurlike hulpbronne word verhoog deur ʼn groeiende wêreld populasie. Die meeste van die groei word verwag in Afrika en Asië. Dit skep die nodigheid vir volhoubare landboupraktyke. Om voedselsekerheid te volhou moet die beperkte natuurlike hulpbronne doeltreffend benut word om landbouproduksie te optimeer. Bewaringslandbou is die mees holistiese volhoubare landboupraktyk tot op hede. Dit verminder omgewingsdegradasie terwyl boerderywinsgewendheid kan verbeter. Die praktyk van bewaringslandbou is in staat om voedselsekuriteit te verbeter terwyl die omgewing onderhou word tot voordeel van toekomstige generasies van beide produsente en verbruikers. ʼn Groot gedeelte van kommersiële graanprodusente in die Wes-Kaap het bewaringslandbou teen verskillende intensiteit aangeneem. ʼn Suiwer vorm van bewaringslandbou word deurlopend nagejaag om die volle voordeel daarvan te benut. Die aanneming van bewaringsboerdery het sonder regeringsbeleid plaasgevind en was dus markgedrewe. Bewaringsboerdery is in ander wêrelddele vir verskillende redes aangeneem, maar was meestal suksesvol. Dit beklemtoon die beweegrede vir die aanneming van bewaringslandbou in die Middel Swartland. Die fisies/biologiese voordele van bewaringslandbou is wel bekend. Die finansiële implikasies van verskillende stelsels binne bewaringslandbou op plaasvlak is nog nie bekend nie. Hierdie studie gebruik proefdata van Langgewensproefplaas om die finansiële implikasies van verskillende boerderystelsels oor die langtermyn te evalueer. Boerderystelsels is kompleks en bestaan uit interafhanklike komponente. ʼn Geheelplaas begrotingsmodel is binne ʼn stelselsraamwerk ontwikkel om verskillende stelsels wat binne bewaringslandboubeginsels ontwerp is, te evalueer. ʼn Geloofwaardige geheelplaasmodel wat ʼn akkurate weerspieëling van realiteit verskaf benodig insig van verskeie wetenskaplike dissiplines. Multidissiplinêre groepbesprekings is gebruik om die gaping tussen die verskillende dissiplines te oorbrug. Die basis vir vergelyking wat gebruik is, is ʼn tipiese plaas in die relatief homogene boerderygebied van die Middel Swartland. Proefdata van verskillende gewasrotasie- en bewerkingstelsels is as die vertrekpunt vir die studie gebruik. Die data is pasgemaak vir finansiële ontledings en om te dien as inset vir die geheelplaasmodelle. ʼn Kern rol van die interdissiplinêre ekspert groep was om te verseker dat die data en die model-ontwerp die onderliggende beginsels van bewaringslandbou reflekteer. Die finansiële evaluasie van die verskillende boerderystelsels wys dat konvensionele landboupraktyke met monokultuur en diepbewerking nie finansieel volhoubaar is nie. Boerdery stelsels onder konvensionele bewerking genereer ʼn negatiewe netto huidige waarde en ʼn opbrengs op kapitaal investering wat laer as die inflasie vlak is. Dit beteken dat investering in konvensionele uiteindelik tot finansiële verlies kan lei. Die finansiële voordele van bewaringslandbou is direk geassosieer met verbeterde grondgesondheid, laer onkruid en plaag-druk en beter opbrengste. Die bewaringslandbou boerderystelsels is ook minder blootgestel aan veranderinge in eksterne faktore wat die gehardheid van die stelsels wat gewas-wisselbou en geenbewerking inkorporeer, beklemtoon. Die boerderystelsel onder konvensionele praktyke sal na verwagting nie volhoubaar wees oor ʼn langer periode van 20 jaar nie.

