ISSUE 4    May 26, 2005

ROLLING SOYBEAN GROUND

The objective of rolling soybean ground is to push rocks and large soil clods down to the soil surface and level the soil to allow a low combine cutter bar height during harvest. This will reduce harvest loss by cutting soybean stems below pods instead of cutting above or through low pods and leaving seeds in the field. Soybean fields are rolled after planting, either preemergence (PRE) or postemergence. Advantages with rolling before the crop has emerged are low potential for plant injury and improved seed-to-soil contact. Disadvantages are increased potential for soil-surface crusting and soil erosion.

Rolling fields after the crop has emerged will potentially cause plant injury including crushed leaves and cracked or broken stems. Plants will die if the stem is broken below the cotyledon leaves, due to loss of all growing points. Injured plants may be more susceptible to lodging and disease. NDSU research and farmer testimony indicates that rolling between the cotyledon and first trifoliate stages of soybean should limit injury potential. Also, rolling during the warmest part of the day on less turgid plants may reduce injury potential. Afternoons are better than mornings.Soybean rolling trials were conducted three years (2001, and 2003-2004) at the NDSU Carrington Research Extension Center. There was a trend of plant population decline as rolling was delayed from PRE to the first or second trifoliate stage. Untreated soybean and pre-merged soybeans rolled showed no visible injury. Rolling soybeans that were <50% cotyledons emerged, cotyledon stage and 1st trifoliate stages showed injury of 5% or less. Early morning rolling at the 3-4 trifoliate stages caused the most visible injury after 4 weeks compared to all other treatments. Seed yield was similar among the unrolled check and rolling treatments.

Duane Berglund
NDSU Extension Agronomist
duane.berglund@ndsu.edu

Greg Endres
Extension Specialist - Carrington
gregory.endres@ndsu.edu

 

BUCKWHEAT CAN NOW BE PLANTED

Buckwheat is planted later than small grain, corn, beans and sunflower. It is very sensitive to spring and fall frosts and any seeding should be delayed until all danger of frost is past. Best planting dates are from May 25 to June 10 in most years. Research date of planting studies at Langdon during 3 years indicated significant buckwheat yield reductions when seeding was delayed to June 22 or later.

It requires about 10-12 weeks after emergence to reach maturity. Buckwheat also is very sensitive to high temperatures and drying winds during blooming time in July and early August. Seedbed preparation is similar to flax. Delayed sowing permits killing several weed crops prior to seeding. Presently, no herbicides are labeled for use in buckwheat for weed control.

Under good moisture and temperature conditions, buckwheat shades the ground rapidly. A seeding rate of 40 to 50 lb A is recommended. Seeding depth of 1 to 2 inches is desirable in moist soil. Shallow seeding is desirable for rapid emergence. A conventional grain drill can be used and seed treatment is not necessary. Buckwheat has limited response to fertilizers. Itís a heavy user of phosphate with needs similar to wheat. Nitrogen application should remain low because of problems with lodging and delayed maturity. Buckwheat should be swathed when most of the seeds are ripe. In the event of frost, swath promptly to reduce shattering losses.

For more information on buckwheat production request NDSU Extension Circular A-687 (Revised 2003) available from your local county extension office or the NDSU Extension Distribution Center. On the NDSU Extension Crops web site at:

http://www.ext.nodak.edu/extpubs/plantsci/crops/a687w.htm

 

RELATIVE MATURITY OF FIELD CROPS

Delayed seeding because of wet field conditions or replanting decisions can be somewhat based on crop growing requirements and development days required for various crops. Below is listed the average days to physiological maturity of many crops grown in North Dakota. Early killing frost plus extreme high temperatures at flowering stages are the two factors most limiting yields of late planted crops.

Time required for maturity varies with variety or hybrid, seeding date, geographic region, and available growing degree days. A shortage of growing degree days can increase days required for maturity. Corn, soybean, sunflower and millet are especially sensitive. Relative maturities for major crop hybrids and varieties are listed in the respective NDSU variety performance circulars.

