Soybean producers intend to plant 73.1 million acres in 1999, up 1 percent from last year. If realized, this will be the largest planted area for soybeans on record. Of the 30 soybean producing states, producers in 10 states intend to plant more acres this year (mainly Midwestern states), while producers in 14 states are indicating fewer acres to be planted in 1999. Six states, including Virginia, are unchanged from last year. Forecast ending stocks are now pegged at approximately 430 million bushels. Season-average soybean prices are predicted at $5.00 to $5.10 per bushel. Global soybean production is less than was previously predicted due to lower yield estimates in South America, but is still at a record high.

The above predictions do not present a good scenario for soybean prices in 1999. The spring high futures market price is usually around the second half of April or the first half of May, but it is not unusual to see more than one price peak. Weather problems usually cause some market excitement, but the timing of this event is very erratic and can occur anytime from early June through November. This sometimes turns into a "bull" market, but is not common. Improvement of soybean prices in 1999 will take a prolonged weather scare and this type of market. If U.S. yields are average or above, prices at harvest could be in the $4.50 range.

Based on the projected ending stocks and outlook for this year's crop based on average yields, Dr. Dave Kenyon, Virginia Tech Economist, suggest the following strategies for marketing your soybean crop using 1999 November soybean futures: .

At $5.30	Sell 1/3 of crop.
At $5.60	Sell additional 1/3 of crop (opportunities may come ~ Aug. 15. Expect less than $5.00 at harvest unless yield concerns in the Midwest arise).
Timing	Sell 2/3 of crop by August 15.
Storage	Evaluate basis and manage Loan Deficiency Payments (LDP) to your advantage.

Preemergence Herbicide Choices

While Roundup-Ready, STS, Liberty-Link, and other new seed technology seem to have taken the soybean industry by storm (I estimated that 30 to 35% of Virginia's soybean crop was planted to Roundup-Ready technology in 1998), there are still many very good "conventional" herbicide programs available. Prices have come down and one should consider a conventional program for their full-season soybean. Even if planning a Roundup-Ready or STS program, a preemergence herbicide will buy some time and possibly widen the window of application for the postemergence application. Table 1 gives the relative effectiveness of preemergence soybean herbicides. Keep in mind rotational restrictions however. Table 2 summarizes the crop rotational restrictions in months after the soybean herbicide has been applied.

Soybean Seeding Rates / Row Spacing / Planting Dates

Questions on seeding rate and row spacing consistently arise this time of year. Virginia, being primarily a double-crop state has been one of the leaders in reducing their row spacing and increasing seeding rates to the most profitable level. While the importance of narrow rows and high plant populations is clear for double-crop production systems, the yield advantage of narrow rows and higher populations in full-season systems is not as evident. Why is this?

The underlying factor behind whether or not one can expect higher yields from narrowing row spacing and increasing plant populations is the percentage of light (i.e., energy) that the leaves can intercept. This relates directly to the process that supports all life on earth, photosynthesis. Photosynthesis is simply put the process in which plants utilize sunlight energy to convert CO2 into simple sugars that can later be converted to carbohydrates, proteins, and fats. To fully utilize all possible sunlight energy, the soybean crop needs to intercept approximately 92-93% of this sunlight. In order to do this, the crop needs to develop at least 3 _ to 4 square feet of leaves for every foot of ground surface by the late bloom and early pod stages. The ratio of square feet of leaves per square foot of land is commonly referred to as leaf area index or LAI. If the crop can meet this minimum LAI requirement, then the production of additional leaf area will not result in increased yields. Many full-season systems produce extra leaf area. A double- crop planting will not always reach this minimum LAI requirement because of the shorter growing season; therefore narrow rows and higher plant populations will be a benefit. Full- season plantings ability to reach requirement will depend on the yield potential of the soil, maturity group, and environmental conditions (mainly rainfall); therefore, there is less response to row spacing narrower than approximately 20 inches as is shown by the table below.

Row Spacing	SEED YIELD*					Planting to Canopy Closure (TN)
	Virginia		N. Carolina		Tennessee
	Full Season	Double Crop	Full Season	Double Crop	Full Season
Inches	Bu/A					Days
36-40	--	--	31.8	27.1	43.9	104
30	41.5	33.8	--	--	47.6	93
20	--	--	35.0	30.6	49.2	84
15	43.1	36.9	--	--	--	--
10	--	--	35.4	31.6	56.4	69
7.5	43.3	38.3	--	--	--	--

*Research results obtained from Reese and Buss, 1990 (VA); Dunphy, 1989 (NC); and Parks et al, 1982 (TN).