To analyse the influence of crop rotations with a different ratio of nitrogen-fixing crops, catch crops and fertilisation with organic fertilisers on the following: 1. Soil enzyme activity; 2. Agrochemical properties of the soil and nitrogen balance; 3. Weed response; 4. Weed seed bank in the soil; 5. Crop yield and productivity. / Agroekosistemų optimizavimo augalų kaita, tarpiniais pasėliais ir organinėmis trąšomis ekologinėje žemdirbystėje tyrimai vykdyti 2004–2009 m., Lietuvos žemės ūkio universiteto Bandymų stotyje, sertifikuotame ekologinės žemdirbystės lauke, karbonatingame sekliai glėjiškame išplautžemyje (IDg8-k) – Calcari-Epihypogleyic Luvisol (LVg-p-w-cc). Tyrimų hipotezė. Optimizuoti agroekosistemas ekologinėje žemdirbystėje galima taikant priemonių kompleksą: parenkant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius bei tręšiant organinėmis trąšomis. Tyrimų tikslas – įvertinti agroekosistemų optimizavimo galimybes ekologinėje žemdirbystėje derinant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius ir tręšiant organinėmis trąšomis. Tyrimų uždaviniai: Ištirti sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių ir tręšimo organinėmis trąšomis įtaką: 1. dirvožemio fermentų aktyvumui; 2. dirvožemio agrocheminėms savybėms ir azoto balansui; 3. pasėlių piktžolėtumui; 4. dirvožemio armens užteršimui piktžolių sėklomis; 5. augalų derlingumui ir bendrosios energijos kiekiui. Mokslinio darbo naujumas. Ekologinės žemdirbystės sąlygomis kompleksiškai įvertintas sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių bei tręšimo organinėmis trąšomis poveikis agroekosistemoms. Tai suteikia naujų žinių apie potencialaus dirvožemio derlingumo palaikymo, pasėlių ir dirvos piktžolėtumo kontrolės... [toliau žr. visą tekstą]

The aim of the work is to find out the application of intercrops and their influence in crop rotation in the cadastral area of Krašovice u Čížové. The first part of the thesis deals with erosion, anti-erosion measures and intercrops. In the second part there is a calculation of erosion shear on given cadastral area. The erosion of soil on the soil blocks is calculated using the Wischmeier-Smith equation (USLE). The wash is then further compared, using crop rotation and crop rotation with the application of intercrops.

O planejamento de rotações de culturas é um tema de interesse em ascensão por permitir uma redução significativa no uso de adubos industriais, agrotóxicos e outros produtos químicos no cultivo, permitindo a auto-sustentação e qualidade das terras cultivadas. Este trabalho centraliza em utilizar rotações para atender uma demanda periódica prédeterminada, respeitando as restrições relativas a aspectos ecológicos que auxiliam na estabilidade geral do solo para definir uma rotação de culturas factível. Modelos matemáticos que consideram um tamanho mínimo de lote a ser usado por uma rotação e métodos heurísticos, baseados em geração de colunas, são apresentados. Uma análise detalhada do comportamento dos métodos perante variações em diferentes parâmetros e critérios é realizada. A primeira heurística, denominada Algoritmo GC-BC, obteve resultados de melhor qualidade e de forma mais rápida que a segunda heurística, denominada Heurística Lote Fixo. Entretanto, combinando ambas heurísticas foi possível obter os resultados mais satisfatórios, ou seja, soluções que respeitam a condição de lote mínimo em um tempo computacional aceitável para um planejamento anual, cujos valores são próximos a um limitante superior. A ideia subjacente de gerar colunas adicionais para um problema mestre restrito produz soluções de qualidade, o que pode vir a ser aplicado em outras áreas de pesquisa que necessitam da geração de colunas para uma resolução em tempo computacional viável / The crop rotation planning is a rising topic for providing a significative reduction on the usage of industrial fertilizers, pesticides and other chemical, allowing the soil to selfsustain. This study focus on using rotations to meet a periodic and pre-defined demand while ecologic restrictions, that help sustain the