Field trials
December 1, 2023

Choose the right fertilizer to avoid nitrogen loss

The poor capacity of soils to retain nitrogen in the form of nitrate ions, largely due to the negative charge of the latter, has long placed nitrogen fertilization of cultivated soils at the center of focus. Managing it correctly is in fact essential to reduce its impact on the environment.

 

 

Why do you need to avoid nitrate runoff

The nitrates leached by rain and irrigation migrate to the deep layers of the soil and reach the groundwater, where they risk accumulating with potential negative consequences on human health. In fact, once ingested, nitrates can be metabolized and transformed into nitrosamines, which are potentially carcinogenic.

At the same time, the accumulation of nitrates in lakes and seas, carried by rivers and/or from crops close to coastal areas, can give rise to eutrophication phenomena, with excessive proliferation of mucilaginous algae and dreadful imbalances in maritime and lake ecosystems.

Finally, it’s important to remember that Nitrogen loss in soil, in addition to impoverishing it, represents a needless cost when administered through fertilization, since it’s removed from the soil layer explored by the roots of plant crops, and thus unavailable to them.

 

The Nitrate Directive and water quality in Europe

To stem the problem of nitrogen loss from cultivated land, in 1991 Europe passed a legislation on the matter, issuing the famous “Nitrate Directive” (Dir. 91/676/EEC), aimed at “reducing the pollution of groundwater and surface water caused directly or indirectly by nitrates of agricultural origin and preventing any further pollution of this type, encouraging the use of good agricultural practices”.

The application of the Directive certainly had positive effects in its first period of application. However, as pointed out by the EU in a Report on Nitrate Pollution published in 2021, thirty years after the enactment of the Directive, starting from 2010, the quality of water in our continent has fallen sharply again, as a result of Nitrate pollution, effectively eliminating the progress made in the previous twenty years of application.

The need for a remedy is therefore evident, by intervening on all factors that may affect the absorption efficiency of nitrogen distributed in our crops.

 

The role of fertilizer formulation

Among these factors, the formulation of the fertilizers distributed certainly plays a major role. Agribios Italiana has always believed in the superiority of organo-mineral fertilization in terms of environmental and nutritional performance. The “protective” role played by high-quality organic matter against the mineral elements contained in Agribios brand fertilizers favors the optimal supply of nutrients to crops.

AGRIAZOTO 300 is a high-strength nitrogen-based organo-mineral fertilizer, designed for the optimal fertilization of nitrogen-hungry crops. The specific composition of the organic matter and the forms of Nitrogen contained, determine a prompt and gradual transfer of the nutritional element which, protected from losses due to evaporation and runoff, best best accompanies the development and needs of the crop.

 

AGRIAZOTO 300: testing on common wheat in the Po Valley

In the 2021-23 growing season, in collaboration with the Centro di Saggio di Terremerse Soc. Coop, a nitrogen fertilization test was conducted on common wheat of the LG Auriga cultivar, comparing Agribios’ AGRIAZOTO 300 with two gradually released fertilizers, with the aim of verifying their nutritional effectiveness and the respective losses of nitrogen due to runoff, in the form of nitrates. The tests were carried out in plots located in the municipality of Ravenna.

The planting of the plots took place in October 2022 and the fertilizers were distributed at the beginning of March 2023, corresponding to the start of the stem elongation, in doses that would guarantee, in all three cases, 120 kg/ha of Nitrogen.

More specifically, the three products tested in their respective theses were:

  • Thesis 1: 32N mineral fertilizer (20% urea + 12% ammonia) + 32% SO3 + DMPP
  • Thesis 2: 30N organo-mineral fertilizer (1% organic + 6% ammonia + 23% urea) + 15% SO3
  • Thesis 3: AGRIAZOTO 300.

Micro sprinklers have been used to perform sprinkler irrigation with the aim of increasing runoff in case of low rainfall. The very rainy weather trend, especially during the month of May, combined with sprinkler irrigation, have strongly favoured the runoff of nitrogen, creating ideal conditions for testing the resistance of the various fertilizers.

The surveys were performed by taking the circulating solution with suction lysimeters positioned 15 and 30 cm deep. Simultaneously with the solution samples, the leaves were sampled and analyzed to verify the nutrient content within the wheat plant.

At the harvest (end of June 2023), the production was measured (t/ha compared to 13% humidity), together with the qualitative parameters: humidity (%), protein (% SS), gluten (at 13% humidity), and the specific weight (kg/hl).

The data collected revealed that:

  • thesis 1, fertilized with chemical fertilizer containing the nitrification inhibitor DMPP, showed the worst performance, both in terms of yield and protein content. In terms of nitrogen release, there is also a nitrogen peak in the two weeks following distribution, followed by low values later on, an indication of poor resistance to runoff;
  • theses 2 and 3 (organo-mineral fertilizers comparison) achieved very similar production yields and a very high protein content. In this case, as far as proteins are concerned, thesis 3 with AGRIAZOTO 300 was the best, with half a percentage point higher than thesis 2, and 2.1 percentage points higher than thesis 1;
  • in terms of Nitrogen in the circulating solution, thesis 3 reveals the presence of nitrate at 15 cm even two months after the distribution of AGRIAZOTO 300 (Graph 1), a fact also confirmed by the higher leaf nitrogen value compared to thesis 2, where a significant nitrate content in solution is never detected.
Graph 1 – Nitrogen content in the circulating solution and in the leaves at the different collection dates.

Therefore, both the organo-mineral fertilizers tested showed significantly higher performance than those of the product with a chemical inhibitor DMPP. In particular, AGRIAZOTO 300 was the most resistant to runoff and, by preserving nitrogen in the soil until the grain filling phase, it made it possible for the grain to achieve a higher protein content.

 


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