Publication Date
1989
Description
The Ley Farming System of southern Australia uses a rotation of cereal and pasture comprising annual Medicago (medic) or Trifolium (clover) species. Pastures regenerate in autumn from the permeable fraclion of seed reserves. For M. truncatula cv. Jemalong barrel medic, this is about 10 % annually (Crawford, 1970). In a survey of medic persistence in South Australia, Carter (1982) found that medic seed in the top 5 cm soil was highly correlated with plant density and production potential in the following year. Seed reserves associated with 400-500 plants/m2 were classed as 'good' in commercial practice, but such cases were uncommon, indicating a need for improved management. If a medic sward produces S seeds per unit area each year and the proportion that survives is X, then seed reserves (R) will be stable at S/ (1-X) seeds per unit area. To achieve a stable density of 500 plants/m2 of Jemalong medic with 250 000 seeds/kg, and X = 0.9, R would need to be 200 kg/ha and S 20 kg/ha/an. In practice, no medic seed is produced in the cereal years of the rotation. In pasture years input is reduced by drought, insect attack and weeds (Tow & Al-Akailah, 1981; Tow & Hodgkins, 1982). High stocking rates reduce spring seed yields and increase summer consumption of pods (Ashton et al., 1979; Carter, 1981; Tow & Al-Akailah, 1981). To manage medic leys the effects of such factors on medic persistence must be understood. This paper presents data for Jemalong medic and proposes a moniloring programme to assist management.
Citation
Tow, P G., "Monitoring Annual Medicago Ley Pastures for Management Decisions" (2025). IGC Proceedings (1989-2023). 32.
https://uknowledge.uky.edu/igc/1989/session4b/32
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Monitoring Annual Medicago Ley Pastures for Management Decisions
The Ley Farming System of southern Australia uses a rotation of cereal and pasture comprising annual Medicago (medic) or Trifolium (clover) species. Pastures regenerate in autumn from the permeable fraclion of seed reserves. For M. truncatula cv. Jemalong barrel medic, this is about 10 % annually (Crawford, 1970). In a survey of medic persistence in South Australia, Carter (1982) found that medic seed in the top 5 cm soil was highly correlated with plant density and production potential in the following year. Seed reserves associated with 400-500 plants/m2 were classed as 'good' in commercial practice, but such cases were uncommon, indicating a need for improved management. If a medic sward produces S seeds per unit area each year and the proportion that survives is X, then seed reserves (R) will be stable at S/ (1-X) seeds per unit area. To achieve a stable density of 500 plants/m2 of Jemalong medic with 250 000 seeds/kg, and X = 0.9, R would need to be 200 kg/ha and S 20 kg/ha/an. In practice, no medic seed is produced in the cereal years of the rotation. In pasture years input is reduced by drought, insect attack and weeds (Tow & Al-Akailah, 1981; Tow & Hodgkins, 1982). High stocking rates reduce spring seed yields and increase summer consumption of pods (Ashton et al., 1979; Carter, 1981; Tow & Al-Akailah, 1981). To manage medic leys the effects of such factors on medic persistence must be understood. This paper presents data for Jemalong medic and proposes a moniloring programme to assist management.
