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Canola (Brassica nupus L.) is a major crop in western Canada, and been used extensively as an alternative crop to wheat (Triticum aestivum L.). Yet, little information is available on the response of this crop to N and P fertilizers in relation to soil tests for these elements under varying environmental conditions. Accordingly, this study was conducted for a 16‐yr period to determine the yield response of canola to N and P fertilizers in relation to soil tests for these elements in northeastern Saskatchewan on black Melfort silty clay (Typic Cryoboroll) previously cropped to spring wheat. Nitrogen fertilizer was applied at 45 and 134 kg N ha−1 in factorial combination with 0, 10, 20, 30, and 40 kg P ha−1. Extra treatments consisted of 10N–20P kg ha−1 and a control with no fertilizer applied. Canola grain and straw response to N and P fertilizer was significant, but the N by P interaction was not significant. The interaction effects of Year by P and Year by N were significant, indicating a wide range of response to applied elements among years because of temperature, precipitation and soil nutrient effects. Grain yield was positively correlated to total precipitation and negatively correlated to mean maximum daily temperature for the months of July and August (R2 = 0.32). The highest grain yield (2.46 t ha−1) was obtained in 1987 with P fertilizer applied at 40 kg P ha−1 (averaged across N rates), 162 mm of rainfall and an average maximum temperature of 21.2 °C. The lowest yield (0.37 t ha−1) was obtained in 1989 with P fertilizer applied at 20 kg P ha−1, 95 mm of rainfall and an average maximum temperature of 25.1 °C. In conclusion, soil tests for N and P accounted for much of the variation in yield response to these elements (r2 = 0.58 and R2 = 0.46, respectively) despite large yield differences among years because of temperature and precipitation.

.1991. The effect of N, P, S, fertilizer, temperature and precipitation on the yield of bromegrass and alfalfa pasture established on a Luvisolic soil. Can. J. Plant Sci. 71: 1047-1055. This study was conducted over a l2-yr period to determine the effect of N, P, and S (elemental) fertilizers on yield of bromegrass (Bromus inermis Leyss.) and alfalfa (Medicago mediaPers.) pasture established on a Gray Wooded, Luvisolic soil (Waitviile loam) in northeastern Saskatchewan. Nitrogen fertllizer was applied at 0. 45. and 90 kg N ha-r in combination with phosphate fenilizer applied at 0 and 20 kg P ha-r. Two additional treatments combined 90 N + 20 P (kg ha -') with 23 S and 45 S tkg ha-'). In the first 3 yr of the study, only the application of N increased yields, from 2.54to 3.45 t ha-r. The combination oftime (yeirs 1978-1980) and N fertilizer appliedup to the rate of90 kg N ha-r resulted in a reduction in percentage alfalfa in the sward from 30.9 to3.8% (Yr x N interaction). Over the 12-yr

