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Extension > Minnesota Crop News > October 2014

Thursday, October 30, 2014

Potassium Fertilizer Considerations for 2015

By Daniel Kaiser
Extension Soil Fertility Specialist


At times potassium (K) can be the forgotten element when determining appropriate rates of fertilizer to apply.  Nitrogen and phosphorus typically are of main concern due to the potential yield response for corn to nitrogen and many soils around the state historically being low in P but medium to high in K.  Potassium should not be a forgotten nutrient as there are situations where K fertilizer can be profitable.

Taking a soil test is the best option for determining where K is needed.  Soil testing for K can be problematic as K levels can vary over the growing season.  The uptake of K in plant residue can well exceed the amount of K removed in the grain.  Potassium in plant stover can play an important role in the nutrition of crops planted the next year.  As plants mature and begin to decay, K taken up during the growing season can be leached out of drying or decaying residue.  The recovery of K can be rapid for plants that senesce leaves early, like soybean, but the recovery of K for crops which residue is slow to break down, such as corn, can be slow.  In both cases the rate of recovery increases with the amount of rainfall.  Waiting as late as possible to sample the soil in the fall and being consistent with sampling timing in a rotation is the best way to try to mitigate potential impacts of seasonal variation in soil test K.

Wednesday, October 22, 2014

Status of the brown marmorated stink bug in Minnesota

By Robert Koch (Extension Entomologist, U of MN), Theresa Cira (Graduate Student, U of MN), Eric Burkness (Scientist, U of MN), Bill Hutchison (Extension Entomologist, U of MN) and Mark Abrahamson (Supervisor, MDA)

Numbers of the brown marmorated stink bug (Halyomorpha halys), a household invader and potential crop pest, appear to be increasing in Minnesota. This pest, originally from Asia, has spread rapidly throughout much of the U.S. and was first detected in Minnesota in 2010. Since 2010, detections of BMSB have occurred throughout the Twin Cities area and in Duluth and La Crescent. Initially, home owners were encountering one or two bugs on or in homes and other buildings during the fall and winter months. However, home owners in Wyoming, MN are beginning to see more of this invader.

Friday, October 10, 2014

Storing, Drying, and Handling Wet Soybeans

By Lizabeth Stahl, Extension Educator - Crops

Harvesting soybeans at a moisture content between 13 to 15% helps maximize weight while minimizing harvest losses. This harvest, however, soybean moisture levels of 16 to 18 % or more have been reported.

Spoilage during storage is a concern when moisture levels are high. If storage temperatures are below about 60F, soybeans at 13% moisture can usually be kept for about 6 months without having mold problems. As moisture levels increase, however, the length of time soybeans can safely be stored decreases. How long can soybeans be stored before mold becomes a concern?

Thursday, October 9, 2014

NDSU Offers Tips on Harvesting, Drying, and Storing Late Maturing and High Moisture Corn

Kenneth Hellevang, Ph.D., P.E.
Extension Agricultural Engineer & Professor, North Dakota State University

Corn reaching maturity about October 1 will normally dry slowly in the field due to cooler ambient temperatures. Standing corn in the field may dry about 1.5 to 3 percentage points per week during October and 1 to 1.5 per week or less during November, assuming normal North Dakota weather conditions. Table 1 below provides field drying rates for corn in Minnesota.

Wednesday, October 1, 2014

Assessing your Need for Sulfur Application in Corn

By Daniel Kaiser, Extension Soil Fertility Specialist

It is important to understand where sulfur that is utilized for crops comes from in order to determine where to best target fertilizer application. In Minnesota, sulfur was not recommended for many crops grown on medium and fine textured soils. Numerous studies were conducted during the 1970's, 80's, and 90's with little to know positive benefits shown except for a limited number of studies where corn was grown on eroded soils. Over the past 10-15 years reports increased as to sulfur deficiencies and research has found that sulfur may be needed for crops most sensitive to sulfur deficiency.

Soil tests for sulfate-sulfur only account for a small fraction of the total amount of sulfur in the soil.  Soil organic matter is a large storehouse of sulfur with as much as 95% of the total sulfur contained in organic matter.  Sulfur in organic matter must be mineralized to sulfate before it can be taken up and assimilated by plants.  It is within this process of mineralization which can explain, in many instances, why responses to sulfur fertilizer have increased.
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