Reduced tillage and living mulches are alternative management strategies that can improve soil quality by minimizing disturbance and building soil organic matter. Weed suppression by these two practices alone is often insufficient to avoid crop yield losses, but their performance in an integrated system is not well understood. This project investigated the production of bell pepper (Capsicum annuum L.) and dry bean (Phaseolus vulgaris L.) in conventional tillage and strip tillage with a living mulch of teff (Eragrostis tef Zucc.) and Korean lespedeza (Kummerowia stipulacea Maxim.). Yields of pepper and bean were generally higher under conventional tillage without living mulch. Weed biomass was not influenced by tillage, and was adequately suppressed by teff in a year when conditions for teff growth were favorable. Mowing appeared to suppress weed growth but not living mulch growth. Soil nitrate and ammonium concentration was generally higher under conventional tillage without living mulch. Delaying living mulch seeding by 15 days after crop establishment generally did not affect weed suppression or crop yield. Soil aggregate stability was not consistently affected by tillage or living mulch. Increased mowing frequency, living mulch planting delay, or distance between the crop row and the living mulch may be necessary to achieve acceptable yields with living mulches.

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 173-188).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.Sc.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 9, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Land Reclamation and Remediation, Department of Renewable Resources, University of Alberta. Includes bibliographical references.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Three field trials were conducted to investigate the effects of mulching on the chemical and biological aspects of the soil as it is reflected by tree performance and fruit quality in ‘Cripps’ Pink’ orchards. In the two trials at Lourensford Estate, where only the soil type differed between sandy silt loam (sandy) and heavy silt loam (heavy), mulches where used as an additive to the soil surface together with a standard, commercial, inorganic fertilization program. Four different mulch types: compost, wood chips, vermi-compost and a geotextile fabric, were compared to a bare surface control in a randomized complete block design. At the heavy silt loam site (site 1), the wood chips treatment was the most effective in regulating diurnal soil temperatures in the top 10 cm of soil (2009/10), whereas all mulches regulated average diurnal soil temperature similarly and more effectively than the control at the sandy silt loam site (site 2). After two seasons of treatment at site 1, the vermi-compost treatment significantly increased soil phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), manganese (Mn), zink (Zn) and boron (B) significantly compared to the control. The wood chips treatment increased Na, K and Ca and compost only increased soil K significantly compared to the control. For site 2, only wood chips (Na and K) and vermi-compost (Na, K and Mg) showed significant increases in soil nutrient elements compared to the control. Yield efficiency was significantly increased by the wood chips (both seasons) and vermicompost (only 2009/10) treatments compared to the control in site 1. In site 2, none of the treatments differed significantly in yield efficiency compared to the control treatment. The number of roots and fine feeder roots were increased (not sign) by the wood chips and geotextile treatments compared to the control. In site 1, all treatments improved the number of roots compared to the control treatment, in contrast with site 2, where the number of roots of the control, compost and vermi-compost treatments was more similar. Fruit quality showed significant differences between the wood chips and vermi-compost treatments compared to the geotextile and control treatments for malic acid, at site 1, at harvest in 2009. This did not differ significantly from the compost treatment. Leaf mineral analysis only