|
|
|
Click here to download a printable version of Virginia Soybean Update Newsletter - PDF format
Documents in PDF format require the Adobe Acrobat Reader to open. If you do not already have the Reader installed on your computer, you can download a free copy from Adobe.
There seems to be more interest in growing early maturing varieties this year. Using early maturity groups is a good management strategy for spreading out harvest and even for spreading risk. However seed quality risks are much higher for early varieties.
In this issue, I discuss seeding rates and whether or not you should consider lowering them. I'm also including some of last year's data on the effect of sprayer traffic on soybean yield. Dr. Bobby Grisso has contributed several articles on fuel saving tips, planter adjustments, and conservation tillage.
I'll keep praying for rain on my end. Hope you do the same.
Return to Index
So, what's caused the shift? Larger acreage and the desire and ability to harvest earlier are probably the main reasons. And, as the Virginia soybean varieties tests have indicated, group IV soybeans are generally yielding as well or better than group V varieties in a full-season production system (see Virginia Soybean Update, Vol. 9, No. 2). This is not necessarily true for double-crop plantings; group V's tend to win out in the southern production areas or when grown on soils of lower productivity.
So, shifting to group IV's has been a good decision for many producers. But, the desire among many producers to grow even earlier-maturing varieties is getting stronger. This usually means a group III, but could also mean an early group IV in the southern production region. So for the rest of this article, I'll just refer to growing an early-maturing variety as just that. Depending on your region, this could be an early group IV (southern growing areas), a group III (northern growing areas), or or even a group II (northern Piedmont or Shenandoah Valley).
So, what are my thoughts on this? In the March newsletter, I emphasized that early-maturing varieties will not consistently yield as well as adapted varieties. Yes, there will be exceptions; 2005 was one of those exceptions. In many locations, the earlier maturity groups performed better than later-maturing varieties. Clearly, this was because of the late-season drought that favored the earlier maturity groups. Don't count on late-August and September droughts to occur every year. Actually, long-term weather data indicate that droughts are less likely in Virginia during this time.
Another unusual event was that the seed quality of the early-maturing varieties was sometimes better than the later-maturing varieties. This was the first time that this has happened since I've been in Virginia. Many who grew the early maturing varieties applied fungicides and felt that the fungicides prevented poor seed quality. While fungicides will improve seed quality, they will not prevent poor seed quality if harvest is delayed or if warm, moist weather persists during seed maturation. And these warm, moist conditions will almost always prevail during September when these early varieties are maturing. Last year was an exception. In 2005, it was warm in September, but not humid. Then it rained and remained warm in October, setting up the later maturity groups for seed quality problems. Again, don't expect a dry September and a warm, wet October every year.
What's the take-home message? If you decide to grow an early-maturing variety, be sure to harvest within a week after the crop matures. Or, seed quality will rapidly deteriorate. You may have to drop the corn head or stop cotton harvest. But, get those soybeans out of the field.
Return to Index
As you can see from the above map, soybean rust has overwintered farther north than the previous year. If you recall, the Tampa Bay area of Florida was the farthest north that rust overwintered in 2004/2005. The warm winter and a general higher inoculum load are probably the reason for it overwintering in northern Florida, and southern Georgia and Alabama this year. Interestingly, the only areas that kudzu survived the winter was in protected sites (culverts, old houses, etc.) of towns and cities. Kudzu generally died back in the rural areas. Although, only a few leaves remained on the vines, this small amount of inoculum will allow that kudzu patch to begin producing more spores sooner. Soybean rust was also found in Mexico and Texas during the winter. Those overwintering sites will likely affect the Mid-South and Midwest to a greater extent than Virginia.
Note in the above map that some of the confirmed sites were "destroyed." What this means is that the few leaves with rust were picked off or the patch might have been sprayed to desiccate the remaining leaves. But, don't think that these actions will eliminate the problem. Remember, the sentinel plot system represents a very small percentage of the total acreage of kudzu. I would suspect that there are other undiscovered patches of kudzu with rust in the area.
So, what does this all mean? First, rust has a head start over last year. Yes, the likelihood of seeing rust in Virginia has increased. But, the spread of the disease will depend largely on wind currents and the environment where the rust is surviving. Predictions at this time of the potential severity of rust in 2006 are at best inaccurate, and at the worse, irresponsible.
