No abstract

The amounts of total S, organic N, organic C, and HI‐reducible‐S obtained from Ap layers of 54 soils collected from five major soil zones in Saskatchewan varied considerably with location within any one zone. However, the mean C/S, N/S ratios and the percentage of total S as HI‐reducible S of the soil organic matter showed similar and consistent trends. The C/N/S ratios ranged from 58:6.4:1 in the arid Chernozemic Brown soils to 129:10.6:1 in the leached Grey Wooded soils. The percentage of total S as HI‐reducible was approximately 50% in the Chernozemic soils in contrast to 36% in the Grey Wooded soils.

Can. J. Soil. Sci. Downloaded from www.nrcresearchpress.com by 54.191.190.102 on 05/11/18For personal use only.

available soil sulphur in an '*S growth chamber experiment. Can. J. Soil Sci. 54:309-315.Growth chamber and laboratory studies of four selected soils diflering in C:N:S ratios and the percentage of total S present as Hl-reducible S in the soil organic matter showed that: (l) the yield response of alfalfa to applied S occurred when the 0.01M CaCl"-extractable soil SO.-S was less than 3.3 pe/e, (2) mineralization of soil organic S was unaffected by the addition of 25 pg S/g to the soils, and (3) the amount of S mineralized was not directly related to the quantity of total S, HI-S or the percentage of total S present as Hl-reducible S. It was noted that the largest amount of S mineralized occurred from the soil with the lowest C:N:S ratios.Des 6tudes en chambre de croissance et en laboratoire de quatre sols choisis, ayant des rapports diff6rents C:N:S et des pourcentages difl6rents de S total sous forme r6ductible par HI dans leur fraction de matidre organique, ont montr6 que (l) la r6ponse de la luzerne i I'application de S se produisait lorsque la teneur en S sulfurique extractible par CaCl" 0.01M 6tait inf6rieure d 3.3 pe/9, (2) I'addition de 25 pg de S/g de sol n'a pas eu d'effet sur la min6ralisation du S organique du sol et (3) la quantit6 de S min6ralis6 n'6tait pas directement li6e i la quantitd de S total, de S r6ductible par HI ou au pourcentage de S total pr6sent sous forme de S r6ductible pas Hl. On a observ6 que la plus grande partie du S min6ralis6 provenait du sol ayant les rapports C:N:S les plus faibles.The plant-available sulphur fraction of soils cbnsidered as potentially sulphur deficient (labile S) includes (a) the readily soluble in-(( 36 kg SO*-S/ha, 0-60-cm laver) for rapeorganic sulphate, (b) the adsorbed sulphate, seed and alfalfa (Hamm et al. 1973). These and (c) part of the organic sulphur which soils may be separated on a zonal basis by is mineralized over the growing season. the C:N:S ratios of the soil organic matter While fractions (a) and (b) can be easily and the fraction of the total sulphur existing assessed using chemical extractants (Reise-as Hl-reducible sulphur (Bettany et al. 1973

Seeds of Zizania aquatica which had been afterripened for a period of 90 days at 1–3 °C remained dormant. Treatment of afterripened seeds with ultrasonic vibrations at 70 kc/s for 10 minutes showed a germination count of 74%. Increasing either the intensity or duration of treatment resulted in lower germination. Warm water treatment of dormant seeds resulted in improved germination for some treatments. Exposure in water at a temperature of 45 °C for 240 minutes resulted in a germination of 71%. Treatment with varying ratios of ethanol to water gave only small improvements in seed germination.