Within the Central Valley of California, the debate regarding nitrogen leaching into the groundwater has exploded as a hot button topic. Farmers throughout California are being forced into a corner. Nitrogen regulations have tightened despite the need for the element as a crucial component of plant growth. With the implementation of SGMA (Sustainable Groundwater Management Act) and more regulations to come, the ability to use nitrogen prolifically is quickly coming to an end. And for good reason, as high levels of nitrogen ingestion from contaminated water sources have been listed as a high-risk carcinogen. Many areas throughout the valley do indeed have high concentrations of nitrates coming from aquifers below. The map below, provided by the National Parks Service, shows nitrate levels in groundwater throughout the state of California.
California farmers, especially those in red areas of the map, should be aware that there is a strong chance the amount of nitrogen they will be legally allowed to apply to their field will drastically reduce. With this in mind, it is going to become increasingly important for farmers and crop advisors, red areas, or otherwise, to enhance efficiency with all of the nitrogen they apply. It’s time for California’s farms to start thinking outside the box for ensuring adequate nitrogen supply to crops. By using or sequestering the majority of nitrogen entering the plant system, the amount of leached nitrogen into groundwater is significantly reduced and even eliminated.
Available not Soluble
Typically, nitrogen is a remarkably soluble nutrient – meaning that the mineral can easily dissolve in water. The solubility of any nutrient does not necessarily indicate that the nutrient is able to be used by the plant. Instead, solubility only implies that nutrients dissolve in water and will typically move through the root zone as water passes through the root zone. For years we have been advised that the only way nutrients can enter the plant is if they are soluble, we now know that this is not true.
There are many nutrients, including nitrogen, that can be held in the soil profile in an insoluble form yet remain available for the plant to use when needed. The concept “insoluble but available” is a paradigm shift in the mindset of nutrient management. New goals in nitrogen application involve using insoluble nitrogen that is ready for plant uptake but does not leach out of the soil profile. To do this, we need to convert the chemical nitrogen (nitrate, ammonium, or urea) into protein through bacterial mineralization. And, while this may sound like the beginning of a science fiction novel, the concept is quite simple. All this means is that the living organisms in your soil consume the soluble nitrogen applied by the farmer and metabolize it to amino acids and proteins. This process is the most pathologically efficient form of nitrogen for your plants because it does not take energy away from your plant to use, but this is concept can be discussed at a later time. When nitrogen is in this protein form, it is made available to the plant at a consistent rate, similar to the concept of spoon-feeding plants. This regular nitrogen supplementation creates strong even growth leading to less susceptibility to insect and disease problems.
How Do You Do it?
The first step is to stop putting large amounts of nitrogen down in single-shot applications and instead aim for 30 units or less of nitrogen in a single treatment. The most significant contributing factor in nitrates leaching to the groundwater is from this old style of farming, where it was common practice to put down 100 units or more in less than a week. Yes, the current recommendation is less than a third of what has been done typically in the past. Dumping large amounts of nitrogen repeatedly on the crop is far from being the most plant efficient or cost-effective practice. However, several advisors will still tell farmers that heavy unit applications are always the best way. Why? Because the mechanism to sequester the nitrogen for consistent plant uptake is not plentiful in the soil.
The second step is to establish a robust microbiota that can sequester the excess nitrogen that is not immediately used by the plant. Using the right microbial inoculants and ensuring their vitality will typically allow for the smaller amounts of excess nitrogen to be held by the microbiota in the root zone. One of the big players in the soil starting that has finally begun to get recognition as a considerable benefit is yellow soil yeast. These yeasts proliferate during the summer and work very effectively at keeping applied nitrogen in the root zone. The yeasts create a lipid layer in the field that works to hold the nitrogen as the water passes through. Similar to oil floating on water, the soil yeast will grab on to the nitrogen applied in its soluble form and hold it in the lipid layer formed by the yeasts, allowing it to stay on top, much like oil does when mixed with water. One advantage is being able to hold applied nitrogen; another benefit is these soil yeast are 42% protein, which creates an average of 67 units of insoluble yet available nitrogen. Biology in the soil just created 67 units of readily available nitrogen in the field and without a single drop of added synthetic fertilizer.
Getting nutrients as a side effect is a massive benefit for farmers, especially with the direction agriculture is heading with increasing regulation alongside increasing demand for high yield crops. You just created a beautiful example of combining soil biology and chemistry to achieve a vastly better, synergistic result. An Axiom of Neoteric Agriculture is using soil biology and soil chemistry together, not thinking of them separately. You can not use solely chemistry or solely biology when trying to grow the best produce in the world.
The path forward for farmers isn’t necessarily an easy one. In an industry that can be slow to adapt, this new wave of regulations will necessitate many to update or completely overhaul their farming practices or else face hefty penalties. The question is: “Who is prepared?” “Who is barely keeping up with the curve?” and “Who is going to struggle, trying to keep things the way that they have always been?”
Which type of farmer are you going to be?