Data/hora: 15/05/2024 11:39:31

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 variation in chemical composition of pasture. I. Calcium, magnesium, potassium, sodium and phosphorus.
Ano de publicação: | 1978
Fonte/Imprenta: | New Zealand Journal of Agricultural Research, v.21, p.341-353, May, 1978.
Idioma: | Inglês

Conteúdo:

As part of a study of seasonal variations in chemical composition of pasture herbage Ca, Mg, K, and Na concentrations, and the ratios K/(Ca + Mg) and Ca/P, were determined by monthly samplings at seven sites in the lower North Island. Grass and cliver components were harvested separately at six sites, and grasses, clvers, and "other species" (herbs) at the seventh. Sub-plots were harvested by hand shears after which sheep were allowed to graze before the plots were enclosed until the next sampliong date. The seasonal patterns in herbage chemical composition were similar at all sites despite wide differences in soil, climate, and dry matter production. For Ca, the highest values in summer and the lowest in mid winter. Calcium concentrations were higher and the variations greater, in clovers than in grasses, and concentrations were even higher in "other species". Trends in Mg were seasonally similar to those for Ca but were much less pronunced; and differences between grasses and clovers were generally small. Potassium showed marked monthly fluctuations which were generally similar in the grass and clover component suggesting an effect of stock urine. High levels occurred in late winter, with a peak in early spring, and the lowest levels in early summer. There were no clear trends in Na concentrations, which were generally quite high in both grasses and clovers. Very high levels in "other species" occur-
red in late autumn to early spring. The K/(Ca + Mg) ratio (in chemical equiavalents) in the grass component generally remained above the proposed critical level of 2.2 for 3-4 months at most sites during the winter and early spring, indicating a possible grass tetany hazard. On the other hand the Ca/P ratio (in percentages) tended to fluctuate about the suggested "ideal" value of 1.5. The results were generally in accord with data from previous investigations on New Zealand pastures.

Thesagro: | Composição Química; Pastagem; Variação Sazonal.
Categoria do assunto: | --
Registro original: | Embrapa Pantanal (CPAP)
Exemplares: | CPAP - (28877-1) - ADD - SP - -- - SP0572 -  - 0572 - DIS