The Nuances of Nitrogen

The Nuances of Nitrogen

There is no mineral that has more impact on your profit, your resilience and your sustainability than nitrogen. In this context, "sustainability" is all-encompassing. It does not just refer to whether or not you leave your soil in the same, or better shape, than you found it. It also relates to your economic sustainability, particularly in relation to your input costs (fertilisers and farm chemicals).

Sustainability is also about your footprint at a planetary level. Agriculture is the largest contributor of greenhouse gases. In fact, farmers produce 80% of the nitrous oxide that is pumped into the atmosphere each year. This is no small thing from a global warming perspective, as nitrous oxide is 310 times more potent than CO2 in terms of thickening the blanket that traps heat and warms our world. However, it is profitability that determines whether most of us sleep well at night, so that shall be our initial focus.

Nitrogen and Your Profit

Nitrogen management is a huge player in determining your bottom line. When we mismanage this mineral, the costs rise and the profits fall. Here are four common problems and their solutions:

1) The Problem: Applying N in the Absence of Sulfur or Calcium

If these partner minerals are low in the soil, they should be included with your nitrogen. Sulfur is an integral component of two of the amino acids that combine to create protein. Plant immunity is protein-driven (as is human immunity). You can not make protein without sulfur and consequently you have a substandard crop, which requires more chemical intervention. Sulfur is also required to fuel the conversion of nitrates to protein. If there is insufficient sulfur to fuel this process, the nitrate-packed leaf becomes a calling card for insects and disease. Calcium determines the cell division and cell strength required for crop quality, disease resistance and shelf-life. Nitrogen fires growth, but without calcium there is no quality, and that growth becomes prime fodder for opportunistic pests.

THE SOLUTION: An ideal granular planting blend might contain granular guano, DAP/MAP, NTS Stabilised Boron Granules™ and elemental sulfur granules. This blend solves the problems directly in the root zone. The guano granules contain plant-available phosphate and ~30% calcium. The boron component ensures that calcium delivers its full promise. Boron can also help activate the silica component of the guano. The humic acid will bond with the DAP/MAP to form a stable phosphate humate. The soluble phosphate will not become locked up in the soil as a result, and the carbon-dense humates can buffer the burning power of the phosphoric acid – i.e., when DAP/ MAP ionises, the resulting phosphoric acid can sizzle both fine roots and precious mycorrhizal fungi attached to those roots. The sulfur granules will ensure the formation of protective protein within the plant.

2) The Problem: Applying N in the Absence of Molybdenum

Molybdenum is required as part of the nitrate reductase enzyme, which converts nitrates to protein. If this mineral is missing, the plant remains packed with nitrates and becomes a calling card for pests. If your soil lacks molybdenum, there will also be an increased need for nitrogen from the bag. This is because molybdenum is required to form nitrogenase, the enzyme that facilitates the conversion of atmospheric nitrogen gas into ammonium nitrogen in the soil. The healthy, resilient plant needs to contain three parts ammonium nitrogen to every one part of nitrate nitrogen. This is very difficult to achieve if you are not getting free ammonium nitrogen from the atmosphere.

THE SOLUTION: The presence of a minimum 0.5 ppm of molybdenum in the soil helps ensure nitrogen fixation and nitrate conversion. Molybdenum can be applied as sodium molybdate at a rate of 300 grams per hectare via fertigation, or 100 grams per hectare as a foliar. There is one caution here. You must ensure that your copper levels are adequate before application of molybdenum, or you may induce a copper deficiency with the antagonistic impact of molybdenum.

3) The Problem: Getting Nitrogen Just Right (“The Goldilocks Effect”)

Nitrogen is the most abundant mineral in the plant and it can certainly have a big impact on yield. This factor can sponsor a belief that more is better – however, this is not the smartest of strategies. When nitrogen is overapplied, it negatively affects the uptake of other minerals. The most notable of these is potassium, the most expensive of all fertiliser inputs. The second major mineral affected by too much nitrogen is calcium. It is obviously not a great idea to apply more nitrogen than what is required, thereby inducing a greater need for an even more expensive input in the process. Similarly, there is a price to pay for reducing the cell-strengthening potential of calcium. Your nitrogen excess will increase the need for chemical intervention when the calcium-deficient plant becomes less resilient.

THE SOLUTION: Observe and monitor to ensure that you get your nitrogen right. This might involve the use of a nitrate meter, a brix meter, a plant sap pH meter or leaf analysis. The Horiba Plant Sap & Soil Nitrate Meter can be invaluable because it so often reveals our excesses. In the dairy industry, for example, we found that the ideal nitrate level for dairy pasture was just 2500 ppm for maximum production and herd health. Many high-production units were way off the mark with nitrate levels above 8000 ppm (with all of the associated problems). They were spending much more than was needed and creating problems in the process. The Refractometer (brix meter) is also helpful because high nitrates in the plant will result in a low brix level. Nitrate nitrogen is uptaken with water and this has an unavoidable dilution effect. The higher the nitrates, the lower the overall nutrition of the plant and the higher the associated pest pressure. Leaf analysis can also be of obvious help, but it takes a little longer than these more instant monitoring tools.

4) The Problem: Tight, Closed, High Magnesium Soils Require Much More Nitrogen to Achieve the Same Yield

Excess magnesium antagonises nitrogen uptake, so more of this mineral is required. These soils also struggle to "breathe" and this impacts natural nitrogen fixation because the nitrogen-fixing bacteria are all highly aerobic. Nitrogen recycling also slows down in these soils because earthworms and beneficial nematodes do not favour soils in which they battle to move freely. When the protein from crop residues is not recycled adequately, you will simply need to apply more from the bag.

THE SOLUTION: Gary Zimmer was at his most profound when he suggested that we must “earn the right to reduce nitrogen”. It is a recipe for failure if we cut back on nitrogen in high magnesium soils without addressing the reasons why we need more N. The key here is to get these soils breathing again with gypsum or elemental sulfur. We must improve the calcium to magnesium ratio and we must boost struggling biology to reclaim soil structure. This might involve the use of Nutri-Life 4/20™, which can be inexpensively brewed and applied to repopulate the microbe workforce. It might also involve the use of NTS Soluble Humate Granules™, as they are the most powerful known fungal stimulants. It is humus-building fungi that are most deficient in our soils and they are critical to the aggregation process that allows optimum gas exchange (oxygen in and CO2 out).

In Conclusion

Nitrogen is important. In fact, it is the most abundant mineral within the plant because it is integral to photosynthesis and protein. If we can get this mineral right, we invariably find that farming can be less stressful, more profitable and much more fun.

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