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Comparing Use Characteristics Between Organic Nitrogen Fertilizers

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For organic growers, there are a myriad of organic nitrogen fertilizers in the marketplace. It is important to understand the efficiencies of each source, so that growers can match their chosen fertilizers with their desired results. In this article, we will examine two examples of organic nitrogen fertilizers – soy protein hydrolysates and Chilean nitrate.

Soy Protein Hydrolysates

As an organic fertilizer, soy protein hydrolysates can be found in many concentrations – as low as 2% in some NPK sources and as high as 16% – as a dry soluble powder. To compliment the dry powder, for those not interested in solubilizing in the field, there are a few liquid formulations, the highest being 10% liquid soy protein hydrolysate.

It is hydrolyzed from soybeans and is approved for organic use across the U.S. Plant-derived organic nitrogen from soy produces an immediately available source of organic N that typically lasts for 30 days. Being stable and soluble in all water conditions, with a neutral charge, it provides a valuable source to sink without limitations.

Amino Acids found in Proteins can constitute a significant nitrogen source for plants and there is an interaction between the uptakes of inorganic and organic nitrogen. (JOPN #32, 2009)

Soy protein provides a natural carbon source and that may be the limiting factor for most soils, especially under stress conditions. Unlike other N sources, another benefit is that plant-derived organic nitrogen does not have any burn risks normally associated with foliar applications – it’s safe to remain on leaf surfaces and does not require higher volumes of water for safety in most sources. It is important to inquire about the amino acid content and availability of material, especially in current market conditions.

In addition to this, soy protein provides a few other benefits:

  • Stable for use as an added ingredient in all fertility programs;
  • Actively promotes the biomass of all soils and will ensure proper uptake and assimilation of other fertilizers;
  • Provides predictable release in stable soil temperatures, with a very low risk for leaching in excess water events such as flooding;
  • No limitations from USDA, USDOT and exempt from FMLA.
young plant growing in soil
Learn the use characteristics between organic nitrogen fertilizers. Know the differences, limitations and what sources are right for your farm.

Chilean Nitrate

Chilean nitrate is usually sold as a 16% nitrogen fertilizer, extracted from northern Chilean natural caliche soil deposits. During refinement, crushed ore is dissolved at 35°C to extract nitrates, sulfates, potassium, and iodine. Nitrate precipitates are removed, crystallized, dried, and prilled. The purified grade contains at least 97% NaNO3 (Stoddard and Silberman, 1995). Also known as Nitrate of Soda or Sodium Nitrate, it is a highly soluble organic N making it a distinctive source of nitrate for the organic industry that is highly effective at delivering immediately usable nitrogen to plants.

Looking past the solubility and availability, Chilean nitrate has several roadblocks and concerns for use in farming. It has a standard salt index of 100 and contains ingredients such as sodium chloride, sodium sulfate, and potassium chloride, which are not more than 1% of the total weight. Salinity stress is known as one of the most significant degraders of soil health and modern agricultural productivity. When using Chilean nitrate, the interference with osmotic regulation of water and nutrients should always be considered and calculated prior to application.

Chilean nitrate 16-0-0 does cause significant carbon losses since it has no recognizable C:N profile. Without taking into account the implications of carbon credits, additional carbon may be needed to maintain the proper C:N profile. As sodium tends to accumulate if not flushed or accounted for, this can also change water availability, creating sodic soils that displace other cations. Calculated calcium applications will help leach out sodic soils if this happens.

Chilean nitrate drawbacks include:

  • Raises soil pH;
  • Salt Index of 100;
  • No more than 20% of total N program per USDA;
  • Listed as hazardous material by USDOT.

The nitrites gassed off by Chilean nitrate are also considered an air quality contaminant and may cause the depletion of other minerals in soils with high watering requirements, causing salinity stress. Nitrites are the largest human source from agriculture and was measured above 75% in 2019 and considered 7% of U.S. greenhouse gasses. Nitrites can remain in the atmosphere for over 100 years and are 300x greater in global warming than carbon dioxide.

In addition to the limitations of Chilean nitrate, high dilution rates are required to prevent burns on foliage. You may be required to monitor wells to ensure that groundwater is not contaminated by nitrates, depending on local county and state regulations.

Nitrates as NO3 may decrease chlorophyll and will slow growth. NO3 will limit Potassium in alkaline western soils. NO3 will induce changes in the soil root zone or rhizosphere and its conversion to Ammonia will accumulate in alkaline soils and promote disease risks. (Carrow, Rieke and Waddington 2001)

Under high use of Nitrates, less of carbohydrates are allocated to sugars that can be transported to roots. This action will result in a stimulation of top growth and a depletion of roots.

By understanding some of the limitations of organic nutrients, growers can avoid pitfalls and availability concerns, minimize risk, and rebuild soil health midseason.

Sponsor Message

At Ferticell, we encourage the use of sustainable, low salt content materials that build soil health. Ferticell can help you learn more about incorporating a clean, sustainable organic nitrogen fertilizer like Explorer™ into your program without limiting factors in both sustainable and organic farms. Contact us to learn more, find a store near you, or call today at (480) 361-1300 to get the answers you need.