ALBERT

Description: Between 60,000 and 40,000 B.P., northeastern Queensland, south New South Wales, and southeastern South Australia were drier than at present. From 40,000–30,000 B.P. a colder climate than at present is indicated from one New Guinea area. Dryness became even more accentuated in northeastern Queensland, whereas many lakes filled up in the southern mainland, probably because of increasing precipitation effectiveness there. Before the end of this period colder conditions than now were already giving rise to slope instability in the Snowy Mountains of New South Wales.The period of 25,000–15,000 B.P. saw the greatest lowering of the New Guinea treeline, reaching an extreme at 17,000 B.P. when glaciers also achieved their maximum extent. This was the time of extensive glaciation in Tasmania and small glaciers formed in the Snowy Mountains. Estimates of the lowering of mean annual temperature range from 6°–10°C. Northeastern Queensland experienced its driest Late Quaternary climate; lakes were contracting throughout the southern mainland and the final phase of substantial desert dune building took place before the period ended.In the Snowy Mountains ice retreat began before 20,000 B.P., as did the construction of clay dunes in the southern semi-arid belt, a process demanding higher temperatures. However, in New Guinea and Tasmania ice retreat and treeline rise did not begin till after 15,000 B.P. Temperatures rose rapidly and everywhere most of the ice had gone by 10,000 B.P., when some lakes filled up in southern Australia, implying an increase in absolute precipitation.In the last 10,000 years climate has been relatively stable although there are some indications that temperature and rainfall were marginally higher than now between 8000 and 5000 B.P. Since then, lake levels have oscillated; a brief, limited resumption of periglacial activity took place in the Snowy Mountains and there were small glacier advances in New Guinea.

Description: Paleomagnetic analysis of samples from the original 600-m-long core from the San Agustin Plains, New Mexico, showed an unquestionable reversal stratigraphy dating the record back to at least 1.6 my. Analysis of pollen, ostracodes, and algae of a duplicate sample section in the vicinity of the original coring site and spanning the last 18,000 yr B.P. shows a much higher resolution than the earlier results.

Description: Municipal effluent is becoming an increasing environmental threat and needs appropriate disposal measures to safeguard soil and environmental quality. As an important source of water and nutrients, municipal effluent could be used to increase productivity in nutrient deficient dry areas. Acacia nilotica L. (Babool) seedlings were grown using municipal effluent. Five treatments comprised: irrigation of soil (without seedlings) with municipal effluent at potential evapotranspiration (PET) (treatment T1), irrigation of seedlings at 0.5 PET (T2), PET (T3), and 2 PET (T4), and canal water irrigation of seedlings at PET (T5). Seedlings in the T3 and T4 treatments attained greater height and collar diameter, and produced 22% and 54% more biomass than those in T5. After 24 months, biomass production was 7.43–12.96 t ha−1 as compared to 5.73 t ha−1 in T5. Nutrient concentrations in the seedlings were positively correlated with effluent quantity (r = 0.82, p 〈 0.01), being greater in foliage than in stems and roots. Uptake of nitrogen (N) was 2.70%, and of iron (Fe) 0.11%, of seedling biomass. Relative increase in metal concentration was greater than that in nutrients. The availability of potassium (K), copper (Cu), Fe, manganese (Mn) and zinc (Zn) in the soil increased twofold and that of NH4-N and PO4-P by 4.5- and 7.9-fold, respectively, in T4 relative to T5. Available NH4-N, PO4-P, Mg and K were highest in the 0–15 cm depth soil, whereas NO3-N, Na, Cu, Fe, Mn and Zn availability were highest in deeper soil layers. Relatively low soil nutrients in T3 compared to T1 indicated withdrawal and accumulation of these nutrients in the seedlings. In several respects municipal effluent benefited A. nilotica seedlings and soil properties, and produced 5.59–12.96 t ha−1 dry biomass. Municipal effluent could help to meet the fuel need of suburban areas, although long-term application of effluent would lead to metal accumulation in soil and plants.

