Show simple item record

dc.contributor.advisorBennie, A. T. P.
dc.contributor.advisorTanner, D. G.
dc.contributor.authorWeyesa, Asefa Taa
dc.date.accessioned2018-05-18T10:36:33Z
dc.date.available2018-05-18T10:36:33Z
dc.date.issued2001-05
dc.identifier.urihttp://hdl.handle.net/11660/8307
dc.description.abstractEnglish: Bread wheat (Triticum aestivum) is one of the major cereals produced in south-eastern Ethiopia. Yields are often low on peasant farmers' fields due to sub-optimal crop management practices. Four multi-factor crop management trials were conducted which ran from 1992 till 2000 at Kulumsa and Asasa in the south-eastern highlands of Ethiopia. Two trials were conducted at each location, one where an ox-plow was used to simulate the peasant farmers methods and on the other trial mechanized farming methods were used. Different crop residue management options, tillage practices and cropping sequences were included as treatments. The crop residue management treatments were burning, partial removal (to simulate grazing by animals) and complete crop residue retention. The tillage practices for the mechanized trial were conventional mouldboard plowing, conservation tillage which was zero tillage at Kulumsa and mimimum tillage at Asasa and for the ox-plow trials it were conventional ox-plowing and minimum tillage. The cropping sequences were continuous wheat and a rotational system of faba beans (Vicia faba) followed by two seasons of wheat. The soil types were a clay intergrade between an eutric Nitisol and a luvic Phaoezem with 50% clay in the topsoil at Kulumsa, and a clay loam calcic Chernozem with 36% clay in the topsoil at Asasa. The objective of the study was therefore to determine the integrated effects of cropping sequence, straw management and tillage practices on the productivity and sustainability of wheat-based farming systems in Ethiopia. Among the crop residue management treatments, burning of stubble tended to increase the grain and biomass yield, as well as the yield components of wheat in most of the years when compared to partial removal and complete retention of stubble. Tillage did not give consistent responses for most of the parameters in either of the trials, with the exception of thousand kernel weight which was consistently higher for zero or minimum tillage in most seasons. Conventional tillage tended to be the superior tillage practice in terms of most of the measured parameters. The faba bean cropping sequence markedly increased wheat yields and the yield components, especially in the first wheat crop following faba beans. This can be ascribed to a higher soil N status. Burning of stubble tended to also enhance wheat N uptake as compared to partial removal or complete retention of the straw. Stubble management and cropping sequence had relatively minimal effects on soil strength expressed as penetrometer resistance. Conservation tillage led to a higher penetrometer resistance particularly in the surface layer of the soil (i.e., 0-15 cm depth), in both the mechanised and ox-plow systems, compared to conventional tillage. The penetrometer resistance of the 0-5 cm depth was negatively related to grain yield, while the penetrometer resistance of at the 20-25 cm depth was positively related to grain y.ield. Retention of straw on the soil surface increased the concentration of most of the important plant nutrients in the upper layer (i.e., 0-15 cm) of the soil as compared to burning and partial removal of the straw. Zero or minimum tillage practices also increased the concentration of some important plant nutrients like phosphorus and potassium in the upper layer of the soil in both system trials. Cropping sequence had little effect on the soil chemical properties. Partial removal or retention of the stubble tended to increase the population density of some broadleaf weed species, while burning had the opposite effect. Burning of crop stubble also markedly reduced the total grass weed population as compared to the other straw management treatments. Broadleaf weed populations were not affected by tillage practices in either the ox-plow or mechanised trials. Grass weeds, however, increased significantly in density under minimum or zero tillage. Broadleaf weeds did not vary markedly in response to cropping sequence, but most of the grass weed populations decreased