MATERIALS AND METHODS.- There were two factors tillage (conventional, minimum and zero) and rotation (100% cereals, 75% cereals and 50% cereals). There were 4 replicates in a split plot design. Wheat plots were further divided into 4 subplots for fungicides.

Conventional till blocks were deep tilled in the fall and spring. Minimum till and conventional till plots were cultivated and harrowed in the fall and spring.

Soil moistures to 120 cm were sampled with a hydraulic probe in the fall and spring and to 15cm following seeding. Soil moisture was determined gravimetrically.

Bulk densities were taken in the spring of 1995 with bulk density ring to a depth of 45 cm and compared bv tillage and with the antecedent conditions in 1991.

All plots were sprayed with 1.25 L ha^-1 Roundup + 1. 1 kg ammonium sulphate in 50 L water on in the spring and or fall as necessary. Herbicides, fungicides and insecticides were applied as required.

Seeding was done with a with a 3 m - 3 rank Concord air seeder with a dual air stream and a paired row opener with 25 cm shank spacing. The nitrogen was mid row banded in the form of 46-0-0. The phosphorus (11-52-0) was seed placed. Peas were seeded narrow knife opener in 1995-96. The flax and canola was seeded with a disc drill with banding knives in 1994. Katepwa wheat, Norlin flax, Garrison canola (1994) and Pursuit tolerant canola (1995-1996), Victoria peas (1994) and Express peas (1995-1996) were sown.

Emergence counts were done by counting plants in three consecutive 0.5 in rows (2 locations per treatment rep). Pre spray and post herbicide application weed counts were taken. Counts were taken with a 1/4 m² quadrant. Two counts per plot were, taken for weeds. Vigour ratings on a 0 to 9 visual scale were taken. The disease ratings based on a modified Horsfall and Barrett scale were done. Head counts were done in wheat on August 2-3, 1996 based on a 1/2m row. Plant heights were taken in wheat on August 8, 1996.

Tilt was applied @ 0.5 L ha^-1 in 200 L on designated wheat subplots once in 1994, twice in 1995 and 3 times in 1996.

Peas were sampled with a Kincaid plot combine. Yields were adjusted to 16% moisture. Wheat yield samples were taken with a Wintersteiger combine in 1994-95 and a Kincaid plot combine (1996). Yields were adjusted to 14.5% moisture. Canola and flax were combined with a Wintersteiger plot combine. Yields were adjusted to 10% moisture.

Economic analysis was based on 1996 local fertilizer costs, crop prices were based on the figures in 1996 "Guidelines For Estimating Crop Production Costs", and pesticide costs were based on the prices given in the "Guide to Crop Protection 1996", both published by Manitoba Agriculture (Appendix B). Machinery and other fixed and variable costs were calculated based on farm sized equipment based on the 1995 "Farm Rental and Custom Rate Guide" and the 1996 "Guidelines For Estimating Crop Production Costs", both published by Manitoba Agriculture.

Statistics were performed with the aid of the PRM 5.0 for Windows statistical package. The ANOVA comparison of means for completely randomized blocks was performed with Duncan's multiple range comparison test at 5%.

Further work is being done by Dr. Cynthia Grant of Ag Canada in Brandon. Samples from April 1991 and October 1996 are being analyzed for nitrate, phosphorus potassium and organic matter differences between treatments. In addition, penetration resistance has been measured. These measurements have not been included in this report.

RESULTS: Tillage had a significant effect on available water in all 5 years of this study. (Table 1). In years where spring moisture was dryer because of lower than normal spring and / or fall moisture such as 1993, 1994 and 1996, average available water was 2 to 5 times greater under zero tillage compared to minimum or conventional till. This translates into quicker emergence, a reduction of root disease potential, a more vigorous plant and greater yield potential. In years such as 1995, when excess moisture may delay seeding, the extra moisture in zero tillage may be a disadvantage, although, traction seemed to be a greater problem in the cultivated plots at seeding in 1995

Zero tillage did not result in cooler soil temperatures and in fact, there was a slightly higher soil temperature in zero tillage compared to conventional tillage when the air temperature was still cool (Table 2). In the slightly warmer air temperatures when peas were seeded, there were no ,differences in temperatures resulting from tillage. Rotation appeared to affect the soil temperatures when seeding on a cool day. The 100% cereal rotation had a warmer seedbed than did the 50% cereal rotation. This was more pronounced in zero till. This is probably due to the insulation properties of the increased straw cover. It would be anticipated that a reverse trend occur on a warm day. There were no differences in seedbed temperatures between tillage or rotation following seeding. The seedbed temperatures fluctuated with air temperatures equally.