showed significant differences at site 2, in 2010, with significantly increased for the following minerals and treatments: Mn (compost and geotextile treatments versus other treatments), Fe (control treatment compared to all treatments except compost), Zn (compost compared to all other treatments) and B (control and compost versus vermicompost, wood chips and geotextile). Fruit mineral analyses showed no differences between treatments at harvest 2009 for either site and 2010, for site 1. At site 2, the Ca percentage of fruit from the wood chips treatment was significantly higher than that of all treatments, except the geotextile treatment. Only in the 2010 analysis at site 2, the mycorrhizal colonization was significantly influenced, where all the mulching treatments showed an increase compared to the control. However, the same trend was observed at site 1. At site 1and 2, the compost, wood chips and vermi-compost treatments in general showed a decreasing trend in percentage plant parasitic and increasing trend in percentage free living nematodes from 2009 to 2010. In general, the geotextile and control treatments showed an increasing trend in the percentage plant parasitic and decrease in percentage free living nematodes. However, this was not the case at 0 – 15 cm soil depth for site 1. In the third trial, at Elgin Experimental Farm (Elgin), bare surface chemical control was compared to mulching in the tree row (mulch) and mulching together with regular application of compost tea (mulch + compost tea). All treatments were combined with different inter row management practices to compose a total of eight different treatments. In the tree row, the control treatment received standard rates of inorganic fertilizer, which was compared to the mulched only treatment. Both the percentage of soil carbon and cation exchange capacity was significantly increased by all the mulch treatments compared to the control. Furthermore, all the mulches increased various soil minerals significantly, however of which only P was significantly increased in both the leaves and fruit. The rate of soil microbial activity and mycorrhizal root colonization was significantly increased by mulching treatments, but resulted in a significantly lower yield efficiency compared to the inorganic control treatment. This can be ascribed partly to the microbial activity of the compost mulch during spring, although it was not quantified per se and to the increase in tree vigour at the end of the trial. The slow rate of N mineralization was reflected indirectly by the significantly lower fruit N for the mulched treatments and the lower rate of microbial activity during spring at this site. With regards to the addition of the compost tea, no significant contributions were evident in terms of tree performance, soil minerals or microbial activity over a period of seven years, compared to the application of mulch only. Compared to the trial at Lourensford Estate, with no significant differences in fruit mineral composition between treatments after two years, fruit mineral analyses of the Elgin trial showed significant differences between treatments after six (2009) and seven (2010) seasons for P for some treatments. Only in 2010 more treatments showed significant differences for N, Mn, Fe and Zn as well. Regarding fruit quality, in agreement with the results at Lourensford Estate, differences were not persistent across all seasons for treatments. / AFRIKAANSE OPSOMMING: Veldproewe is geloods om die effek van verskillende deklae op grond chemiese en – biologiese aspekte en die effek daarvan op boom prestasie en vrugkwaliteit in ‘Cripps’ Pink’ appelboorde te ondersoek. In die eerste twee proewe te Lourensford Landgoed, waar slegs die grondtipe verskil het tussen die sanderige slik leem (ligter) en swaarder slik leem (swaar) gronde, is deklae toegedien saam met ‘n standard bemestingsprogram en mikro-besproeiingstelsel. Vier deklaagtipes: kompos, houtspaanders, vermi-kompos en geotekstiel material, is vergelyk met die onbedekte, skoon bewerkte, kontrole in ‘n total ewekansige blokontwerp. By die swaar grondtipe (perseel 1), was die