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Spotty Sugarbeets in NE ND, and NW MN (8/03/17)

I have had several questions regarding early yellowing of sugarbeet in NE North Dakota and NW Minnesota during the past couple weeks.

Spotty Sugarbeets in NE ND, and NW MN

I have had several questions regarding early yellowing of sugarbeet in NE North Dakota and NW Minnesota during the past couple weeks. Early in the season, I began noticing that this season would be different than last in regards to N release from soil mineralization. Last year was an amazing year, with greater check plot yields in several studies with low beginning soil nitrate levels. I estimated that 100-150 pounds N per acre were released during the season in some of my studies. In contrast, the check plots in low-residual N studies this year exhibited N deficiency early, and observations made me believe that soil mineralization rates were going to be very low. In the northeast part of the state, where the aftermath of last year’s extremely wet conditions lingered into late May, those persistently wet conditions also would not contribute to high N mineralization. Crops planted into those soils would likely have to contend with saturated subsoils for some time, which would restrict rooting depth. After a couple early season rains on sugarbeets following planting, conditions have become dry. Peak time for N mineralization is usually until the end of June, but this year it probably ended sooner than that.

Growers and consultants have all observed green beets and yellow beets at small spatial scales. That indicates to me that what is being seen is the effect of microenvironment in our ‘flat’ fields, where a little more moisture in one area has encouraged more N release, while drier conditions right next to that area have experienced less N release.

Earlier this season some growers side-dressed N to obviously N deficient beets. Studies conducted by John Lamb at U of MN and others in the drier years 30 years ago indicated that sidedressing about 6-leaf stage beets would sometimes effectively result in greater sugar, but sidedressing at later growth stages nearly always resulted in lower sugar yield and lower profits.

Dave Franzen

NDSU Extension Soil Specialist

701-799-2565

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