Biologicals and Nutrient Use Efficiency

As crop fertility inputs increase, the need for using soilborne nutrients more efficiently increases as well. This is not a new concept and occurs naturally without prompt. The soil is full of biological processes and is continuously converting organic substances to inorganic, or plant available, forms. There are, however, products in the marketplace that try to add to the native soil biology with varying success.

To better understand how biological organisms use, convert, neutralize and upcycle nutrients they must be categorized and uses described. According to Cornell University, the different types of biologicals, or microorganisms, are best described as living and non-living. The living microbes may include nitrogen fixing bacteria and decomposers. Nitrogen fixing bacteria are microorganisms that can convert dinitrogen from the air using an enzyme called nitrogenase. Nitrogenase is very sensitive to oxygen exposure and needs an anaerobic environment to convert dinitrogen to ammonia. Decomposers simply break down organic matter and residue into available forms of nutrients. The microbes that consume organic matter and residues consist of bacteria, fungi and actinomycetes.

Each type serves a purpose in the process. Bacteria need warm soils and nitrogen to consume simple forms. Fungi and actinomycetes break down cellulose and lignin which take the longest to recycle. This is why residue worked in with tillage tools too deep may not break down for several seasons because fungi need oxygen to work. To make residue cycling quicker, it just needs more soil to surface contact. This can be done by utilizing chopping corn heads/aggressive knife rollers, crimpers/rollers, and tillage practices to name a few.

The non-living section of microbes are derived from living organisms and used as bio-stimulants. Humic and fulvic acids and sugars aid in the processes of residue and organic matter conversion. Living organisms need a multitude of factors to align to reach their full potential. Certain requirements must be met depending on the type of microorganism they are. Perhaps this is why research and yield data has been inconsistent, across the marketplace, for biological additives for cropping systems.

 As mentioned above, some microbes prefer oxygen and cool temperatures to perform their best. So, when introducing a live, or dormant, biological to the soil and/or plant what precautions are being taken? This may require climate cooled storage facilities with aerators for long-term shelf life and quick application windows. Others prefer no oxygen and warmer temperatures. In this instance, knifing (or subsurface application) of a bacterial application may be necessary. Most soils already contain necessary biological life. They may just need better fundamentals like moisture, air, organic matter and nitrogen.

Cornell University Nutrient Management Spear Program. (n.d.). Nutrient release from organic materials (Agronomy Fact Sheet #127). Cornell University College of Agriculture and Life Sciences.