Research Article

Planting Date and Seeding Rate Effects on Sunn Hemp Biomass and Nitrogen Production for a Winter Cover Crop

Table 2

Growing degree days measured for sunn hemp during the 2007 and 2008 growing seasons in east-central Alabama.

MonthSunn hemp growing degree daysa
Wheat 2007Wheat 2008 Corn 2007 Corn 2008
PD1bPD2bPD1PD2PD1PD2PD1PD2

June404.4163.3332.586.7
July544.4544.4538.9538.9
Aug.313.9499.2359.4295.818.6163.9
Sep.458.1458.1439.4369.2
Oct.300.8325.3227.5247.8
Nov.32.817.5

Total1262.81206.9871.4985.01054.7834.7830.8634.5

aGDD until termination. Calculated as [(maximum temp. + minimum temp.)/2] −10°C.
bPlanting date of sunn hemp immediately after cash crop harvest (PD1) and planting date of sunn hemp 2 weeks after cash crop harvest (PD2).