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ISSUE 16  AUGUST 26, 1999

 

ESTIMATE CORN YIELDS IN YOUR FIELDS

    With silking finished on corn that is progressing in a timely fashion in order to mature before the average frost date, estimates of the relative grain yield can be done. First, count the number of harvestable ears per 1/1000th of an acre. With 30-inch rows that is a row length of 17 feet, 5 inches and with 22-inch rows count the number of ears down 23 feet, 9 inches of a row to determine the estimate. Within this ear count area, also count the number of kernel rows on the ears of every fifth plant. Also, count the number of kernels per row on these same ears. Remember to only count kernels that are developing well (do not
count kernels on the tip that are less than half the size of those mid-way up the ear). Average the total number of ear rows counted within the area, then separately average the total number of kernels per row within the area. If possible, move to various areas of the field and repeat the above estimations and average your findings. Next use the following formula to determine yield:

    (avg ear#) x (avg row #) x (avg kernel #)   

= bu / acre

90

    Remember, this estimate of relative grain yield will be underestimated in a year with good grain fill conditions.


ESTIMATE SOYBEAN YIELDS PRIOR TO HARVEST

    Soybean yields can be estimated before harvest. Yield estimates on this crop are most accurate within weeks of maturity, namely within no more than three weeks prior to harvest. However, check your fields to determine how the crop is progressing up through harvest.

    First, find the number of feet of row needed to make 1/1000 of an acre. For 30" rows this would be 17' 5"; for 28" rows this would be 18' 8"; for 20" rows this would be 26' 2"; for 15" rows this would be 34' 10"; and, for 10" rows this would be 52' 3" for the length of a single row equal to 1/1000 of an acre.

    Second, find out the plant population. Count the number of plants in 10 randomly selected sample areas and average. Multiply this average by 1000.

    Third, run a pod per plant count. Count the number of pods per plant on 10 randomly selected plants from each sample area and average.

    Fourth, find the pods per acre. Take the result from your plant population (step 2) and multiple it times your result on pods per plant (step 3).

    Fifth, find the number of seeds per acre. Take your pods per acre result (step 4) and multiply it times 2.5 seeds per pod (an estimate).

    Sixth, find the estimated pounds per acre. Take your seeds per acre (step 5) and divide by 2,500 seeds per pound. (This is an estimate on seed size. For a better estimate use the seeds per pound listed on the tag from the seed planted.)

    Seven, estimate yield. Use the result from your pounds per acre (step 6) divided by 60 (pounds per bushel) to estimate your yield in bushels per acre.

Denise A. McWilliams
Extension Crop Production Specialist
dmcwilli@ndsuext.nodak.edu

 

WINTER WHEAT PRODUCTION TIPS

    Winter wheat has the potential to be a highly productive crop in North Dakota. Advantages of winter wheat include; more efficient labor and machinery use, reduced weed problems particularly wild oat, and often a higher yield potential. Winter survival is a limitation to winter wheat in North Dakota.

    Earlier crop development helps in avoiding some disease and insect pressure. Winter wheat is no more resistant to scab than spring wheat, however, with a three week developmental advantage it may avoid late infection periods that will affect spring wheat. Orange wheat blossom midge only lay eggs in developing heads between head emergence and flowering. Flowering in winter wheat is complete before the midge emerge effectively avoiding the pest.

    Well-established winter wheat is more competitive with summer annual weeds than spring cereal grains, resulting in less dependence on chemical weed control. A healthy stand of winter wheat has good ground cover which shades the soil and acts as a strong competitive force against weed growth. Wild oats is rarely a problem in vigorous winter wheat fields.

    Planting and fertilizing the crop in the fall lightens spring planting work loads. Since winter wheat will be ready for harvest two to three weeks before spring wheat the harvest work load is also spread out. Spreading out planting and harvest provide more efficient use of machinery.

    Winter survival - Winter survival is the most critical factor in successfully producing a winter wheat crop in the Northern Plains. Cultural practices that help ensure winter survival are those that provide snow cover to maintain warmer soil temperatures in the crown area, just above the plant's root system. NDSU research indicates that 3 inches of snow cover will prevent winter kill due to low temperatures. While three inches of snow is sufficient protection during most of our winters, 4 to 6 inches will further reduce the extent of crown injury and increase stand survival.

    Several methods can be used to enhance snow cover. Winter wheat can be no-till seeded directly into flax, barley, mustard, sunflower, or other standing crop residues left to catch the snow. Seeding into wheat or durum stubble will increase the risk of some diseases, but is preferred to seeding into clean-tilled fields, particularly where disease is less of a problem, since the stubble will enhance moisture conservation and protection from cold weather.

