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Performance and environmental effects of forage production on sandy soils. I. Impact of defoliation system and nitrogen input on performance and N balance of grassland
Author(s) -
Trott H.,
Wachendorf M.,
Ingwersen B.,
Taube F.
Publication year - 2004
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.2004.00405.x
Subject(s) - grazing , grassland , agronomy , forage , environmental science , fertilizer , productivity , human fertilization , nitrogen , pasture , silage , zoology , nitrogen fixation , composition (language) , biology , chemistry , linguistics , philosophy , organic chemistry , economics , macroeconomics
Abstract Grassland and its management is central to the productivity of and nitrogen (N) losses from dairy farms in north‐west Europe. Botanical composition, production and N surplus of grassland were assessed during five consecutive years. The experiment consisted of all combinations of five defoliation systems: cutting‐only (CO), rotational grazing (GO), grazing + one (MSI) or two silage cuts (MSII) and simulated grazing (SG). Four mineral N fertilization rates (0–300 kg N ha −1 year −1 ) and two slurry levels (0 and 20 m 3 slurry ha −1 year −1 ) were applied. Fertilizer N was more efficient in producing net energy (NEL) in grazing‐dominated, low white clover systems (GO and MSI systems: 70 and 88 MJ NEL kg −1 N) than in white clover‐rich systems (MSII, CO and SG systems: ≤60 MJ NEL kg −1 N). While sward productivity in system MSI was similar to that in system GO, system MSII benefited from increased N 2 fixation at low N rates. There were small differences in NEL concentrations of the herbage between defoliation systems. Crude protein concentration of the herbage increased with increasing N supply from fertilizer, excreta and N 2 fixation. N surpluses (−63 to +369 kg N ha −1 year −1 ) increased with increasing grazing intensity and increasing N fertilization rate. The average response in N surplus applied was 0·81, 0·59, 0·40, 0·33 and 0·24 kg N ha −1 in systems GO, MSI, MSII, CO and SG respectively.