Beginner’s corner
Fertility Management
in Container Plants
by Guy Sela
Testing both irrigation water and leachate (drainage) solution
for several parameters is an essential part of regular monitoring of fertilization and irrigation in container plants.
These parameters should include at least EC, pH and the
percentage of leachate. Simple test kits are also available
for other parameters, such as nitrates and chlorides. For a
more comprehensive analysis, water samples should be sent
to a laboratory.
The main goal of testing the leachate solution is to quickly
identify trends, indicating dynamics in plant requirements and
salt content in the container. A single test result is not enough
to get a clear picture, and periodical testing is an important
tool for that purpose.
During irrigation, leachate solution content is dynamic.
For example, here are EC values tested in the same leachate
solution at different times during irrigation. EC of irrigation
water was 1.0 ds/m:
150
Maximum Yield USA | March 2012
Time during irrigation (min)
EC of leachate solution (ds/m
10
2.1
20
1.7
30
1.3
Interpretation of leachate test results depends entirely
on the percentage of leachate out of the irrigation water
amount. The same result (EC or any nutrient level) measured in different percentage of leachate solution can get
completely different interpretations.
Let's consider the following case:
Irrigation water
EC
N-NO3 (ppm)
1.0
80
Lecheate
EC
N-NO3 (ppm)
1.6
140