Seeding to Physiological Maturity or Swathing Stage (days)

Barley

70-85

 

Soybean

95-110

Oats

82-98

Sunflower

90-110

HRSW

83-98

Dry Bean

90-110

Durum

85-100

Proso millet

70-90

Flax

85-95

Buckwheat

70-80

Corn

90-110

Sugarbeet

Frost

Canola

85-100

Triticale

80-90

Mustard

85-100

Lentils

80-90

Field pea

85-95

   

Duane R. Berglund
Extension Agronomist
dberglun@ndsuext.nodak.edu

 

EVALUATING STANDS OF SMALL GRAINS

With the recent rains and warmer temperatures, small grains planted in April and early May have emerged. Winter wheat is beginning to show accelerated growth with some already in the jointing stage. Generally, conditions have been favorable for small grain emergence and winter wheat reportedly survived the winter well. Now is a good time to evaluate small grain stands to determine if replanting is in order and to learn what worked well or not so well in establishing/maintaining a stand of small grains. Limited or excessive soil moisture, poor seed quality, equipment malfunctions and winter injury (in the case of winter wheat) are the most common factors affecting plant stands.

Factors to consider before replanting

First make an accurate assessment of your stand. At first glance plant stands or early season damage can look much worse than it really is. There are times, however, when stands are actually worse than they might appear at a distance. If poor emergence is not uniform, focus only on those areas of the field that will likely need to be replanted. For small grains take plant counts from 4 or 5 randomly selected areas within the field or part of the field of focus. Count plants within a predetermined length of row and convert the number into plants per square foot.

Published recommendations on the minimum acceptable stand before replanting will be more profitable than keeping the existing stand range from 30-55% of the optimal stand (i.e. 8-15 plants/ft2 in spring wheat). Only consider keeping stands on the lower side of this range if the population is more or less uniform; there are no large gaps or skips in the field. For sparse stands that are not replanted, care must be taken to ensure that weeds are adequately controlled. When considering reseeding, note that late sown crops have lower yield potential. Yield is reduced by 1 to 1.5% for each day planting is delayed beyond May 15th. When planting after May 20 replant with a higher seeding rate to compensate for the reduced tillering of the later planted crop. After June 1, consider growing the earliest varieties that are available (varieties released by SDSU tend to be earlier than those released by NDSU) in addition to the higher seeding rate, one may consider growing an alternative crop with a shorter maturity. Planting small grains after June 21 is not recommended.

Diagnosing Causes of Poor Stands

For stands that are less than desired, determining the case of poor establishment may provide useful information that can be applied in subsequent years. Factors to look for include: seed and seedling diseases, seeding depth, poor uniformity in seed drop, poor drainage and waterlogging, and dead or low vigor seed. In addition, for winter wheat check for factors such as stubble height, phosphorus sufficiency and variety when evaluating winter survival. Winter wheat varieties developed in North Dakota or Canada consistently have better winter survival than those developed elsewhere (see http://www.ag.ndsu.nodak.edu/aginfo/smgrains/WWsurvial.htm  for the rating of winter survival in 2002/03).

 

STRATEGIES FOR DELAYED CORN PLANTING

Though most corn in the state has been planted, there are pockets where planting has been delayed because of excess moisture. For northern counties the final plant date for corn may have been reached by the time this goes to print so full crop insurance will not be available. For the southern counties, however, a relevant question is "what is the best hybrid maturity to grow now that the optimum planting date for corn has passed?" Research conducted in 2003 and 2004 at Fargo and near Lisbon addressed this very question. Treatments in these experiments consisted of hybrids with differing maturities planted at three dates (early May, mid-May and early June). Data from this research suggests that you should stay with your "full-season" hybrid through May 20th. When planting is delayed to early June, however, hybrids that are 7 to 10 days earlier than the "full-season" hybrids will likely be more profitable to produce (see the following table for the relative maturity of the hybrid that produced the highest dried grain value in the 2003 and 2004 experiments). When using these data, remember that 2003 was an extremely favorable year for grain drying, and 2004 was an unusually cool summer, so the optimum maturity length for early May planted corn for Fargo and Lisbon would be in the 90-95 relative maturity range. More complete details of these experiments can be found at http://www.ag.ndsu.nodak.edu/plantsci/rowcrops/cornall.htm

The relative maturity rating of the hybrid that produced the highest dried grain value at differing dates of planting, Fargo and Lisbon, 2003 and 2004. (See table).

Planting Date

Fargo 2003

Lisbon 2003

Fargo 2004

Lisbon 2004

 

Relative Maturity Rating in Days

1 May

97

98

92

92

16-20 May

99

99

92-96

92

3-8 June

90

90

79

83

Joel Ransom
NDSU Extension Agronomist - Cereal Crops
joel.ransom@ndsu.edu


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