Description: Reactivation of sand drift is a common phenomenon in arid areas and needs suitable surface vegetation in association with overstorey trees for better stabilization. Regeneration and survival of Cassia angustifolia seedlings were studied in relation to different adult neighbours and soil water content with a view to developing effective surface vegetation and control of sand drift. Acacia tortilis, Prosopis juliflora and Calligonum polygonoides were the experimental adult neighbours. Observations were recorded at distances of 0–1.0 m (inner canopy [IC] zone), 1.0–1.5 m (outer canopy [OC] zone) and 1.5–2.5 m (outside the canopy [OS] zone) from the neighbours. Seeds and regenerated seedling densities were higher in the C. polygonoides plot than the other two neighbours and the control plots. The density was higher in the OC zone of the C. polygonoides and P. juliflora plots, the OS zone of the A. tortilis plot and the IC zone of the control plot. Both inter- and intraspecific competition resulted in high mortality during July–October in A. tortilis and P. juliflora plots. Seedling survival decreased in February and June, but the density, which was greater in the IC zone, was positively correlated with that in July and with the soil water content (SWC). The ultimate survival of seedlings was higher in the neighbour inclusion than control plots. The soil water content (SWC) was generally higher in the Calligonum polygonoides plot than that in the A. tortilis and P. juliflora plots. With distance from the adult neighbours, the SWC increased in the 25–50 cm and 50–75 cm and decreased in the 0–25 cm soil depth layers. Shoot height and biomass of one-year-old C. angustifolia seedlings were higher in the C. polygonoides plot than in the plots of other neighbours. A negative relative neighbour effect for most of the growth variables suggests that the adult neighbours facilitated regeneration, survival, growth and biomass of C. angustifolia seedlings. C. polygonoides was the best neighbour, with better soil water content at depth and the most positive influence on seedling growth; it is therefore a suitable planting partner for C. angustifolia in promoting the effective stabilization of dunes.

Description: Decrease in productivity of pastureland is a common problem in dry areas and needs to be enhanced through conservation and management of soil biodiversity and available plant resources. Diversity and population dynamics of soil arthropods, and soil nutrients were studied in different silvopastoral (tree-integrated grassland) systems for effective management and enhancement of grassland productivity. The most prominent combinations of trees and grasses in silvopastoral systems of the selected sites were Prosopis cineraria with Cenchrus ciliaris and C. biflorus (PC), Acacia nilotica with Elusine compressa and C. ciliaris (AN), Zizyphus nummularia with C. ciliaris and E. compressa (ZN), Capparis decidua with C. biflorus and Digitaria marginatus (CD) and A. senegal with C. ciliaris and D. marginatus (AS). Pure grass blocks outside tree canopy were selected as control plots. Acari, Myriapoda, Coleoptera, Isoptera, Collembola and other soil arthropods were the major soil faunal groups. Relative densities of Acari, Myriapoda and other arthropods were highest in silvopastoral systems and those of Coleoptera, Isoptera and Collembola were highest in pure grass plots. Variations in soil arthropod populations in response to rainfall, soil water content and soil temperature indicated greater sensitivity of these groups to environmental factors. The highest densities and negative relative tree effect (RTE) values of Acari, Myriapoda and other soil arthropods in the ZN, Coleoptera in the AS, Isoptera in the CD and Collembola in the AN systems indicated that these soil arthropods preferred the silvopastoral systems involved. Seasonal variations in soil organic matter and available NH4-N, NO3-N and PO4-P were similar to those of soil arthropods. The concentrations of soil nutrients were highest in the ZN system, which had the highest densities of soil arthropods. The other systems with high populations and soil nutrient status were the CD and AS. Silvopastoral systems based on Z. nummularia, C. decidua and A. senegal promoted soil arthropod populations and enhanced soil nutrient status, highlighting the positive role of tree presence and the need for proper management to promote soil biodiversity, nutrient cycling and sustained production in a fragile environment.

Description: SUMMARYIn a 3-year study, maize (Zea mays L.) sown on 11 November or 1 December produced longer ears, higher grain yield per plant and greater grain yield per hectare than maize sown on 21 October. However, 100-kernel weight was greater when the crop was sown on 21 October and 11 November than on 1 December. There were no differences in yield characters or grain yield between cultivars or between row orientation. The sowing dates, maize cultivars and row direction had no influence on the number of ears per plant.

Description: SummaryIn a 2-year field study, all the maize cultivars tried (Partap-1 Ageti-76, Ganga-5 and DHM-103) produced similar length of ears and equivalent grain yields. However, Partap-1 and Ganga-5 produced greater 100-kernel weight and greater grain yield per ear but fewer ears per hectare than Ageti-76 and DHM-103. The yield attributes and grain yields of maize sown on 19 December, 29 December and 8 January were identical and were superior to those of the 19 January sowing. Maize sown on 19 December, 29 December and 8 January exhibited longer ears, more ears and fully developed kernels and thereby produced greater grain yields than the 18 January sowing.During 1983–4, in the 19 December and 29 December sowings all the cultivars gave identical grain yields. In the 8 January sowing Partap-1 and Ageti-76 produced similar yields and proved better than Ganga-5 and DHM-103. In the 18 January sowing Ageti-76, Ganga-5 and DHM-103 yielded more than Partap-1.