Agronomy Notes

November 8, 2000
agronomy notes

Contents

SOYBEANS

Dr. Alan Blaine

This year turned out to be the worst year ever for many soybean growers, as drought conditions caused problems statewide. Since much of the soybean crop is grown in a dryland setting, growers must continue to carefully consider variety selection, the use of early maturing varieties, and planting dates.

Variety selection. This year has proven how unpredictable a growing season can be. Varietal differences are observed every year, but quite a few varieties showed their ability to withstand adverse conditions this year. Many varieties that looked good last year proved failures this season. This emphasizes the need for a yield history, preferably at least two years of yield data, before planting a large acreage in new varieties.

Early maturing varieties. Due to the earliness of the past couple of growing seasons, we will see an increase in early maturing varieties. Some interest is being expressed in Group III's, but the bulk of the plantings to early maturing varieties should be in IV's. From a dryland standpoint, Group IV's offer a greater potential to increase yields than any of the later maturity groups.

If we could predict the weather, we would know exactly what and when to plant. Since this cannot be accomplished, Group IV's allow us the opportunity to increase yields by setting pods during a time frame more conducive for fruit set. For the 2000 soybean crop, pod set was as good as farmers have experienced. However, there was not enough moisture to fill them out after pod set.

Another consideration is the use of Roundup Ready varieties. As a whole, when growing conditions become extreme, the Roundup Ready varieties seem to be more greatly affected. While the Roundup Ready option is an excellent technology, especially dryland, growers need to do their homework regarding varietal performance prior to planting.

Many producers would be better off planting a proven variety like Hutcheson rather than take chances with a new variety. If you do plant new varieties, do not plant more than 5 to 10 percent of your acreage in any variety with less than two years of state yield data. This may seem slightly extreme, but your entire crop depends on the variety you plant. This is a decision you will live with all year and one that should not be made lightly. Roundup Ready varieties are getting better, but few of them have the yield history needed to put all your acreage in them.

With more than 250 varieties available for sale, variety selection is a monumental task. The 2000 growing season was quite extreme, but several varieties consistently performed in the top 10 to15 percent. These are the varieties growers should plant on the bulk of their soybean acreage.

Planting dates. One input over which growers have less control is planting dates. Early planting should be a goal of every soybean producer in this state. Although farmers grow other crops, in order to make soybeans profitable, they must plant soybeans as early as possible. Unless you are double cropping or planting behind flood waters, soybeans growers should have a goal of planting soybeans before you start planting cotton. While growers need to spread their risks with maturity groups, not enough growers are taking advantage of the option of early planting.

After this past season, we can look for three things to take place: Roundup Ready acreage, Group IV plantings, and the percentage of acreage planted early will all increase. All of these options are good, but we will still need to do some advance planning regarding how to make these things work. Preliminary yield information (Group IV's and V's) are currently available. If you would like a copy, please contact your county extension office.

CORN

Dr. Erick Larson

Crop Rotation. Low commodity prices have producers searching for a magical market. While a few may be lucky enough to find such a market, there is one method anybody can use to increase profitability: crop rotation. The reason is simple; crop rotation significantly increases productivity of all your crops in the long run. Reports consistently indicate 10 to 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, such as the late season drought (on cotton and soybeans) this year.

How long should I 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 substantially rise the longer corn is grown continuously. This reduces potential gross return, while substantially increasing potential risk and/or input costs. Therefore, farmers should not grow corn in the same field for more than two years.

Fall Corn borer control. Fall tillage can greatly reduce survivability of overwintering corn borers. Fall discing shreds stalk tissue and (most importantly) may dislodge, tear up and expose the crown area of the stalk. The crown is the primary overwintering area in the stalk for the southwestern corn borer. Operations which do not disturb this area, such as stalk shredding, subsoiling and rowing up, will not significantly reduce overwintering survivability. Stalk shredding may be effective against European corn borers, since they overwinter higher up the stalk, but this species is not as prevalent as the Southwestern corn borer, except in some extreme northern counties.

