Table 1.  Average Soil Test P Results As Influenced by Several Sampling
                    Methods Used On a 3.4 Acre Field.1

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                                           Soil Test P Level (lbs/A)
                                    _______________________________________
                          No. of               Std.       (%)     std.error
    Sampling Procedure    Samples    mean    deviation    c.v.    of mean
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1 - every 8 ft across a    162       25.2      9.1         36       0.7
    40-ft swath at 9
    locations along a
    750-ft swath in
    3 alternate swaths

2 - 40-ft x 50-ft grid      54       27.4     11.9         43       1.6
    taken at 9 locations
    along a 750-ft swath
    of 200-ft width

3 - 200-ft x 100-ft grid     9       27.1      8.9         33       3.0
    in a swath 750-ft long
    and 200-ft wide

4 - Random zig-zag  
       left-right            9       24.9      7.5         30       2.5
       right-left            9       24.9      5.0         24       1.7

5 - 3 samples taken          9       24.0      7.0         29       2.3
    down center of 750-ft
    swath of 40-ft width
    in 3 alternate swaths

6 - Diagonal across area
       SW-NE                 6       29.7     13.4         44       5.5
       SE-NW                 6       26.7      5.8         22       2.4
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1 Field dimensions: 750-ft x 200-ft





 
  
        Table 2. Comparison of Sampling Intensity, Independent Sampling,
            and Lab Analysis at Different Dates on Soil Test Results
                        From a Small Area (0.56A)

                                    
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                                                                     Area Randomly Sampled2
                      Area Intensively Sampled1/            Sampler A  Sampler B
               ________________________________________  ________________________

                        Std.    Std. error Range of the
Soil Test       Mean  deviation  of mean   Mean + S.D.(3)  wk. 1(4)  wk. 2(4) wk. 1(4)  wk. 2(4)
_________       ____   _________________________________________________________
   pH           6.30      0.17      0.03       6.13 to 6.47       6.64        6.32          6.63    6.30
Buffer pH       6.72      0.08      0.02       6.64 to 6.80       6.75        6.83          6.77    6.88
K (lbs/A)       259        27       5.5        232 to 286         239         235           278      264 
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(1)  Av. of 24 blocks within a 300-ft x 82-ft area (0.56 Ac) with 6 core
    samples taken per block (total of 144 cores).
(2)  Sampled independently by 2 people (A and B) who each took 10 random cores
    from the 300 ft x 82 ft area.
(3)  Range of readings based on the average of the 24 subsampled blocks plus
    and minus 1.0 standard deviation (68% of the readings fall within this
    range).
(4)  Readings from subsamples from sampler A and B sent to lab on two different
    weeks.
    
 


   
    
 
  
Table 3.  Comparisons of 100 Analyses for Two Quality Control Soil Samples
          (March 30 to August 4, 1995).
 
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                                 Standard     Range For     Actual Range
Sample     Measurement   Mean    Deviation    2 Std. Dev.   100 Analyses
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RS0137        pH         6.86        0.07         6.72-7.00      6.76-7.04
           Buffer pH     6.94        0.04         6.86-7.02      6.86-7.01
           P (Lbs/A)     111         6.5            98-124         95-126
           K (Lbs/A)     174         8.5           157-191        163-206

RS0142        pH         5.46        0.04         5.38-5.54      5.35-5.60
           Buffer pH     6.70        0.05         6.60-6.80      6.59-6.78
           P (Lbs/A)     67          3.1            61-73          57-73
           K (Lbs/A)     233         8.2           217-249        218-256
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