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Defoliation frequency affects litter responses and nitrogen excretion by heifers in palisadegrass–forage peanut pastures
Author(s) -
Gomes Fernanda de Kássia,
Homem Bruno Grossi Costa,
Oliveira Michael David Batista Luaemar,
Dubeux José Carlos Batista,
Boddey Robert Michael,
Bernardes Thiago Fernandes,
Casagrande Daniel Rume
Publication year - 2020
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.1002/agj2.20240
Subject(s) - brachiaria , forage , grazing , agronomy , cycling , zoology , litter , legume , canopy , biology , botany , forestry , geography
Legumes can contribute significantly to nitrogen (N) input in grazing systems. Grazing management is a critical factor affecting N cycling in mixed pastures, altering the legume N input as a result. This study assessed how defoliation frequency affects N cycling in rotationally stocked palisadegrass ( Brachiaria brizantha ) and forage peanut ( Arachis pintoi ) pastures. Treatments included four grazing management strategies, defined by the rest period interruption when the canopy reached 90 (90LI), 95 (95LI), and 100% (100LI) of photosynthetically active radiation interception (LI), and a fixed rest period of 42 d (42D). A 2‐yr experimental period was adopted. Existing litter was greater at 100LI (2208 vs. 1964 kg ha −1 ; average of 42D, 90LI, and 95LI, respectively). Greater defoliation frequency (42D and 90LI) resulted in increase of litter legume proportion, resulting in greater decomposition rate, lower litter half‐life ( p < .001, and p = .015, respectively), and greater N cycling (91 vs. 64 kg ha −1 season −1 ). Less frequent defoliation (100LI) resulted in reduced total forage intake, proportion of legume intake, and lower N intake compared with other treatments ( p = .007, p = .081, and p < .001, respectively). Greater defoliation frequency increased N cycling via litter, but did not affect excretion due to compensation with stocking rate. Defoliation frequency between 90 and 95% LI optimizes N cycling in palisadegrass‐forage peanut mixed pastures.