WHEAT

Dr. Erick Larson

Late Planting. Dry seedbed conditions may be delaying wheat planting and emergence in many areas. The optimum wheat planting dates extend to November 10 for North MS, November 15 for the Delta, November 25 for South MS, and December 10 for coastal regions. Wheat planting delayed 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). However, the relatively warm winter conditions common in the south usually permit emergence and sufficient tillering for even late-planted wheat. Producers can readily compensate for these problems by increasing seeding rate and planting varieties with a relatively short vernalization requirement. Fall application of 20 to 30 pounds of nitrogen will also stimulate tillering.

RICE

Dr. Joe Street

The 2000 rice acreage was down about 30 percent from 1999. The USDA's estimated 218,000 acres is close to my unofficial county survey. Much of the acreage shifted to cotton because of the profit potential with the insurance program. The remaining acreage was shifted to soybeans. In general, yields look good and are better than 1999. The initial estimated yields of 5,800 pounds per acre were increased to 6,050. Since much of the Mississippi rice is stored on the farm, it is too early to know the exact yields. Although growers will seldom say they are happy with yields, most are not unhappy with their 2000 yields. Although daytime temperatures were high, nighttime temperatures were not as high as 1999, and yields were not adversely affected. It appeared early in the season that diseases were going to be a problem. However, the very high temperatures and low humidity seemed to stop sheathblight, and it was not as severe as expected. With only a few exceptions, neither kernel smut nor false smut was a problem. One of the primary problems influencing quality was stinkbugs. This was the worst year in recent memory for stinkbug infestation, and pecky rice is higher than normal. Milling yields are average to below average, but the initial milling yields look better than 1999.

The primary variety grown was Lemont on 60 percent of the acreage with Priscilla on 27 percent and Cypress on 5 percent. Cocodrie was grown on 4 percent of the acreage with a limited acreage of Wells, Jefferson, and XL6. Yields from all the new varieties were very good.

If commodity prices remain steady, there will probably be a 15 to 20 percent increase in rice acreage in 2001.

SOIL TESTING

Dr. Keith Crouse

Soil testing is the basis of a sound soil fertility program. Therefore, a fertilizer recommendation is only as good as the soil sample submitted. Remember that you should always take the soil sample from a uniform area, usually about 10 acres or less in size. Take enough separate cores within the soil area for a representative soil sample. Generally, this is about 15 to 20 cores. Take your soil cores from the surface to plow layer. Mix your soil cores thoroughly. Send a full soil box or a pint of soil for analysis. If soil results indicate low soil pH and fertility, you can make corrections this fall by following recommendations of your soil analysis.

For most crops, lime should be incorporated into the top 5 to 6 inches of the soil, preferably at least three months before planting. MSU-ES Soil Testing Laboratory's lime recommendations assume that limestone being used has a calcium carbonate equivalent (CCE) of 100 percent. Remember that Mississippi has two limestone grades, A and B; the grade of limestone used determines the amount of lime needed.

NUTRIENT AND SOIL MANAGEMENT

Dr. Larry Oldham

There is a difference between soil testing and making fertilizer recommendations. Soil testing estimates the level of nutrients in a soil which will be plant-available over the course of a growing season. Fertilizer recommendations are based on interpretations of the soil test results.

Basic philosophies behind the recommendation process include the sufficiency philosophy, the maintenance method philosophy, and the cation nutrient balance philosophy. In today's difficult economic circumstances, producers should verify the philosophy behind recommendations based on soil testing programs. Then the manager should develop an economically feasible and defendable nutrient management program.

The sufficiency philosophy is based on crop response and used by most land grant universities. The expected plant growth response at various soil test levels determines the fertilizer application recommendation.

Another widely used philosophy is the maintenance method. The nutrients removed at harvest are replaced on soils that test medium or high in phosphate and potash.

Cation nutrient balance is used by some for fertility recommendations based on the theory that some correct nutrient balance exists that will result in maximum crop response. There is a fine line between this philosophy and another aspect of soil fertility and plant nutrition. This balance is not the same as attaining the famous "Law of the Minimum," which holds that growth will increase until some input is insufficient to continue further growth.