    To avoid a "green bridge" for movement of wheat streak mosaic virus, volunteer wheat and grass weeds should be controlled two weeks prior to planting. Grain stubble should be left at least 6 inches tall to obtain the minimum snow cover required. Hoe drills, which permit deeper seed placement and trap snow in furrows over the seed row, are highly recommended for bare fallow, stubble mulch or chemical fallow fields to improve winter survival.

    Planting - The recommended seeding dates for winter wheat are September 10 to September 30 in the southern half of North Dakota and September 1 to September 15 in northern regions. Planting after the recommended dates may reduce winter survival and grain yields and also delay maturity of the succeeding crop. Planting prior to the recommended date unnecessarily depletes soil moisture reserves, increases risk of disease and may reduce winter survival.

    Winter wheat should be seeded at a rate of 1,000,000 viable seeds per acre or about 80 pounds per acre. Higher seeding rates are suggested for late seeding or for poor seedbed conditions.

    Only the most winterhardy varieties available should be considered when growing winter wheat in North Dakota. Of the current varieties, Roughrider, Agassiz, Seward, Elkhorn, Ransom and Crimson possess the best combination of winter hardiness and yield. When wheat streak mosaic virus is a concern Crimson should be grown, of the varieties adapted to North Dakota it has the best tolerance. See NDSU Extension circular A-574 for detailed agronomic information on available winter wheat varieties.

    Variety selection is one of the simplest ways to ensure maximum production. Selecting the variety that performs the best at several locations over multiple years is the best choice. Table 1 summarizes yield, test weight and protein from 1999 trials. A more comprehensive summary of 1999 winter wheat yield data is available from your county agent or can be found on the North Dakota Small Grains web page

(http://www.ag.ndsu.nodak.edu/aginfo/smgrains/smgrains.htm).

Foundation seed of winter wheat is available from the Agronomy Seed Farm in Casselton (701) 347-4743. A list of certified seed can be found on the Web at:

                                www.ag.ndsu.nodak.edu/aginfo/seedstock/fss/fsshome.htm.

 

Table 1. Avg yield, test weight and protein of winter
wheat varieties grown at 4 locations in North Dakota
.

Variety

T.Wt.
lbs/bu

Protein
%

Yield (bu/A)

1999

3 Yr. Avg

Agassiz

60.7

14.5

65.8

57.2

Alliance

60.4

12.1

65.7

53.4

Arapahoe

60.3

13.9

70.6

58.5

CDC Kestrel

58.5

12.4

72.6

64.2

Crimson

62.2

13.5

65.0

--

Elkhorn

60.1

13.9

62.4

58.4

Erhardt

60.4

14.5

67.4

--

NeKota

61.4

13.5

65.7

54.6

Norstar

60.7

13.1

67.6

--

Ransom

59.8

13.7

68.5

60.3

Roughrider

61.9

14.7

63.0

55.8

Seward

60.1

13.0

68.8

62.7

Tandem

60.9

14.2

64.2

--

Windstar

62.2

14.1

66.5

58.4

Mean

60.7

13.6

66.8

58.2

    Fertilizer applications for winter wheat should be based on soil tests and yield expectations. Winter wheat's nitrogen need in the fall is low and does not exceed the rate that can safely be applied in the drill row at seeding time. Spring applications of nitrogen should be based on a soil test. The best combination of yield and protein are achieved with applications just prior to jointing. Nitrogen applications on snow are not recommended. Snow compaction under wheel tracks destroys snow insulation properties and results in winterkill beneath the track. Movement of N offsite is also a problem on deeply frozen soils when snow melts in the spring.

    Phosphorus aids overwinter survival by stimulating root growth and fall tillering. The secondary root system that develops with tillering is essential for a healthy deep-rooted plant capable of withstanding stress. If winter wheat is planted on bare soil an application of phosphorus is essential. While important, the contribution of phosphorus to overwinter survival is secondary to varietal hardiness and soil temperatures at the growing point in the plant crown.

    Additional information is available in NDSU Extension publications: Fertilizing hard red spring wheat, durum, winter wheat and rye, SF-712; Winter Wheat Production in North Dakota, EB-33; The North Dakota fertilizer hand book, EB-65.

Michael D. Peel
Small Grains Extension Agronomist
mpeel@ndsuext.nodak.edu


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