in the faba bean rotation. A three years rotation, consisting of two consecutive wheat crops followed by one faba bean crop reduced the incidence of take-all, but had little effect on the eyespot incidence. Both zero or minimum tillage dramatically inhibited the take-all incidence relative to conventional tillage, but had little effect on eyespot incidences. Stubble burning had no consistent effect on the incidence of either of the diseases. The incidence of eyespot was higher in the full stubble retention practices compared to partial removal. A partial budget analysis reflected that the practice consisting of faba beans in rotation with wheat, combined with stubble burning, was the lowest cost option for ox-plow production systems. The practice of a faba bean-wheat rotation plus full stubble retention was the lowest cost option for mechanised production systems. The economic optimum practice' for both the mechanised and ox-plow systems at Kulumsa was combining stubble burning with conventional tillage and continuous wheat. However, for the Asasa mechanised trial the economic optimum practice was combining stubble burning with conventional tillage and a faba bean-wheat crop rotation, while for oxplowing it was combining stubble burning with minimum tillage in a faba bean-wheat crop rotation. Moreover, the index of variability of the nett benefit of each trial did not vary markedly between the low-cost and the economic optimum treatments. This means that the stability of farm level income will not be affected significantly by adopting the economic optimum practices for each zone. Pot experiments were conducted to determine the effect of the different straw management practices on wheat seedling development under controlled conditions. Straw retention had a negative effect upon most of the measured seedling growth parameters. The nil straw treatment (i.e., the control) grew better than the other application levels. Straw retention levels higher than 2.5 t ha-! impeded seedling development. Burning of the straw reduced the negative effect of straw application. The incorporation of the straw in to the soil resulted in the most pronounced inhibition of seedling development. The application of fresh straw was more harmful than naturally degraded straw.en_ZA
dc.description.abstractAfrikaans: Broodkoring (Triticum aestivum) is een van die belangrikste grane wat in suidoos Ethiopië geproduseer word. Lae oesopbrengste word deur die bestaansboere behaal as gevolg van nie-optimale gewasbestuurspraktyke. Vier gewasbestuursproewe, wat elk vanaf 1992 tot 2000 geduur het, is te Kulumsa en Asasa in die suidoostelike hooglande van Ethiopië uitgevoer. Twee proewe is by elke lokaliteit uitgevoer, nl. een waar 'n osploeg en die tradisionele praktyke van die plaaslike boere toegepas is en die ander waar gemeganiseerde boerderymetodes gebruik IS. Verskillende oesreste bestuursopsies, grondbewerkingspraktyke en gewasopeenvolgings is as behandelings ingesluit. Die oesreste bestuursbehandelings was brand, gedeeltelike verwydering (om beweiding van lande te verteenwoordig) en behoud van al die oesreste. Die grondbewerkingspraktyke vir die gemeganiseerde proewe was konvensionele skaarploegbewerking en bewaringsbewerking nl. deklaagbewerking by Asasa en geenbewerking by Kulumsa. Vir die tradisionele proewe was dit konvensionele osploegbewerking en minimumbewerking. Die gewasopeenvolgingsbehandelings was jaar-na-jaar deurlopend koring en 'n wisselboustelsel van boerbone (Vicia faba) gevolg deur twee seisoene koring. Die grondtipes was 'n klei tussengraad van 'n eutriese Nitisol en 'n luviese Phaoezem met 50% klei in die bogrond by Kulumsa en 'n kleileem kalsiese Chernozem met 36% klei in die bogrond by Asasa. Die doel van die studie was om die geïntegreerde effek van oesrestebestuur, bewerkingspraktyke en gewasopeenvolging, op die volhoubaarheid van koringproduksie-boerderystelsels in Ethiopië te ondersoek. Die verbranding van oesreste het in verskeie seisoene die hoogste graan en biomassa opbrengste gegee. Daar was geen konsekwente effek van grondbewerkingspraktyke op meeste van die oeskomponente nie, met die uitsondering van die duisendkorrelmassa wat altyd die hoogste op die geen- of minimumbewerking was. Konvensionele bewerkingspraktyke het geneig om die beste praktyk te wees in terme van al die gemete