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作为牧草化学成份季节性变化研究的一部份,Ca、Mg、K和Na的浓度以及K/(Ca+Mg)、Ca/P的比率是在下北岛的七个地方逐月采样测定的。在六个试验地分别刈割禾草和三叶草的样品,而在第七个试验地则刈割各种禾草、各种三叶草和“其他草种”(草本植物)的样品。小区用手剪刈割,收割之后,各区重新封闭作下一次采样之前,允许绵羊放牧。尽管土壤、气候和干物质产量差别很大,但是,所有试验点的牧草化学成份的季节变化趋势都相似。如Ca,其最高含量出现在夏季,最低含量出现在仲冬。三叶草含Ca的浓度比禾草高,变化也较大,“其他草种”含Ca的浓度则更高。Mg的季节性变化与Ca有同样的趋势,但远不如Ca那么显著,且禾草与三叶草的含量之间的差别一般较小。K含量随着月份的波动很明显,在考虑家畜尿影响的情况下,这种波动在禾草和三叶草中一般是相似的,隆冬时节含量高,早春时达到高峰,初夏时含量最低。Na的浓度没有明显的变化趋向。它在禾草和三叶草中一般都很高;在“其他草种”中,深秋至早春这段时间内含量很高。在多数地方,冬季和早春期间的3—4个月内,禾草组成成份中K/(Ca十Mg)比率(以化学当量计)一般都高于已推荐的临界值2.2,这暗示可能对牲畜有引起饲草性痉挛症的危险。另一方面,Ca/P比率(百分比)则有在建议的“标准”值1.5附近波动的趋势。这些结果一般都与以前在新西兰牧场上研究所得的资料一致。
As part of a seasonal variation study of pasture chemical composition, concentrations of Ca, Mg, K and Na and K / (Ca + Mg), Ca / P ratios were determined monthly by sampling at seven sites in the Lower North Island. Grass and clover samples were mowed in six trials, while in the seventh trial samples of various grasses, various clover and “other grasses” (herbaceous plants) were mowed. Community cut with hand-cut, after harvesting, the district reclosing for the next sampling before allowing sheep grazing. Despite the large differences in soil, climate and dry matter yields, seasonal changes in pasture chemical composition at all sites are similar. Such as Ca, the highest content appears in the summer, the lowest content appears in the midwinter. The concentration of Ca in clover was higher than that in grass, and the change was also greater. The concentration of Ca in other species was higher. Seasonal changes in Mg have the same tendency as for Ca, but are far less pronounced than Ca, and the differences between grasses and clover are generally small. The K content fluctuates significantly with the months, considering fluctuations in livestock urine, the fluctuations are generally similar in grass and clover, with high in winter and high in early spring and lowest in early summer. The concentration of Na has no obvious change trend. It is generally high in grasses and clovers; in “other grasses,” it is high from late fall to early spring. In most places, the K / (Ca 10 Mg) ratio (in stoichiometries) of the grass components is generally above the recommended cutoff of 2.2 within 3-4 months of winter and early spring, suggesting that Livestock have the risk of causing forage spasms. On the other hand, the Ca / P ratio (percentage) has a tendency to fluctuate around the suggested “standard” value of 1.5. These results are generally consistent with the previous study of the pastures in New Zealand.