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dc.contributor.advisorKotzé, E.
dc.contributor.advisorDu Preez, C. C.
dc.contributor.authorLoke, Palo Francis
dc.date.accessioned2015-09-21T10:29:11Z
dc.date.available2015-09-21T10:29:11Z
dc.date.copyright2012-01
dc.date.issued2012-01
dc.date.submitted2012-01
dc.identifier.urihttp://hdl.handle.net/11660/1258
dc.description.abstractEnglish: Farmers have largely depended on intensive soil cultivation to reduce nutrient stratification and therefore distribute nutrients homogeneously across the root zone for optimum crop productivity. This attempt however, has led to serious soil organic matter degradation and nutrient outflows. Consequently, food production for the increasingly growing world population was severely threatened. Crop residues as a source of organic matter and nutrients, when properly managed, can restore or improve soil fertility, and hence crop yields. The different residue management practices on some soil fertility indicators have been examined since 1979 in a long-term wheat trial at the ARC-Small Grain Institute near Bethlehem in the Eastern Free State on an Avalon soil. The observations established in 1999 indicated that soil nutrient and organic matter stratification still continues, therefore it was found necessary to further investigate the effects of these residue management practices on some soil fertility indicators, nutrient uptake and wheat grain yield. The applied field treatments include two methods of straw disposal (unburned and burned), three methods of tillage (no-tillage, stubble mulch and ploughing) and two methods of weeding (chemical and mechanical). Soil samples were collected in 2010 at various depths viz. 0-50, 50-100, 100-150, 150-250, 250-350 and 350-450 mm and analyzed for organic C, total N and total S as organic matter indices, pH, some macronutrients (P, K, Ca, Mg and Na) and CEC, as well as some micronutrients (Cu, Fe, Mn and Zn). At mid-shooting stage, plants were sampled in each treatment plot, oven-dried at 68 ºC, weighed, milled and analyzed for N, S, P, K, Ca, Mg, Na, Cu, Fe, Mn, and Zn. The grain yield data of wheat for the 26 years were supplied by the ARC-Small Grain Institute for use as a supplement to the soil data. The methods of straw disposal and tillage had variable influences on soil organic matter indices. Unburned straw increased total N and S, but reduced organic C when compared to the burned straw. No-tillage increased organic C only in the 0-50 mm soil depth when compared to stubble mulch and ploughing. No-tillage and stubble mulch resulted in a higher total N to a soil depth of 450 mm relative to mouldboard ploughing. Ploughing on the other hand, and to some extent stubble mulch, increased total S more than no-tillage in the upper 250 mm soil depth. Mechanical weeding enhanced these indices to 450 mm soil depth as opposed to chemical weeding. No-tillage and to some extent stubble mulch suppressed acidification in the upper 100 mm and lower 350-450 mm soil depths. Mechanical weeding also increased soil pH when compared to chemical weeding. No-tillage combined with either chemical weeding or straw burning suppressed acidification in the surface soil, whereas mechanical weeding combined with either no-tillage or mouldboard ploughing retarded acidification in the subsoil. The concentrations of P, K, Mg, Mn and Zn were higher in the burned treatments than in the unburned plots. The reverse was observed with Ca, Na and Cu. In contrast, mouldboard ploughing, and to some extent stubble mulch, resulted in an accumulation of Cu in the upper 100 mm soil depth when no-tillage served as a reference. Chemical weeding enhanced P, K, Mg, Na and CEC, but resulted in lower Ca, Cu, Fe, Mn and Zn contents when compared to mechanical weeding. The applied management practices were also tested on nutrient uptake and grain yield. Although not always significant, the burned straw increased nutrient uptake, but resulted in a lower wheat grain yield when compared to unburned straw. Despite the beneficial effects of no-tillage and stubble mulch on the fertility status of this Avalon soil, higher nutrient uptake and grain yield were perceived under mouldboard ploughing. Mechanical weeding also enhanced the uptake of most of the studied nutrients relative to chemical weeding. Mouldboard ploughing combined with either unburned straw or chemical weeding increased nutrient uptake and wheat grain yield. However, irrespective of the applied field treatments, nutrient concentrations in oat straw were below optimum levels, and possibly plants were already suffering acute nutrient deficiencies.en_ZA
