Level 4 Data summaries and links to related documents and reports

Key findings (brief)

• Pastures were large consumers of soil derived N (58 – 154 kg N/ha), while wheat and lupins were inefficient users of soil N (29 – 51 kg N/ha).
• A high rate of decomposition of organic matter was observed due to the sandy soil (annual net N mineralisation ranged from 80 – 130 kg N).
• Legumes were able to add adequate rates of organic N to soil to ensure rates of net N mineralisation sufficient to support cereal yields in excess of shire averages.
• In practice, the asynchrony in supply and demand for N resulted in the inefficient use of soil-derived N by wheat.
• The lupin-wheat treatment resulted in greater N/ha, 27kg (60% of total soil NO₃⁻) as opposed to the pasture-wheat rotation which resulted in 4kg N/ha (25% of total soil NO₃⁻).
• The amount of NO₃⁻ in soil at the start of the growing season was affected by previous crop, with a lower range following wheat (31-68kg N/ha) than following legumes (40-106kg N/ha). The large quantities of NO₃⁻ in the soil at the break of the season contributed to NO₃⁻ leaching.
• Greater N uptake by capeweed (Arctotheca calendula L.) than by either wheat or lupin was the main reason for the lower amount of NO₃⁻ leached in pastures.

Key tables and figures extracted from data, literature and miscellaneous publications

Various clippings

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