Agronomy Notes

February, 2002

Contents:

COTTON
FORAGES
WHEAT
CORN
RICE
SOYBEANS
NUTRIENT AND SOIL MANAGEMENT

 

 

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. I am in hopes that cotton acreage will shrink from the 1,600,000 acres harvest in 2001. Acreage in the line of 1,100,000 to 1,200,000 actually fit our available soils and needed cropping pattern better than the high acreage. In today's economic climate, inflated acreage is not sustainable.

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 2002 that will revolutionize cotton production. We must, however, begin to try to balance yield and quality factors. I understand that grower's 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 midsouth 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 2001 Cotton Variety test results or go to www.msucares.com, go to crops, go to cotton and click on Variety Trails. This will lead you to a PDF copy of the 2001 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.

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 tests 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.

FORAGES KEY TO SUSTAINABLE LIVESTOCK PRODUCTION

Dr. Malcolm L. Broome

In the not to distant past, most farms had both crop and livestock enterprises with one dependent on the other. They even complemented each other biologically and economically. Today, however, the scene has changed dramatically, not from dependence on one another, but to separation and specialization of crop and livestock production systems. Yet, despite this change there are many farmers and ranchers who still integrate crop and livestock farming enterprises such as dairy farms, cattle and cash grain, even some sheep, goat, and swine operations. The actual management systems may be quite different, but all address some specific points in order to be sustainable.

All ruminant livestock producers can protect their income by managing their land resources for optimum forage production. Research indicates that cattle will take about 30,000 bites a day and if forages are of sufficient quantity (height and density) the animal can get a "mouthful" with each bite. Goats need a higher availability of forage because they graze higher on the plant and sheep somewhat less because they graze lower to the ground than either cattle or goats. Problems arise when forage falls below the dry matter threshold per acre which is approximately 1000 - 1200 pounds or forage shorter than 3 - 4 inches because animal intake is reduced and production decreases. The animal may increase grazing time but can't compensate to take in enough nutrients even though quality of the forage is good. Livestock producers must utilize forages correctly especially with the current price situation if they are to be sustainable.

In order to manage forage properly, the stocking rate must be correct for the type of forage available. Habit plays a role on most Mississippi cattle farms - open the gate and let the livestock have the run of the entire area. Planning to manage the forage to extend the grazing season is not considered in most pasture situations. If pasture is depleted, production falls and/or purchased feed or harvested forage must be supplemented adding to the expenses. The point is ruminants utilize forages and we need to control consumption and utilize the growth of a pasture correctly. This leads to a management term called feed budgeting which is an evaluation of forage availability, growth rate, and animal demand.

This budgeting process can be very useful when a pasture surplus or shortage is on the horizon. By planning ahead the manager can match animal nutrition to quality forage availability. Crop residues following harvest can also figure into the management plan where farmers have crop and livestock enterprises, used extensively in the past. The change to modern, temporary fencing will make this possible once again since most cropped acreage is not fenced today. This same fencing will also be useful to help manage or control graze large pastures by dividing into smaller pastures or paddocks. With the manager using sufficient control, forage can be better utilized and excess forage harvested for hay. It is interesting that as pastures decline beef cattle maintain better intake levels than do sheep or goats. Therefore, non-lactating cattle in sufficient condition for calving might be budgeted to "clean up" pastures.

For a livestock operation to be sustainable, the manager must plan a grazing system to meet the nutritional requirements of the animals on that farm or ranch. Points of that plan are:

  • Complete pasture inventory.
  • Match forage resources with nutritional needs.
  • Learn to assess the forage to determine animal intake.
  • Remember cool season grasses, legumes, and warm season grasses differ in nutrients.
  • In high quality grazing, animals may not have to consume as much forage to meet protein needs.

As you can see there are a number of points to consider in raising livestock on forages and minimizing the use of more expensive feeds. Feed costs can be kept to a minimum by observing animal condition and performance and understanding seasonal variations in feed and forage quality, a critical step to sustainable livestock production.

RICE

Dr. Joe Street

February is the time to start thinking about applying a burndown herbicide if you have vegetation, especially dock, in fields where you expect to plant rice. With the new aerial restrictions on application of burndown herbicides such as glyphosate (Roundup Ultra Max, Touchdown or Glyphomax) or Gramoxone, an application of 2,4-D to small hard to control weeds such as dock can be a very effective treatment. The new burndown regulation divides the state into two zones with different windows of application restrictions so check the zone in which you fields are located. One scenario is to use 2,4-D in late winter then use a burndown such as glyphosate or Gramoxone at or near planting. A residual herbicide may be added to the burndown but I prefer to have the residual herbicide applied after planting to extend residual weed control toward the permanent flood. There are many advantages to planting no-till or into a stale seedbed and in times of low prices, reducing the tillage trips is one way to reduce costs. With the newer grain drills that provide better seed to soil contact, many growers are able to plant into a moist seedbed and eliminate the need for flushing.

With the introduction of Command three years ago, the use of residual herbicides has increased. About 75 percent of the rice acreage in Mississippi was treated with Command in 2001. In 1999 and 2000, Command efficacy was good to excellent primarily because of timely rainfall and to some extent flushing. In 2001, we experienced a relatively dry April and Command performance was not as good as previous years. Soil moisture with Command is not as critical as other herbicides but it must have adequate moisture for activation. In my experience, the best timing for Command application is to dry soil soon after planting and then flush within five days if adequate rainfall does not occur to activate the Command. If Command is applied to moist soil where weeds have germinated but not yet emerged, performance may not be satisfactory because Command does not have the "reach-back" that occurs with Facet or Bolero. If rice is planted no-till or into a stale seedbed with adequate moisture for rice germination, flushing will still be required to get maximum control from Command. In this situation, Facet could be a better choice because of the reach back capability to get the weeds that emerge before moisture can be applied. Even in this situation, moisture is required to get the herbicide into the zone of activity. If you are not willing to flush a soil applied herbicide, you might consider a postemergence weed control program. I have already addressed the water requirements for Newpath herbicide in the Clearfield system in earlier articles. Newpath is root absorbed and therefore moisture is essential to get maximum weed control. If you use Newpath, (assuming approval) you should be willing to flush.

