Agronomy Notes

November, 2001

Contents:

FORAGES AND PASTURES
COTTON
CORN
WHEAT
CERTIFIED CROP ADVISER NEWS

 

FORAGES AND PASTURES

Bahiagrass, Curse or Blessing

Dr. Malcolm Broome

Bahiagrass (Paspalum notatum Flugge) is a warm-season perennial grass grown on more than one million acres in Mississippi. Most of this acreage is in central and south Mississippi and is used for grazing with some hay harvested from pasture. Bahiagrass is ideally adapted to the droughty, sandy soils of the lower Coastal Plain. It will produce good grazing on the upper coastal Plain soils, except in extreme north Mississippi where the temperatures are low in winter.

Bahiagrass forms a deep, extensive root system in which few other plants are able to encroach after a sod had developed. It tolerates a wider range of soil conditions than other grasses, will produce moderate yields under low fertility, and it withstands close grazing. It is planted from seed and it is also a heavy seed producer that begins putting up seed heads in early summer. In fact, it is often spread by cattle grazing the heads and carrying the seed to new pastures where it will germinate after passing through the cattle in the manure.

There are nine types of bahiagrass with eight named cultivars that are planted across the South. "Pensacola" is the most widely grown cultivar in Mississippi. It was found growing near Pensacola, Florida, in 1935 by Escambia County Extension Agent Ed Finlayson. It has long, narrow leaves and taller seed culms (stem) than other cultivars. Its persistence, ability to grow on poor soils, and excellent seed production have caused it to be more widely planted than others.

Tifton 9' bahiagrass, a larger growing selection of Pensacola was developed by Glenn Burton at the Coastal Plain Experiment Station, Tifton, Georgia, and was released in March 1987. It is reported to have similar digestibility, but stronger seedling vigor than Pensacola and develops longer leaves. Although the quality is about equal, Tifton 9's yield is about 30 percent higher than that of Pensacola.

Argentine is a broadleaf variety introduced in 1944 from Argentina, with seeding and spreading characteristics similar to Pensacola, although Argentine usually puts up fewer seed heads. Argentine is better adapted to the fairly well-drained soils that maintain good moisture during the summer; of all the cultivars, Argentine is highest in quality. It is easily damaged by hard freezes and doesn't begin growth as early in the spring as others do.

The other cultivars, Paraguay and Paraguay 22', Tifhi-1 and Tifhi- 2', and Wilmington are not recommended for Mississippi because of their productivity and seed difficulties.

The best seeding dates for bahiagrass are February 1 to June 1. The earlier you seed in the spring the better your chance for getting a sod the first year. Newly seeded bahiagrass fields must be protected from overgrazing and should be allowed to produce seed the first year. It usually takes one growing season for a good sod to develop. Fifteen pounds of seed per acre will produce a good sod by the second growing season; if you plan to allow the grass to reseed the first year, use a seeding rate of 30 pounds per acre.

Bahiagrass should be planted into warm soil on a well-prepared, firm seedbed and covered about 2 inches deep. The optimum temperature range for seed germination is 85 to 95º F. Seed should be broadcast at 15 to 20 pounds per acre, but a higher rate of up to 30 pounds will result in a quicker establishment. Where land to be established in bahiagrass is prepared in the fall, the seeds can be planted with a winter annual, such as ryegrass but the higher seeding rate should be used and the ryegrass gotten off the pasture by late April. The seedlings are not very competitive with weeds. Therefore, weed control is very important during the first months in the life of a new Bahiagrass pasture. Do not graze for about 3 months or until the stand has covered the bare soil.

Lime the soil to a pH of 5.8, and you may not need to apply lime again for several years. For new plantings, apply 30 pounds of nitrogen(N) per acre, all of the phosphate, and half of the potassium recommended by the soil test as soon as the plants have emerged. If a good stand is present after 30 to 45 days, put out the remaining potassium and 60 pounds of N. With normal rainfall, use about 1 pound of actual nitrogen for each day of active growth which should be from May through August. You can apply up to 200 pounds of N per acre annually if you graze or harvest the forage as hay. Apply 60 pounds of N after each cutting and plan to get at least four cuttings, with five possible most years south of Highway 84. Apply extra nitrogen only to produce forage that can be used for grazing or hay. If nitrogen is to be applied only one time during the season, an April or May application will give the best results; under this type of management, a pH of 5.5 is sufficient. Where phosphate and potash are needed, you can apply a complete fertilizer mixture, such as 13-13-13 or equivalent, at the rate of 400 to 600 pounds per acre for the spring fertilization.

