Peer Reviewed Data
Have you ever wondered if soil microbes can release tied-up fertilizer on your farm?
We bet you have, it’s a hot topic in agriculture right now. This page will begin to, and continue to, provide questions and answers you have that affect your farm, by identifying scientific research from the best minds in soil microbiology and plant pathology. When it comes to research, generally speaking, you may find yourself getting suffocated by it. Why? Because you may feel that what works in the science community doesn’t work in real world agriculture; so why even bother with it?
Though we agree, to a certain point and empathize with this line of thought, because it can get heavy; we believe all research is good and allows other research the opportunity to build upon it. What may be vetted out through the science community provides everyone involved (scientist and grower) a baseline , if everyone remains objective. The scientific method in and of itself, in its purest form, establishes credibility for all of us to build upon and benefit from.
There are many forms of “research,” namely, peer-reviewed, university, in-house, third-party, grower trials, etc. The one principal that is critical with any of it, however, is Integrity.
If the objectives are not clear and unbiased then you have junk-research, and there is plenty of that that unfortunately causes people money and time with little to no results.
Our advice is to take several forms of research that cover your topic, concern or interest and look for patterns that may exist. Patterns of performance that are consistent among many forms of research are more credible than just from one form of research.
AgriGro West believes there is value in every form of honest research, however peer reviewed science sets the standard, generally speaking. What is peer reviewed science?
It is research that has been scrutinized by other experts of the same field of study before publishing. This is done in order to prove the accuracy and validity of those that contributed.
Why is that important?
Bias is the cancer of pure research and these professionals conduct and evaluate their hypotheses without bias.
With that foundation, AgriGro West hopes you will find credible answers to questions you may have regarding crop production and the role microbiology has in it. If you don't, let's talk and we'll get you answers.
How do beneficial microorganisms impact the diseases that I spray with fungicides?
Scientists have known for over 20 years that soil bacteria and fungi can be of enormous benefit to growers by preventing and reducing the effect of many pathogenic diseases. Diseases like “damping-off” or fusarium wilt, stripe rust, and Ascochyta blight are responsible for significant damage to yields every year in a large number of important crops such as corn, potatoes, wheat, and cotton (1)(2)(3).
The current belief of mainstream agriculture asserts that breeding for resistant cultivars and spraying fungicides are the only viable options available to growers to protect their crops from disease (2). However, this could not be further from the truth. Studies have linked the maintenance of healthy soils to their ability to suppress pathogens in a multiplicity of ways. A diverse microbiome plentiful in bacteria and fungi will compete fiercely for nutrients, stealing them away from pathogens that need them to survive and grow (4).
As well, a variety of bacteria have been identified for their unique capacities to fight various pathogens. Some protect crops from diseases by producing antibiotics and anti-fungal substances that attack diseases directly (5)(6)(7). For many other diseases that threaten crops, there are bacteria that are ready and willing to protect them (3)(8).
(1) Natural Disease Control in Cereal Grains - ScienceDirect
(2) https://www.researchgate.net/profile/Hakeem-Shittu/publication/292243135_Fusarium_Wilts_An_Overview/links/56b252c908ae795dd5c7b24f/Fusarium-Wilts-An-Overview.pdf
(3) https://www.nature.com/articles/s41598-021-93939-6
(4) https://www.pnas.org/doi/abs/10.1073/pnas.1109326109
(5) https://academic.oup.com/femsec/article/45/1/71/534624
(6) https://link.springer.com/article/10.1007/s00374-011-0556-2
(7) https://www.tandfonline.com/doi/abs/10.1080/09583150400015920?journalCode=cbst20
(8) https://onlinelibrary.wiley.com/doi/full/10.1111/jph.12850?casa_token=30uCNaI6KD0AAAAA%3AN518RC_svBkzD4K9grpeB6I_jySLuRleAseY-rZFlQDIBKYJKxqqYiZIt3CSud43eV1MbUn1ZKbNXA
How much newly applied fertilizer gets lost to tie-up, leaching and volatilization and never gets into the plant?
Crop-available nitrogen is present in two chemical forms: nitrate and ammonium. Nitrate is water-soluble and more susceptible to leaching, while ammonium is prone to volatilization. Nitrates travel with water, leading to fertilizer being washed away by rain and irrigation into the soil below the root zone, or away from the field (1). According to estimates from the University of Idaho, only 50% of the nitrogen applied as fertilizer reaches the plant, with 25% lost due to leaching and another 25% due to volatilization (2).
The risk of ammonia volatilization increases with certain factors, such as moist or frozen soil, the presence of crop residue, and sandy soils with low organic matter content. This applies to all ammonium-based fertilizers, including urea, which eventually break down into ammonium in the soil. While rainfall or irrigation events shortly after fertilization can reduce these negative effects, the risk remains higher for dryland growers who lack access to irrigation equipment (3).
The terms "fixation" or "being tied up" are often used to describe the loss of phosphorus, potassium, and ammonium. Soils high in calcium can pose a challenge to phosphorus fertilization because phosphorus can undergo chemical reactions that render it unusable by crops (4). Potassium and ammonium have a strong attraction for soil particles and can be held so tightly that they may not be immediately available to crops.
However, this is not a permanent loss of the nutrients, as they may be gradually released over time and become available to crops in subsequent years (5).
