About the most common mistakes when making starter fertilizers, specialists from the State University of Mississippi, USA, Larry Oldham and Eric Larson are told.
Fertilizer burn
If fertilizers are entered along with seeds or very close with them when sowing, it is possible to burn.
Many fertilizers are salts that are dissolved in the corresponding ions in soil water. Imagine a table salt, which dissolves in water to the appropriate positive and negative Na + and Cl- ions. This dissolution creates a pressure drop, so water moves from plant roots into the surrounding soil (i.e. osmosis). Plants can fade, refund and die from the lack of water. This is called a fertilizer burn and can lead to a significant loss of germination.
This situation in the traditional spreading of fertilizers rarely occurs, as they are distributed to the larger area.
Similarly, starting fertilizer with 5 cm strips above and 5 cm below is a method designed to prevent contact with seedlings. Well-soluble fertilizers with a low saline index should be used, such as ammonium polyphosphate (10-34-0) or orthophosphates. Retail merchants and consultants should be familiar with the relevant recommendations for these applications.
Ammonia poisoningWhen using some nitrogen fertilizers, there is an additional risk of injury, which can be expected from alone content of the salt if the ammonia is allocated when entering the soil.
Ammonia is toxic and can freely penetrate into plants cells.
Urea, CAS, ammonium thiosulfate and diammoniumphosphate (DAP) represent more problems associated with ammonia than MAP, ammonium sulfate or ammonium nitrate.
The excretion of ammonia can be accelerated due to higher pH values or in the bulk of the soil, or as a result of the reaction near the fertilizers made.
Weather and soils are importantSoil conditions are important to determine why injuries may arise in some years, not to others.
Harvest damage is most likely when seedlings grown on sandy soils with a low content of organic substances are directly affected by fertilizers.
Dry weather increases the likelihood of injuries. In wet soils, fertilizer salts are diluted by diffusion away from the strip, but the diffusion does not occur in dry soils. Concentrated fertilizer increases the risk of burn.
Soils with low cation exchange ability having a rough structure and low organic substance content less react less with fertilizers than soils with a higher cation exchange ability (fine-grained).
The soil temperature is also part of the problem, since the roots grow slowly in cold soils, and they are longer exposed to a higher fertilizer concentration.
(Source: www.farmprogress.com. Authors: Larry Oldham and Eric Larson, Mississippi State University).