Agronomy Notes

February, 2003

Contents:

SOYBEANS
FORAGES AND PASTURES
SOIL and NUTRIENT MANAGEMENT
CORN
WHEAT
COTTON

 

 

 

 

 

 

SOYBEANS

Dr. Alan Blaine

The 2003 growing season is rapidly approaching, and following this past harvest season, many questions are on growers minds. We must stay focused because numerous production improvements have been made in recent years, but as in most endeavors, there is still room for improvement.

A lot of input goes into producing a crop but if you will concentrate on three inputs you can produce above average yields consistently: 1) early planting, 2) earlier maturity groups, and 3) high yielding varieties. Additional inputs such as pH, soil fertility, weed control, etc. must be addressed, but if you will take care of the basics and then concentrate on these 3 inputs we can make a profit growing soybeans.

If you have not yet made varietal decisions, it is important that you do so now. Varietal differences exist and every producer in this state needs to plant varieties that performed in the top percentile. As you choose varieties, consider harvest capabilities. In dryland settings, early maturing varieties (IV's) are still the best game in town. For this system to be successful, early planting is a integral part. The 2003 Variety Trials and a list of high yielding varieties are currently available to help with this decision. These bulletins are available in your county extension office or on the internet at the MSUcares website. Go to crops, soybeans and finally soybean variety trials.

A restriction on aerial application of Roundup, Touchdown, and Gramoxone will be in place again this year. Applications will not be allowed from March 15 through the end of April, south of Highway 8 and March 25 through the end of April, north of Highway 8 unless an exemption is granted. If significant acreage has not been planted by those dates, the restriction will move back allowing more time for application even after these dates are in effect. Supplemental labels and guidelines are available from the office of the Bureau of Plant Industry.

As you consider planting dates, think early. Early burndowns are an integral part of an early planting system. Early burndowns cost less to apply, help conserve moisture, minimize tillage trips, and eliminate some of the potential risks associated with later applications. The restricted time period for the use of aerial application may cause some growers to burndown earlier, but it can actually be beneficial, and opens up an opportunity to consider residual materials in combination with Roundup, Touchdown, or Gramoxone such as Delta Goal, 2,4-D, Clarity, Valor, Harmony Extra, etc. Keep in mind, don't get in too big a hurry to apply burndown materials. The two recent arctic blasts have helped suppress growth and possibly killed some winter vegetation, and winter weather may not be over yet.

Remember: Variety trials are available in your county Extension office or on the internet. If we can be of any assistance, please do not hesitate to give us a call.

 

FORAGES AND PASTURES

Dr. David Lang

Improve Gain of Summer Stockers -There is a need in the southeast to develop summer stocker systems to maintain viable animal gains (> 1.5 lbs/day) through late summer. Forage quality of introduced summer grasses such as Bermudagrass and Bahiagrass is generally too low to provide adequate gains with growing steers or heifers. Summer stockers in the southeast are generally sold at weaning in May or June due to low animal performance on existing forage systems Feeder cattle prices historically peak in August. Utilization of improved forage species such as switchgrass and hybrid bermudagrass combined with intensive grazing strategies provide the opportunity to retain cattle value in the southeast.

Native warm perennial grasses are underutilized due to their poor persistence under frequent harvests currently implemented within existing management systems. Switchgrass is a well adapted species known for its long persistence and unusually high animal performance despite relatively low measures of forage quality. It has good yield potential (2 to 4 tons/acre), even without fertilizer. Switchgrass has been shown to produce live weight gains with steers of nearly 2.2 lbs/day compared with 1.3 lbs/day with bermudagrass. It's digestibility is of 63 to 66 when it's vegetative. However, digestibility declines in late summer to less than 50 %.

A grazing study conducted by Dr. Mike Boyd and myself indicated steers grazing Alamo switchgrass (SG) gained 1.20 lbs/day in 2001 and 2.1 lbs/day in 2002 from May to August. This large discrepancy was due to attempts in 2001 to allow the cattle to graze each paddock for 3 to 4 days in order to force animals to eat down the SG and keep it more vegetative. In 2002, the occupancy time per paddock was decreased to 1-2 days. This allowed steers to graze more leaves rather than stems. Sumrall bermudagrass (BG) produced 607 lbs of beef/ acre in 2002 with an ADG of 1.4. Alamo switchgrass produced 425 lbs beef/acre and Tifton 44 bermudagrass grew 566 lbs beef/acre. This was over a 90 to 100 grazing period from May to August. Beef production in 2001 was less due to lower stocking rates and less intensive rotational grazing. Alamo produced 307 lbs, Sumrall produced 463 lbs, and Tifton 44 grew 415 lbs beef/acre in 2001. A common bermudagrass/dallisgrass pasture produced 401 lbs in 2001 and 549 lbs beef/acre in 2002. These productive gains deserve a closer look. It required 240 to 320 lbs of actual N/acre (split 3-4X) to stimulate the grasses to these high production levels. Economic and marketing analyses of these data are not yet complete, but the potential looks promising.