We will continue our monitoring program for rust and aphids in Virginia, and keep everyone updated. For the latest information, go to our Virginia website: http://www.ppws.vt.edu/ipm/soybeanrust/index.htm, which has a link to the national site: http://www.sbrusa.net/
Return to Index
But, can we expect this response every year in every field? I say no. Take the 2005 Orange experiment (Fig. 9.2.2) for example. The soil type at this site is a Davidson clay loam. Although the Orange soil has higher plant-available water-holding capacity than the Appling sandy loam at Blackstone, early-season rainfall was much lower. At first look, these data seem too variable to draw any conclusions. But upon further examination of the individual plots, I found that we really had two separate tests within the field. One end of the field (reps 3 and 4; blue symbols) was much lower yielding than the other (reps 1 and 2; red symbols). What's significant about these data is that in the lower-yielding area of the field, higher populations were needed to maximize yields. On the other hand, the response in the higher-yielding portions of the field was very similar to Blackstone.
So, just because some research indicates that much lower seeding rates could be justified, it doesn't mean that we should necessarily make the cut. The Orange data is very similar to other data that I've accumulated over the years that show that soils with l
ower productivity will require higher seeding rates to maximize yield potential. Of course high rainfall (the main yield-limited factor in Virginia) can allow a poor soil to produce great yields. That's why we didn't see an striking response to seeding rates during the high rainfall years of 2003 and 2004. In years of low early-season rainfall and on soils with low plant-available water-holding capacity, there is a higher probability of getting yield responses to relatively high seeding rates.
In addition to soil productivity, one must consider maturity group. A later maturity group will produce a larger canopy; therefore seeding rates can be lower than for earlier maturity groups.
If you significantly lower your seeding rates from the levels shown on Table 9.2.1, then you are taking a risk. Unfortunately, the level of risk is sometimes unknown until after the fact. So be careful. I would suggest that you do some testing on your fields. Try 20 to 30 thousand less seed per acre and see how you fair. Your farm and fields will likely behave somewhat differently than your neighbors.
Table 9.2.1. Final plant population suggestions (no. per acre x 1,000) for Virginia soybeans.
| Avg. Yield Potential* (bu/acre) | Maturity Group | May 1-31 | June 1-15 | June 16-30 | July 1-15 |
|---|---|---|---|---|---|
| 20-30 | III | 140 | 160 | ---- . | ---- |
| IV | 130 | 150 | 200 | 220 | |
| V | 120 | 140 | 180 | 200 | |
| 30-40 | III | 120 | 140 | 200 | ----- |
| IV | 110 | 130 | 180 | 200 | |
| V | 100 | 120 | 160 | 180 | |
| >40 | III | 100 | 120 | 180 | ----- |
| IV | 90 | 110 | 160 | 180 | |
| V | 80 | 100 | 140 | 180 |
Return to Index
With diesel prices on the rise, a little bit of savings can go a long way when it comes to taking steps to conserve fuel on the farm. In many situations, every dollar saved in fuel may save a farmer $5 to $10 in total production costs. There are many simple things a farmer can do to save fuel that won't cost a thing or will cost very little. Here are some ways to "put dollars in the bank, not in the fuel tank:"
Invest in conservation tillage. You can cut tractor use in half by switching to no-till.
Consider auto-steering. It is a substantial investment, but auto-steering makes it easier to adopt controlled traffic. This will minimize or eliminate compaction in the cropping zone, leading to higher yields with no-till and a quick payback.
Maintain proper tire inflation. On the average farm, the majority of tires are over inflated. Over inflation causes excess wheel slippage.
Select the right tires. Although more expensive, radial tires outperform bias tires because of their design. Other tire tips include: replace tires with worn out lugs; use single tires unless duals are needed for traction and flotation, or a controlled traffic system; instead of triples, consider using wider duals. Extra tires can increase rolling resistance and use more fuel.
Keep vehicles well maintained. Regular upkeep includes changing air and fuel filters. Scheduled maintenance saves fuel and increases power. Partially plugged fuel filter reduces the amount of fuel getting to the engine, thereby losing power.
Choose fuel-efficient machinery. Just as with car models, tractors can vary on fuel efficiency. The University of Nebraska offers information on tractors and their fuel efficiency to help buyers make a decision between models. For information on tractors built since 1999, log on to tractortestlab.unl.edu.
Shut off idling engines. Don't let a diesel engine idle more than about 10 minutes. Research shows it's less efficient to keep an engine idling for warmth than it is to re-start it. Of course, results may change in extremely cold weather.
Don't' waste fuel. For example, don't subsoil 16 inches if going 12 inches deep is doing the job. Eliminate "recreational tractor tillage & driving." To reduce the number of trips equipment is driven to and from fields, add a carrier to the tractor or combine for a small motorcycle or scooter to use rather than driving the equipment back home.
