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Thorough mixing of lime with the soil is a standard recommendation for lime application. However, the implements and passes that may be used to achieve this in Australian cereal farming are unclear. Therefore, 2 experiments were conducted to examine the incorporation of lime applied at 0, 2 and 5 t/ha using a range of different agricultural implements and numbers of cultivation events. Shoot dry matter and grain yield of wheat were measured in the year of lime application in both experiments. The plots were resown to wheat in the following season by direct drilling, and measurements were repeated. In a dry season, high soil disturbance (rotary hoe and disc harrow) improved the response of wheat to lime in the first year of experiment 1. In experiment 2, rainfall was higher, and the advantage from thorough incorporation was less clear. However, the rank order of incorporation methods and lime responsiveness was positively correlated with that in experiment 1 for both dry matter and grain yield; thorough incorporation tended to give better responses to lime than ?poor' incorporation (light harrowing). In the second year of experiment 1 there was limited evidence of the influence of incorporation method on lime response. In the second season of both experiments the effects of incorporation method on lime response had dissipated or other effects were more important. We found that to maximise grain yield responses to lime, the most effective incorporation was achieved with a disc harrow or with multiple passes with a tined implement (scarifier). Incorporation limited to a light harrow was inadequate. However, any effects of method of incorporation reduced or disappeared in the following season, even when direct drilling was used and there was limited further soil disturbance.

Abstract. Long-term agricultural experiments such as the Temperate Pastures Sustainability Key Program (TPSKP) present significant challenges in the areas of planning and design, conduct, analysis and reporting. This paper concentrates on 2 aspects, namely, the experimental design and the statistical analysis. For long-term agricultural experiments which examine the effects of management strategies over time, an enumeration of the initial biodiversity is essential and permits the allocation of treatments to plots in such a way that potential bias in the estimation of treatment effects due to lack of uniformity in experimental units (plots) is reduced in the covariate analysis. Spatial replication is considered essential and the design should include at least 2 starting dates for management strategies so that the possible interaction between the year of start and the management strategy can be described. The data resulting from repeated measurement of herbage mass of major individual species or species groups represent a longitudinal data set with complexity due to the staggered commencement of treatments and also in part due to the nature of some of the strategies (closure and cuts). The analysis presented is the cubic smoothing spline approach of Verbyla et al. (1999) which integrates cubic splines, random coefficients, covariance modelling and estimation of systematic deviation. This approach, based on linear mixed models and using residual maximum likelihood (REML) has the flexibility to cope with the staggered imposition of management strategies and permits the partitioning of trends into smooth and non-smooth components, thereby quantifying species persistence and seasonal influence under each management strategy.

This article considers the design of early generation variety trials with a prespecified spatial correlation structure and introduces a new class of partially replicated designs called p-rep designs in which the plots of standard varieties are replaced by additional plots of test lines. We show how efficient p-rep designs can be readily generated using the modified Reactive TABU search algorithm. The expected and realized genetic gain of p-rep and grid plot designs is compared in a simulation study.

Summary. Pitfall traps were used to monitor the seasonal activity of ants in 2 citrus orchards in the Murrumbidgee Irrigation Area of south-western New South Wales for 22–24 months (November 1992–August/October 1994). Twenty-four species were recorded (22 species at Yanco and 18 species at Cudgel), with Iridomyrmex rufoniger group species being numerically dominant at both sites (63 and 59% of total captures at Yanco and Cudgel respectively). Meat ants, Iridomyrmex purpureus (F.Smith), were a significant (9%) component of trap captures at Yanco where regular soil cultivation was practised, but were less common (<1% of captures) at Cudgel. Sample species richness was generally greater at the Yanco site (mean 9.3 species per trapping interval compared with 6.6 at Cudgel). Total ant captures and sample species richness showed a positive correlation with mean daily temperatures over trapping intervals. Variations in seasonal activity were shown by the numerically dominant species, with 2 distinct patterns being evident. Whilst all taxa were less active during winter, some species [I. rufoniger group sp. 2, Pheidole sp., Rhytidoponera metallica (F.Smith)] continued to forage, albeit at reduced levels. Other species of Iridomyrmex including I. rufoniger group sp. 1 and I. purpureus ceased foraging almost entirely during June–September. Iridomyrmex species are known to interfere with the biological control of honeydew-producing insects in citrus orchards, and our results indicate that ant control programs in southern New South Wales should be initiated in late August–early September to achieve optimal results.