houtspaanderbehandling die effektiefste om die daaglikse skommelings in grondtemperatuur te reguleer in die boonste 10 cm, teenoor die sanderige perseel (2), waar al die deklae die daaglikse grondtemperatuur meer effektief as die kontrole behandeling gereguleer het. By perseel 1, het die vermi-behandeling ‘n betekenisvolle toename getoon teenoor die kontrole behandeling in grond fosfaat (P), kalium (K), kalsium (Ca), magnesium (Mg), natriuim (Na), mangaan (Mn), sink (Zn) en boor (B). Alhoewel dit nog nie tans gekwantifiseer kan word nie, is ‘n gedeelte van die toename heel moontlik te wyte aan die samestelling van die deklaag. Die houtspaander- en komposbehandelings het ‘n betekenisvolle verskil in toename tot gevolg gehad in grond K en Na in vergelyking met die kontrole. In die geval kan die toename van die komposbehandeling aan die invloed van die sampestelling van die deklaag toegeskryf word, maar nie in die geval van die houtspaanderbehandeling nie. Die geotekstielbehandeling het, soos verwag, nie betekenisvolle verskille ten opsigte van die kontrole getoon nie, aangesien die samestelling van die geotekstielmateriaal nie voedingstowwe tot die grond kan toevoeg nie. By perseel 2, het beide die houtspaander- en geotekstielbehandelings betekenisvolle toenames in grond elemente (K, Mg) getoon teenoor die kontrole behandeling. Die ander elemente het nie noemenswaardige verskille teenoor die kontrole getoon nie. Weer eens kan die toename in die vermi-kompos toegeskryf word aan die samestelling van die deklaag, maar nie in geval van die houtspaanders nie, wat ‘n moontlike rol van ander faktore soos temperatuur en grondvog in die opname en beskikbaarheid van voedingselemente toon. Op 30 cm diepte in perseel 1, het die vermi-kompos behandeling betekenisvolle hoër Na, K, Mg en P getoon as die kontrole. Die houtspaanderbehandeling het betekenisvolle hoër Na, K en Ca getoon as die kontrole. Geen een van die ander behandelings het enige betekenisvolle veranderinge ten opsigte van voedingselemente getoon nie. Vir perseel 2 by die gronddiepte, het die houtspaanderbehandeling betekenisvolle toenames in grond Na en K getoon teenoor die kontrole. Geen van die ander behandelings het enige betekenisvolle veranderinge ten opsigte van voedingselemente getoon nie. By hierdie dieper gronddieptes is ‘n soortgelyke verandering in elemente waargeneem as by die vlakker gronddieptes vir perseel 1, in geval van P en K. Mg en Na het volgehoue verandering vir die vermi-komposbehandeling in die dieper gronddieptes getoon vir die makro-elemente, maar nog nie in geval van mikroelemente nie. In perseel 2 – het toenames in K en Mg in die vermi-komposbehandeling ook voortgeduur en die veranderinge vir beide persele mag toegeskryf word aan die samestelling van die deklae per se. Dit blyk dat die veranderinge in die komposbehandeling nie so konstant voorgekom het in die materiaal wat in die proewe toegedien is nie. Nietemin kan die kompos- en vermi-komposbehandelings ook ander grond faktore beïnvloed en die bydra van die minerale elemente afkomstig uit die samestelling van die deklaag moet eers bereken word alvorens afleidings gemaak word. By beide persele het die komposbehandeling die opbrengseffektiwiteit verminder in vergelyking met die kontrole behandeling. Die opbrengseffektiwiteit is betekenisvol verhoog in die houtspaanderbehandeling (beide seisoene) en vermi-komposbehandeling (net 2009/10) in vergelyking met die kontrole in perseel 1. In perseel 2 het teen behandeling betekenisvol in opbrengseffektiwiteit verskil ten opsigte van die kontrole nie. Die aantal wortels en fyn, voedingswortels het ‘n dramatiese (nie-betekenisvolle) toename getoon by die houtspaander- en geotekstielbehandelings. In perseel 1 het alle behandelings die aantal wortels verhoog ten opsigte van die kontrole in kontras met perseel 2, waar die aantal wortels in die kontrole, kompos- en vermi-komposbehandelings ongeveer dieselfde was. Stamwaterpotensiaal het onveranderd gebly ongeag van die behandeling, wat moontlik beïnvloed is deur die hoë besproeiingskedulering siklus. Geen verskille tussen behandelings of persele is gevind nie. Alhoewel dit net