Table 4 Optimal predictors and responses for the four sources of phosphorus and two wetting techniques.

From: Optimizing phosphorus released in calcareous soil amended with bone char and bone ash using response surface methodology and desirability function

P-Source

Extraction method

Optimal predictors

Optimal responses

Individual desirabilities

Time,

days

PL,

mg kg

Avail. P,

mg/kg

Solub. P,

mg/kg

Solub. Ca,

meq/l

Solub. Mg,

meq/l

pH

Avail. P,

mg/kg

Solub. P,

mg/kg

Solub. Ca,

meq/l

Solub. Mg,

meq/l

pH

BA

DW

27.7

4000

39.21

1.00

2.71

2.74

8.52

1.00

0.37

0.70

0.95

0.31

AW

41.8

3479.1

52.08

2.72

5.98

3.45

8.26

0.89

0.88

0.66

0.74

0.30

BC

DW

44.3

2983.8

24.26

0.36

2.71

1.60

8.43

0.77

0.79

0.38

0.83

0.72

AW

54.2

4000

36.24

2.28

6.23

4.15

8.01

0.92

0.92

0.60

0.76

1.00

PR

DW

88.4

3717.4

12.54

0.38

3.77

1.95

8.16

0.72

0.95

0.53

0.98

0.71

AW

14.3

4000

771.49

0.32

5.73

3.30

8.15

1.00

0.25

0.81

0.68

0.11

SSP

DW

14

4000

809.53

1.39

17.94

7.21

7.49

0.91

0.87

0.76

0.95

0.94

AW

14

4000

739.82

8.44

22.41

4.03

7.21

0.83

0.95

0.76

0.32

0.95

  1. BC: bone char; BA: bone ash; PR: phosphate rock; and SSP: single superphosphate.
  2. DW: distilled water; AW: acidified water; PL: phosphorus level.
  3. Avail. P: available phosphorus; Solub. P: soluble phosphorus; Solub. Ca: soluble calcium; Solub. Mg: soluble magnesium.
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