soils stability, define a valid crop rotation. Mathematical models that consider a minimum size of a used lot associated with a given rotation and heuristic resolution methods, based on column generation, are presented. A detailed analysis of the methods behaviour before changes on parameters and criteria is performed. The first heuristic, called GC-BC Algorithm, achieved better and faster results compared to the second heuristic, called Fixed Lot Heuristic. However, combining both heuristics produced even better results, that is, solutions that respect the minimum lot sizing restrictions in good execution time for an annual planning. The idea behind of generating additional columns to the restricted master problem produces good quality solutions, which may be applicable in other research areas that require column generation for their resolution with a reasonable execution time

Propomos avaliar a influência da rotação de culturas na infecção de milho transgênico (Bt) e cobertura morta por F. verticillioides e na presença de fumonisinas em amostras provenientes de Palmital e Capão Bonito. O isolamento fúngico da cobertura morta e do milho foi realizado em DG18 e DRBC, respectivamente. Os fungos isolados pertencentes ao gênero Fusarium foram identificados até espécie. Utilizamos, para análise de fumonisinas, Cromatografia Líquida de Alta Eficiência. Micobiota da cobertura morta revelou maior frequência de Cladosporium spp. Nas amostras de milho, F. verticillioides foi o fungo mais isolado. Dentro do gênero Fusarium, a espécie F. verticillioides foi a mais frequente. Análise micotoxicológica do milho revelou a presença de fumonisinas em 88,9% das amostras provenientes de Palmital e em 86,1% de Capão Bonito. Dos isolados de F. verticillioides 84,6% foram produtores de FB1 + FB2. A presença de F. verticillioides e fumonisinas nos grãos de milho estabelece um problema econômico e de saúde pública. / The objective of this study was to evaluate the influence of crop rotation systems on the infection of maize grains and mulch by F. verticillioides and on the presence of fumonisins in maize samples collected in Palmital and Capão Bonito. Surface seeding (DG18) and direct seeding (DRBC) were employed for fungal isolations from mulch and maize, respectively. Identified isolates belonging to the genus Fusarium were further classified at the species level. Analysis of the mulch mycobiota revealed a higher frequency of Cladosporium spp., whereas in maize samples, F. verticillioides was the most frequently isolated fungus. High-performance liquid chromatography (HPLC) was used for mycotoxicological analysis of the grain samples. Maize from Palmital and Capão Bonito presented fumonisins in 88.9% and 86.1% of the samples, respectively. From the F. verticillioides isolates, 84.6% were producing FB1 + FB2. The high incidence of F. verticillioides in maize grains represents a serious problem, due to its potential in causing diseases in humans and animals.

Este trabalho teve como objetivos avaliar a omissão de nutrientes e a influência de fitorreguladores na emissão e desenvolvimento de brotações de E. urophylla x E. grandis. Devido a escassez de estudos quanto aos teores e quais nutrientes interferem no desenvolvimento da floresta em segunda rotação e quanto ao uso de fitorreguladores a campo com o objetivo de estimular a emissão de brotação, fez-se necessário este estudo que visa aumentar o leque de conhecimento sobre a silvicultura do eucalipto de segunda rotação e os mecanismos para melhorar seu desenvolvimento. O estudo foi realizado em dois povoamentos localizados em duas áreas da empresa International Paper do Brasil (IP), nos municípios de Brotas e Mogi Guaçu, região Nordeste do Estado de São Paulo. Os solos tanto da área experimental localizada na região de Brotas quanto a de Mogi Guaçu são classificados como Latossolos Vermelho Amarelos. O clima de ambas as áreas é do tipo Cwa. A colheita foi feita nos povoamentos com idade de 6,5 anos. Foram avaliadas sobrevivência das brotações aos três e seis meses, o diâmetro das brotações