in die tweede seisoen (2010) gemeet is, was daar geen betekenisvolle verskille in gemiddelde loot groei van eenjaarlote tussen die behandelings of persele nie. Vrugkwaliteit het betekenisvolle verskille getoon in appelsuur (malic acid) in die houtspaander- en vermi-komposbehandelings teenooor die geotekstie- en kontrole behandelings in perseel 1, by oes 2009. Laasgenoemde het nie betekenisvol van die kontrol behandeling verskil nie. Hierdie verskille het nie na opberging voortgeduur nie. Geen betekenisvolle verskille in vrugkwaliteit het voorgekom by perseel 2, tydens oes, of na opberging nie. Gedurende oes 2010, asook na opberging, is geen verskille in vrugkwaliteite van enige persele opgemerk nie. Behandelingsverskille in blaar-analises is waargeneem tussen vermi-kompos- en die ander behandelings, met uitsondering van die geotekstielbehandeling in Februarie 2009, perseel 1. Geen ander betekenisvolle verskille vir enige element het voorgekom tussen behandelings in perseel 2 nie. Gedurende 2010 is geen betekenisvolle verskille tussen behandelings ten opsigte van blaar-analises gevind vir perseel 1 nie. Betekenisvolle verskille in blaar- en vrugmineraal-analises was in perseel 2 teenwoordig as volg: Mn (kompos- en geotekstielbehandelings teenoor al die ander behandelings), Fe (kontrolebehandeling teenoor alle ander behandelings behalwe die komposbehandeling), Zn (komposbehandeling teenoor al die ander behandelings) en B (kontrole en komposbehandelings teenoor vermi-, houtspaander- en geotekstielbehandelings (gedurende 2010. Die vrugmineraal-analises het geen verskille getoon tussen behandelings by oes 2009 vir enige perseel, of 2010 vir perseel, 1 nie. By perseel 2 was die Ca persentasie in die vrug in die houtspaanderbehandeling betekenisvol hoër as die van die ander behandelings, uitgesonder die geotekstielbehandeling. By perseel 1, het al die behandelings die persentasie mycorrhiza-kolonisasie verhoog in vergelyking met die kontrole, alhoewel dit nie betekenisvol was nie. By perseel 2 was daar wel ‘n betekenisvolle toename in die persentasie mycorrhiza-kolonisasie by al die deklaagbehandelings in vergelyking met skoonbewerking van die kontrole behandeling. Die persentasie plant-parasitiese nematodes was baie variëerend met gronddiepte by beide persele. Die houtspaander- en vermi-komposbehandelings in perseel 1 het ‘n afwaartse tendens getoon in die persentasie plant-parasitiese en toename in persentasie vry-lewende nematode vanaf 2009 na 2010, in die 0-15 cm diepte. In teenstelling, het die geotekstiel- en komposbehandeling ‘n toenemende tendens getoon in die persentasie plant-parasitiese en klein afname in persentasie vrylewende nematodes vanaf 2009 tot 2010. Geen betekenisvolle verskille in nematode getalle is waargeneem in gronddiepte 15 -30 cm grond in die perseel nie. In perseel 2 is geen betekenisvolle verskille in aantal nematodes gevind gedurende die twee seisoene tussen behandelings of binne persele op 0-15 cm gronddiepte nie. Nietemin het die houtspaander-, kompos- en vermi-komposbehandelings die persentasie plant-parasitiese verlaag en die van die vry-lewende nematode verhoog vanaf 2009 tot 2010, in vergelyking met die kontrole in die 15-30 cm gronddiepte. Slegs die houtspaanderbehandeling het betekenisvolle verskille getoon teenoor die kontrole. Die geotekstiel- het dieselfde tendens as die kontrole behandeling getoon, met ‘n toename in persentasie parasities- en afname in persentasie vry-lewende nematode. Die kontrole en geotekstielbehandelings het nie betekenisvol van mekaar verskil nie. Die aantal erdwurms en meso-fauna was baie laag tydens die eerste twee jaar by beide die persele en data is daarom nie statisties verwerk nie. By die derde proef, is ‘n skoonbewerkte oppervlak, wat chemiese beheer (kontrole) behels het, vergelyk met deklaagbehandelings in die boomry (deklaag) en behandelings waar kompostee saam met die deklaag toegedien was in die boomry (deklaag + kompostee). Al die behandelings is gekombineer met verkillende tussenry behandelings wat ‘n totaal van agt verskillende behandelings behels het. Hierdie verslag konsentreer slegs op die behandelings in die