CONSERVATION TILLAGE PRODUCTIVITY CENTRE BULLETIN 1992
-D.R.S. Rourke and A.P. Hargrave
The Conservation Tillage Productivity Centre is located on 50 acres of land bordering highway #10, 1/2 mile northeast of Minto, Manitoba.
The Centre is sponsored by the Manitoba - North Dakota Zero Tillage Farmers' Association and is funded by the federal and provincial government through "Farming for Tomorrow". The Centre is a commitment by the cooperating partners to support sustainable agricultural production through the development of agricultural practices that are economically and environmentally sound.
The Centre was established to fulfil two main objectives:
All CTPC activities are designed to support and complement on-farm soil conservation measures undertaken by farmers and soil and water conservation organizations in Manitoba and North Dakota.
Conservation tillage activities at the Center focus on evaluating:
Spring burn off is a practice we associate with replacing the tillage in a crop production system. Roundup is the preferred herbicide in that it is:
The price of Roundup @ $9.95 per liter has reduced burn off costs substantially over the past decade, but farmers are working hard to make it more effective and less costly. 1992 data show that the most effective and cost efficient rate is 0.5 1 per acre with 1 lb of ammonium sulphate in a water volume of 5 gallons per acre. A decrease in rate of Roundup to 1/3 L ac - 1 reduced control of wild buckwheat, but adequately controlled weeds such as green foxtail, volunteer cereals, and stinkweed. The addition of bromoxynil (Pardner) or dicamba (Rustler) reduced the control of green foxtail and volunteer wheat. The addition of surfactants did not improve control of wild buckwheat in 1/2 L ac -1 of Roundup with 1 lb of ammonium sulphate. Most surfactants, in fact, reduced control.
Quackgrass left uncontrolled can reduce yields substantially. Quackgrass can be controlled easily with 1/2 L as -1 of Roundup in the fall or spring if the quackgrass is not under stress. An increase in rate to 1.0 L ac -1 or 2.0 L ac -1 did not improve control or yields. The treatments sprayed once every three years had gone residual control after two years, although not as good as 1/2 L as -1 annually. For the second year, spring application had better long term control than the fall control the second years, spring application had better long term control than the fall control because of improved quackgrass activity at the time spraying.
Pre harvest Roundup shows potential for quackgrass and Canada thistle control by spraying the weeds while they are actively growing. Quackgrass was controlled by 1/2 L ac -1 as well or better than the higher rates of Roundup. Condition and biotype of quackgrass, environmental conditions and spraying equipment can influence results. Monsanto recommended 1 L ac -1, but under conditions at Minto 0.5 L ac -1 worked very well. Canada thistles left unchecked reduced wheat yields compared to all treated yields. The highest yields were observed from the post emergent Lontrel treatments. Fall treatments of dicamba (Banvel) and 2-4D reduced wheat emergence. The high rates of dicamba reduced yields. Lontrel (0.3 L ac -1 and 0.6 L ac -1) and Banvel (1.0 L ac -1) provided the best control of control of Canada thistle. Monsanto have indicated that when Roundup is used pre harvest rather than post harvest, Canada thistle control will increase to about 80% with much better consistency. A combination of pre harvest Roundup and in crop use of Lontrel should easily handle the worst Canada thistle problems.
This group of herbicides including trifluratin, ethalfluralin and traillate are not normally associated with zero till due to the need for soil incorporation. New research has shown that triallate can be surface applied. 1992 results at the CTPC show some promise for the use of trifluralin with minimum or even no incorporation . This may be good news for those with Group 1 resistant weeds and want to zero till! Trials were done with lentils and barley. Wild oats were successfully suppressed with Treflan in both barley and lentils with no incorporation. It appeared that the incorporation of the herbicides stimulated more wild oat germination compared to no incorporation (catch 22). Wild buckwheat populations appeared to increase as incorporation decreased in lentils. The treflan was very successful in suppressing wild buckwheat without incorporation. At this time, however, work is preliminary and the trifluralin may have been aided by a snowfall shortly after application in the fall of 1991 as well as a wet spring. The early snow would have reduced herbicide degradation by light and the early snow and wet spring conditions would have helped to leach the chemical into the soil thereby enhancing control.