aos doze meses, a altura das brotações semestralmente e o número de brotos das cepas aos três, seis e doze meses pós-colheita. Para avaliar os efeitos da omissão de nutrientes na indução e desenvolvimento das brotações de um clone de eucalipto, foram aplicados os seguintes tratamentos: T1: controle; T2: fertilização completa; T3: sem fertilização nitrogenada (-N); T4: sem fertilização fosfatada (-P); T5: sem fertilização potássica (-K); T6: sem fertilização com Cálcio e Magnésio (-Ca e Mg); T7: sem fertilização com boro (-B); T8: sem fertilização com cobre (-Cu); T9: fertilização comercial da empresa, aplicada após o colheita da floresta. Na avaliação do efeito dos fitorreguladores na emissão de brotações foram utilizados os seguintes tratamentos: T2: fertilização completa; T10: fert. completa + calciocianamida; T11: fert. completa + thidiazuron (TDZ); T12: fert. completa + tiouréia. Não houve relação entre a sobrevivência e os tratamentos avaliados. Ambas as áreas experimentais apresentaram sobrevivência acima de 90% aos seis meses de avaliação, não apresentando resposta diferenciada entre os tratamentos. Em Brotas, os tratamentos com omissão de K e fertilização comercial foram os tratamentos com menor desenvolvimento em altura e diâmetro para a espécie de E. urophylla x E. grandis, ressaltando e deficiência deste na formulação da empresa. Já em Mogi Guaçu, P e N e com maior ênfase, o Cu influenciaram negativamente no desenvolvimento em altura e diâmetro. A quantidade e vigor das brotações não foram alteradas em relação à testemunha com o uso de fitorreguladores na cepa. Não houve melhor desenvolvimento quanto ao número e vigor das brotações com o uso de TDZ em relação aos demais fitorreguladores testados. / This study aimed to evaluate the effects of omission of nutrients and the influence of the bioregulators calciocianamide, thidiazuron (TDZ) and thiourea in the coppincing of an Eucalyptus urophylla x Eucalyptus grandis clone. Due to lack of studies concerning the contents and nutrients which interfere with the development of second-rotation forest and on the use of growth regulators in the field with the aim of stimulating the emission of budding, it was necessary that this study aims to increase the range of knowledge on forestry eucalyptus and mechanisms to improve their development. The study was carried out two stands located in two areas of the company International Paper of Brazil (IP) in the municipalities of Mogi Guaçu and Brotas, at the northwestern of the state of São Paulo. The soils of the experimental area both located in the region of Brotas and Mogi Guaçu are classified as Oxisols Red Yellow. The climate of both areas is Cwa type. The harvest was done in stands aged 6.5 years. There were evaluated the number of shoots, the stem diameter and height of shoots. To evaluate the effects of nutrient omission in the coppincing a eucalyptus clone, there were applied the following treatments: T1: control, T2: complete fertilization; T3: without nitrogen fertilization (-N) T4: without phosphate fertilization (-P), T5: without potassium fertilization (-K), T6: without calcium and magnesium fertilization (-Ca and -Mg), T7: without boron fertilization (-B), T8: without copper fertilization (-Cu); T9: commercial fertilization, applied after the harvest of the forest. In evaluating the effect of growth regulators in issuing shoots there were used the following treatments: T2: complete fertilization; T10: complete fert. + calciocianamida; T11: complete fert. + TDZ; T12: complete fert. + thiourea. There was no relationship between survival and the treatments. Both experimental areas showed over 90%stump survival at the sixth months of evaluation. On Brotas, the K stood out as being the most limiting nutrient for development in coppice height, stem diameter and shoot number of an E. urophylla x E. grandis clone. In Mogi Guaçu, N and P, were the limiting nutrients for development of the clone under study. The use of growth regulators did not influence the development of plants as nutrient uptake and shoot induction.

