Research Article

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

Table 4

Sunn hemp biomass yield, N concentration, and N content for planting date (PD) and seeding rate (SR) when planted after wheat harvest and corn harvest during 2007 and 2008 in east-central Alabama.

Biomass yield (Mg/ha)N concentration (g/kg)N content (kg/ha)
Treatment200720082007200820072008

Wheat
Planting date
 PD1a4.04.515.626.562.9116.7
 PD2b2.06.611.513.821.590.7
 LSD0.051.01.05.75.115.740.8
Seeding rate (kg/ha)
 172.55.613.620.635.7107.1
 342.95.513.920.543.3104.3
 503.25.813.419.044.7101.9
 673.25.413.420.545.0101.5
 LSD0.050.91.43.57.122.336.8
Corn
Planting date
 PD1c0.83.235.416.827.648.9
 PD2d1.63.325.817.040.352.7
 LSD0.050.72.73.77.019.826.1
Seeding rate (kg/ha)
 171.23.131.317.635.047.0
 341.33.729.617.436.664.3
 500.93.428.816.925.146.9
 671.33.032.715.939.244.8
 LSD0.050.31.05.24.610.117.5
ANOVA (P > F)
Wheat
PD0.00260.00020.12910.00000.00000.1701
SR0.37010.93630.98840.95870.80550.9873
PD × SR0.54620.95980.48310.98530.92190.8714
Corn
PD0.02610.92890.00000.93440.16640.7334
SR0.02860.41830.42600.86930.04470.1025
PD × SR0.01690.27080.75150.65960.20850.2750

aPlanting date on 8 June 2007 and 11 June 2008.
bPlanting date on 22 June 2007 and 26 June 2008.
cPlanting date on 17 August 2007 and 22 August 2008.
dPlanting date on 31 August 2007 and 5 September 2008.