Data/hora: 10/06/2024 08:01:18

Biblioteca(s): | Embrapa Pantanal.
Data corrente: | 01/08/1995
Data da última atualização: | 01/08/1995
Autoria: | METSON, A. J.; SAUNDERS, W. M. H.
Título: | Seasonal variations in chemical composition of pasture. II. Nitrogen, sulphur, and soluble carbohydrate.
Ano de publicação: | 1978
Fonte/Imprenta: | New Zealand Journal of Agricultural Research, v.21, p.355-364, 1978.
Idioma: | Inglês

Conteúdo:

Seasonal variations in pasture herbage for total nitrogen (Nt), total sulphur (S1), the nitro-
gen/sulphur ratio ((N/S)1), non-protein (Nap), total water-soluble carbohydrates (TWSC), and the N1/TWSC ratio, were studied by montly samplings at seven sites in the lower North Island. Trends in N, were similar in grass and clover components of the pasture, although clover levels were generally higher than grass levels. Highest concentrations oc-
curred in the late autum to early spring, and lowest in summer , although the summer minimum was much more evident in grass than in clover. Monthly fluctuations were similar in grass and clovers, suggesting possible random effects from urinary return of grazing sheep. Seasonal variations in S, were not pronunced, but levels in grasses were generally higher than those in the corresponding clovers, reflecting the greater tendency of grasses to accumulate sulphate-sulphur where the soil sulphur supply is not limiting. However, (N/S)t ratios ranged from 7 to 16 in grasses, and from 14 to 21 in clovers, suggesting that the sulphur supply may have been barely adequate at some sites. Nap levels were determined only in mixed herbages and tended to follow N1 levels. Nap comprised 16-20% of N, with little variation between sites. TWSC levels varied considerably between sites, and from month to month, which was not unespected for a constituent known to show wide diurnal and seasonal fluctuations. the mean levels showed some indication of a minimum in late summer to autumn, and a maximum in winter. The N/TWSC ratio was frequently above the reported danger level of 0.3 (for spring grass pastures in the semi-arid ranges of western U.S.A.), but its significance as an indicator of a grass tetany hazerd under New Zealand conditions is not known.

Palavras-Chave: | Pasture.
Thesagro: | Composição Química; Pastagem; Variação Sazonal.
Thesaurus Nal: | chemical composition; seasonal variation.
Categoria do assunto: | --
Registro original: | Embrapa Pantanal (CPAP)
Exemplares: | CPAP - (28879-1) - ADD - SP - -- - SP0574 -  - 0574 - DIS