Replace worn out parts. Keeping any ground-engaging tools sharp makes a big difference when it comes to saving fuel and improving speed and field efficiency.
For more information review the factsheets:
http://www.ext.vt.edu/pubs/bse/442-451/442-451.html
http://www.ext.vt.edu/pubs/bse/442-450/442-450.html
Return to Index
Now is the time to check on how well your planting equipment will perform. Take your empty planter to the field as soon as weather and field conditions allow. Level the planter in the field, making sure that the toolbar is at the proper height and leveled front-to-rear, perhaps even slightly "tail" down.
This allows for the full range of movement of the parallel links on the row units, helps keep the planter on the row, and aids in seed-to-soil contact. In addition, make sure that the planter carrying wheels are exactly centered between the rows and that they are carrying some weight. This is especially important if there are any ridges in the field from cultivation or harvest.
Once the planter is leveled, try "blind" planting with empty seed boxes. Stop with the planting units in the ground and check to see if the depth gauge wheels are in firm contact with the soil surface. If they are not, tighten the down pressure springs and try planting again. You may have to add weight to the planter for the springs to work against and to keep the drive wheels firmly on the ground. By putting a small amount of seed in a couple of rows, seed-to-soil contact and seed-vee closing can be observed as well. However, all these items should be rechecked when actual planting begins and as conditions change during the planting season.
Check the planter's performance by evaluating the four functions of seeding equipment. By checking residue cutting and handling, soil penetration, seed-to-soil contact, and seed-vee closing, one can make the adjustments or modifications necessary to solve any problems encountered. There is plenty of time to make adjustments or buy attachments, if needed, before planting begins.
With any piece of equipment, the owner's manual is the starting point for the initial settings and for making any adjustments. Valuable recommendations and trouble-shooting tips are in the manuals and also available from others who own and operate similar equipment.
For more information review the factsheet: http://www.ext.vt.edu/pubs/bse/442-456/442-456.html
Return to Index
Practical Suggestions for Success
Environment: Temperature and rainfall patterns of an area provide the foundational information for understanding what type of tillage systems are likely to be most successful. Is rainfall generally limiting or is excess moisture a consistent problem? This environmental information, coupled with field-specific soil characteristics, establishes the fixed parameters that must be considered when designing a crop management system. If rainfall is typically limiting or temperatures are relatively high, chances are good that a reduced tillage system will work well. Design your cropping system to take full advantage of existing environmental conditions.
Soil Characteristics: Soils with good surface drainage are more suited to no-till and other reduced tillage methods. Soils with good internal drainage are also more suited to less intensive tillage practices. Good surface or internal drainage can offset the lack of the other, but if both internal and external drainage are limiting, reduced tillage systems face significant challenges. Try reduced tillage systems first on fields with good drainage.
Crop Rotation: While mono-cropping in reduced tillage systems is certainly possible, chances of success are greater when a variety of crops are used in the rotation. Numerous studies have shown that no-till, continuous corn will not yield as well as no-till corn rotated with other crops, particularly a legume such as soybean or alfalfa. This diversity of crops in the rotation is most important on poorly-drained soils. In moisture-limiting environments, cropping intensity is also an important consideration. No-till increases the amount of water available to the crops, so more intense rotations can be used to utilize this extra water. When reducing the intensity of your tillage system, consider a crop rotation including some diversity.
Crop Selection: Reduced tillage systems like no-till have been used successfully in many crops including corn, sorghum, wheat, sunflowers, canola, cotton and soybean. In each case, success depends on uniform distribution of residue from the previous crop, proper planter adjustment and stand establishment, adequate nutrient management, and an effective weed control program.
Hybrid or Variety Selection: Although the best-performing corn hybrids in one tillage system are generally the best-performing hybrids in another tillage system, hybrid selection remains critical to success with reduced tillage. Choose hybrids or varieties with good emergence, early vigor and disease resistance.
Residue Management: Uniform residue distribution while harvesting the previous crop is extremely important. Residue that has not been properly distributed can make uniform stand establishment very challenging for any planting equipment. Row cleaning devices for in-row residue removal can improve stand establishment in environments where high soil moisture and low soil temperature typically delay seedling development. When planning to implement a reduced tillage system, be prepared to uniformly distribute crop residue at harvest and have a planter equipped to perform in high residue situations.
