Investigation of the effects of poultry manure-based nutrient substitutes on soil inorganic nitrogen forms in a soil incubation experiment

The adequate quantity and quality of organic matter in soil is a fundamental criterion for nutrient management practices that meet today's challenges. In Hungary, a significant decline in soil organic matter content has been observed in many areas over recent decades. Adequate replacement is problematic for many farmers due to decreasing livestock populations and increasing environmental challenges. On the other hand the large quantities of manure generated during intensive poultry farming cannot be applied directly but, when fermented and supplemented, it can be spread effectively, offering an excellent solution for enhancing the organic matter and nutrient content of the soil.

In our studies, we examined the effects of fermented and pelletized poultry manure products in soil incubation experiments under varying water capacities on meadow chernozem soil. The experiments were conducted for one month. Treatments were terminated weekly to provide continuous information on the processes occurring in the soil. At the conclusion of the experiment, soil samples were taken from two depths in the pots, and after appropriate sample preparation, the pH of the samples was measured using electrochemical methods, while the ammonium and nitrate nitrogen contents were determined by photometric methods.

Our results indicate that the applied products did not significantly affect the soil pH in the tested layers, regardless of the water capacity levels. Compared to the control, all the tested products increased both the ammonium and nitrate contents of the soil. The increase in nitrate concentration exceeded the increase in ammonium content across all treatment combinations. It was found that the amount of ammonium-N in the different soil layers varied less than the nitrate concentration, and the levels of moisture availability also slightly influenced the quantitative relationships and ratios of the nitrogen forms produced.

Compared to the absolute control, nitrate concentration was four times higher, and ammonium concentration was twice as high in the soil layers. Among the nitrogen forms, nitrate was dominant. The positive effect of the product on the soil’s readily soluble and plant-available nitrogen supply was statistically demonstrated.

Acknowledgements: The research presented in the article was carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF 2.3.1 21 2022 00008 project.