Reduction of the number of passes over the field while maintaining yields is for some a desirable goal because of increased moisture and reduced costs, soil disturbance and time. The CTPC examined two forms of nitrogen with sweeps + sweep tip NH3 injectors, two paired row openers; 1)4/6" with N placement 1" inside and 2" below the seed and 2)3/7" with N place 1.5" below the seed and backswept seed row openers and a double shooting narrow row opener in 1992.
Wheat emergence was higher with the urea source than the anhydrous source for all openers. The wheat was severely damaged with the narrow row regardless of the rate or nitrogen source and with 90 lbs N ac -1 anhydrous, the crop suffered total damage. An increase in rate from 45 to 90 lbs N ac -1 with anhydrous did not reduce emergence rates using the paired row openers.
Throughout the growing season, the anhydrous treatments were slightly more stunted and sparse than the urea counterparts. This difference did diminish toward the end of the growing season. The narrow row treatments were more sparse than the other treatments.
Wheat yields increased with an increase in urea fertilizer for the paired row openers and sweeps. Only the sweeps with NH3 injectors showed and increase in yield moving to the high rate of anhydrous. Anhydrous @ 45 lbs ac -1 was as economical as any urea treatment for all openers. The paired row and sweeps with injectors had the best returns at that rate. Seed placed urea at increasing rates decreased wheat emergence when the seed was placed in a 3/4" row and urea was placed 1" below the seed. Placing the seed and urea in a 8" row with sweeps or a paired row with about a 3" separation did not reduce the emergence significantly compared to the broadcast ammonium nitrate treatment. The 90 lb ac -1 rate in the wide row did look visibly thinner and stunted throughout the growing season.
Yields did not increase with increases of nitrogen fertilizer past 18 lbs ac -1 with narrow openers. There were noticeable increases in yields with increased nitrogen inputs up to 54 lbs ac -1 with sweeps and 90 lbs ac -1 with paired row openers. These rates were also the most economical. It is interesting to note that yields and net returns from broadcast ammonium nitrate at 54 lbs ac -1 were similar to yields and net returns of the seed placed seed placed urea @ 54 lbs ac -1 with any opener.
Adequate and balanced fertility is essential for the production of a healthy crop. Many techniques can be used to efficiently place additional nitrogen. Two method which should be avoided are urea placed directly with the seed and pre-seeding broadcast fertilizer. The former because of seedling damage and the later because of stimulation of weeds like green foxtail. However, using some placed fertilizer (about 20 to 30 lbs ac -1) and broadcasting the reainder as 34-0-0 at the 4 to5 leaf stage of the crop was successful in producing higher yields and net returns. In the 1992 trial too much N was added at the time of seeding (49 lbs ac -1) at the high rate which resulted in poor emergence of barley.
Barley yields responded positively to the higher fertilizer rate (compared to 76 lbs ac -1) for all treatments except seed placed. The additional yields were not enough to compensate for the added costs except for the dribble liquid and split application (34-0-0). Although the reason is unknown, pre seeding broadcast 34-0-0 appears to work well for wheat but poorly for barley.
3. ROW SPACING
Quicker canopy development and higher yields were reported from narrower seed row spacing with a double disc opener or a paired row opener. Yields increased as the row spacing decreased from 10" to 4½" when P2O5 was seed placed and ammonium nitrate was broadcast. The disadvantage of the wider row spacing on the air seeder was overcome with paired row openers or sweeps.
Zero till seedbeds are more moist than tilled seedbeds. This can result in quicker emergence and improved yields because of more available moisture. Higher yields were realized for the second consecutive years from zero till treatments compared to minimum and conventional till systems. Flax yields on barley stubble from all zero till treatments were higher than all the minimum till and conventional till treatments.
Crop rotations are important to reduce diseases, insect and weed problems and can be used to help rotate herbicides for better overall weed control and reduced weed resistance. Yields may also improve! Highest yields were reported from the CTPC with a 50% cereal rotation under zero till. Cereal yields increased more with crop rotation diversity under zero till than for minimum till or conventional till.
The largest net returns from wheat and barley and mustard were from zero till with a 50% cereal rotation. Both zero till and minimum till showed improved net returns with a 75% or 50% cereal rotation. Zero till had higher costs than conventional till primarily because of herbicide costs, while conventional till had higher machinery and labour costs.