Planter Adjustment: Planter adjustments important for success with reduced tillage systems include: keep planter units level, ensure down pressure is adequate, adjust coulters so they cut residue but don't run too deep, adjust residue managers to move residue but not soil, ensure seeding depth is uniform and the seed furrow is closed - providing good seed-to-soil contact.
Weed Control: Be prepared for an increase in perennial weeds and small-seeded weeds. Start clean Ð don't plant into a dense mat of live weeds. Control weeds and previous perennial crops with a herbicide application before planting. Be sure to have a post-emergence herbicide plan in place. Where they are available, herbicide-tolerant crops can help.
Nutrient Management: Regular soil testing is important in any tillage system, but is critical before establishing a reduced tillage system such as no-till. Collect soil samples and apply and incorporate any P, K and lime required before converting a field to no-till. Minimize the risk of N losses with proper placement and timing of N applications. While nutrients can be surface applied in no-till systems, injection may help minimize losses and improve plant availability.
Soil Compaction: Minimize soil compaction by controlling traffic. Confining wheel traffic to specific areas can reduce root growth limitations caused by excess soil compaction.
Insects and Diseases: Selecting hybrids or varieties with good resistance to the most common local diseases and insects is very important for reduced tillage systems. Crop rotation can be very beneficial to break insect and disease life cycles. Monitor crops closely to detect problems that can be corrected during the growing season. Where available, crops with built-in protection against corn borers or rootworms have proven to be very effective. Insecticide seed treatments can also provide insect protection.
Manure Management: When livestock are part of the agricultural system, be sure to take advantage of the benefits of applied manure. If surface applications are made, be sure applications are uniform. Manure injection can help minimize nutrient losses while maintaining surface residues for maximum soil and moisture conservation.
Cover Crops: Cover crops can play a major role in building soil organic matter. Cover crops can help improve the chances for no-till success in soils that are low in organic matter and susceptible to compaction.
Rotational Tillage: Some growers use different tillage systems for different crops and this may be beneficial on poorly-drained soils. Remember that the organic matter gains from reduced tillage will be lost when tillage intensity is increased.
Getting Started
These ideas can improve the chances of success when trying a new reduced tillage system: Seek advice from other growers who are successfully using a reduced tillage system. Communicate with soil scientists or others who might be conducting tillage system research. Attend plot tours or field days demonstrating tillage methods. Join a tillage club or grower association focused on reduced tillage. Plan carefully for crop rotation, residue distribution, use of planter attachments, fertilizer application and herbicide program. Conducting on-farm research is one way to gain personal experience and learn what works and what doesn't. Attend tillage-related conferences or workshops.
Submitted by Bobby Grisso
Taken from Meese, B. 2005. Reduced Tillage Systems for Crop Production. Crop Insights 15(4):1-3
Return to Index
Tramlines are basically traffic lanes placed in a field at planting. These traffic lanes match the width of the sprayer tires and are spaced to match the width of the spray boom. See the diagram on the following page for clarification.
Tramlines have several advantages. One is uniform application of nutrients and pesticides, with no skips or overlaps. With soybean rust, you'll easily be able to tell where the skips are. And doubling of fungicide on some parts of the field will definitely not compensate for the skips in the other parts. Another advantage is that they act as a guide for repeated applications. Tramlines are much easier to follow than foam markers. And, tramlines offer a means to control traffic and reduce compaction. Of course today's technology (i.e., light bars, auto-steer tractors, etc.) will accomplish the same results. But, there are more advantages.
Tramlines may actually help with spraying in wet fields because the unplanted strips become somewhat compacted. There is less likelihood that the sprayer will be stuck in the field. Remember, soybean rust will not wait for the fields to dry.
Probably the most important advantage of installing tramlines in soybeans is higher yields from not running over 2-3 feet tall soybeans. Of course if you're in wide rows (>20-24"), you won't need tramlines. But, most of Virginia's acreage is planted in 7 1/2 to 20 inch rows, making it much harder to fit a sprayer without damaging the crop. We've seen a rapid move to drills, and we experienced the yield increases associated with that move, especially for our double-crop plantings. But, these yield increases could be negated if we run over one or two rows while spraying for rust.
There hasn't been very much research conducted concerning the effect of running over soybeans late in the growing season until this past year. Older data out of Ohio is shown below. The research was conducted on 7 1/2 -inch soybeans and two of the rows were destroyed during pesticide application. Note that the amount of yield loss varies with the spray boom width because less total rows are damaged. But, even with a large boomed sprayer, yield losses approach 1/2 to 1 bushel per acre. You need to just add this cost to your fungicide application cost, if not using tramlines.
