Joint International Conference on Long-term Experiments ...

Relative yield (100 NP/NPK), %
Relative yield (100 NP/NPK), %
1.A. Winter wheat 1.B. Winter wheat
Y’ = 100 (1-10 –cx ); n = 59; Y’ = 1/(ax+b); n = 59
c: = 0.0153; r = 0.67
4.0
a = 0.04; b = -0.29; r = 0.72
100
80
60
40
20
0
0 100 200 300 400 500
AL-K2O, mg/kg
Grain increases (NPK-NP), t/ha
3.0
2.0
1.0
0.0
0 100 200 300 400 500
AL-K2O, mg/kg
2..A. Maize 2.B. Maize
Y’ = 100 (1-10 –cx ); n = 86; Y’ = 1/(ax+b); n = 86
c: = 0.0083; r = 0.77 a = 0.01; b = -0.02; r = 0.70
100
4.0
80
60
40
20
0
0 100 200 300 400 500 0 100 200 300 400 500
AL-K2O, mg/kg
AL-K2O, mg/kg
Figures 1 and 2. Relationship between the AL-K2O contents of K control (NP) plots and
responses of winter wheat and corn to K fertilization, calculated from the database of
Hungarian field trials on K fertilization, 1960–2000, using the Bray-Mitscherlich approach
Responses to K fertilization were eliminated when soil K test values exceeded 160-170
mg/kg for winter wheat, 170-180 mg/kg for alfalfa and 200 mg/kg for maize (Figure 1-
3.).
58
Grain increases (NPK-NP), t/ha
3.0
2.0
1.0
0.0