The Availability of P and K Contained in Pea and Fababean Residue to a Subsequent Crop
Assess the availability, release and use of P and K from field pea and fababean residues, to subsequest cereal crops.
IPNI-1995-CAN-SK16
30 Aug 2001
Justification
- Reason:
Pulse crops in general and peas in particular have become an important component in crop rotations in Western Canada. The beneficial effect of including legumes in crop rotations on subsequent crop yield and soil quality is well documented (Campbell et al. 1990). However, less well understood are the reasons why crop yields immediately following a legume are usually higher compared to no-legumes. The yield benefit in a subsequent crop has traditionally been attributed mainly to the release of plant available nitrogen (N) from the legume reside during residue decomposition. Recently, data has been collected (Stevenson and van Kessel 1995) which suggests that the contribution of N to the yield benefit may be relatively small and that factors other than nitrogen, such as reduced disease pressure, may be important. Another possible reason for increased yield is related to the effect of legume residues on the availability of the other plant nutrients such as phosphorus (P). Soluble P compounds contained in the above-ground residues of cereal crops are readily released to the soil by leaching (Gares and Schoenau, 1994) and have been shown to make a significant contribution to the P available to a subsequent cereal crop. Legumes such as peas and particularly fabebean have a high demand for phosphorus, with large amounts of phosphorus contained in the straw or residue component (WCFA 1990) which could make a significant contribution of available P to a subsequent crop. However, information on this contribution is lacking, with current soil tests and fertilizer P recommendations not adequately accounting for the contribution of residue P to the plant available P pool.
Economic Impact:
Documenting the availability of P contained in pulse crop residues to a subsequent crop will allow for more accurate fertilizer P recommendations, which take into account this contribution. The resulting better management practices should further encourage the use of legumes in rotation and enhance their associated benefits on soil quality and long term fertility.
Environmental Impact:
More accurate fertilizer P recommendations for crops following legumes will reduce environmental concerns surrounding over-fertilization and will encourage the use of soil conserving extended rotations including legumes.
Market Impact:
The results of this project will be disseminated through scientific publications, workshops, and producer meetings so that the individuals or agencies responsible for fertilizer guidelines will receive the information and be able to revise and refine their recommendations.