Table 9.2.2. Effect of sprayer traffic on soybean yield.
| Spray Boom Width (ft) | No. of Rows Covered/Pass | Percent Yield Loss |
| 50 | 80 | 2.5 |
| 60 | 96 | 2.1 |
| 70 | 112 | 1.8 |
| 80 | 128 | 1.6 |
| 90 | 144 | 1.4 |
Newer data from Indiana shows even slightly higher damage from wheel tracks. In 2 experiments, Purdue University researchers ran over 7.5-, 15-, and 36-inch soybean rows with Apache and Spray Coupe applicators at the R1 (beginning bloom), R3 (beginning pod), and R5 (beginning seed) development stages. They also ran over rows at R3 + R5 (twice) and at R1 + R3 + R5 (3 times). Yield averaged 54 bushels per acre at Location 1 and 67 bushels per acre at Location 2. Running over rows at any development stage significantly reduced yield in the 7.5- and 15-inch row spacing. The second and third trip over the field did no additional damage. No yield reduction occurred in the 30-inch rows. Table 9.2.3 shows the effects of spray boom width on soybean yield at both locations.
Last summer, we also studied the effect of sprayer traffic on soybean yield in Virginia. Two experiments (full-season and double-crop) were conducted to determine the effect of running over rows late in the growing season to simulate reproductive stage fungicide applications. Three row spacings were used: 7.5, 15, and 36 inches. Traffic and fungicide (with or without Quadris fungicide) treatments were applied at the R5 stage. With no traffic, full-season yields averaged 42, 39, and 30 bushels per acre for the 7.5-, 15-, and 36-inch row spacings, respectively. Double-crop yields averaged 48, 52, and 38 bushels per acre for the 7.5-, 15-, and 36-inch row spacings, respectively (no traffic). Fungicide had no effect on yield; therefore results shown below are averaged over fungicide treatment. Table 9.2.3 shows the percent yield loss from plots containing four 36-inch, eight 15-inch, and sixteen 7.5-inch rows. Four 7.5-inch rows were run over and two 15-inch rows were run over in each plot, which amounted to taking out 25% of the crop. The table also extrapolates the percent yield loss that one would receive depending on the width of the spray boom. Keith Balderson, Essex County Agent, found a similar yield loss in an on-farm test.
Table 9.2.2. Effect of spray boom width on soybean yield loss, averaged over row spacing, Indiana, 2005.
| Boom Width (ft) | Location 1 | Location 2 | ||
|---|---|---|---|---|
| -------------------------------------Yield Loss---------------------------------------- | ||||
| Bu/A | % Total | Bu/A | % Total | |
| 30 | 8.8 | 14.7 | 3.8 | 6.3 |
| 60 | 4.4 | 7.4 | 1.9 | 3.2 |
| 90 | 2.2 | 3.7 | 1.0 | 1.6 |
| 120 | 1.1 | 1.8 | 0.5 | 0.8 |
Table 9.2.3. Effect of sprayer traffic on soybean yield in full-season and double-crop soybean, Suffolk, VA, 2005
| Planting Date | Row Spacing | % Soybean Yield Loss due to Sprayer Wheel Traffic | ||||
|---|---|---|---|---|---|---|
| Plot | 40 ft boom | 60 ft boom | 75 ft boom | 90 ft boom | ||
| May | 7.5 | 12.5 | 1.4 | 1.0 | 0.8 | 0.7 |
| 15 | 20.2 | 2.2 | 1.7 | 1.3 | 1.1 | |
| 36 | 4.6 | 0.6 | 0.5 | 0.4 | 0.3 | |
| June | 7.5 | 28.6 | 3.2 | 2.4 | 1.9 | 1.6 |
| 15 | 25.4 | 2.8 | 2.1 | 1.7 | 1.4 | |
| 36 | -2.6 | -0.3 | -0.3 | -0.2 | -0.2 | |
Do we lose any yield due to tramlines? In full-season soybeans, I'd say no. In double-crop, I would suspect that we'd lose a little. But, I'd also suspect that the yield loss without trams would be higher. I'll continue research to evaluate that traffic in the coming year.
In summary, I feel that the time is right for tramlines in soybeans. Installation is fairly simple. For the simplest system, you can just block the drill openings that correspond to the tramlines. Or, you can purchase devices that establish the lanes only where you want them.
Return to Index
Sincerely,
David L. Holshouser
Return to Soybean Update