Hanna Instruments HI 993310 - Manual (Page 6)

10 11
How to prepare the saturated soil-paste samples for analysis
A) Soil extraction:
1) Extract the soil as indicated below:
- Take one sample for every 1000 m 2 (0.25 acre) of homoge-
neous plot of land.
- For smaller plots, at least 2 samples are recommended (the
more samples are taken, the more representative the end-result
will be).
2) Avoid extracting samples from soil showing obvious anomalies.
Treat this type of soil separately.
3) Take the same quantity of soil for each sample. For example,
use bags with the same dimensions (1 bag per sample).
4) Depth of extraction:
- General: dig and discard 5 cm (2") of the topsoil.
- Herbaceous crops: from 20 to 40 cm (8" to 16").
- Orchards: from 20 to 60 cm (8" to 24'’).
B) Soil sample preparation:
1) Spread the soil samples on the page of a newspaper and let
them dry in a shady place, or in an oven at 40°C (104°F).
2) Crumble the dried soil and mix all the samples together to
obtain an homogeneous mixture. Discard stones and vegetable
residues.
3) From this mixture, take the soil sample for the analysis.
C) Saturated soil-paste preparation:
1) Strain the soil with a 2-mm sieve.
2) Mix for about 30 seconds one part of soil and two parts of distilled
water.
3) Wait for 1 hour.
4) Filter the solution and measure the conductivity.
Tolerance of some common plants to the soil conductivity (Ayers &
Westcot, 1976).
• EC
0
= maximum of tolerated soil conductivity (salinity).
• EC
75
= with this soil conductivity value the 75% of the maximum
yield is produced.
• EC
100
= minimum soil conductivity value, then the yield starts
decreasing.
ORCHARD
Grapevine
Orange & Lemon
Apple & Pear
Walnut
Plum
Peach
Apricot
VEGETABLES &
HERBACEOUS CULTIVATIONS
Melon
Spinach
Cauliflower
Tomato
Watermelon
Potato
Lettuce
Pepper
Carrot
Onion
Strawberry
Oat
Cotton
Sugar beet
Soybean
Maize
Bean EC
0
(mS/cm)
12
8
8
8
7
6.5
6
16
15
13.5
12.5
10
10
9
8.5
8
7.5
4
28
27
24
10
10
6.5
EC
75
(mS/cm)
4.1
3.3
3.3
3.3
2.9
2.9
2.6
5.7
5.3
5.5
5.0
4.4
3.8
3.2
3.3
2.8
2.8
1.8
13
13
11
6.2
3.8
2.3
EC
100
(mS/cm)
1.5
1.7
1.7
1.7
1.5
1.7
1.6
2.2
2.0
2.8
2.5
2.5
1.7
1.3
1.5
1.0
1.2
1.0
8
7.7
7
5.0
1.7
1.0