Tillage did not affect bulk densities below 15 cm (Table 3). Conventional tillage had a lower bulk density at both the 0 to 5 cm and 5 to 10 cm depths compared to both minimum and zero tillage. The bulk density was higher in the minimum till treatment than the zero till and conventional till treatments in the top 15 cm.

Seed treatment increased the number of wheat plants to emerge in all tillage x rotation treatments (Table 4). The use of a 50% cereal rotation with seed treatment appears to be important to establish a competitive wheat crop when zero tillage is used. With minimum tillage and conventional tillage the use of seed treatment is important, but rotation was not a significant factor. Reduced tillage improved pea and canola emergence, but flax emergence tended to be reduced.

The primary weed population in wheat before post emergent herbicides consisted of kochia, redroot pigweed, green foxtail, volunteer canola and flax, stinkweed and wild buckwheat. Of these weeds, green foxtail, kochia, wild buckwheat and redroot pigweed were more plentiful in conventional and minimum till treatments than in zero till treatments. Stinkweed, volunteer flax were more of a problem in zero till. There were generally fewer weeds in the zero till wheat treatments after the herbicide application compared to minimum and conventional till wheat. Kochia, redroot pigweed and stinkweed were not controlled very well in the conventional and minimum till treatments. Kochia, stinkweed, redroot pigweed, wild buck-wheat and volunteer wheat were the main weed problems in peas, canola and flax. Post-emergent herbicides adequately controlled all weeds in zero tillage with the exception of wild buckwheat. Kochia and wild buckwheat were problems in both minimum till and conventional till treatments after the application. Kochia populations in particular was a factor in reducing yields in 1995 and 1996.

Seed treatment in wheat delayed the onset of septoria in wheat in the years where the incidence of disease was early (1994 and 1996). This difference was present through the growing season. . The use of foliar fungicides greatly reduced the incidence of septoria in wheat in years of heavy infestation. In 1994, improved rotation in zero tillage and when both seed treatment and foliar fungicides were used in tilled treatments reduced the incidence of septoria. In 1995, the same trend was evident in zero till only. In 1996, rotation and tillage did not have an effect on the incidence of septoria.

The use of seed treatment combined with a foliar fungicide improved yields in 1994 and 1996 (Table 5). A cool seedbed and soil borne diseases reduced plant stands in 1994. In 1996, the seedbed was moist and cool resulting in similar conditions as in 1994. Combining a 50% rotation with seed treatment tended to improve plant stands, improving plant vigour and delaying the onset of foliar diseases for all tillage systems. The use of seed treatment and foliar fungicides improved yields for all rotations and tillage systems compared to seed treatment or foliar fungicides alone. Yield increases were most significant in the 50% cereal rotation with zero till. Minimum till and conventional till systems with a 50% cereal rotation also benefited significantly with the use of foliar fungicides and seed treatment.

Wheat head counts were increased by a better rotation (Table 6). The use of foliar fungicides increased the number of heads in all tillage treatments. Neither tillage nor seed treatment appeared to have an effect on the head count.

Plant heights appeared was the primary influenced by tillage (Table 7). In the presence of tillage rotation became a factor. Early season moisture may be -the cause of these differences. Higher moisture levels may lead to increased vegetative growth. There were no significant differences in plant heights due to fungicides.

Septoria was a problem in 1994. The use of both a seed treatment and a foliar fungicide significantly increase wheat Yields over untreated wheat in all rotation and tillage comparisons (Table 8). Rotation and tillage also had an effect on wheat yields. Tillage tended to improve wheat yields in the continuous cereals treatment. Improving the rotation to 50% cereals increased wheat yields in all tillage treatments, but most significantly in zero tillage. With the 50% cereal rotation, reduced tillage increased wheat yields.

Crop rotation was more important in zero till than minimum or conventional till in 1995. The poorest wheat yields in zero till were with a 100% cereal rotation treatments (Table 9). When foliar fungicide was used, yields were not different between a second year of wheat, or wheat following flax, canola or peas or between treated and untreated seed. In the absence of a foliar fungicide treatment, wheat yields were enhanced when following flax, canola or peas in the rotation as compared to wheat on wheat. Minimum till yields tended to be highest in continuous wheat or following flax. Conventional till yields tended to be highest in a 75% rotation following wheat. Wheat yields following flax tended to be suppressed when a foliar fungicide was applied.

