Agronomy Notes

October, 2001

Contents:

NUTRIENT AND SOIL MANAGEMENT
FORAGES AND PASTURES
RICE
CORN
WHEAT
SOYBEANS

 

NUTRIENT AND SOIL MANAGEMENT

Dr. Larry Oldham

We are in the process of finalizing plans for the Agronomic Professional Continuing Education Workshop at the Bost Extension Center on February 11-13. We have packed four days of information into three days this year. The last day, February 13, will be the annual winter meeting of the Mississippi Chapter of American Society of Agronomy.

Due to scheduling concerns, the instruction over the first two days will include a mixture of Nutrient Management, Pest Management, and Crop Management. The third day will be Nutrient Management and Soil/Water Management, and include an unique presentation by Jerry Litton of Jackson.

 

FORAGES AND PASTURES

Dr. Malcolm Broome

Fertility has a Role in Forage Quality - Quality in forages is dependent upon adequate soil fertility. Application of commercial or organic fertilizers is needed on most Mississippi pastures to provide nutrients for forage growth and survival. To grow quality forages as a crop, producers must understand nutrient management. The most commonly applied fertilizer elements or nutrients are nitrogen (N), phosphorus (P), and potassium (K).

Of these three elements, N is the one most often applied to forages, mostly grasses. N is the growth element that helps grasses produce rapid, vegetative growth under favorable growing conditions: water, sunlight, and correct temperatures for species. Grasses take up most of their N in the nitrate form, which is quickly converted in the plant tissue to protein. When poor growing conditions such as cool, cloudy weather or drought occur, grass growth is slowed; while this reduces protein production, it does not reduce nitrate uptake if soil supply is high. This can lead to the risk of levels toxic to livestock. Usually the forage will need to contain at least 0.15 percent nitrate nitrogen dry matter (DM) basis.

The amount of N applied will depend on the target yield, not on a soil test, as this is not commonly a part of soil test recommendations. Generally, warm season grasses produce more forage per pound of N applied than cool season grasses do. A good rule of thumb for increased yield is that 1 pound N adds 20-30 pounds of DM for cool season grasses, and 30-50 pounds for warm season grasses. Expect this increased growth period to last 4-6 weeks following application. Weather can cause this to change, especially when too dry or too wet!

In Mississippi soils, phosphorus (P) is generally low unless it has been applied previously as fertilizer. P does not very readily leach from the soil profile; in grazing situations, P can be easily maintained or even accumulate. P could be more of a problem

from surface runoff creating surface water quality problems. Much of that ingested by cattle is recycled back into the soil in the manure.

Potassium (K) is needed in much larger amounts by forages-in fact, in amounts nearly equal to N. Adequate K is needed to maintain vigor and winter hardiness in forage plants. K can also be quite mobile in the soil profile, so it does not generally build up over time. K needs to be replaced at the rate of 30 - 40 pounds per acre per ton of hay removed.

Forages need other elements, also. These elements are needed in lesser amounts and are rarely limiting with proper soil pH: calcium (Ca), magnesium (Mg) and sulfur (S). On very sandy soils with low organic matter, S will probably need to be added, especially for winter annuals. If soil pH is below 5.5, all forages will generally benefit from the application of lime. Where legumes such as alfalfa or clovers are to be grown, a pH of 6.0 or higher should be maintained. For assistance with a balanced pasture fertility program, contact your local county agent.

 

RICE

Dr. Joe Street

This rice crop is almost harvested and it appears that it will be record year for yield. USDA has predicted yields at 140 bushels per acre; although it is too early to be certain, that prediction may be a little low. With so much of the rice stored on the farm, it is difficult to get exact numbers; based on comments from several growers who have weighed their crop, many growers are averaging 150 to 160 bushels per acre and some higher than that. Some growers are reporting yields of over 200 bushels per acre with the XL6 hybrid. Favorable weather conditions for rice growth and development during the growing season plus the shift to higher yielding varieties resulted in exceptional yields in many cases. Even with the rains of late August, quality is still holding and will probably be above average for head rice although total milling yield may be a little low in some cases. Although the stinkbug population was one of the highest in recent memory, control measures were effective, and stinkbug damage is not as great as had been expected. Except for a few situations of downed rice, this appears to be a good year overall for rice production.