Switchgrass is difficult to establish and seed costs are high, so I would not recommend planing to plant much right away. It's also being touted as bioenergy feedstock for industrial production of energy from crops, but that industry is yet to be developed. Someday, however, switchgrass may be recommended as an early to mid summer grazing crop followed by utilization of the ungrazed stems by a power generation plant or as industrial source of hydrogen fuel (now used to power rockets) and other chemicals from synthetic gas. For now, stick with improved bermudagrass, or what you already have, and do your best to increase the level of inputs to maximize economical returns on your pastures.

 

SOIL and NUTRIENT MANAGEMENT

Dr. Larry Oldham

The Natural Resources Conservation Service released proposed rules on January 30 for the Environmental Quality Incentives Program for a thirty day comment period.

The national priorities of the program are:

  • 1) reducing non-point source pollutants in impaired watersheds, protecting groundwater, and conserving water quantity;
  • 2) protecting air quality;
  • 3) reducing erosion and sedimentation; and
  • 4) promoting the recovery of at-risk species habitat.

Nationally, 60% of the EQIP funding will go to livestock related practices. Each EQIP contract which includes an animal waste storage system will be REQUIRED to develop and implement a Comprehensive Nutrient Management Plan.

There will be an increased emphasis on locally led conservation. One way this will be implemented is through Local Working Groups of USDA agency representatives, including local Extension employees.

There are many other details yet to emerge from the EQIP program, particularly concerning non-animal agriculture. For example, NRCS is proposing to encourage the trading of water quality credits by not retaining 'ownership' of cleaner water credits derived through an EQIP contract that may be sold by the landowner to another party. The agency would like comments on this during the 30 day period.

 

CORN

Dr. Erick Larson

Managing Weather Limitations - Growing corn in Mississippi can be very profitable, but does have considerable risk which producers should address with management practices. The primary environmental risks include wet springs and hot, dry summers. Growers should utilize raised beds on fields with marginal drainage to relieve waterlogging and warm the soil for better seedling establishment and vegetative development. Early burndown herbicide application helps both these problems because it promotes warmer, drier seedbeds during the spring and encourages earlier planting. Early planting helps corn avoid stress associated with mid-summer drought. Irrigation can help alleviate water stress, but does not over-ride the importance of early planting (because of heat stress).

Burndown herbicide timing: Moist soil conditions often severely restrict planting time during the optimum corn planting period. Utilizing a late winter burndown herbicide to control winter vegetation allows producers to manipulate soil moisture and encourage earlier planting. Killing winter weeds several weeks before planting allows the soil to absorb much more solar energy, compared to soils covered by a blanket of lush weed vegetation. This warms and dries the soil, which widens planting time windows and promotes corn seedling vigor. Burndown herbicides utilizing glyphosate should be applied four to six weeks before planting to gain these advantages.

High Yield Key: Someone recently asked me to suggested a hybrid that had 250 bushel per acre yield potential. Actually, nearly all corn hybrids possess the potential to yield well more than 250 bushels per acre. In fact, a hybrid available in Mississippi produced 408 bu./a. two years ago in east central Iowa. It is up to us to manage our corn crop so we may harvest as much grain that mother nature will support. Without downplaying the importance of hybrid selection - inadequate fertility may limit corn yields statewide more any other management input. Everyone knows corn requires substantial nitrogen application, however, nitrogen is not normally the nutrient limiting yield. Corn requires nearly twice as much phosphorus and about 40-50% more potassium compared to cotton and soybeans. Additionally, low soil pH (below 6.0) restricts nutrient availability and stunts crop growth drastically (resulting from increased availability of toxic elements) at pH below 5.5.

Risk of ultra-early planting: Abnormally warm, dry conditions sometimes allow an opportunity to plant corn during a period which is normally too wet to plant. Although early planting is a critical component of successful corn production, planting corn extremely early (well before recommended dates), even if soil temperatures are warm, provides little if any agronomic benefit, while risking stand failure. Extraordinarily early planting enhances maturity very little, because corn growth rate is correlated to temperature, and heat unit accumulation (GDD 50) is historically very low during early March.

Guidelines for corn planting date: The standard guideline for determining earliest planting date is when morning soil temperature at a two inch soil depth is 55 degrees F or 50 degrees F at a 6 inch soil depth. Planting before the soil temperature is warm enough for germination greatly increases the potential for stand failure, because germination growth rate is dependent upon soil temperature. Soil temperature may vary depending upon soil texture, slope, or color and amount and type of crop residue. Thus, randomly measuring soil temperature with a thermometer within a field should provide a reliable indicator of desirable conditions for stand establishment. Corn produces highest yields when planted within 4 - 5 weeks after soil temperature is warm enough for germination. This has historically corresponded with the following calendar dates:

Geographical Region of Mississippi:

Southern : February 25 - March 15

Central: March 5 - April 10

North-Central: March 15 - April 20

Northern: March 20 - April 25

Aerial burndown restrictions: The Mississippi Dept. of Agriculture and Commerce will institute restrictions of burndown herbicides by aircraft to prevent off-target drift again this spring. This year's restrictions will be similar to last year, except Delta counties will be divided into two zones (north and south) divided by Highway 8. Aerial applications will be prohibited in the South zone from March 15 through April 30, and the North zone from March 25 through April 30, except by permit from an authorized Bureau of Plant Industry employee.

