Dry matter accumulation of oats sown at five different sowing dates

In crop rotations the harvest date of the first crop affects the sowing date of the succeeding crop which then influences the potential annual yield of the rotation. This study measured the dry matter accumulation and growth rate of oats, cv Milton, sown on five different dates 4 March (S1), 28 March (S2), 21 April (S3), 12 May (S4) and 3 June (S5) in 2008. Each sowing was sequentially harvested until October. More than 15 t DM ha-1 was obtained from oats sown in March but the yield declined to 7.7 t DM ha-1 in the June sowing. Using a base soil temperature of 0 °C Milton accumulated yield at between 8 and 13 kg DM Cd-1 . The earlier autumn sowings accumulated more heat units and therefore had higher dry matter production. Winter growth of S4 and S5 was < 19 kg DM ha-1 d -1 . Low growth rates in these treatments occurred because they failed to reach a critical leaf area index before cool temperatures restricted canopy development. However, these later sown crops responded rapidly to warm spring temperatures. The final yield from the October harvest reflects the yield potential prior to sowing a maize or kale crop for summer