Forage production and quality of tall wheatgrass (Thinopyrum ponticum) pastures under halo-hydromorphic conditions
2024
Federico Fina | Nicolás Bertram | María Laura Gatti | Germán D. Berone
Tall wheatgrass is a perennial C3 grass widely used in halo-hydromorphic environments. Nitrogen fertilization is an important tool to improve forage production and nutritive value. The present objective was to determine the impact of nitrogen fertilization on the forage quality and its relationship with forage production in late spring. Three independent sites were selected in late spring using soil salinity and water table attributes (salinity and depth) as indicators and classified as low, intermediate, and high HHM (halo-hydromorphism) environments. On each site, forage production and forage quality were assessed under two levels of nitrogen fertilization: without (N0) and with nitrogen fertilization (N150). Nitrogen fertilization improved the nutritive quality of tall wheatgrass at all sites by maintaining high crude protein levels and increasing dry matter digestibility without morphological changes, indicating intrinsic quality improvements in the blades and/or sheaths. An inverse relationship was found between biomass and forage quality, suggesting the need for frequent grazing to prevent excessive biomass accumulation and maintain high blade proportions, enhancing animal performance. However, low ground cover raises salinization risk, so grazing methods should maximize high-quality forage harvest without damaging post-grazing biomass. Finally, due to the risk of N losses, in HHM environments conducting site-specific zoning is a fundamental prerequisite for implementing N fertilization practices aimed at improving both forage production and quality.
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