boomry, waar die kontrole behandelings wat ‘n standaard bememestings program ontvang het, vergelyk word met die deklaag behandelings, wat geen alternatiewe bemesting ontvang het nie en as organise alternatiewe beskou word in ‘n ‘Cripps’ Pink’ appelboord. Klem in die verslag is gelê op die hoof effekte van die behandelings op vrugkwaliteit. Beide die persentasie grondkoolstof en die katioonuitruilkapasiteit het ‘n betekenisvolle toename getoon by al die deklaagbehandelings in vergelyking met die kontrole behandeling. Terselfdetyd, het al die deklaagbehandelings ook verskeie grondminerale betekenisvol verhoog, waarvan slegs P betekenisvol in beide die blare en vrugte verhoog is. Die tempo van grondmikrobe aktiwiteit en micorrhiza-kolonisasie van die wortels is betekenisvol verhoog deur die deklaagbehandelings, maar het gerealiseer in ‘n betekenisvolle laer opbrengseffektiwiteit in vergelyking met die anorganiese, kontrole behandeling. Dit kan onder andere toegeskryf word aan die mikrobe aktiwiteit van die komposdeklaag gedurende die lente – alhoewel dit nie per se in die studie gekwantifiseer is nie, sook die toename in vegetatiewe groeikrag aan die einde van die proeftydperk. Dit is wel indirek gereflekteer deur die betekenisvolle, laer vrug N van die deklaagbehandelings en die laer tempo van mikrobe aktiwiteit gedurende die lente by die deklaagbehandelings op die perseel. Wat die toedienning van kompostee betref, het dit geen betekenisvolle bydra gelewer in terme van gewasprestasie, grondminerale of microbe-aktiwiteit oor ‘n tydperk van sewe jaar in vergelyking met die behandelings waar die deklaag geen kompostee ontvang het nie. In vergelyking met die proef by Lourensford Landgoed, met geen betekenisvolle verskille in vrug mineral-analises tussen die behandelings oor ‘n tydperk van twee jaar nie, het die proef te Elgin wel betekenisvolle verskille tussen behandelings na 6 (2009) en 7 (2010) jaar getoon in geval van P, vir sekere behandelings (4,7,8 versus 1,2,6). Slegs in 2010 het meer behandelings betekenisvolle verskille getoon vir N, Mn, Fe en Zn. Rakende vrugkwaliteit - in ooreenstemming met resultate van 2009 vir perseel 1 te Lourensford Landgoed - het beide seisoene betekenisvolle verskille ten opsigte van appelsuur getoon in Elgin. Die verskille het egter nie konstant in al die behandelings voorgekom nie. Stysel afbraak, totaal oplosbare stowwe en fermheid het ook betekenisvolle verskille tussen behandelings getoon in Elgin – maar dit was nie konsekwent oor behandelings of seisoene nie en het ook nie voorgekom in die Lourensford Landgoed persele nie.

Made available in DSpace on 2014-06-11T19:30:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01-19Bitstream added on 2014-06-13T19:40:03Z : No. of bitstreams: 1 tokura_lk_dr_botfca.pdf: 1103503 bytes, checksum: c13458e08e332be0ff5bbff0fa6c279c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho teve como objetivo avaliar o efeito de pontas de pulverização e da palha de milheto na deposição da calda aplicada sobre seis espécies de plantas daninhas. Foram utilizadas cinco pontas de pulverização (XR 11002; TJ60 11002; AI 110015; TJ60 11006 e TX-VK8), seis espécies de plantas daninhas (Ipomoea grandifolia; Euphorbia heterophylla; Commelina benghalensis; Bidens pilosa; Brachiaria plantaginea e Sida rhombifolia) e a condição sem e com presença de 5t.ha-1 de palha de milheto na deposição da calda aplicada. As pulverizações nas plântulas foram realizadas em pósemergência inicial (duas a quatro folhas) utilizando o corante FDC-1 Azul Brilhante (concentração de 0,8%), como solução traçadora. A pressão e o volume de aplicação (L.h-1) para cada ponta de pulverização foram realizados de acordo com as informações fornecidas pelo fabricante. No primeiro estudo foram realizados seis experimentos, sendo que 10 plântulas de cada espécie foram lavadas com 50mL de água destilada e a quantidade de solução tracadora estimada em densidade óptica de 630nm. No segundo estudo, cada plântula foi lavada com 25mL de água destilada permitindo estabelecer a quantidade de solução traçadora ou a solução de aplicação depositada em cada planta. Todos os