AOAC RI ERP EBOOK FOR FERTILIZERS

Table – 2 Analyses of Twelve Fertilizer Samples for Urea by AOAC Method 2003.14

Fertilizer Sample

Lab ID

Total –N*

% Urea-N

Mean

Std. dev.

Lab 1

Lab 2

1 2 3 4 5 6 7 8 9

0.21 0.06 0.05 0.00 0.01 0.19 0.07 0.25 0.37 0.01 0.14 0.07

29.89 28.54 28.44 28.33 28.47 24.95 30.78 30.06 28.01 28.13 26.36 29.87

12.04

12.45

26-068-03 26-051-01 26-068-02 26-076-07 26-076-06 26-076-08 26-079-01 26-086-04 26-103-02 26-103-03 26-100-03 26-010-02

12.25

8.63 8.68 8.45 8.58

8.51 8.57 8.45 8.60

8.57 8.63 8.45 8.59

16.08 12.55 12.56 12.09

15.70 12.70 12.07 11.36

15.89 12.63 12.32 11.73

10 11 12

6.85

6.83

6.84

15.55

15.28

15.42

X� σ x n σ 2

9.37

9.51

9.44

Average

10.95

10.84

- - - - - - - - - -

- - - - - - - - - -

Standard Deviation Number of samples

2.97

2.87

12

12

Variance

8.80

8.21

Pearson Correlation

- - - - - -

- - - - - -

0.99 1.30 0.11 1.80 0.22 2.20

T Stat

P(T

* Note: Total-N includes other forms of nitrogen in addition to unreacted (free) urea A statistical comparison (Students t-test, df, and, P) indicated that the results from two labs were statistically similar. The results for the analyses of the Free and Unreacted urea in these twelve fertilizers by two independent Labs using AOAC Official Method 2003.14 are shown graphically as well in Figure 2.