In livestock production systems, it is of great importance to seek alternatives that allow mitigating nitrous oxide (N2O) emissions, within which the use of plant covers capable of reducing the nitrification process has been considered.
It should be clear that these systems are highly dependent on synthetic nitrogen fertilizers, essential for maximizing productivity. However, plants are rarely able to assimilate more than 50% of the applied nitrogen fertilizer.
In a research carried out by José Luis Contreras Santos, Manuel Ramón Espinosa Carvajal, Jorge Cadena Torres, Judith Martínez Atencia, Cindy Falla Guzmán and Jeyson Garrido Pineda, the aim was to evaluate the dynamics of N2O flows in soils under livestock occupation covered with improved grasses and nitrogen fertilization.
Study
This research was developed in a beef production system in the middle valley of the Sinú River, in which N2O fluxes were monitored over a 12-month period. An experimental design of randomized complete blocks was used, in an arrangement of divided plots and two repetitions, where the main plot corresponded to Brachiaria humidicola and Panicum maximun cv Tanzania with bare soil with subplots of three doses of nitrogen fertilization. (Read: Nitrogen fertilization would mitigate climate change)
Information on N2O flows was collected on a monthly basis under the conditions of the Turipaná de Agrosavia research center.
The research was carried out in an area in which 12 hectares were selected with nitrogen fertilization using urea with a concentration of 46% nitrogen. These applications were used broadcast, superficially in three fractional applications of the total dose, which were carried out under moist soil conditions.
Results
Regarding the soil, it was shown that the physical and chemical properties before and after the completed experimental period were similar between treatments. For the dynamics of the nitrous oxide flux, these showed a strong relationship with variations in rainfall.
At the beginning of the experimental period, in periods of low rainfall, the N2O fluxes reached the lowest emission averages. Also, it was observed that with the beginning of the rains, the N2O flows increased, registering the highest values and where there was a maximum peak of emissions.
In relation to the treatments evaluated, a significant interaction was observed between the N2O fluxes and the nitrogen doses and the cover used. In the case of pasture Brachiaria humidicola, the N2O fluxes increased with the increase in the fertilization dose. (Read: Do you apply good fertilization practices?)
What’s more, a similar behavior was analyzed in the pasture Panicum máximum cv. Tanzania where the increase in N2O emissions were 2.0 to 2.7 times higher when applying higher doses of nitrogen to the soil.
In soils without pasture cover, N2O fluxes were higher than in soils with cover and also increased with increasing doses of nitrogen fertilization.
Conclusions
The growing tendency to fertilize pastures with nitrogen sources to increase forage availability increases the risk of generating high amounts of N2O into the atmosphere. However, the use of covers with grasses can partially attenuate these effects, where different species or cultivars can exert a better function.
According to these results, the pasture Brachiaria humidicola established in livestock production systems in the Middle Valley of Sinú, could contribute to a greater extent in reducing nitrous oxide emissions by more than 40%compared to other pastures that usually occur in the region.
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