Maize fertilizer investigations on the Atherton Tableland, Queensland

Responses ranging from 10 to 47 bus/ac were recorded to nitrogen fertilizer application in three of six experiments conducted from 1960 to 1963 on red loam soils. Lack of nitrogen response in the remaining experiments was associated with either high fertility, incidence of tropical rust, or abnormally dry conditions. Residual effects of nitrogen were small. Responses to superphosphate varied from nil to 19 bus/ac, and residual responses were evident for up to two years on soils containing less than 70 p.p.m. available P2 05. Potash applications were of little significance

Hierarchical development of dominance through the winner-loser effect and sociospatial structure

In many groups of animals the dominance hierarchy is linear. What mechanisms underlie this linearity of the dominance hierarchy is under debate. Linearity is often attributed to cognitively sophisticated processes, such as transitive inference and eavesdropping. An alternative explanation is that it develops via the winner-loser effect. This effect implies that after a fight has been decided the winner is more likely to win again, and the loser is more likely to lose again. Although it has been shown that dominance hierarchies may develop via the winner-loser effect, the degree of linearity of such hierarchies is unknown. The aim of the present study is to investigate whether a similar degree of linearity, like in real animals, may emerge as a consequence of the winner-loser effect and the socio-spatial structure of group members. For this purpose, we use the model DomWorld, in which agents group and compete and the outcome of conflicts is self-reinforcing. Here dominance hierarchies are shown to emerge. We analyse the dominance hierarchy, behavioural dynamics and network triad motifs in the model using analytical methods from a previous study on dominance in real hens. We show that when one parameter, representing the intensity of aggression, was set high in the model DomWorld, it reproduced many patterns of hierarchical development typical of groups of hens, such as its high linearity. When omitting from the model the winner-loser effect or spatial location of individuals, this resemblance decreased markedly. We conclude that the combination of the spatial structure and the winner-loser effect provide a plausible alternative for hierarchical linearity to processes that are cognitively more sophisticated. Further research should determine whether the winner-loser effect and spatial structure of group members also explains the characteristics of hierarchical development in other species with a different dominance style than hens

Effect of plant density on maize yield on the Atherton Tableland, Queensland

From 1953 to 1961, the open-pollinated maize variety Kairi Durum grown at 11,900 plants per ac showed an average yield advantage of approx. 6 bus over lower density stands. Yields of the hybrid GH128 were sensitive to plant density in 1959, but were independent of treatment in 1961, when abnormally dry conditions prevailed, and in 1962, when tropical rust was prevalent. With currently available hybrids, plant densities above 14,000 plants per ac are not recommended, due to the possibility of lodging

Energy-band structure of SiC polytypes by interface matching of electronic wave functions

We interpret SiC polytypes as natural superlattices, consisting of mutually twisted cubic layers. A method is presented to calculate the electron band structure of any polytype, based on an empirical pseudopotential description of cubic SiC. Bloch and evanescent waves belonging to cubic layers are matched at interfaces in order to make up the wave functions of the respective polytypes. Band gaps of hexagonal and rhombohedral modifications are in excellent agreement with experimental data such that the nearly linear relationship between the indirect gap and the hexagonal nature is reproduced. A simple explanation of this relationship is given in terms of a Kronig-Penney-like mode

Effects of plant density on maize yield on the Atherton Tableland, Queensland

From 1953 to 1961, the open-pollinated maize variety Kairi Durum grown at 11,900 plants per ac showed an average yield advantage of approx. 6 bus over lower density stands. Yields of the hybrid GH128 were sensitive to plant density in 1959, but were independent of treatment in 1961, when abnormally dry conditions prevailed, and in 1962, when tropical rust was prevalent. With currently available hybrids, plant densities above 14,000 plants per ac are not recommended, due to the possibility of lodging

Energy-band structure of SiC polytypes by interface matching of electronic wave functions

We interpret SiC polytypes as natural superlattices, consisting of mutually twisted cubic layers. A method is presented to calculate the electron band structure of any polytype, based on an empirical pseudopotential description of cubic SiC. Bloch and evanescent waves belonging to cubic layers are matched at interfaces in order to make up the wave functions of the respective polytypes. Band gaps of hexagonal and rhombohedral modifications are in excellent agreement with experimental data such that the nearly linear relationship between the indirect gap and the hexagonal nature is reproduced. A simple explanation of this relationship is given in terms of a Kronig-Penney-like mode