experimentos foram realizados em delineamento inteiramente casualizado com quatro repetições e 10 plântulas de cada espécie em esquema fatorial 2x5 e as médias comparadas pelo teste t ao nível de 5% de probabilidade. No segundo estudo, os valores de deposição foram ajustados ao modelo de Gompertz. Em termos médios, a presença de 5t.ha-1 de palha de milheto reduziu em 20,12%, a 2 deposição de calda de aplicação na condição de pós-emergência inicial. A grande variabilidade dos depósitos unitários inviabiliza a comparação das pontas a partir de valores médios, modais ou medianos para... . / The aim of this reserch was to evaluate the effects of pearl millet on the deposition of application solution on six weed species. It were studyed five nozzle tip types (XR 11002; TJ60 11002; AI 110015; TJ60 11006 and TX-VK8), six weed species (Ipomoea grandifolia; Euphorbia heterophylla; Commelina benghalensis; Bidens pilosa; Brachiaria plantaginea and Sida rhombifolia) and the conditions without and with 5t.ha-1 of pearl millet mulch. The applications were carried out in early post-emergence (two and four leaves) using the dye FDC-1 (at the concentration of 0,8%) as a tracer. The pressure and the application volume (L.ha-1) were selected for each nozzle tip types according to the information of the dealers. In the first set of six experiments, ten plants of each species were 4 washed in destilled water and the amount of traces was stimated by the aplical density at 630nm. In the second set of experiments, each plant was washed in destilled water allowing to stablish the ammount of tracer or application solution deposited on each plant. All the experiments were designed completelly randomized with four replications and ten plants of each species per plot. In average, the presence of 5t.ha-1 of pearl millet mulch reduced in 20,12% the deposition in early post-emergence. The great variability of the unitary deposits makes unfeasible the comparison of the application technologies using mean, modal and median values. The most apropriate characteristics to compare of the quality of the applications accomplished with different points, correspond to the functions of non accumulated frequencies and the values of deposits associated to the lowest percentis of the accumulated frequencies. In the presence of mulch, the species of E. heterophylla, B. pilosa, B. plantaginea and S. rhombifolia were the most difficult be reached by the application droplets. For these species, the best results... (Complete abstract, click electronic address below).

O presente trabalho foi desenvolvido com o objetivo de avaliar os efeitos da intensidade de chuva e diferentes quantidades de palha de cana-de-açúcar sobre a eficácia de herbicidas aplicados em pré-emergência no controle da tiririca. Foram realizados dois experimentos, ambos conduzidos em casa-de-vegetação. O delineamento experimental adotado foi o de blocos casualizados, com 4 repetições, para os dois experimentos. No primeiro experimento os tratamentos foram distribuídos em um esquema fatorial 3 x 3 x 2 x 2, constituídos pela combinação entre quantidades de cobertura morta de palha de cana-de-açúcar que foram adicionadas à superfície do solo (0, 10, 20 t/ha), herbicidas aplicados em pré-emergência (sulfentrazone a 0,8 kg i.a./ha e imazapic a 147 g i.a./ha) e um tratamento sem aplicação de herbicida, intensidades de chuva (10 e 20 mm), e épocas em que foram simuladas chuvas após a aplicação dos herbicidas (24 e 168 horas). No segundo experimento os tratamentos foram distribuídos em um esquema fatorial 2 x 3 x 5, constituídos pela combinação entre quantidades de cobertura morta de palha de cana-de-açúcar (0, 15 t/ha), herbicidas aplicados em pré-emergência (sulfentrazone a 0,8 kg i.a./ha e imazapic a 147 g i.a./ha) e um tratamento sem aplicação de herbicida, e épocas em que foi simulada chuva após a aplicação dos herbicidas (0, 3, 6, 9 e 12 dias). Em ambos experimentos foram avaliados: o número de plantas por vaso, biomassas secas da parte aérea e das estruturas do sistema subterrâneo, e número de tubérculos e bulbos sadios. A partir da análise dos resultados, para o