Know what you grow in
Table 4. The levels of elements found in
rockwool and perlite after a season of use as
a rooting media for hydroponic greenhouse
tomatoes (according to Mehlich No. 3
Extraction); The the drip irrigation method
was used
ROCKWOOL
ELEMENT
PERLITE
WATER MEHLICH WATER MEHLICH
SOLUBLE
NO. 3
SOLUBLE
NO. 3
- - - - - - - - - - - - - - - - LBS/A - - - - - - - - - - - - - - - -
Phosphorus (P)
142
1,066
32
384
Potassium (K)
3,552
3,382
439
513
Calcium (Ca)
231
5,244
237
1,071
Magnesium (Mg)
124
1,177
43
65
Sulfur (S)
31
764
-----
-----
Boron (B)
0.5
1.7
0.29
0.6
Copper (Cu)
0.5
2.0
0.09
0.35
Iron (Fe)
-----
3,040+
-----
-----
Manganese (Mn)
2.0
104
0.34
8.0
Zinc (Zn)
1.6
26
0.08
2.0
Mehlich No. 3 extractable elements for unused rockwool and perlite
are given in table two.
Know What You
Grow in
Elemental content in a rooting media can be a
significant factor that affects the nutritional status
of a growing crop. There is an interaction that
can occur between an applied nutrient solution
formulation and the rooting media, suggesting that
matching media characteristics with a nutrient
solution formulation is important in order to
avoid an elemental insufficiency from occurring.
Nutrient element accumulation in a rooting
media can be due both to a residue increase,
as well as a possible formation of precipitates,
combining to significantly affect the nutritional
status of the growing crop. A nutrient solution
formulation excessive in its elemental content will
result in a significant accumulation of an element,
or elements, with the potential to adversely
affect the nutritional status of the growing crop.
However, when one knows what the elemental
rooting media content is, one can match it with
an appropriate fertilizer or nutrient solution
formulation in order to avoid the potential of a
plant nutrient insufficiency. MY
BY
Dr. J. Benton
102
Maximum Yield USA | September 2012