1 https://extension.umn.edu/nitrogen/understanding-nitrogen-soils#leaching-761710
2 https://www.uidaho.edu/-/media/UIdaho- Responsive/Files/Extension/publications/bul/bul0899.pdf?la=en
3https://landresources.montana.edu/soilfertility/documents/PDF/pub/Urea%20vol%20factors%20BMP%20combo.pdf
4 https://blog-crop-news.extension.umn.edu/2022/11/p-and-k-fixation-in-soil-what-you-need.htm
5 https://extension.missouri.edu/programs/nutrient-management/nm-potassium/
How much of an impact do soil microbes have releasing tied-up nutrients, whether from applied fertilizer or plant residue breakdown?
Microbes, such as bacteria and fungi, play a pivotal role in enhancing soil fertility in agricultural systems. They are involved in the various processes that convert atmospheric nitrogen and fertilizer into nutrients available to crops. One example is the symbiotic relationship between rhizobia bacteria and legumes. These bacteria reside in nodules attached to the plant's roots and have the ability to transform atmospheric nitrogen into ammonia. Other bacteria will then convert the ammonia into nitrate, a plant-available form of nitrogen. (1) When the legume plant eventually dies, the nitrogen is released back into the soil to be absorbed by crops. (2). Thread-like fungi called mycorrhizae create similar relationships with plants. Their large underground network of roots attaches to those of a plant, greatly expanding the plant’s reach and increasing access to nutrients and water. A large study showed that potato yields increased in fields where they were inoculated by mycorrhizae. (3)(4) Another experiment proved the efficacy of these microbes when mycorrhiza was found responsible for 80% of the total phosphorus absorbed by the plant. (5)(6)
Soil contains numerous nutrients that are technically present but not readily available to crops, or soluble. This is true for the macronutrients nitrogen, phosphorus, and potassium. Fortunately, certain specialized microbes have the ability to free these nutrients, thus reducing reliance on external inputs like fertilizers. Studies conducted at The Ohio State University have demonstrated that increased microbial activity plays a crucial role in making nitrogen available. Soils with a microbial activity ranging from 1% to 3%, combined with 3% organic matter content, can generate up to 90 pounds of nitrogen annually. (7) Furthermore, when an abundance of bacteria is present and active, this leads to a proliferation of other microbes that consume them such as protozoa thereby releasing nitrogen additional nitrogen into the soil. The initial form of nitrogen created in this process is ammonium, a form not yet ready for crop use. (8) Next, a host of nitrifying bacteria called Nitrosomonas transform ammonium into nitrites. (9) In the final step, a group of bacteria called Nitrobacter, turn the nitrite into nitrate. A form that can finally be taken up by crops. (10) Phosphorus is often tied-up in molecules with other elements like calcium and is lost through immobilization and thus insoluble. Bacteria called gluconobacters help loose these chemicals bonds and set the phosphorus free by secreting organic acids. Some of these acids work to lower the pH of the soil which causes bonds to release the phosphorus while others act as chelators by replacing nutrients like phosphorus that are held tightly by clay particles. (11)(12) Similarly, certain soil bacteria exist that solubilize potassium. Enormous amounts of potassium already exist in the soil, but are in a mineral form unavailable to crops. (13) Bacteria known as KSMs or potassium solubilizing microbes such as Bacillus circulans and Acidothiobacillus ferrooxidans produce organic substrates like lactic and propionic acids that react with soil minerals solubilizing the potassium and becoming available to crops. (14)(15)
1) https://extension.umn.edu/nitrogen/understanding-nitrogen-soils#nitrogen-cycle-760361
2) https://www.symbio.co.uk/uploads/PDFs/The%20Role%20of%20Soil%20bacteria.pdf
3) https://link.springer.com/article/10.1007/s00572-015-0661-4
4) https://link.springer.com/article/10.1007/BF00937189
5) https://www.researchgate.net/profile/Reda-Gaafar/publication/26433587_Monitoring_of_Cultivars_Identity_and_Genetic_Stability_in_Strawberry_Varieties_Grown_in_Egypt/links/56c81c2008ae96cdd067efcb/Monitoring-of-Cultivars-Identity-and-Genetic-Stability-in-Strawberry-Varieties-Grown-in-Egypt.pdf#page=21
6) https://link.springer.com/article/10.1007/BF00000098
7) https://ohioline.osu.edu/factsheet/SAG-16
8) https://www.envirothonpa.org/wp-content/uploads/2014/04/7-Soil-Biology-Primer.pdf
9) https://www.sciencedirect.com/science/article/pii/S003807170500297X?casa_token=cFBd8xREgxYAAAAA:_mLdajVBl0Jdztpd2Pl6Iv-iztHAOWW1Y7fUwFcaZ9LiMzVw5-AbVLl2NCptZmKITApLgYXuNIo
10) https://www.sciencedirect.com/science/article/abs/pii/B9780123946263000107
11) https://www.sciencedirect.com/science/article/abs/pii/B9780128234143000253
12) https://www.sciencedirect.com/science/article/abs/pii/B9780128162095000052
13) https://extension.umn.edu/phosphorus-and-potassium/potassium-crop-production
14) https://annalsmicrobiology.biomedcentral.com/articles/10.1186/s13213-022-01701-8
15) https://pubmed.ncbi.nlm.nih.gov/30404208/