parameters. Die boerboon-koring wisselboustelsel het hoër koringopbrengste tot gevolg gehad, veral in die eerste seisoen koring wat op die boerbone gevolg het. Hierdie reaksie is veral aan 'n hoër grond- stikstofstatus toegeskryf. Die verbranding van oesreste het ook 'n verhoogde stikstofopname deur koring tot gevolg gehad. Die oesrestebestuurs- en gewasopeenvolgingsbehandelings het mm effekte op grondsterkte, uitgedruk as penetrorneterweerstand, gehad. Die bewaringsbewerkingspraktyke het hoër penetrometerweerstande in die boonste 150 mm, as die konvensionele praktyke gehad. Die pentrometerweerstand vir die 0 tot 50 mm diepte het 'n negatiewe verwantskap met oesopbrengste gehad terwyl die waardes op 200 tot 250 mm diepte 'n positiewe verwantskap getoon het. Behoud van alle oesreste op die oppervlak met bewaringsbewerking, het 'n verhoging van plantvoedingstofkonsentrasies in die boonste 150 mm tot gevolg gehad. Dit was veral die geval met fosfor en kalium. Die brand van oesreste het die populasiedigtheid van verskeie breëblaar en gras onkruide vermeerder. Die populasie van breëblaaronkruide IS me deur bewerkingspraktyke ge-affekteer nie maar die populasiedigtheid van sommige grasspesies het veral betekenisvol toegeneem m die nummum- en geenbewerkingsbehandelings. Gewasopeenvolging het geen effek op die breëblaar onkruide gehad nie maar die graspopulasies het toegeneem by die boerboon-koring wisselboubehandelings. Die boerboon gevolg deur die twee seisoene koring wisselboustelsel het die besmetting van vrotpootjie by koring bejerk maar geen effek op oogvlek gehad nie. Die voorkoms van vrotpootjie by koring was ook laer by die verskillende bewaringsbewerkingsbehandelings terwyl dit geen effek op oogvlek gehad het nie. Brand van oesreste het geen effek op die voorkoms van beide vrotpootjie of oogvlek gehad nie. Die voorkoms van oogvlek was hoër waar al die oesreste behou IS, m vergelyking met gedeeltelike verwydering. is gedoen. Dit het getoon dat 'n stelsel bestaande uit 'n boerboon-koring 'n Gedeeltelike begrotingsontleding van die behandelings en behandelingskombinasies wisselboustelsel gekombineer met brand van oesreste die goedkoopste vir die tradisionele praktyk is. Vir die gemeganiseerde praktyke was wisselbou gekombineer met volle behoud van oesreste die goedkoopste stelsel. Die ekonomiese optimum stelsels vir beide die gemeganiseerde en tradisionele praktyke te Kulumsa, was 'n kombinasie van brand van oesreste met konvensionele bewerking en deurlopende koringproduksie. Vir Asasa gemeganiseerd was dit 'n kombinasie van oesreste verbranding, konvensionele bewerking en boerboon-koring wisselbou. Vir die tradisionele praktyke te Asasa was dit brand in kombinasie met minimumbewerking en wisselbou: Vir al die proewe het die variasie-indeks van die netto voordeel tussen die goedkoopste en die ekonomiese optimum behandelingskombinasie nie noemenswaardig verskil nie. Dit beteken dat die stabiliteit van die plaasvlak inkomste nie veel deur die aanvaarding van die aanbevole stelsels ge-affekteer sal word nie. Potproewe is uitgevoer om die effek van die verskillende oesreste bestuursopsies op die groei van koringsaailinge onder gekontroleerde toestande te ondersoek. Die behoud van koringstrooi het bykans al die groeiparameters van die koringplante benadeel, veral by vlakke hoër as 2.5 t ha". Die verbranding van oesreste het die beste groei verseker terwyl die vermenging van die oesreste met die grond die swakste saailingontwikkeling tot gevolg gehad het. Vars en natuurlik verouderde strooi is gebruik waarvan vars strooi die nadeligste was.en_ZA
dc.description.sponsorshipEAROen_ZA
dc.description.sponsorshipCIMMYT/CIDAen_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectConservation tillageen_ZA
dc.subjectCompactionen_ZA
dc.subjectCrop residueen_ZA
dc.subjectCrop rotationen_ZA
dc.subjectFaba beanen_ZA
dc.subjectGrain yielden_ZA
dc.subjectNutrient uptakeen_ZA
dc.subjectWheaten_ZA
dc.subjectWheat -- Ethiopia -- Yieldsen_ZA
dc.subjectCropping systems -- Ethiopiaen_ZA
dc.subjectCrop residue management -- Ethiopiaen_ZA
dc.subjectThesis (Ph.D. (Soil Science))--University of the Free State, 2001en_ZA
dc.titleEffects of stubble management, tillage and cropping sequence on sustainable wheat production in the South-Eastern highlands of Ethiopiaen_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record