Planting Date and Seeding Rate Effects on Sunn Hemp Biomass and Nitrogen Production for a Winter Cover Crop
Table 3
Sunn hemp population, plant height, and stem diameter for planting date (PD) and seeding rate (SR) planted after wheat and corn harvest during 2007 and 2008 in east-central Alabama.
Population (plant/m2)
Height 12 WAPa (cm)
Stem diameter (mm)
Treatment
2007
2008
2007
2008
2007
2008
Wheat
Sunn hemp planting date
PD1b
73.8
80.5
155.2
173.3
4.84
6.61
PD2c
55.4
107.0
131.7
180.0
4.18
5.61
LSD0.05
21.4
19.1
10.1
16.9
0.82
0.90
Sunn hemp seeding rate (kg/ha)
17
31.5
46.0
145.5
172.4
4.77
6.97
34
53.8
66.0
141.5
174.5
4.66
6.33
50
77.5
102.5
149.1
183.3
4.38
6.07
67
95.5
160.5
138.0
176.4
4.22
5.07
LSD0.05
25.0
17.0
12.2
9.1
0.76
0.89
Corn
Sunn hemp planting date
PD1d
51.0
105.0
76.8
128.8
3.68
4.45
PD2e
27.3
100.8
93.7
128.6
3.85
4.35
LSD0.05
17.3
20.4
21.7
34.3
0.71
0.72
Sunn hemp seeding rate (kg/ha)
17
20.5
56.5
79.5
127.3
3.68
4.96
34
28.0
85.0
85.7
129.0
3.94
4.48
50
44.0
121.5
84.3
128.7
3.65
4.23
67
64.0
148.5
91.5
129.7
3.77
3.94
LSD0.05
17.2
17.0
9.9
8.2
0.69
0.54
ANOVA (P > F)
Wheat
PD
0.0781
0.0145
0.0015
0.3461
0.0831
0.0344
SR
0.0002
0.0000
0.2877
0.1017
0.4230
0.0025
PD × SR
0.7331
0.0067
0.1650
0.0063
0.9620
0.8520
Corn
PD
0.0122
0.6108
0.0912
0.9862
0.5620
0.7309
SR
0.0002
0.0000
0.1201
0.9367
0.8130
0.0068
PD × SR
0.0591
0.0113
0.2353
0.9438
0.3348
0.9400
aWAP: weeks after planting.
bPlanting date on 8 June 2007 and 11 June 2008.
cPlanting date on 22 June 2007 and 26 June 2008.
dPlanting date on 17 August 2007 and 22 August 2008.
ePlanting date on 31 August 2007 and 5 September 2008.
