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ISSUE 2  May 10, 2001

 

HIGH N PRICE STRATEGIES

Most producers will pay somewhere between $360 and $400/ton for ammonia this spring if they are lucky and there are no spot shortages. This is roughly twice the price of year 2000. So with an inflexible budget, how would they make ends meet? The first important thing to know is the status of soil nitrate. Once a soil test is made, different rates may be applied to different fields. Certainly there is a good chance that N can be allocated. Secondly, know the needs of crops. Crops such as spring wheat and durum require aggressive N strategies for good protein and yield. Cutting rates across the board is a recipe for disaster. Unless you want to grow junk wheat, donít cut rates for wheat or durum. However, oilseed crops, flax, dry beans soybeans, sugarbeets, barley and sunflowers will do well or sometimes better if rates are conservative. Certainly, there are producers every year who lose quality payments on malting barley and sugarbeets due to higher than needed N rates. Be conservative on yield estimates, and if you are a beet grower, aggressively demand zone soil testing to do a better job of managing N on your beet crop. Dry bean growers with a history of good nodulation should not need high rates of N. Dry bean growers who normally grow 1,500 pounds/acre yields should not be fertilizing for 2,000. The rates in the NDSU dry bean fertility circular assumes growers will be conservative on yield goals. The same is true for flax. Too many flax growers wish and fertilize for 40 bushels, when 25-30 is more commonly grown. Be realistic and there will not be as much lodging in fields this fall. Sunflower growers should understand that the presence of deep N is no accounted for in recommendations, but sunflowers have the ability to retrieve this deep N. Higher than needed N levels result in lower oil content and lower premiums. In some cases, lower N levels for sunflowers may be justified. High N levels for canola mean heavy top growth and the possibility of higher risk for Sclerotinia. Make N rates reasonable for your areas history. Thirdly, grow crops with a low N requirement, such as soybeans, field peas, lentils, garbanzo beans. If properly inoculated, field peas and lentils need no additional N, soybeans need up to 50 lb/acre in a first year of production and similar N levels in following years if nodulation is poor and there is history of chlorosis.

Fourthly, take advantage of previous crop credits. Almost any broadleaf crop will contribute some N to the subsequent crop, except perhaps for canola. Previous crop recommendations for annual and perennial legumes and for sugarbeet appear in NDSU circular SF-882 available from a county agent or on-line at http://www.ext.nodak.edu/extpubs/soilfert.htm . In addition, crops following any sunflower crop could easily take a 10 lb N credit for sunflower leaves and following potatoes, 10-20 lb N/acre.

 

COMPATIBILITY OF RHIZOBIUM WITH SEED TREATMENTS

The following are results taken from a journal article by Curley and Burton, Agronomy Journal, 1975, 67:807-808.

Survival of R. japonicum (we call it Bradyrhizobium today) on chemically treated bean seed.

Treatment

Time after treatment, hours

 

1

4

24

------Rhizobia count---------

None

400ab

375ab

260ab

Thiram

410a

400a

200bc

Carboxin

350bc

315c

300a

Captan

330c

330bc

170c

PCNB

90d

70d

15d

Nodulation of 2-week old soybeans as influenced by treatment

Treatment

Time after treatment, hours

 

1

4

24

-----Taproot nodules/10 plants----

None

68a

56a

48a

Thiram

66a

45a

48a

Carboxin

45b

31b

8b

Captan

4c

4c

10b

PCNB

6c

4c

3b

What these data show are two principles-

  1. Inoculate and seed within about 4 hours.
  2. Beware of Captan and PCNB. Thiram is safest, followed by Carboxin if it goes in the ground quickly.

 

FERTILIZER ON A BARGE COULD BE THERE AWHILE

Barge traffic is still bottled up on the Mississippi River. The river will open up from north to south starting about May 7, but it will be closed around mid-Wisconsin until at least next week. Estimates on opening the river to traffic as far south as St. Louis are not available yet. The web site for helpful river opening information is as follows- http://www.mvr.usace.army.mil/navdata/icemiss

Barge is the preferred method of transportation from the ports on the Mississippi to the upper Midwest. Much of our fertilizer is imported this year from overseas. One good thing about the current lack of seeding is the demand for fertilizer has been spread out as compared to the possibility of everybody needing it at once. This has helped keep fertilizer prices more reasonable so far. But it has used a lot of stored fertilizer up on the earlier plantings, and the later plantings will need to rely on new sources of supply. And one, the barge traffic, is not going to be there anytime soon.

 

IN THE DARK ABOUT FERTILIZER N RATES?

For crops that will be side-dressed, such as corn and sunflowers, soil testing is still possible after seeding. If this is done, do not consider a previous crop credit from soybeans for example, as much of the mineralization from that crop will already be realized in the soil test results by mid-May. The same would be expected for crops following sugarbeets, sunflowers and potatoes.

As the season progresses, most crop yield potentials will decrease. Sugarbeet yield decrease about 1 ton/week after April 20, and 2 ton/week after May 15. Decrease N rates accordingly or risk low sugar discounts this fall. To keep barley in malting grade, reduce N levels 30 lb/acre after May 15. This date will vary earlier or later depending on whether the fields are north or south in the state. Keep wheat and durum rates aggressive, but high yield potential will begin to evaporate towards the end of May in most areas of the state.

Dave Franzen
NDSU Extension Soils Specialist


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