Je McPhee

The effect of initial soil water content and tillage implement on seedbed formation

Abstract This study was undertaken to determine the effect of initial soil water content and various tillage implements in producing a suitable seedbed tilth on a cracking clay soil (Entic Chromustert). The soil was tilled with one, two and three passes of a tined implement, a disc and a rotary hoe at three different initial soil water contents. Bulk density, aggregate size distribution and cone index were measured before and after tillage. Soil water content was measured before tillage only. Results tend to indicate that finer tilths were produced at drier initial soil water contents and with an increasing number of implement passes. Soil bulk density and cone index were reduced after tillage. Initial soil water content appears to be the controlling factor in producing a suitable seedbed tilth. All combinations of implement, number of passes and initial soil water contents appeared to produce reasonable seedbed tilths over the range of water contents examined.

Spacing uniformity-yield effects and in-field measurement

Trials were done to investigate the effects of spacing uniformity on crop yield, and to assess a method of measuring spacing uniformity without the need to calculate the coefficient of variation. Spacing uniformities ranged from perfect to the worst observed in a previous field survey. Improved spacing uniformity gave increased marketable yields, with an improvement of 10% in gross return over the worst uniformity treatment. Such improvements are possible in commercial situations with proper attention to equipment maintenance and calibration and uniformity of seed piece size.Spacing uniformity is often measured by the coefficient of variation, which is derived from the mean and standard deviation of measured seed piece or plant spacings. This is not the best method to use, since the measure of uniformity is referenced to the actual spacing, not the desired or target spacing.The alternative method of assessing spacing uniformity involved counting the number of spaces that lie in a pre-determined “acceptable range” and calculating the percentage of “acceptable spaces”. The necessary calculations are easy if a suitable number (e.g. 40 or 50) of seed piece spaces are used.

Automatic chemical applicators for cattle

Mustering and other cattle management operations are a significant cost for beef producers on extensive properties in northern Australia. As a result, a range of cattle handling equipment has been developed which uses animal behaviour patterns to simplify some tasks. Two “animal-powered” devices were developed to automatically apply parasite control chemicals to cattle as they passed through one-directional spear gates. Both applicators were based on wheel-driven pumps, and dispensed chemicals in proportion to the length of contact between the device and the animals body. Application rates were within 10% of existing recommendations for animals in the most common weight range of 250–500 kg. The applicators were simple to install and remove, allowing easy transfer between sites.