Key Points
- Nitrogen (which in the form of nitrate is very soluble) can be lost via leaching from soil when water, in excess of plant requirements enters soil and drainage occurs.
- Over a seven year period (2001-07), winter leaching losses from the Millennium Tillage Trial site averaged 28 kgN/ha/year under a range of different tillage practices on winter fallowed soil. Growing forage crops through winter reduced this average loss by nearly 50% to 15 kgN/ha/year.
- Significant amounts of nitrogen can be leached from permanently fallow soil where no plants are grown, even where no fertiliser is applied. This shows the important role of plants in taking up N.
- Timeliness and type of tillage method used for sowing autumn crops (also slug and grass grub control) can have important implications for ensuring good crop establishment. The potential for loss of N via leaching is increased where plant cover is poor. Less N may be leached where crops are sown early and slugs/grass grubs are controlled effectively.