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)
Treatment
2007
2008
2007
2008
2007
2008
Wheat
Planting date
PD1a
4.0
4.5
15.6
26.5
62.9
116.7
PD2b
2.0
6.6
11.5
13.8
21.5
90.7
LSD0.05
1.0
1.0
5.7
5.1
15.7
40.8
Seeding rate (kg/ha)
17
2.5
5.6
13.6
20.6
35.7
107.1
34
2.9
5.5
13.9
20.5
43.3
104.3
50
3.2
5.8
13.4
19.0
44.7
101.9
67
3.2
5.4
13.4
20.5
45.0
101.5
LSD0.05
0.9
1.4
3.5
7.1
22.3
36.8
Corn
Planting date
PD1c
0.8
3.2
35.4
16.8
27.6
48.9
PD2d
1.6
3.3
25.8
17.0
40.3
52.7
LSD0.05
0.7
2.7
3.7
7.0
19.8
26.1
Seeding rate (kg/ha)
17
1.2
3.1
31.3
17.6
35.0
47.0
34
1.3
3.7
29.6
17.4
36.6
64.3
50
0.9
3.4
28.8
16.9
25.1
46.9
67
1.3
3.0
32.7
15.9
39.2
44.8
LSD0.05
0.3
1.0
5.2
4.6
10.1
17.5
ANOVA (P > F)
Wheat
PD
0.0026
0.0002
0.1291
0.0000
0.0000
0.1701
SR
0.3701
0.9363
0.9884
0.9587
0.8055
0.9873
PD × SR
0.5462
0.9598
0.4831
0.9853
0.9219
0.8714
Corn
PD
0.0261
0.9289
0.0000
0.9344
0.1664
0.7334
SR
0.0286
0.4183
0.4260
0.8693
0.0447
0.1025
PD × SR
0.0169
0.2708
0.7515
0.6596
0.2085
0.2750
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.