Section 5
Chapter 4,633

A study of mole drainage with simplified cultivation for autumn sown crops on a clay soil 5. losses of nitrate nitrogen in surface run off and drain water

Dowdell, R.J.; Colbourn, P.; Cannell, R.Q.

Soil and Tillage Research 9(4): 317-332


ISSN/ISBN: 0167-1987
Accession: 004632583

Direct drilling of autumn-sown cereal crops [wheat, oats] reduced the loss of nitrate in drainage. Losses of nitrate nitrogen in water draining from arable land have been measured for 4 seasons, 1980-1984. The field experiment was on a mole-drained clay soil in southern England. Autumn-sown cereal crops were established by direct drilling or after ploughing and traditional seed-bed preparation. Losses ranged from 3 to 75 kg N ha-1 year-1, with an average of 34 kg N ha-1 year-1. Most of the loss (about 90%) was removed via the mole-drain system. Measured loss of nitrate from the direct-drilled soil was 76% (range 48-89%) of that lost from the ploughed soil. Mole drains apparently increased loss of nitrate directly to the river system. In the absence of mole drains, nitrate loss in surface drainage averaged 6 kg N ha-1, compared with 4 kg N ha-1 in the presence of drains. However, in one year, exceptionally high amounts of nitrate (80 kg N ha-1) were lost from undrained, direct-drilled land because of poor crop establishment; deep leaching of nitrate in the undrained soil was not measured. Approximate calculations show that up to half the autumn-applied fertiliser-N was lost by leaching and up to 15% of spring applications.

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