Although the data shown above is representative of the average response of soybean to row spacing, it does not get to the underlying assumption that LAI and light interception is the factor responsible. Research is underway to better clarify row spacing and plant population requirements for Virginia using LAI and light interception. Last year in an experiment to evaluate row spacing and plant population on maturity group IV soybean planted full-season, no yield response to row spacing (9-inch vs. 18-inch) or to plant population (ranging from less than 50,000 to over 200,000 plants per acre) was evident. This was very unusual since our full-season plant population recommendations are 100,000 to 140,000 plants per acre. Are our recommendations wrong? Can we really get by with such low populations? Not necessarily. One must put the above situation in context. The experiment was conducted on a Pamunkey loam soil, one of the best soils in Virginia. Adequate early season moisture was available to enable the crop to reach the minimum LAI requirements, regardless of plant population or row spacing. Therefore, no yield response in plant population occurred. Below is the data for one of the varieties in the experiment.

So, what does all this mean? What row spacing and plant population is recommended for full-season plantings? The current full-season recommendation of 100,000 to 140,000 plants per acre is still appropriate and there is little yield benefit from narrowing rows to less than 15 to 20 inches. But, what population in the above range is appropriate. Although more data is needed to confirm what I'm about to state, I believe that the following is true. On a good productive soil with high plant-available water-holding capacity, the low range should be adequate. On a less productive soil with low plant-available water-holding capacity, the higher range will be needed. This is opposite from what may be recommended for corn, but corn does not compensate for too little or too much leaf area like soybean. I must however emphasize that uniform emergence is necessary for maximum potential yield. Gaps in the stand will reduce yield, even if average populations are high. Therefore, if stand uniformity is a problem due to planter, drill, or soil conditions, then lean towards the higher recommendation. In addition to soil type, the maturity group grown will affect the recommendation. Use the middle to upper ends of the scale for an earlier maturing variety (MG III or early MG IV). Utilization of an early maturing variety on a sandy soil should require plant populations in the upper end of the scale.

More information on this should be obtained in 1999 research and hopefully recommendations can be modified to fit a particular field or soil type. Below is a table with suggested soybean seeding rates at different row widths.

Row Width	Full-Season		Double-Crop
	Short Varieties	Medium/Tall Varieties	All Varieties
inches	seeds/foot*
36	11.0 to 18.5	9.3 to 12.8	**
30	9.2 to 15.3	7.7 to 10.7	**
24	7.4 to 12.3	6.1 to 8.6	11.0 to 13.5
18	5.5 to 9.2	4.6 to 6.4	8.4 to 10.1
12	3.6 to 6.2	3.1 to 4.2	5.5 to 6.8
6	1.8 to 3.1	1.6 to 2.1	2.8 to 3.4

*Seeding rate adjusted for assumption of 75% emergence. Desired full-season plant population (plants/acre) for short varieties is 120,000 to 200,000 plants/acre; for medium or tall varieties is 100,000 to 140,000 plants/acre. Plant population for double-crop soybeans should be 180,000 to 220,000 plants/acre.
**Double-crop soybean should not be planted in row widths of less than 24 inches.

Soybean Seed Treatments

Soybeans will occasionally require seed treatments of nitrogen-fixing bacteria, fungicides, and/or molybdenum. The situations in which each is needed and some precautions are described below.

Nitrogen-Fixing Bacteria. Soybeans are legumes and generally do not need to be fertilized with nitrogen. This is because of a symbiotic relationship with soil bacteria called Bradyrhizobia. These bacteria attach themselves to the soybean root and form nodules. In exchange for nutrition derived from the soybean plant, the Bradyrhizobia capture nitrogen from the soil air and provide most, if not all, of the soybean nitrogen needs. When is an inoculant needed? Soybean nitrogen- fixing bacteria do not attach to other crops, therefore will decline if soybeans are not being grown. But, these bacteria can remain in a field for 5 to 10 years after the last soybean crop. However, it is recommended that an inoculant be used if the field has not been planted to soybeans in the last three years. Otherwise, the soil will usually contain enough bacteria to produce a high-yielding crop. Inoculant is available as granular, liquid, and peat based. If needed, growers should purchase fresh inoculant dated for 1998 and should uniformly coat the seed.

