What impact does dairy cow pugging have on clover N2 fixation and long- term farm production?

Authors

  • J. Menneer
  • S. Ledgard
  • C. Mclay
  • W. Silvester

DOI:

https://doi.org/10.33584/jnzg.2001.63.2432

Abstract

The effects of a single, moderate or severe pugging event in early spring on pasture production, clover growth, and N2 fixation were measured during a 1-year study on dairy pasture in the Waikato. Moderate and severe pugging of the poor-draining Te Kowhai soil resulted in annual pasture production decreases of 21% and 45%, respectively. Clover showed a much greater decrease in production than grass (65% vs. 38%) following severe pugging, and indicates that clover is more susceptible to the negative effects of pugging than grass. Nitrogenase activity showed a rapid decrease (up to 90%) within 3 days of pugging, and reflected the measured decrease in air-filled porosity (from 16% in the non-pugged to an average of 11% for the moderately and severely pugged treatments) and measured loss of root biomass. On an annual basis, the total amount of N fixed decreased from 151 kg N/ha in the control to 109 kg N/ha (-28%) and 45 kg N/ha (-70%) in the moderate and severe treatments, respectively. Longer-term effects of the decrease in clover DM yield from a single moderate or severe pugging event each year were modelled using a dynamic dairying model of N cycling. After 10 years, pugging was predicted to decrease N2 fixation, soil organic N and grass growth, and result in a loss in milk production of 21% and 54%, respectively. On a whole farm basis, if moderate and severe pugging occurred on 50% and 10% of the farm, respectively, this would represent a decrease in milk production of 16% (e.g., from 1000 to 840 kg milksolids ha/year). Keywords: dairying, N2 fixation, pasture production, pugging, ryegrass, white clover

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Published

2001-01-01

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Section

Articles