Bahiagrass must be closely grazed or clipped to keep it tender and succulent for good quality. When properly fertilized, this grass will tolerate close grazing without damage. When bahiagrass has grown 10 to 12 inches tall, it produces little new growth and the longer it stands, the lower its quality drops. Harvest for hay or grazing about every 30 - 35 days to maintain forage quality. When Pensacola bahiagrass is adequately fertilized and harvested at least three and four times per year, it will produce up to 5 tons of hay per acre with average rainfall. Each ton of hay removes about 30 pounds K2O (potash) per acre. Inadequate potash application will result in low hay yields, especially if hay is harvested from the same pasture for several years.

High stocking rates and rotational grazing are required for best utilization of bahiagrass. A grazing pressure of three to five cows per acre on a 10- to 14-day rotation is suggested for high-quality grazing. After each grazing, clip the tall uneven areas to allow uniform regrowth and scatter the manure piles as needed to encourage uniform grazing.

On old grass sods where the soil is compacted, it helps to renovate or subsoil when the soil is dry to break the compaction layer. Response is similar to a fertilizer application. Renovate on the contour. Using either some single-shank subsoiler or spring-tine harrow is preferred to a chisel plow, since the chisel plow tears up the sod and requires diking to level the field making the erosion potential much higher on most pastures. This renovation works well where ryegrass and clover are being overseeded. Refer to Extension Information Sheet 829 Overseeding and Sodseeding Permanent Summer Pastures for more information. Clovers may be overseeded on bahiagrass pastures alone or in combination with ryegrass.

Bahiagrass has a unique trait of accumulating nutrients in its stolons. There is some evidence that the stolons in a mature stand of well-fertilized bahiagrass may contain a 2 to 3 year reserve of nutrients. The quality of bahiagrass is adequate for mature beef cattle, but weaned calves or stockers make relatively low gains, especially in late summer due to grass quality at that time. Within any season, the older the grass the lower the protein and digestibility. However, for its cost of establishment and stand persistence, bahiagrass is a forage grass worth having when managed properly.

COTTON

Dr. Will McCarty

The 2001 cotton production season is just about history. This was a very "different" year for Mississippi cotton growers. Weather cooperated better than in several years and some of the state's cotton produced very good yields. However, some did not. Probably the biggest concern with the 2001 crop is quality. As of October 15, the 2001 crop had an average length of 32.2 with 24.7% of the bales having a length less than 34. Strength was averaging 27.2. Micronaire is the big news; the average mike was 49 with 47.6% being 50 and greater. This was a very high mike and short staple crop. Was it weather? Was it variety? Was it management? More likely, it was a combination of factors, but variety played a big part.

The quality of this year's crop and many other topics will be discussed at the Cotton Production Short Course, December 5-7, 2001. Contact your local Extension office for more information.

Variety Selection: Variety selection is one of the most important business decisions cotton growers make. The long standing and ongoing position of the MSU Extension Service is to extend variety trial research results, coupled with direct professional experience, to allow crop producers to make their own informed variety selection decisions.

General guidelines for variety-related recommendations by MSU-ES scientists are these:

1) to recommend that crop producers combine MAFES variety trial information with on-farm personal experience to select varieties that will perform well on their farms

2) to recommend that crop producers try new varieties only on a very limited acreage 3) to recommend that crop producers plant the bulk of their commercial acreage in proven performers

4) to recommend that growers evaluate fiber quality as well as yield

5) to recommend that crop producers critically evaluate the need for value-added traits in transgenic varieties.

Fall Jobs - Cut stalks as soon after harvest as is possible. This will help in boll weevil control efforts. Sandy soils should be subsoiled when compaction problems are shallow enough to shatter and soils are dry enough. Avoid tillage operations on wet soils. Leave subsoiled fields rough until spring.

Alternate Practices for "Clayey" Soils - Heavy-textured soils offer several options. Consider some form of reduced tillage or stable seedbed system. Heavy soils are excellent candidates for fall tillage. Fall hipping, and planting on a stale row after a burn-down program in the spring, is a good option. For heavy-textured soils, planting on a stale seedbed may mean the difference in planting on time in late April/early May, planting in June, or not planting at all. Controlled traffic, confining all traffic to a particular pattern, is a very good tillage alternative, can reduce tillage trips, improve soil tilth, and increase profits.

Monitor Soil Fertility Levels - Fall is an excellent time to test soil. Cotton is an intensely managed crop and requires high levels of fertility to produce acceptable yields. While cotton farmers generally practice good soil fertility programs, there is still a lag in soil fertility levels. If pH levels are low and soil test recommends lime, it is critical that it be applied. If pH levels are low, applied nutrients such as nitrogen, potassium-especially phosphorous-will not be as effective.

