A field was artificially eroded by levelling in 1957. Continuous cropping to barley for 7 yr followed by a wheat-fallow rotation for 14 yr without nutrient application did not significantly improve the soil productivity of severely "eroded" land. Subsequently, a wheat-fallow experiment was conducted from 1980 to 1985 to determine the effects of 30 Mg ha−1 feedlot manure or 150 kg commercial fertilizer N (as urea) + 150 kg commercial fertilizer P (as triple superphosphate) ha−1 on restoring the productivity to soil from which 10–20 cm or 46+ cm of soil had been removed. The manure and commercial fertilizer treatments essentially restored productivity within the first year, as measured by wheat yields, regardless of severity of erosion. During years of drought stress which often occur under dryland conditions, the manure application on the "eroded" soil treatments resulted in yields greater than those on check or fertilized plots. The manure significantly increased the organic matter, total N, NO3-N, available P, and water-stable aggregate status of the soil. There was a decrease in the difference in carbohydrates between undisturbed and 'eroded' plots from 1982 to 1984. Key words: Soil erosion, manure, commercial fertilizer, topsoil loss, soil organic matter, productivity

y=a+b(I-e-c(t'tl'l fort>L, (1) where a is the soluble fraction (Vo), b is the slowly digestible fraction (7o), c is the rate of disappearance (7o h-1), r is the time of incubation (h), L is lag time (h).Protein solubility was estimated as the soluble fraction, while effective rumen degradability was estimated using the model proposed by Merlens (1917): Blood samples were obtained via jugular venipuncture from male lambs approximately 3 wk from the start of the experiment on 13 June and prior to slaughter. Samples were preserved at -20"C and later analyzed for PUN (Technicon 1977 ribs. Probe measurements were taken on the left side of the unsplit carcass 2.5 cm from the carcass midline for rib-eye meisurements and 11 cm from the midline for TD' Carcasses were chilled for 24h at 1"C. The cold carcasses were sectioned with a knife between the l2th and 13th rib while hanging, exposing the entire right and left rib eye (m' longissimus thoracis). Average fat depth was determined at three locations along the rib-eye by using a ruler' Marbling was determined by subjective ranking based on a scale of 1-9, with 1 corresponding to extreme marbling and 9 to no marbling. Muscle (longissimus thoracis) colour was assessed using a reflectance meter (Minolta Chroma Meter II, Minolta Camera Co., NJ). Kidney and pelvic fat was removed from each carcass and weighed. Chemical AnalYsisFeces and feed were dried at 55"C and then ground to pass a l-mm screen for determination of nutrient content' Dry matter content was determined by drying at 135oC to a constant weight. Gross energy was determined by bomb calorimetry (Parr Instrument Corp., Moline, IL). Organic matter was determined by ashing samples in a muffle furnace at 550'C; CP content was determined by micro-

Chlorsulfuron was applied to wheat at rates of 0, 10, 20, and 40 g ai ha-1in three locations at Lethbridge and Brooks between 1980 and 1984. The soil pH and organic matter contents at Lethbridge and Brooks were 8.0 and 2.1% and 7.4 and 3.0%, respectively. Rotational crops were seeded for up to 7 yr after chlorsulfuron application. The criteria used to indicate when susceptible crops will grow safely were no significant yield loss at the 40 g ha-1rate and the magnitude of the upper confidence limit for this difference. The following times after application before crop yields were not affected were required at Lethbridge: barley, 2 yr; canola, 3 yr; peas, beans, 4 yr; flax and potatoes, 5 yr; alfalfa and sugarbeets, 6 yr; and lentils at least 7 yr. The effect of chlorsulfuron residues in the soil on rotational crops appeared to be similar at Brooks and at Lethbridge. Estimated chlorsulfuron concentrations were related to the tolerance of rotational crops.

Donunen, J. F., LrNpwer-r-, C. W. AND KozuB, G. C. 1986. Restoring pro-ductivity to an artificially eroded Dark Brown Chernozemic soil under dryland conditions. Can. J. Soil A field was artificially eroded by levelling in 1957 and then continuously cropped to barley for 7 yr. Subsequently, a wheat-fallow experiment was conducted from 1965 to 1979 to determine the effects offour fertilizertreatments and green manure (yellow sweet clover) on restoring the productivity to soil that had been "eroded" to various depths. Aftet 22 yr and l4 crops, the productivity ofthe land from which soil was removed has been improved but not fully restored. Although green manuring with yellow sweet clover improved soil structure, wheat yields were not improved because of competition for soil moisture and poorer in-crop weed control in this part of the rotation. For personal use only.