primeiro experimento conclui-se que, para o herbicida sulfentrazone, a presença de 20 t/ha de palha de cana-de-açúcar diminuiu a eficácia do herbicida. O herbicida imazapic teve um bom desempenho tanto na ausência quanto na presença de palha, e causou redução das variáveis estudadas independente da intensidade de chuva. A intensidade de chuva de 10 mm, não foi suficiente para transpor o herbicida sulfentrazone na quantidade de 20 t/ha de palha. Já a intensidade de 20 mm foi suficiente para lixiviar o herbicida até mesmo na maior quantidade de palha. O herbicida sulfentrazone suporta mais a permanência na palha, pois apresentou melhor eficácia em relação ao imazapic, quando a chuva foi simulada 168 horas após a aplicação dos herbicidas. Para o segundo experimento pode-se concluir que, as épocas em que foram simuladas as chuvas, não afetaram as variáveis estudadas, não havendo, portanto, diferença se a chuva ocorreu no dia em que foi aplicado o herbicida, ou se ocorreu um período sem chuva de 12 dias. Os herbicidas sulfentrazone e imazapic reduziram o número de plantas, o número de tubérculos, biomassa seca de bulbos, biomassa seca de rizoma e raiz, e biomassa seca da parte aérea, independente da presença de palha. / The present work was developed with the objective of assessing the effects of the intensity of rain and different quantities of sugar cane mulch residue on the efficacy of herbicides applied in pre-emergence for the purple nutsedge control. Two experiments were performed, both conducted in greenhouses. The experiments were performed by randomly choosing blocks with four repetitions. In the first experiment, the treatments were distributed in a factorial scheme 3 x 3 x 2 x 2, constituted by the combination between quantities of dead coverage of sugar cane mulch residue which were added to the soil surface (0, 10, 20 t/ha), herbicides applied in preemergence (sulfentrazone at 0,8 kg i.a./ha and imazapic at 147 g i.a./ha) and a treatment without the application of herbicides, rain intensities (10 and 20 mm), and seasons in which were simulated rains after the application of herbicides (24 and 168 hours). In the second experiment, the treatments were distributed in a factorial scheme 2 x 3 x 5, constituted by the combination between quantities of dead covering of sugar cane mulch residue (0, 15, t/ha), herbicides applied in pre-emergence (sulfentrazone at 0,8 kg i.a./ha and imazapic at 147 g i.a./ha), a treatment without the application of herbicides and seasons in which were simulated rains after the application of herbicides (0, 3, 6, and 12 days). It was evaluated in both experiments: the number of plants per vase, dry biomasses from the aerial parts, from the underground system structures and the number of healthy tubers and bulbs. From the analysis of the results of the first experiment, it may conclude that, to the herbicide sulfentrazone, the presence of 20 t/ha of sugar cane mulch residue diminished its efficacy. The herbicide imazapic had a good performance with the absence as well as with the presence of the mulch residue, and caused a reduction in the varieties studied independently of the intensity of rain. The intensity of rain of 10 mm, wasn’t sufficient to overpass the herbicide sulfentrazone in the quantity of 20 t/ha of mulch residue. But the intensity of 20 mm was enough to lixiviate the herbicide even in the biggest quantity of mulch residue. The herbicide sulfentrazone endures more the abiding on the mulch residue, because it presented a better efficacy in relation to the imazapic, when the rain was simulated 168 hours after the application of the herbicides. From the second experiment it may conclude that the season in which was simulated rains, it didn't affect the varieties studied, therefore there was no difference when the rain occurred on the day when the herbicide was applied, or if it occurred on a 12 day period without rain. The herbicides sulfentrazone and imazapic reduced the number of plants, the number of tubers, dry biomass of bulbs, dry biomass of rhizoma roots and dry biomass of the aerial parts, independently of the presence of mulch residue.