According to my unofficial survey, acreage is 253,000, very close to the USDA estimate of 250,000 acres. There was a tremendous shift to the newer high-yielding varieties. The primary varieties planted were Cocodrie (40%), Lemont (29%), Priscilla (20%) and Wells (4%). Clearfield rice and XL6 were planted on limited acreage. .

With record yields and limited markets for rice, much of the rice will continue to be stored on the farm. Do not peak grain in the bins, or aeration will be uneven. Air flows through the area of least resistance; therefore the peak will not get adequate aeration and will start heating from respiration. Avoid placing rice in the bin above the level of the flighting of the stirral. After drying to 12 to 12.5 percent moisture, and after the moisture has been stabilized for 7 to 10 days, cool rice to 45 to 50 %F at 40 to 60 percent relative humidity. This tempers rice and will generally increase whole milling yield by up to 2 percent. The cooling also conditions rice for winter cold temperatures and retards insect eggs from hatching. Once the rice is cooled to 45 to 50 %F, check the temperature every two weeks in the center of the bins and under vents.

After November, do not add high heat for drying. This will cause the bins to sweat if heated during the day and moisture will migrate to the center of the bin surface. During winter storage, grain temperature is as important if not more important than moisture. If you cannot get the rice cooled properly, a fumigant may be needed to control the insects. After a heavy rain, windstorm or snow, check the bins for leaks.

 

CORN

Dr. Erick Larson

Addressing Fertility Problems - Fall is the best time of year to address many fertility problems. Soil acidity is a perennial problem due to our warm, rainy climate. Applying and incorporating lime during the fall allows pH neutralization before crop growth begins. This will also improve nutrient availability. The increasing use of corn in crop rotations has also contributed to phosphorus and potassium deficiencies. Phosphorus (P) deficiency is especially prevalent when corn is grown following a rice crop, because the absence of a flood reverts soluble ferrous phosphates to unavailable ferric phosphates. Considerable phosphorus application is required to overcome this phenomenon. Phosphorus deficiency also often occurs following cotton or soybeans, because corn requires twice as much P as cotton or soybeans. Potassium (K) deficiency often occurs following a high-yielding soybean crop, since soybeans remove twice as much potassium from the soil as a cotton crop. Yearly soil testing for corn will provide a phosphorus recommendation which will prevent these problems. Take soil samples this fall, so that incorporation and neutralization of lime and broadcast fertilizer may occur before next spring. However, delay application of potassium on low CEC soils until spring because of leaching problems.

Fall Weed Control - Fall is the best time to reduce populations of some tough perennial weeds, including Johnsongrass and Bermudagrass. These perennial weeds are most susceptible to chemical application at this time of year, because they are storing energy in their rhizomes in preparation for winter. A translocated herbicide, such as Roundup or Touchdown, will be drawn into the rhizomes and have a higher likelihood of killing these reproductive organs. Chemical applications should be made when weeds are actively growing and at least two weeks before the normal first frost date. Tillage or stalk shredding should not be done after harvest, unless Johnsongrass has time to regrow to the boot stage. Successive tillage after chemical application should preferably be delayed 4-6 weeks.

 

WHEAT

Dr. Erick Larson

Don't Plant Wheat Early: Planting too early unnecessarily exposes wheat to potential development, fertility and numerous pest problems which ultimately reduce yield potential. The purpose of the wheat planting date is to establish a stand and begin tillering activity before cold winter temperatures cause dormancy. Wheat plants are most tolerant of freezing temperatures during tillering growth stages. However, early-planted wheat may proceed past the tillering stages before winter induces dormancy, particularly during a warm season. This usually causes winter or spring freeze damage and nitrogen deficiency related to excessive fall development. Early planting also promotes infestation of insects and disease infection. Lush vegetative development encourages fall infestation of aphids, Hessian fly and Fall armyworm. Aphids serve as a vector for Barley yellow dwarf, a disease that stunts wheat development and may cause substantial yield reduction, particularly from fall infection. Fall infestations of both Hessian fly and Fall armyworms may destroy stands. Hessian fly also cause broken stems and lodging in the spring.