 

WHEAT

Dr. Erick Larson

Wheat Nitrogen fertilization: In the mid-south, nitrogen application timing typically has a significant effect on wheat productivity. The initial topdress of a split application should be applied when dormancy breaks in late-winter during tillering stages (Feekes growth stage 3 or 4 - normally early February) and not exceed 50% of the total seasonal amount. The timing of this initial topdress will be particularly important this year, since a lot of wheat was planted late, limiting tillering thus far. The purpose of this application is to promote tillering and head size. The final topdress application should be applied by the time the first node appears at the beginning of stem elongation (jointing, Feekes growth stage 6). This application delivers the main nutritional needs of the crop. This generally occurs in early-March. Growers who choose to apply spring nitrogen in a single application should time it at Feekes growth stage 4 or 5. Recommended spring nitrogen rates vary from 90 - 140 lbs./a. with higher rates within this range recommended on clay soils and high yield potential wheat. Urea-ammonium nitrate solution (N-sol 32%) topdress applications should be limited to a maximum of 50 pounds N per acre to prevent substantial leaf burn.

 

COTTON

Dr. Will McCarty

The coming year will be a decisive year for many cotton growers. This winter, growers have struggled to make not only production decisions but more importantly, crop selection decisions. Many growers still do not know what crops they will plant, how many acres or what fields will be planted to what crop.

Over the past years, cropping systems have changed. Problems with reniform nematodes have increased, reduced till acreage has increased, and the (very sound) practice of crop rotation has increased. Rotating cotton with corn, grain sorghum or a soybean-wheat system can be very beneficial to not only the cotton but the rotation crop as well. Cotton behind corn will generally yield about 100 to 200 pounds of lint per acre more than continuous cotton. Like wise, corn planted behind cotton will tend to produce higher yields and have less soil born insect problems. As more and more acreage is being rotated and produced in a reduced till system, the need to understand land and soil management increased. Different crops have different requirements and place different demands on the land. The need for sound management increases rather than decreases.

Variety Selection: Plant the bulk of your acreage in varieties that are proven performers, and experiment with new ones on a limited acreage basis. There are no new varieties on the market in 2003 that will revolutionize cotton production. We must, however, begin to try to balance yield and quality factors. I understand that growers compensation is directly proportional to yield. I also understand that there are no "real premiums" being paid for high quality. A growers premium for growing high quality, or base quality, fiber is that he does not get additional discounts. We may not like it, but that is the way it is. If the recent trends in cotton quality continues, Mississippi, and the mid-south will develop the reputation for growing short staple, high mike cotton. If current trends continue, future markets may be negatively influenced. Review cotton variety trial data carefully and select a variety mix that will spread risk and result in improves average quality. Contact your local county Extension Office for copies of the 2002 Cotton Variety test results.

Soil Testing and Soil Fertility: The merits of a sound, frequent soil testing program are well know. However, in times of low prices growers may tend to practice "false economy" by slashing fertility and especially liming programs.

If you are practicing a crop rotation program, especially cotton: corn, soil pH is critical. Neither cotton nor especially corn, are tolerant of low pH conditions. As you can see from the table below, each crop has different nutrient demands, especially where phosphorus and potassium are concerned. Be sure your fertility program is balanced to favor crops grown in rotation.

Nitrogen Management: Do not over apply nitrogen fertilizer. Research shows that about 50 pounds per acre of supplemental nitrogen are required per bale of realistic yield potential on loams to sandy loam soils and 70 pounds per acre per bale on clay to clay loam soils. Nitrogen rated higher than this can delay maturity and reduce yields.

Match your method of application to your cropping system. Plan now - if you are going to use a nitrogen solution (UAN in particular) in reduced till or no-till programs - knife it into the soil. Especially if used as a side dress. Applying ammonia forms of nitrogen to the soil surface, especially on recently limed fields or fields with heavy residue, can result in losses on N. If you must apply UAN to the surface, increase your N rates 20% or so to compensate for losses. Decisions must be made on a field by field basis - don't apply nitrogen blindly.

As you can see from the table below, in a reduced till system all nitrogen sources are not necessarily created equal.

Potassium: I will not go into a lot of detail here, but potassium management is critical to high yields and quality. There are a lot of data, from numerous southern states, to support the fact that cotton responds to potassium fertility. Recent test indicate that there may be differences in potassium response due to tillage effects. There is some indication that in no-till and/or reduced till fields cotton may respond to higher application levels of K than in conventional tillage.

Practice sound fertility management - especially at low commodity prices.

Drainage: The need for adequate drainage and water management are critical; you must address these areas to allow proper benefits from crop rotation.

 

 

Department of Plant and Soil Sciences
Box 9555
Mississippi State, MS 39762

Will McCarty, Ph.D.
Extension Leader

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