Browsing by Author "Ham, GJ"

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An initial evaluation of surge irrigation as a management tool for the Burdekin sugar industry : Final report 89/7
(1991) Ham, GJ
Conventional furrow and surge irrigation were compared during the growth of second and third ratoon sugarcane crops on a duplex soil in the Lower Burdekin district. Data collection was severely hampered during this investigation by the prevailing weather. Crop yields produced by both irrigation systems were almost identical. Surge irrigation reduced pumping times by 15.7-23.5% compared with conventional irrigation, thus reducing irrigation costs directly by these percentages. Further savings would result from lower maintenance on pumping equipment. Soil moisture distribution along the furrow and 'out times' for irrigation sets were more uniform for surge irrigation than conventional irrigation.
Biomass accumulation in sugarcane : final report 79/9028
(1984) Kingston, G; Ham, GJ; Ridge, DR; Leverington, KC
Growth analysis experiments were conducted at Ayr and Bundaberg from 1979 to 1982 to study biomass accumulation in plant and ratoon crops of sugarcane. Crops were planted and ratooned in March, June, September and December, and harvested at 6, 9, 12 and 15 months of age. Data were acquired for yields of total fresh and dry matter, in addition to yields of the following vegetative components: dry leaf, green leaf, tops and stalks. Fibre analyses were determined on all components, while glucose, fructose and sucrose % were also determined in the latter three components. It was shown that yield of total dry matter increased with age at harvest for all months of crop initiation. Potential for dry matter accumulation was closely associated with intercepted solar radiation. Growth for three months was ranked December-March > March-June > September-December > June-September. These rankings represented the interaction of crop growth stage with solar radition. The proportion of total dry matter allocated to soluble and structural carbohydrate was shown to be dependent on variety as well as an interaction between age at harvest and month of harvest. Canes older than nine months of age, harvested between June and December, had established a plateau type equilibrium between the proportion of total dry matter in soluble and structural carbohydrate. Good prospects existed for forward extension of the crushing season to March for ethanol production based on 15 month old cane. Models were developed to describe the growth of yield components of the biomass in relation to intercepted solar radition, month of crop initiation, age at harvest and crop class.
Final Report SRDC Project BS146S Farming Sodic Soils - A Situation Statement and Future Direction
(1997) McMahon, GG; Ham, GJ; Cox, AZ
Aims of project were to document research on, and farming systems for, cropping sodic soils to sugarcane, and through an expert review of research and current practices for farming sodic soils identify directions for future research and extension efforts on the subject.
Final report SRDC project BSS197 : Products and mechanisms for the amelioration of sodic soils
(2005) Ham, GJ
This project set out to examine a number of issues associated with sodic soils. These included: 1) the impact of soil sodicity on crop production; 2) the reduction of adverse impacts of soil sodicity through irrigation management and/or the use of soil ameliorants; 3) the properties and potential efficacy of a range of products being marketed as 'soil ameliorants' throughout the northern part of Queensland; 4) the means by which a selection of these ameliorants effected beneficial changes to sodic soils; and 5) to establish a close linkage between these investigations and a method for the field identification and measurement of sodicity being developed in a closely associated Sugar CRC project.
Review of sodic soils research in the Queensland sugar industry
(1995) Cox, AZ; Ham, GJ; McMahon, GG
Increasing levels of sodium on the clay, in the absence of high levels of soluble salts, are not believed to be toxic to the cane plant. Any adverse effect on crop production is through deterioration of the soil structure (Crema, 1994). Under wet conditions, increased clay dispersion accompanies increasing exchangeable sodium percentage (ESP). This is associated with sealing and crusting in surface soils and dense subsurface clays which resist penetration of roots. Even if water does penetrate the surface, it is held very strongly in the very small pores formed in the dispersed soil. It is difficult for roots to withdraw this moisture. The end result of sodicity is similar to that of salinity, water stress. Both infiltration and water storage are adversely affected. Reclamation of sodic soils can be achieved by application of gypsum or lime to promote replacement of sodium on the clay particles by calcium, and hence improve soil structure. Research work indicates that sugarcane yields on sodic soils with ESP less than 25 can be improved by up to 20% with the application of gypsum 10t/ha (Ham etal., 1995). Improvements in yield can also be achieved by improving surface and subsurface drainage to promote leaching of displaced sodium salts from the soil profile. Reduction of natural slope from 0.49% to 0.07% has also improved sugarcane yield by 24% over the crop cycle (Ham etal.,1995). Research has developed ways of increasing production on sodic soils. With the expansion of the cane industry into marginal areas there has been associated extension campaign, concentrating on farm planning and demonstrating the benefits of applied gypsum (Ham etal., 1995). A good example of this is the Burdekin where the BSES program on sodic soils is estimated to have resulted in an extra 26,000 tonnes of cane to the Burdekin district in 1994 alone with a gross value to the industry of $1.02m.