Expected Grain Yield Due to Various Planting Dates and Final Plant Populations
Planting Date
Plant Population (Final) Per Acre
10,000 12,000 14,000 16,000 18,000 20,000 22,000 24,000 26,000 28,000 30,000 32,000 34,000 36,000
Percent of Optimum Yield
10-Apr
62
68
73
68
82
85
88
91
92
93
94
94
93
91
15-Apr
65
71
76
81
85
88
91
94
95
96
97
96
96
94
20-Apr
67
73
78
83
87
90
93
96
97
98
99
98
98
96
25-Apr
68
74
79
84
88
92
94
97
98
99
100
100
99
97
30-Apr
68
74
79
84
88
92
95
97
99
100
100
100
99
97
5-May
67
73
79
83
87
91
94
96
98
99
99
99
98
97
10-May
65
71
77
82
86
89
92
94
96
97
97
97
96
95
15-May
63
69
74
79
83
87
89
92
93
94
95
95
94
92
20-May
59
65
71
75
80
83
86
88
90
91
91
91
90
89
25-May
55
61
66
71
75
79
81
84
85
86
87
87
86
84
30-May
49
55
61
65
70
73
76
78
80
81
81
81
80
79
4-June
43
49
54
59
63
67
70
72
74
75
75
75
74
73
9-June
36
42
47
52
56
60
62
65
66
67
68
68
67
65

Source: Nafziger. 1994. J. Prod. Ag. 7:59-62. Yield response to planting date extrapolated beyond May 25 with concurrence of author.

Note: The highlighted area represents the optimum ranges (98 to 100% yield) of plant populations and planting dates for productivity levels greater than about 125 bushels per acre. Optimum plant populations for soils with historical yields less than about 100 bushels per acre will likely not respond to final plant populations greater than about 24,000 plants per acre. (R.L. Nielsen, Purdue Agronomy)