A study was conducted during the 1982, 1983 and 1984 breeding seasons with 277 crossbred bulls, 1 to 3 yr of age, that were evaluated for physical soundness, testicular development, seminal quality, and both sexual and social behavior immediately before exposure to crossbred cow herds ranging in size from 89 to 329 cows. Crossbred cow herds were exposed to 4 to 24 bulls per breeding group (mean of 14) at a mean female: male ratio of 21.2 +/- .6:1 under extensive range conditions for 31 to 62 d (mean 46.6 d). All resulting calves were blood-typed to determine the number of calves sired by each bull as an estimate of his fertility. The mean number of calves sired by 1- (n = 116), 2- (n = 126) and 3-yr-old (n = 35) bulls was 4.7 +/- .1, 8.2 +/- .1 and 10.5 +/- .1, respectively. A regression model for predicting bull fertility under multiple-sire, range breeding conditions was selected that accounted for 29% of the total variance in fertility. Similar models accounted for a greater proportion of variance in fertility of 1-yr-old (37%) than of 2-yr-old bulls (22%). Due to the large amount of unexplained variation, the model could not predict individual bull fertility precisely. However, this study demonstrated that selection of herd sires with large scrotal circumference, low backfat thickness, low levels of primary sperm defects, and a low number of mounts in combination with a moderate number of services during libido testing would be expected to improve fertility of beef bulls used under extensive range conditions.

metribuzin and chlorsulfuron treatments, alfalfa and sainfoin stands were almost free ofdandelions. In sainfoin plots, dandelion control produced large increases in sainfoin and total herbage yield. In alfalfa plots, dandelion control had no effect on alfalfa yield or total yield. In sacco dry matter digestibility in a 72-h experiment was higher for dandelions than for alfalfa, whereas protein digestibilities were similar for these herbages. The protein content was less in dandelions than in alfalfa at the first harvest.Thus, dandelion control in sainfoin may increase yield, whereas dandelion control in alfalfa does not seem to increase yield but may increase protein content and marketability.

A study was conducted to determine the effect of sclerotial dryness, temperature during sclerotia formation, and relative humiditiy during incubation on myceliogenic germination of sclerotia of two isolates of Sclerotinia sclerotiorum (Lib.) De Bary. In the absence of exogenous nutrients, sclerotia germinated more readily at 100% RH than at 95% RH or lower. Desiccation of sclerotia is an important factor affecting myceliogenic germination and hyphal growth. At high humidity, either in an atmosphere with 100% RH or on moist sand, desiccant-dried sclerotia germinated readily and produced vigorous hyphal growth that often developed into colonies. On the other hand, fresh, untreated sclerotia germinated less readily and produced limited growth of hyphae that rarely developed into colonies. There was generally no effect of temperature at which sclerotia formed on germination. The incidence of seed rot and seedling wilt of sunflower was significantly (p < 0.05) higher when desiccant-dried sclerotia were used as inoculum rather than fresh sclerotia.Résumé : Les auteurs ont étudié les effets de la dessiccation des sclérotes, de la température au cours de la formation des sclérotes, et de l'humidité relative en cours d'incubation sur la germination mycéliogène des sclérotes de deux isolats du Sclerotinia sclerotiorum (Lib.) De Bary. En absence de nutriments exogènes, les sclérotes germent plus facilement à 100% d'humidité relative qu'à 95% ou moins. La dessiccation des sclérotes est un facteur important affectant la germination mycéliogène et la croissance des hyphes. À haute humidité, ou à 100% d'humidité relative ou sur sable humide, les sclérotes séchées en présence d'un agent desséchant germent facilement et donnent une croissance mycélienne vigoureuse qui se développe souvent en colonie. Comparativement, les sclérotes frais et non-traités germent moins facilement et produisent des hyphes à croissance limitée qui forment rarement des colonies. La température à laquelle se forment les sclérotes est généralement sans effet sur leur germination. La présence de pourriture des graines avec flétrissement des plantules de tournesols était significativement plus élevée (p < 0,05) lorsque les sclérotes séchés en présence de desséchant ont été utilisés comme inoculum, plutôt que des sclérotes frais.

The effect of high (HED) and medium energy diets (MED), fed to Hereford (H) and Angus (A) bulls from 6 through 24 mo of age, on scrotal circumference (SC), paired testes weight (PTW), epididymal sperm reserves (ESR) and seminal traits were examined. Over 3 yr, 120 bulls were involved. Angus exceeded H for both SC and PTW. Hereford bulls in yr 2 had smaller SC than in yr 1 or 3 but the response for A was consistent. Year affected PTW. In yr 2 Hereford bulls fed HED had 75% fewer ESR than MED-H bulls (9.3 vs 37.2 X 10(9]. Comparably treated A bulls had similar ESR numbers (29.2 vs 33.4 X 10(9]. In yr 3, epididymal sperm reserves of HED-H were depressed by 35% compared with MED-H (23.1 vs 35.7 X 10(9], whereas HED-A had 14% fewer ESR than did MED-A bulls (28.6 vs 33.1 X 10(9]. It was not obvious why H bulls were more susceptible to the effects of HED. Seminal quality of HED bulls was inferior to that of MED bulls, particularly with respect to progressive motility and the incidence of sperm in which a crater defect of the head was present at 2 yr of age. In yr 2 all seminal traits were severely depressed in 2-yr-old HED-H. Feeding HED to young H and A bulls reduced their reproductive potential.