Crop rotation was very important for wheat yields in the zero tillage treatment in 1996 (Table 10). Continuous wheat yielded the lowest in all fungicide combinations. Going from continuous wheat to a 75% cereal rotation improved wheat yields. The 2nd and 3rd years of wheat in this rotation out yielded continuous wheat, but further yield increases were observed in wheat treatments following peas, canola or flax. Both conventional till and minimum till treatments followed the same trends as zero till, although differences were not as large.

Average zero till yields (6 years) were highest in a 50% cereal rotation (Table 11). The yields within the two wheat years in the rotation have also been consistent. Yields decreased with each successive year of wheat in the 75% rotation compared to the first year after an oilseed. Yields in all four years of a 100% rotation were about the same as the third wheat year in the 75% rotation. Wheat yields for minimum till and conventional till also tended to be higher with a 50% rotation, although not by the same magnitude as zero till. Both minimum till and conventional till wheat yields were lower in the second and third years of wheat compared to the first year of wheat in a 75% cereal rotation. Wheat yields in the 100% cereal rotation were similar to the 2nd and 3rd year of the 75% rotation. Wheat yields were very similar between tillage practices in a 100% and 75% cereal rotation. With a 50% rotation wheat yields were higher in zero tillage compared to conventional and minimum till.

Average flax, pea and canola yields were hip-her in zero till than in both conventional and minimum till. Pea Yields tended to be higher in the 75% rotation, due to a lower incidence of bacterial blight in these treatments in 1994. Canola yields were not significantly affected by these rotations.

The use of foliar fungicides was profitable in only one of three years (1994). In 1996, fewer applications may have made the fungicides more profitable.

Based on a six year average, zero till with a 50% cereal rotation was the most profitable treatment (Table 12). The 100% cereal rotation was the more profitable rotation under minimum tillage, while the 75% rotation was the best rotation with conventional tillage. Costs were generally lower in zero tillage than both minimum and conventional tillage. The largest difference was in machinery costs. Herbicide costs were higher in zero tillage, but the difference was negligible in the last 2 years of the study.

Extrapolating the results from a trial scale to a 400 hectare farm, a zero till 50% rotation would net $17,400 more than any other tillage or rotation (75% rotation with zero tillage) (Table 13). The net profit from zero till was 164% higher than minimum till with a 50% rotation. Net profit was about equal between minimum till and zero till when a 100% cereal rotation was used.

W=wheat, w2=wheat (1994-96), b=barley (1991-93), m=mustard (1991-93), f=flax, c=canola (1994-96), p=peas (1994-96)

Table 12. Average revenue and expense report by rotation and tillage. Minto 199-1996.

Zero tillage did not delay seeding compared to conventional tillage. Seeding equipment was able to "float" with higher moisture content in zero tillage.

Higher surface soil moisture content translated into quicker emergence and more available water translated into higher yields.

Soil temperatures at seeding were the same for all tillage treatments.

Seed treatment increased wheat emergence, improved plant vigor, delayed the incidence of septoria, increased yields and net returns.

Canola and pea emergence was increased in a reduced tillage environment, but flax emergence tended to decrease.

Weeds such as green foxtail, wild oats, kochia and redroot pigweed were reduced with zero tillage and more easily controlled with in crop herbicides.

Weeds such as stinkweed, wild buckwheat and volunteers increased in zero till canola, flax and peas. Overall, weed control was more successful in zero till.

'The use of foliar fungicides increased wheat head counts and plant heights. In 2 of 3 years, yields were increased, but in only 1 of 3 years was the use of foliar fungicides economical.

A good rotation was more important in zero tillage than minimum or conventional tillage for yield increases and economic returns.

Canola, pea and flax yields were higher in zero tillage than in minimum or conventional tillage.

Overall costs were lower in zero tillage compared to minimum and conventional till. This difference would be expected to increase as fuel costs rise and herbicide costs decrease.

A 50% cereal rotation in zero tillage produced the highest overall yields and the highest net returns of all treatments.

Further Research:

The incidence of bacterial blight in peas (1994) seemed to be higher in peas on barley stubble compared to wheat stubble and in conventional till compared to zero till.

The economic of folia