A word regarding the effect of soil fungicides on the Bradyrhizobia bacteria is needed. Certain fungicides are detrimental to Bradyrhizobia. Do not combine inoculants with the fungicides containing Captan or PCNB because these fungicides can harm the bacteria and reduce nodule counts, especially if you are growing soybean in a field for the first time. On the other hand, fungicides containing thiram, carboxin, or metalaxyl are generally safe to combine with the bacteria. If combining inoculant with any fungicide, the inoculant should be applied immediately before planting.

Seed Fungicides. Fungicide seed treatments can be used to reduce seedling disease and improve soybean stands. Generally, if the soil temperature is above 65 degrees, the seedling should rapidly emerge and a fungicide is not needed. However, if using soybean seed whose germination is between 75 and 85% or planting into cool wet soils, a fungicide may be warranted. Seed with germination below 75% should not be used; seed treatments cannot make up for poor quality seed or of low germination. Rhizoctonia is probably the most common fungus attacking soybean in Virginia. The table below lists registered fungicide seed treatments for soybean and their range of control. An effective seed treatment for soybean will contain either captan or thiram as the base component. The others listed may be beneficial supplements where specific problems exist.

Common name	Trade name	Range of control
captan	Various	Broad range of fungi
thiram	Various	Broad range of fungi
thiabendazole	Various	Fusarium spp., Cercospora spp., etc.
carboxin	Vitavax	Sclerotium rolfsii, Rhizoctonia spp.
PCNB	Terraclor	Same as above
metalaxyl	Apron	Pythium spp., Phytophthora spp.

Another soil-born disease that can occur in Virginia is "Essex Disease". This disease is caused by species of Fusarium and results in poor seedling emergence and root rot of established plants. Yield losses on the variety "Essex" and other susceptible varieties can be quite severe. The above seed treatments have little activity on the disease complex, but many varieties including Hutcheson, Chesapeake, and Accomac have good resistance. Contact seed companies to verify their varieties' resistance levels.

Molybdenum. Molybdenum is a micronutrient required for nitrogen fixation. If in short supply, poor nitrogen fixation will occur. Most Virginia soils contain adequate molybdenum for plant growth, however that availability of molybdenum declines with pH. If the pH drops below 5.5, a molybdenum seed treatment can be justified. However, if soil pH is 5.5 or below, yield potential is very low due to other pH-related problems. Therefore, it is not recommended that molybdenum be applied unless soil pH approaches 5.5-5.8. A much better solution is to maintain pH at levels between 5.8 and 6.2. Like some of the fungicides, molybdenum can harm nitrogen-fixing bacteria; therefore, if both are needed, mix the inoculant and molybdenum immediately before planting.

Preplant Nitrogen for Soybean

Many producers and crop advisors feel that a small amount of nitrogen applied to soybean at or before planting gives the young soybean plant a "jump start" or "pop up" effect, similar to that when applied in corn. However, research throughout the U. S. has not shown a consistent or significant yield benefit. Below is data from Virginia showing this lack of response. In most cases, 20 to 25 pounds per acre is applied and this should not harm the nitrogen-fixing bacteria, but the application represents an added expense. Although nitrogen is relatively inexpensive this year, potentially low profitability of the crop should give an added incentive not to apply unjustifiable inputs.

Soybean Yield Contest Winners

A total of 42 soybean producers across Virginia entered the 1998 Soybean Yield Contest, 24 in the full-season category and 18 in the double-crop sector. Below is a listing of the winners and varieties used.

Full-Season:

Producer	County	Brand & Variety	Yield (bu/A)
Jay Justice	Fluvanna	Pioneer 9396	71
Richard Williams, Jr.	City of Suffolk	Montague Farms MFS 591	65.8
David Fitzgerald	Augusta	NK S46-W8	64.8
Tommy Roundtree	City of Suffolk	Pioneer 9594	62.6

Double-Crop

Producer	County	Variety	Yield (bu/A)
Richard Williams, Jr.	City of Suffolk	Southern States SS516	58.7
Larry Brown	Southampton	Hutcheson	53.3
Bill Nelson	Henrico	Pioneer 94B81	53.3

Soybean Update Available on the Web

This and past issues of the Soybean Update are available on the Web at the site address listed below. I would like to eventually move to this type of delivery in the future. I will eventually arrange the site so you may download and print the newsletter. http://www.vaes.vt.edu/tidewater/faculty/holshouser/soybeanup/soybeanup.html

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