Nas últimas décadas, diversas propostas de técnicas e de processos visando aumentar a sustentabilidade da agricultura ganharam evidência. Tais propostas geram novos modelos de planejamento em que devem ser considerados aspectos técnicos e ecológicos de produção, bem como o acesso de pequenos agricultores familiares ao mercado consumidor. Neste tipo de planejamento da produção, a rotação de culturas desempenha um papel fundamental, pois contribui para a manutenção dos recursos produtivos, para a minimização do uso de recursos não-renováveis e para o controle biológico da população de herbívoros, patógenos e plantas espontâneas. Nesta tese abordamos dois problemas de Programação de Rotação de Culturas (PRC) focados na produção de base sustentável de hortaliças: o problema de PRC com restrições de Adjacências (PRC-A) e o problema de PRC com atendimento da Demanda (PRC-D). O planejamento da produção de hortaliças é complexo pois envolve, em geral, um grande número de culturas com limitações específicas quanto à época de plantio e com períodos de cultivo e produtividades muito variáveis. A programação de rotação de culturas para as áreas de plantio é formulada como um modelo de otimização 01 e, para os dois problemas, em cada programação considera se tanto aspectos técnicos (época de plantio e colheita etc.) quanto ecológicos (adubação verde, pousio etc.). No problema PRC-A o objetivo é a maximização da ocupação das áreas produtivas em que as restrições de plantio são estendidas às áreas adjacentes. Como a formulação matemática para o problema tem, em geral, um número muito grande de restrições e variáveis, com matriz de restrições esparsa e bloco-diagonal, o modelo é reformulado com a Decomposição DantzigWolfe, o que permitiu sua resolução por procedimentos baseados em geração de colunas, heurísticos e exatos. No problema PRC-D desejase suprir a demanda de um conjunto de hortaliças tendo-se disponível um conjunto de áreas heterogêneas. As culturas passíveis de plantio, bem como as suas produtividades, dependem da área considerada. O problema foi formulado como um modelo de otimização linear em que cada variável está associada a uma programação de rotação de culturas. O modelo contém potencialmente um número grande de programações de rotação e é resolvido por geração de colunas. Experimentos computacionais usando instâncias baseadas em dados reais confirmam a eficácia dos modelos e das metodologias propostos para os problemas / Over the last decades, various proposals for techniques and processes to increase agricultural sustainability have been put forward. These proposals bring new planning models in which technical and ecological production aspects must be considered, as well as the access of small farmers to the consumer market. In this type of agricultural production planning, crop rotation plays a fundamental role as it contributes to maintaining productive resources, to reducing the use of non-renewable resources, and to biologically controlling the population of herbivores, pathogens and spontaneous plants. In this thesis, two problems concerning the Crop Rotation Schedule (CRS) focusing on sustainable production vegetables are addressed: the problem of the CRS having Adjacent constraints (CRS-A) and the problem of the CRS under Demand constraints (CRS-D). Production planning of vegetables is complex as it generally involves a large number of crop species having specific limitations regarding the planting season and very varied production times and productivity. The crop rotation schedule problem is formulated as an optimization model 0-1, and for both problems, in each schedule technical (planting and harvesting season etc.) and ecological (green manure, fallow etc.) aspects are considered. Concerning the CRS-A problem, the aim is to maximize the occupation of cropping areas in which planting constraints are extended to adjacent areas. As the mathematical formulation for the problem generally has a large number of restrictions and variables and the structure of the constraint matrix of the problem is sparse and block-diagonal, the model has been reformulated using the Dantzig-Wolfe Decomposition strategy, which has enabled the use of a heuristic and exact procedures based on the column generation approach for its resolution. In the CRS-D problem, the aim is to meet the market demands for vegetables having a set of heterogeneous cropping areas available. The potential planting crops, as well as their productivity, depend on the considered cropping area. The problem is formulated as an optimization linear model in which each variable is associated to a crop rotation schedule. The model may include a large number of rotation schedules and is solved by the column generation approach. Computational experiments using instances based on real-world data confirm the efficiency of models and methodologies proposed for the problems