The long-term, unbiased research base for attaining ideal cation balance ratios is sketchy at best. The maintenance philosophy is intuitively attractive, and has been shown to effectively store nutrients in soils. The sufficiency philosophy is based on extensive, laborious research using a wide variety of crops and soils.

Recent research shows that all approaches can lead to excellent crop yields in good weather conditions. However, there were very large differences in the costs of the recommended fertilizers. Nutrients applied according to the sufficiency philosophy cost less and produced the same yields as the more expensive recommendations based on the other systems.

Verify the philosophy behind the recommendations based on the soil testing program. Then develop an economically feasible and defendable nutrient management program.

FORAGES AND PASTURES

Dr. Malcolm Broome

Hay Quality Relates to Animal Performance. Hay is the most widely grown, mechanically harvested agronomic crop in the United States, but hay quality is not uniform. Quality hay will have a high percentage of total digestible nutrients (TDN), protein and leaf-to-stem ratio with a low percentage of fiber. Quality hay for beef cattle is vitally important as production inputs continue to increase. However, storage and feeding losses can greatly reduce hay quality. On many farms, these losses can add 10 percent to the cost of cattle production.

In Mississippi, most hay is now baled in round bales and stored outside, allowing moisture to play a major role in dry matter losses. Since hay quality is determined when the forage is cut, proper storage and feeding is necessary to maintain as much of this quality as possible. At safe moisture levels (18 percent or less) most fungi and bacteria cause little damage, but when hay is stored outside, weathering causes leaching of nutrients. The outer circumference of the bale is primarily affected, so package size (diameter) contributes to the extent of losses. Research by D. R. Buckmaster (1993) at Penn State University found that a bale 3 feet in diameter with spoilage to a depth of 5 inches has 50 percent dry matter loss, but a six-foot bale has 25 percent, only half as much. Spoilage at this level can be expected in Mississippi, as research has shown. This has important implications on purchasing a baler, if hay must be stored outside.

The bale storage area should be well-drained, such as the top of a sloping area adjacent to where the hay will be fed, with the bales positioned up and down the slope. Ideal areas would have a north/south orientation and a southern exposure. The flat ends of bales can be butted together but the round sides should not touch unless the hay is to be covered with plastic or tarp. The bale itself should form a thatch that will (initially) help shed the rain; bale density, type of forage, and weeds present in the bale can reduce this process. Water can easily penetrate the tops of round bales of summer annual (millet, sorghums) and small grain (oats) hay stored outside. The importance of thatch is evident if you realize a 6 foot by 6 foot roll of hay can absorb 22 gallons of water from an inch of rain.

The other factor affecting hay loss on most farms is outside feeding; these losses can be as large as storage losses. Outside feeding losses include trampling, loss of leaves, weather deterioration and fecal contamination resulting in animal refusal. Research has shown these losses can be as high as 60 percent where no attempts are made to minimize loss. Most round bale hay is fed on the sod in a pasture; with thoughtful planning, producers can keep these losses at less than 10 percent.

If no racks or rings are used, producers can reduce waste by feeding on the basis of one cow for each foot of outside circumference of the bale, and putting out only a one day supply. The average cow will eat 18 to 20 pounds of hay per day. Obviously, this method will increase labor costs. When using racks or rings, select a feeding area that will provide as much drainage away from the site as possible, and put out no more hay than can be consumed in three or four days. Moving these feeding sites will help spread manure more uniformly across the pasture and reduce the severity of sod damage. Producers should try to use a feeding method that will minimize hay quality losses and sod damage, without increasing labor costs too much.

High quality hay is leafy, has been cut at the correct stage of growth, smells good, and is free of weedy material or toxic factors (mold). Hay quality is best determined by laboratory analysis, and should be matched to animal needs. The highest quality hay might be fed to young calves, yearlings, bred heifers and lactating cows. The lower quality could be fed to mature, dry cows and bulls when not in the breeding season. With hay supplies short this winter, feeding hay properly can mean better animal performance and economic returns.

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