Nitrogen
Nitrogen is one of the most important nutrientsfor plant growth and the driving force behind crop production.
In fact, it allows you to:
- Rapid and vigorous growth of leaves, stems, and roots.
- Improved photosynthesis, thanks to chlorophyll, which captures the sun's energy.
- Protein production, which is essential for plant development.
- Greater resistance to stressors, such as drought or certain diseases.
An appropriate nitrogen application thus helpsproduce healthier, more productive, and higher-quality crops.
However, in some cases, there may also be an excess of nitrogen, which can have a negative impact on the existing crop.
Symptoms and Consequences
Excess nitrogencauses signs that are visible to the naked eye:
- Excessive and too rapid vegetative growth
- Tall plant
- Thin stems
- Thin, dark green leaves
- Greater susceptibility to disease
- Foliage Development in Fruit Trees
- Lodging issues (e.g., corn)
- Reduction in sugar content (e.g., fruits and vegetables)
Note
The symptoms of nitrogen excess observed in the field may differ from those described in this article. Your experience and knowledge of your field will be essential for analyzing these symptoms.
These symptoms impact farmers, in particular, by affecting crop yield and quality. Additionally, extra pest control measures may sometimes be necessary, leading to higher production costs.
Furthermore, every unit of nitrogen not absorbed by crops represents an investment that yields no return, especially in a context where fertilizer costs remain high and are subject to significant fluctuations.
Finally, if excess nitrogen in the soil is not absorbed by a crop, it is at risk of leaching. The economic loss is then immediate.
The Causes
Several factors can explain the accumulation of nitrogen in the soil.
In general, this excess nitrogen is the result of applying too much fertilizer or manure relative to the crop's actual potential.
In addition,climatic conditions(drought, excess water, growth stress) play an important role. They limit crop growth and reduce their nitrogen uptake.
Furthermore,the mineralization of organic matter—whichis particularly active in the fall or spring—can release significant amounts of nitrogen that were not anticipated.
Certaincrop rotationsalso contribute to the accumulation of nitrogen residues; this is the case with legumes.
Finally, the lack of plant cover between two crops contributes to the retention of a significant amount of mineral nitrogen in the soil profile and increases the risk of excess nitrogen and losses due to leaching.
The amount of nitrogen in the soil should be determined based on the needs of the next crop.
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Possible Solutions
There are several measures that can be taken to limit this excess nitrogen.
Burying wheat straw: Straw residues are rich in carbon. Microorganisms will break them down into organic matter by consuming nitrogen from the soil. As a result, the soil will regain a nitrogen-to-carbon balance suitable for subsequent crops.
The use of uncomposted manure to prevent organic matter from breaking down too quickly once it reaches the soil. However, if the fibers in the manure are coarse, some of the nitrogen in the soil will be used up to break them down.
Choosing Cover Crop Species
Different species can be classified based on their C/N ratio. This ratio defines a plant’s ability to lignify during its life cycle and reflects the rate at which the vegetation cover decomposes after it is destroyed.
The higher the carbon content of the material, the slower it will decompose and the more soil nitrogen it will consume—which is exactly what we’re looking for in this case.
Here are several species that can address this issue:
- Buckwheat, buckwheat, sorghum/millet for post-harvest planting from June 15 to August 1
- Cruciferous vegetables such as white mustard, brown mustard, Abyssinian mustard, and forage radish, for sowing starting August 15
These species are ideal for addressing the issue of excess nitrogen in the soil, but must be combined with other species to address various problems (such as soil compaction, the presence of nematodes, or severe soil crusting, among others).
You can find our complete line of suitable products in the " Plant-Based Cutlery" section.