In the United States, farmers receive a nitrogen credit of 20-30 lb N/ac following soybeans. Can we expect the same here in Manitoba?

If a crop like corn is grown after soybeans and compared to corn-after-corn, the nitrogen requirement is less, and is often referred to as a soybean nitrogen credit.  But soybeans do not leave much nitrogen remaining after harvest – either in the residue or in the soil.  It is just that soybeans immobilize or tie up less nitrogen than heavy corn stover. 

With our more diverse crop rotations this benefit after soybeans does not amount to much.  In fact a 50 bu/ac soybean crop provides only a 6 lb N/ac benefit compared to a previous crop of flax.  So we do not suggest much of a nitrogen credit following soybeans.

More details please visit MAFRI’s website at: https://www.gov.mb.ca/agriculture/soilwater/nutrient/pdf/fer01s02.pdf

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Should I add nitrogen to my corn stalks so they decompose quicker?

Each year we receive this question and the answer is still no.  Grain corn does produce high amounts of crop residue with a high C:N ratio, meaning microbes will immobilize or soak some nitrogen out of the soil during decomposition.  But if the corn has been adequately fertilized with nitrogen for good yield potential, there should remain sufficient nitrogen for orderly decomposition. 

What minimizes decomposition rate is our lack of suitable conditions for microbial activity, specifically heat and, this fall, perhaps moisture. 

 More details please visit MAFRI’s website at: https://www.gov.mb.ca/agriculture/soilwater/nutrient/pdf/fer01s03.pdf

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