Low Soil pH = Low Yields - Fall is the preferred time to apply lime; fall is also an acceptable time to apply mixed fertilizers to soils with a CEC of greater than 7. On soils with a CEC of less than 7, leaching of fall-applied fertilizer may be a concern.

Growing cotton in low pH soils can lead to root growth problems, nutrient deficiencies, and/or toxicities. Liming acid soils will improve plant growth and significantly increase the efficiency of applied fertilizer nutrients. In fact, if pH levels are in the low 5's or high 4's, applying fertilizer nutrients may be almost a waste of money. If lime is required, it should take precedence in a fertility program.

Selecting lime material is also important. When selecting lime materials, be sure they meet the requirements for Grade A as set by the state's lime law; this law, which is for your protection, regulates the quality of material that can be sold as agricultural lime. Particle size and calcium carbonate equivalent (CCE) are the major considerations, and of these two, particle size is perhaps the more important. The larger the particle size, the slower the material will react and the poorer the quality of the material.

Be careful as you select materials. Pelletized lime and/or liquid lime materials can be good sources, but consider the CCE and quantity of application. If the recommendations call for l ton per acre of a 90-percent CCE material, applying 500 pounds per acre of a 95-percent CCE material will not meet the requirements. Always consider the CCE of the material you select.

Nematodes: Populations of nematodes, especially Reniform, have been going up each year. If you have not had your soil sampled for nematodes, you should-especially if growth and yields have been erratic in fields or parts of fields. Using nematicides and/or rotating with corn/grain sorghum have proven to provide significant yield increases in Reniform infested fields. However, infestations must first be detected before any control strategies can be implemented.

CORN

Dr. Erick Larson

Crop Rotation - Low commodity prices have producers searching for magical marketing opportunities. While a few may be lucky enough to find such an opportunity, one method that anybody can use to increase profitability is crop rotation. The reason is simple: crop rotation significantly increases productivity of all crops in the long run. Reports consistently indicate 10-20 percent yield advantages for cotton or soybeans grown in rotation with corn on Mississippi farms. Crop rotations normally improve yields because many weed, insect, nematode and disease problems build up when using the same management program every year in continuous cropping. Crop rotation systems effectively disrupt many of these cumulative effects, preventing problems and reducing input costs. Crop rotation allows the producer to attack the predominant weed problems by altering tillage systems, changing herbicide chemistry, and disrupting weed life cycles. Corn rotations can also improve soil physical structure by recycling more organic matter and changing from a taprooted crop to a fibrous root system. Numerous other beneficial effects of rotation have been reported, including improvements in soil fertility, soil moisture, soil microbes, and phytotoxic compounds and/or growth promoting substances originating from crop residues. Growers can maintain these benefits by continuing to rotate crops on a yearly basis. A crop rotation system also spreads risk in case of unpredictable problems.

How long should you grow corn? - The rotational benefits described above generally diminish every year after the first year in a rotation system. Additional yield, soil improvements, weed control, and nematode benefits are sometimes realized by a two-year rotation, particularly if the field has been continuously cropped for a long time. However, yields will gradually decline, and pest problems will rise substantially, the longer corn is grown continuously. This reduces potential gross return, while substantially increasing potential risk and/or input costs. You should not grow corn in the same field for more than two consecutive years.

WHEAT

Dr. Erick Larson

Late Planting - The optimum wheat planting dates extend to Nov. 10 for North Mississippi; Nov. 15 for the Delta; Nov. 25 for South MS; and Dec. 10 for coastal regions. Delaying planting past the optimum dates is not as likely to reduce yield potential as with summer row crops, particularly in the south. Yield potential can be reduced if tillering suffers or wheat fails to vernalize (failure to experience sufficient cold temperature to trigger head development the following spring). Producers can compensate for these problems by increasing seeding rate and planting varieties with a relatively short vernalization requirement. Fall application of 20-30 pounds of nitrogen will also stimulate tillering.

CERTIFIED CROP ADVISER NEWS

Dr. Larry Oldham

The Agronomic Professional Continuing Education Workshop will be February 11-13, 2001 in the Bost Extension Building on the campus of Mississippi State University. The last day (February 13) will be a joint meeting with the Mississippi Chapter of the American Society of Agronomy.

The Conference website is http://www.msucares.com/crops/workshop/. Look at the tentative agenda on the website to see what best fits your needs and interests.

 

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

Will McCarty, Ph.D.
Extension Leader

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