Nitrogen fixation by pasture legumes as influenced by soil or fertiliser nitrogen
1989
Ledgard, S.F. (Ruakura Agricultural Centre, Hamilton (New Zealand))
Describes two field experiments examining N fixation by "Grasslands Kopu" and "Grasslands Huia" white clovers grown with ryegrass. Nitrogen fertilizer application at rates of up to 50 kg N/ha showed relatively little effect on N fixation except for a maxima from addition of 5 kg N/ha. The proportion of clover N fixed from atmosphere N was about 4-7% higher for Kopu than Huia, although they both derived similar amounts from the soil. Atmosphere N fluctuated seasonally and was inversely related to levels of inorganic N in soil. Atmosphere N declined during summer and the highest transfer of fixed N from clover to associated grasses also occurred during summer
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