You are already familiar with Ricestar and this year Regiment, a new herbicide from Valent, will be available. Regiment is effective against barnyard grass, johnsongrass, hemp sesbania and joint vetch plus several other broadleaf weeds. Dow AgroSciences expects to receive registration for Clincher for control or grasses including barnyard grass, sprangletop and broadleaf signalgrass. These herbicides will be welcome additions to rice weed control.

The price of rice herbicides continues to change so consider the cost of the total program when planning your weed control efforts. Having a soil applied herbicide in place may give you better options for postemergence treatments but it may also increase the cost of the total program.

CORN

Dr. Erick Larson

Low risk crop? 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 questionable 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 midsummer drought. Irrigation can help alleviate water stress, but does not overrule the importance of early planting (because of heat stress).

Low input? Successful corn production requires considerable preemptive inputs, particularly to provide fertility. 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. Low soil pH (below 6.0) limits nutrient availability further and will substantially increase availability of toxic elements at pH below 5.5.

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 green weed vegetation. This warms and dries the soil, which widens planting time windows and promotes corn seedling vigor. Burndown herbicides should be applied four to six weeks before planting to gain these advantages.

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 (before recommended dates), even if soil temperatures are warm, provides little if little if any agronomic benefit, while causing considerable risk of 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, 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) and not exceed 50% of the total seasonal amount. This normally occurs during early-February. 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. Rates may often be reduced if the wheat's spring visual appearance is dark green, resulting from considerable carryover nitrogen from the previous crop or fall nitrogen application. 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.

SOYBEANS

Dr. Alan Blaine

The 2002 growing season is rapidly approaching. Because of the lack of knowledge regarding a farm bill and record low prices of all the major commodities, a lot of uncertainty exists.

Today's varieties are much better than 10 years ago. Not only are improvements from varieties being observed, producers are paying more attention to details regarding soybeans. As in most endeavors, there is still room for improvement. Two major areas not adequately covered are in-field scouting and marketing. There are many factors that are out of our control, but these are two that can have a tremendous impact on the bottom line and can be influenced.

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 an integral part. The 2002 Variety Trials and a list of high yielding varieties are currently available to help make this decision. All varieties are not created equal, so don't take this decision lightly.

As you formulate plans, center your program around a good seed treatment program. Not just any seed treatment, but one that is effective at controlling pythium. Materials that are effective against pythium are Apron, Apron Max, Allegiance, Stelleto, just to name a few. An Apron type material should be the base for any seed treatment program for soybeans. In the past if you felt you have had problems getting your crop off to a good start, give some thought to increasing your Apron rate. Doubling the Apron rate may be the cheapest insurance you can buy. Depending on your seeding rate, this increase will cost approximately 40-70 cents/acre. The proper seed treatment is very important with early plantings. Do not neglect to use this option to the fullest.

Some major changes have once again been implemented in the burndown arena versus last year. A restriction on aerial application of Roundup, Touchdown, and Gramoxone has been put in place. 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. Although these restrictions are in place, everyone should find these restrictions a much better option versus last year. Supplemental labels and guidelines are available from the office of the Bureau of Plant Industry.

As you consider early plantings 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.

Remember: you cannot control all inputs, but variety selection is one input you can control if you start early. Variety trials are available in your county Extension office. Give them a call and pick up a copy. If we can be of any assistance, please do not hesitate to give us a call.

NUTRIENT AND SOIL MANAGEMENT

Dr. Larry Oldham

Don't forget the Agronomic Professional Continuing Education Workshop on February 11, 12 and 13. The last day will be a joint meeting with the Mississippi Chapter of the American Society of Agronomy.

There is increasing curiosity about TMDL's and how they will affect agriculture. TMDL's are Total Maximum Daily Loads. They comprise a form of water pollutant budget, allocating how much of certain substances a waterbody can assimilate without problem, that become impaired or violate state water quality standards. Nitrogen, phosphorus, and sediments are three potential pollutants for which TMDL's may be developed.

Each published TMDL will contain these components:

  • waterbody name and location
  • identification of the pollutant
  • the water quality standard for the waterbody
  • amount of pollutant allowable to meet standards (pollution budget)
  • load reduction needed to meet standards
  • sources of the pollutant
  • wasteload allocation for runoff (nonpoint sources) and other sources of pollution
  • margin of safety consideration of seasonal variation public comment period
  • EPA review and approval

When a TMDL is established, states must provide reasonable assurance that all affected sources will be able to meet their allocated load reductions. For point sources, such as industries and wastewater treatment facilities, reasonable assurance is to be provided through permitting.

For nonpoint sources such as agriculture, the assurance will consist of a watershed implementation plan, which describes voluntary actions, or Best Management Practices (BMPs), necessary to achieve compliance. The delivery mechanism to achieve the goals must also be given that will ensure their implementation throughout the watershed.

TMDL's under current rules are being developed in Mississippi pursuant to a consent decree in a court case between environmental organizations and regulators. Because of the many miles of streams listed in the state as possibly impaired, this is a challenging, daunting task.

Applicable BMP's include proper fertilizer timing for crop use, increasing excess water residence time on the soil surface, basing fertilizer application rates on soil test recommendations, and increasing crop residue.

(Some material from Carrie Borel et al., LSU AgCenter, 2001).

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

Will McCarty, Ph.D.
Extension Leader

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