Optimum Planting Dates: The suggested wheat planting dates (within 10-14 days of the average first frost date in the fall) should provide warm enough temperatures and long enough days for seedling emergence and tillering to begin before dormancy occurs. This normally corresponds to:

North and Central Mississippi: October 15 - November 10
Delta Region: October 20 - November 15
South Mississippi: November 1 - November 25
Coastal Region: November 15 - December 10

Seeding Rates: Producers should try to establish 1.0 to 1.3 million plants per acre or 23 to 30 plants per square foot. Assuming 85 percent successful emergence planting with a grain drill, you will need a seeding rate of 1.2 to 1.5 million seeds per acre. Using the number of seeds per pound listed on the seed tag, you can then calculate how many pounds of seed per acre are needed. For example, 1.35 million seeds per acre divided by 13,500 seeds per pound is 100 pounds of seed per acre. This seeding rate is equivalent to 18 seeds per foot with a seven inch drill spacing. If planting with a drill is not feasible, assume about 70 percent emergence with broadcast seeding, combined with mechanical incorporation, or 55 percent emergence with aerial or broadcast seeding.

 

SOYBEANS

Dr. Alan Blaine

Harvest of this years' crop is rapidly coming to a close. What started out as possibly the best crop ever grown in Mississippi deteriorated very quickly.

The problem was devastating and widespread, and was identified as phomopsis. Like Aflatoxin, phomopsis is present in the field; however, due to the extended wet conditions, it reached damaging levels never before observed. Some fields went from irrigation termination to unharvestable in less than 2 weeks.

Mississippi producers planted the highest percentage of Group IV's (approximately 60%) ever, and the earliest-planted crop ever. Regardless of what you may be hearing or thinking, this problem was not a Group IV problem or an early planting problem. Phomopsis did affect Group IV's primarily, but only those that were mature or approaching maturity when the overcast/extended wet conditions hit.

Normally, August is one of the driest months of the year; even when rains do come, the sun usually comes out quite soon afterward. Weather conditions experienced this August have not occurred since 1957. What many have failed to recognize is that we experienced the effects of an extended hurricane with no wind. These conditions did not occur just in MS, but in the neighboring states of Texas, Louisiana, and Arkansas, as well.

From about mid-August to shortly after Labor Day, we experienced cloudy, overcast conditions, heavy dews, thick fogs and (particularly south of Highway 6) several inches of rain. Although the amount of rainfall was a major factor, the phomopsis problem was also seen in areas where rainfall amounts were minimal.

A large number of acres planted in Group III's and early-planted Group IV's harvested before mid-August were unaffected by phomopsis. Problems also occurred in cotton, grain sorghum, rice, corn, and some vegetables.

One reason a large percentage of our crop was exposed to the phomopsis problem was that conditions conducive to the problem lasted for about 2 l/2 to 3 weeks. When the first wet spell occurred, the problem was worse on several varieties, especially those gray in color. After the next wet spell, many other varieties succumbed to the problem.

Early varieties that were hardest hit were: Delta King 4868, DPL 4690 and DPL 3478. Producers have observed problems with many more varieties, but these were some hit the earliest.

In most cases, location and the stage of maturity (more than variety) determined the effect of phomopsis.

Knowing this is no consolation regarding this year's crop.

Some of the comments we are hearing around the state:

  • "I am not going to plant any more Group IV's."
  • "I am not going to plant early ever again."
  • "Due to all these late seasons weeds, I am never going to plant Roundup Ready soybeans without a pre-emerge again."
  • "I am not going to plant Roundup ready soybeans anymore."

Proceed cautiously as you make plans for next year and beyond. Certainly you should reevaluate your individual situation, but do not make any major changes based on just one year's information/resource

We specialists are attempting to gather as much information as possible to address your concerns. Over the next couple of months, you can expect a discussion of what we have observed, and what we have learned from this year's crop.

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

 Will McCarty, Ph.D.
Extension Leader

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