Leaching of sulfur (S) on sandy soils may limit the effectiveness of S fertilizers especially when applied at sowing. The effectiveness of S sources for canola (oil seed rape, Brassica napus L.) grown in sandy low S soils of south-western Australia is not known. This study was completed to determine the relative effectiveness of gypsum and a gypsum-based by-product from synthetic rutile processing called Canola Blue for canola grown in low S soils of the region. Canola Blue is a mixture of gypsum and elemental S, and is granulated so its effectiveness may vary from gypsum. We measured the effectiveness of the two S sources in the glasshouse for young seedling growth and for minimizing S leaching. In the four field experiments, the two S sources were evaluated for relative effects on canola seed yield and the concentration of oil in seed. Canola Blue applied at sowing was as effective as gypsum for canola growth in the glasshouse and when applied at 35 days after sowing (DAS) was as effective as gypsum for seed yield in the field. For the glasshouse study, Canola Blue when applied to the soil surface (topdressed) at 35 DAS was as effective as gypsum in achieving a rapid recovery of leaves from S deficiency symptoms and of shoot growth. Where S deficiency appears during the growing season, topdressing with Canola Blue appears to be as effective under the conditions of this experiment as was gypsum. However, the S in Canola Blue was less prone to leaching than that applied as gypsum.

Rationale Relatively little is known about the short-term pulmonary effect of passive cigarette smoke exposure in the normal, nonasthmatic individual. Methods Ten healthy subjects went to naturally smoky environments (bars, nightclubs, or restaurants) and serially recorded pulmonary and nonpulmonary symptoms (Sxs), performed pulmonary function tests, and recorded carbon monoxide (CO) levels every 30 minutes for up to 3 hrs. Results Subjects had no Sxs upon entering the smoky environment. After 60 minutes of smoke exposure, subjects developed substantial nonpulmonary Sxs (eyes, nose and throat), but complained of virtually no pulmonary Sxs (wheezing, chest tightness, coughing, shortness of breath). Despite the paucity of pulmonary Sxs, the forced expiratory volume in 1 second (FEV1) dropped 14.7% from baseline after 60 mins, and decreased further to 20.4% below baseline after 2 hrs. The CO level rose steadily from unmeasureable levels at the beginning of exposure to a peak level of 20 parts per million at the end of the smoke exposure. There was a strong linear correlation between increasing CO levels and decreasing FEV1 values (r=0.9159; p Conclusions Short-term passive exposure to cigarette smoke produces significant decreases in pulmonary function in normal, nonasthmatic subjects, despite the relative absence of pulmonary Sxs. In these subjects, these nonpulmonary Sxs appear to be better markers of decreasing pulmonary function than traditional pulmonary Sxs. Finally, increasing levels of CO in the smoky environment are strongly associated with decreasing pulmonary function, suggesting that this component of cigarette smoke may play a role in the pathogenesis of cigarette smoke-induced asthma.

The accumulation of organic matter has been suggested to be one of the causes of soil acidification. We examined the effect of applying clover shoots, clover roots, and lupin leaves which differed in concentrations of N and excess cations/ash alkalinity on the pH of 2 acidic soils from Western Australia over a 28-day incubation period. Addition of the legume residues at rates of 1·54 and 3·08 g/kg soil increased soil pH by up to 0·6 units at Day 0 and 0·7 units at Day 28 after incubation. The increase in soil pH was the greatest with addition of lupin leaves, followed by clover shoots, and the least with clover roots. The increase in pH correlated well with the amounts of ash alkalinity added as plant materials. Ammonium concentrations were generally increased by addition of the plant materials, but with time the concentrations decreased in the Kojonup soil and increased in the Moora soil. Nitrate concentrations were similar between the treatments, and increased with time. Addition of legume residues slightly increased the pH buffer capacity of both soils at Day 0 but not at Day 28. After 28 days, 37–51% of clover shoots and 36–51% of lupin leaf had decomposed compared with 22-38% of clover roots. The results suggest that rapid changes in soil pH following application of plant materials are related to the concentration of excess cations and decomposition of the material and that the application of legume shoot residues, which usually have high concentrations of excess cations, is not the likely cause of soil acidification.

Phosphorus deficiency is common in crop production. This pot experiment examined whether the supply of Ca(H2PO4)2 affected acid production by N2-fixing plants of 5 grain and 4 pasture legume species grown in a P-deficient sandy soil for 60-64 days. The legume species differed greatly in their response to P application. Lupinus albus, L. luteus, and Biserrula pelecinus were less responsive to P supply than Cicer arietinum, Vicia faba, Medicago polymorpha, Ornithopus sativus, and Trifolium subterraneum, which in turn were less reponsive than L. angustifolius. Increasing P supply up to moderately deficient levels increased the amount of acid production per unit shoot biomass (specific acid production), and further increasing P decreased specific acid production. The effect of species on acid production was greater than the effect of P supply. Among the species, C. arietinum had the highest specific acid production and B. pelecinus the lowest. Specific acid production was correlated with concentrations of excess cations and ash alkalinity as well as Ca and Mg but not P in shoot. There was a very good agreement between total acid production and total content of excess cations in the whole plant, irrespective of P supply and plant species. The results suggest that acid production by legumes under various P supplies is related to the imbalance of cation and anion uptake.

The capacity of subterranean clover (Trifolium subterraneum L. cv. Clare), medic (Medicago murex Willd. cv. Zodiac), serradella (Ornithopus sativus Brot. line SP1/13), biserrula (Biserrula pelecinus L. line Mor99), and woolly clover (Trifolium tomentosum L.) to acidify soil under N2 fixation was compared in a pot experiment using a poorly buffered sandy soil. The amount of acid produced per kg shoot dry matter (specific acid production) varied betweefin species and with growth stages, ranging from 44 to 128 cmol/kg shoot. Subterranean clover and serradella acidied soil to a greater extent than woolly clover and medic, whereas biserrula acidified soil least. Irrespective of pasture species and growth stage, specific acid production correlated well with concentrations of excess cations and calcium in shoots. Furthermore, total excess cation, ash alkalinity, and calcium in shoots were all good indicators of total acid production across all of the species.

We formulate the radiation theraphy treatment planning (RTTP) problem as constrained optimization in L^2. This is accomplished by first describing the dose operator as a bounded operator from ''Treatment Space'' into ''Patient Space''-both suitable L^2 spaces. Within this context we examine two problems of interest in RTTP. First, we take the case where the sources of radiation are fixed a priori and provide algorithms which lead to the optimal choices of beam profiles for these sources. Secondly, we look at the problem of simultaneously choosing the sources and beam profiles and also suggest an algorithm for this case.