In drought-prone arid and semi-arid areas, limited plant available water exerts a tremendous negative effect on crop production, leading to undesirable low crop productivity, untold food insecurity, and never-ending poverty. In-field rainwater harvesting (IRWH or In-field RWH) is specifically designed to trap rainfall within the field and optimise its use to benefit crop yield and quality, and improve water use efficiency (WUE) in these regions. Two RWH-crop field experiments were established in the semi-arid area of the Hatfield Experimental Farm, University of Pretoria, South Africa. The first RWH-potato experiment was conducted during the 2009/2010 growing season while the second RWH-Swiss chard experiment was carried out during the 2010/2011 growing season. Three cropping systems were involved: (1) conventional tillage (CT), (2) tied-ridges (TR), and (3) IRWH with three different design ratios of runoff area to cropping area (1:1, 2:1 & 3:1). The runoff area of each design ratio was either bare (B) or plastic-covered (P) and this resulted in six IRWH treatments. Therefore, there were a total of eight treatments: CT, TR, 1:1B, 1:1P, 2:1B, 2:1P, 3:1B and 3:1P. For both growing seasons, the total plot area yields and WUEs of TR and CT were in general higher than those of the IRWH treatments. This is because TR and CT had more plants per plot than the IRWH treatments and the rainfall recorded for the specific seasons were sufficient, so there was little advantage in collecting/harvesting additional water. In terms of yields and WUEs expressed on the net cropped area, the IRWH treatments had higher yields and WUE than CT and TR because they captured more runoff than the latter treatments. Field trials are expensive, laborious and time consuming, therefore models were developed to predict potential runoff and crop growth and yield of different RWH techniques or design ratios. During the current investigation, runoff models such as the linear regression, curve number (CN) and Morin and Cluff (1980) models were used to describe and simulate runoff generation from this ecotope. The empirical rainfall-runoff linear regression model indicated that runoff efficiency declined as runoff length increased. The statistics revealed that the CN and Morin and Cluff (1980) models simulated runoff very well. Moreover, the use of a generic crop growth Soil Water Balance model (SWB) showed potential to simulate crop growth and yield for different RWH techniques and design ratios. During the present study, the SWB model was modified by incorporating linear runoff simulation models in order to predict the soil water balance and crop yield under different RWH design scenarios. Field data collected on the study ecotope contributed to the parameterization and calibration of the SWB model for the crops involved. The SWB model was in general, successfully calibrated for the potato crop, while the calibration for the Swiss chard crop was generally not as successful, most probably because of the continuous growing and harvesting system followed (approach for pastures). The scenario simulation results for potato suggested that for the study ecotope, if land is limiting, CT, TR and smaller design ratios (1:1) are the best options in terms of yield per total plot area. However, if land is not limiting, larger design ratios (2:1 and 3:1) are better options, according to the yields per net cropped area outcomes. The SWB model shows promise as a useful tool to assist in the selection of the best RWH strategy and the ideal planting date under specific conditions with minimal input requirements. However, there is a need to upgrade it to a 2D SWB model for better accuracy under a range of conditions. / Dissertation (MScAgric)--University of Pretoria, 2014. / lk2014 / Plant Production and Soil Science / MScAgric / Unrestricted

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22782号 / 農博第2425号 / 新制||農||1081(附属図書館) / 学位論文||R2||N5302(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 中村 公人, 教授 星野 敏, 教授 藤原 正幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

In der vorliegenden Arbeit wird ein Simulationsmodell zur Bestimmung der Beregnungsmenge vorgestellt, um das Absinken der Temperatur unter 0°C eines mit einer Plastikfolie abgedeckten Bodens möglichst zu verhindern. Es wurden numerische Berechnungen für den nackten Boden und für den mit Folie abgedeckten Boden mit und ohne gleichzeitiger Frostschutzberegnung durchgeführt. Die Ergebnisse zeigen z.B., daß die Bodenoberflächentemperatur bei einer Beregnung von nur 75% der Sollvorgabe relativ stark absinkt. Dieses liegt an der relativ großen Gefrierwärme von Wasser. Ein nur mit Folie abgedeckter Boden schützt nur in den wenigsten Fällen vor Bodenfrost. Die Simulationsergebnisse stimmen gut mit den gemessenen überein. / A model to determine the minimum amount of water required to hold the soil temperature above 0°C under a plastic mulch is presented. Numerical experiments with and without consideration of the mulch foil, with and without sprinkling of the mulch foil were performed. The results substantiate that sprinkling par example at 75% of the usual used rate of water is sufficient to avoid that the soil temperature falls below 0°C because of the relative big freezing energy of water and that mulching alone cannot prevent the soil temperature from decreasing below that value. The model results are in good agreement with observations.