dc.description.abstractAfrikaans: Boere het grootliks staatgemaak op intensiewe grondbewerking om voedingstof-stratifikasie te verminder en dus voedingstowwe homogeen te versprei regoor die wortelsone vir optimum gewasproduktiwiteit. Hierdie poging het egter gelei tot ernstige grond organiese materiaal degradasie sowel as voedingstofverliese. Gevolglik is voedselproduksie ernstig bedreig vir „n toenemend groeiende wêreld populasie. Gewasreste is „n bron van organiese material en voedingstowwe, en indien dit reg bestuur word kan dit grondvrugbaarheid herstel of verbeter, en dus ook gewasopbrengste. Die verskillende oesreste-bestuurspraktyke op sekere vrugbaarheidsindikatore word al vanaf 1979 bestudeer in „n lang-termyn koringproef by die LNR-Kleingraan Instituut naby Bethlehem in die Oos-Vrystaat op „n Avalon grond. Die observasies wat in 1999 gemaak is, dui aan dat grondvoedingstof en organiese materiaal stratifikasie steeds gebeur, dus was dit nodig om verdere ondersoek te doen op die effekte van hierdie oesrestebestuurspraktyke op sekere grondvrugbaarheids-indikatore, voedingstofopname en graanopbrengste van koring. Die toegepaste behandelings sluit in twee metodes van oesreste wegdoening (nie-brand en brand), drie metodes van bewerking (geen-bewerking, deklaagbewerking en konvensionele bewerking) en twee metodes van onkruidbeheer (chemies en meganies). Grondmonsters was geneem in 2010 op verskeie dieptes nl. 0-50, 50-100, 100-150, 150-250, 250-350 en 350-450 mm en geanaliseer vir organiese C, totale N en totale S as organiese materiaal indikatore, pH, sommige makrovoedingstowwe (P, K, Ca, Mg en Na) en KUK, sowel as sommige mikrovoedingstowwe (Cu, Fe, Mn en Zn). By mid-stamverlenging stadium is plantmonsters geneem in elke behandelings-perseel, geoond-droog by 68 ˚C, geweeg, gemaal en geanaliseer vir N, S, P, K, Ca, Mg, Na, Cu, Fe, Mn en Zn. Die oesopbrengsdata van die koring vir 26 jaar was voorsien deur die LNR-Kleingraan Instituut om bykomend te gebruik saam die gronddata. Die metodes van strooi-wegdoening en bewerking het varierende gevolge gehad op grond organiese materiaalindikatore. Strooi wat nie gebrand is nie het totale N en S laat toeneem, maar organiese C laat afneem in vergelyking met die brand van strooi. Geen-bewerking het organiese C laat toeneem slegs in die 0-50 mm gronddiepte in vergelyking met deklaag- en konvensionele bewerking. Geen-bewerking en deklaagbewerking lei tot hoër totale N tot op „n gronddiepte van 450 mm relatief tot konvensionele bewerking. Konvensionele bewerking, en tot „n mate deklaagbewerking, het egter totale S laat toeneem meer as geen-bewerking in die boonste 250 mm gronddiepte. Geen-bewerking en tot „n mate deklaagbewerking het versuring onderdruk in die boonste 100 mm en onderste 350-450 mm gronddiepte. Meganiese onkruidbeheer het ook die grond pH laat toeneem wanneer dit vergelyk word met chemiese onkruidbeheer. Geen-bewerking gekombineer met chemiese onkruidbeheer of brand van strooi, het versuring onderdruk in die oppervlak grond, terwyl meganiese onkruidbeheer gekombineer met geen-bewerking of konvensionele bewerking „n vertraging van versuring in die ondergrond tot gevolg het. Die konsentrasies van P, K, Mg, Mn en Zn was hoër in die gebrande behandelings as in die ongebrande behandelings. Die teenoorgestelde kon waargeneem word met Ca, Na en Cu. In teenstelling het konvensionele bewerking, en tot „n mindere mate geen-bewerking daar toe bygedra dat Cu geakkumuleer het in die boonste 100 mm gronddiepte wanneer geen-bewerking gedien het as „n verwysing. Chemiese onkruidbeheer het P, K, Mg, Na en KUK verhoog, maar het gelei tot „n laer Ca, Cu, Fe, Mn en Zn inhoud wanneer vergelyk word met meganiese onkruidbeheer. Die toegepaste bestuurspraktyke was ook getoets op voedingstofopname en oesopbrengs. Alhoewel nie altyd betekenisvol nie, het die brand van reste voedingstofopname laat toeneem, maar het gelei tot „n laer koring oesopbrengs wanneer dit vergelyk word met ongebrande reste. Ten spyte van die voordelige effekte van geen-bewerking en deklaagbewerking op die vrugbaarheidsstatus van hierdie Avalon grond, is hoër voedingstofopname en oesopbrengste onder konvensionele bewerking waargeneem. Meganiese onkruidbeheer het ook die opname van meeste van die voedingstowwe verhoog relatief tot chemiese onkruidbeheer. Konvensionele bewerking gekombineer met ongebrande reste of chemiese onkruidbeheer het voedingstofopname en koring oesopbrenste verhoog. Alhoewel, ongeag van die toegepaste behandelings, was die voedingstof konsentrasies in die hawerreste onder die optimum vlakke, en plante het moontlik reeds akute voedingstoftekorte gehad.af
dc.description.sponsorshipInkaba yeAfricaen_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectWheat -- Yielden_ZA
dc.subjectCrop residue managementen_ZA
dc.subjectNutrient uptakeen_ZA
dc.subjectDissertation (M.Sc.Agric. (Soil, Crop and Climate Sciences) )--University of the Free State, 2012en_ZA
dc.subjectResidue managementen_ZA
dc.subjectSoil fertilityen_ZA
dc.subjectWheat grain yielden_ZA
dc.titleLong-term effects of residue management on soil fertility indicators, nutrient uptake and wheat grain yielden_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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