Factors limiting wheat grain yield under zero tillage on a sodosol in Southern Queensland

Thomas, Gregory Alan (2000). Factors limiting wheat grain yield under zero tillage on a sodosol in Southern Queensland PhD Thesis, School of Land, Crop and Food Sciences, The University of Queensland.

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Author Thomas, Gregory Alan
Thesis Title Factors limiting wheat grain yield under zero tillage on a sodosol in Southern Queensland
School, Centre or Institute School of Land, Crop and Food Sciences
Institution The University of Queensland
Publication date 2000
Thesis type PhD Thesis
Supervisor F.P.C. Blamey
G.D. Smith
S.A. Waring
Total pages 340
Language eng
Subjects L
0908 Food Sciences
620100 Field Crops
Formatted abstract

Zero tillage has important benefits for long-term stability and productivity of cropping soils, because of its potential to reduce soil erosion and to arrest the decline in soil organic matter resulting from long-term cultivation and cropping. However, the potential for producing higher grain yield under zero tillage than under conventional tillage, as a result of higher soil water storage under zero tillage, has not always been realised in experimental work and in commercial practice. Factors which may result in lower yield under zero tillage in various situations include reduced availability of nutrients, increased incidence of plant diseases and insect pests, poor crop establishment, poor fallow weed control, soil compaction, lower soil temperature, increased frost damage and inadequate management expertise. In previous research, the relative importance of these factors and the conditions under which they may influence yield were not always clearly identified. A multi-disciplinary study was conducted in southern Queensland to identify and assess the effect of factors limiting wheat (Triticum aestivum L.) grain yield under zero tillage, to define the conditions under which these factors influence yield and to propose strategies for eliminating or minimising these constraints to production.

A field experiment was conducted on a sadie, texture-contrast soil (Sodosol) in the Billa Billa area, approximately 45 km north of Goondiwindi in southern Queensland. A total of eight trials was conducted over a period of five years (1990-91 to 1994-95). Treatments and measurements were designed to determine whether the main factors limiting wheat yield under zero tillage (ZT) were as a result of deleterious soil chemical, physical or biological properties, compared with conventional tillage (CT). A range of soil nutrient conditions was established by varying the types, rates and times of fertilizer application. To determine the importance of biological factors on crop growth and yield, soil fumigation, nematicide application, residue burning and cultivar (Cunningham and Sunco) treatments were included. Rotations of wheat and chickpea (Cicer arietinum L.) or lucerne (Medicago sativa L.) were also included to study their effects on soil properties and disease occurrence. Treatments were evaluated under raingrown conditions and also with supplementary, strategic irrigation to simulate wetter seasonal conditions than those occurring naturally and give results at a wider range of yield levels. Annual rainfall from 1990 to 1994 varied from 1 6-41% below the long-term average of622 mm, but annual rainfall was above-average in 1995 (713 mm)…………………………


Keyword cropping soil
Zero Tillage

Document type: Thesis
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