Forage seed yield response to N and P fertilizers and soil nutrients in northeastern Saskatchewan. Can. J. Soil Sci. 79: 265-271. There is no information on the effect, in northeastern Saskatchewan, of N and P fertilizers on forage seed production as influenced by these nutrients in the soil. Therefore, experiments were conducted at eight sites from 1988 to 1991 to determine the effect of N and P fertilizers and soil nutrients on seed yields of alfalfa (Medicago media Pers.), smooth bromegrass (Bromus inermis Leyss.), crested wheatgrass (Agropyron cristatum L.), intermediate wheatgrass (Agropyron intermedium [Host.] Beauv.) and timothy (Phleum pratense L.). Nitrogen fertilizer (urea) was applied on grasses annually at 0, 50, 100 and 150 kg N ha -1 in factorial combination with 0, 9 and 18 kg P ha -1 (monoammonium phosphate and triple superphosphate) and on alfalfa at 0 and 50 kg N ha -1 in combination with 0, 9, 18, 26 and 53 kg P ha -1 . Nitrogen significantly increased forage seed yields of all species except alfalfa. Phosphorus increased yields of forage seed for all crops except intermediate wheatgrass. The site, N, P and year and their interactions influenced seed yields. Seed yields ranged from a low of 0.29 t ha -1 for smooth bromegrass in 1990, a dry year, to a high of 1.24 t ha -1 in 1989 a cool, moist year. The yield response to N and P fertilizers was affected by available soil N and P. Relative to control, the percentage increase in grass seed yield from applied N and P fertilizers was highly related to the available soil N and P (R 2 = 0.93). The estimated smooth bromegrass seed yield response to 50N-9P kg ha -1 was 0.54 t ha -1 when the soil had intermediate amounts of available N and P (2 mg N ha -1 and 8 mg P ha -1 , 0-to 60-cm and 0-to 15-cm depths, respectively). On a soil that tested high in available N and P, there was no response to fertilizer. Regression equations were developed that can be used to estimate forage seed yield response of different species in relation to available soil nutrients. These results are useful for estimating the most economical return on fertilizer investment for forage seed production in Saskatchewan.Key words: Forage, seed, N, P, fertilizer, soil tests, correlation Loeppky, H. A., Horton, P. R., Bittman, S., Townley-Smith, L., Wright, T. et Nuttall, W. F. 1999. Effets de la fumure N et P et de la biodisponibilité de ces éléments dans le sol sur le rendement de semences fourragères dans le nord-est de la Saskatchewan. Can. J. Soil Sc. 79: 265-271. Dans le nord-est de la Saskatchewan, on ne dispose d'aucune information sur l'effet de la fumure N et P sur la production de semences fourragères en fonction des quantités disponibles de ces éléments dans le sol. Des expériences ont été conduites de 1988 à 1991 à 8 emplacements pour déterminer l'effet des engrais N et P, ainsi que des disponibilités de ces éléments dans le sol, sur le rendement semencier de la luzerne (Medicago media Pers.), du brome inerme (Bromus inermis Leyss.), de l'agropyre à crête (Agropyron crista...

. 1986. Crop residue management practices, and N and P fertilizer effects on crop response and on some physical and chemical properties of a Black Chernozem over 25 years in a continuous wheat rotation. Can. J. Soil In the Black soil zone ofthe Canadian Prairies seedbed preparation is important for handling crop residues from high yields and for incorporating herbicides and fertilizers into soil in the fall or prior to seeding in spring. There are numerous tillage implements available to the producer for this operation. The question often arises as to the relative merits and demerits of using these implements, especially with respect to their effect on yield and on soil quality. A25-yr continuous spring wheat study was carried out at Melfort, Saskatchewan, in a splirplot design. The main plots were: four fall tillage implement treatments (plow, heavy duty cultivator, one-way disc and double disc), chopped straw in the fall and spring burn of straw. Four rates of fertilizer (0/0, 5/10, 22.5110 and 45l10 kg ha-' N/kg-' 6a-t P) were subplots from 1959 to 1977; the fertilizer rates were doubled for 1978 to I 983 . The results showed that there was no significant effect of tillage on yield but there was a significant fertilizer by tillage interaction. The spring burn treatment gave the highest yield (2073 kg ha-t; and the plow treatment the lowest yield (1963 kg ha-'). Fertilizer increased yields when moisture was adequate and either had no effect or depressed yields when precipitation was low. Only the plow treatment caused a loss of organic C and N. All tillage treatments increased the erosive fraction of the soil (fraction <0.83 mm) compared to the chopped straw and spring burn treatment. The application of the 90120 kg ha-r rate of N and P fertilizer decreased the proportion of soil aggregates <0.83 mm. There was no significant effect of tillage treatment on soil moisture conserved over the winter. There also was no tillage effect on NOr-N in the soil measured in the spring, but burning caused a significant increase in sodium bicarbonate-soluble P. The chopped straw treatment was concluded to be the best choice because the unincorporated residues will protect the soil best through the fall and winter and it is the easiest to implement. Where herbicides or fertilizers need to be fall-incorporated, any of the mechanical tillage implements except the plow should be equally suitable.