Agriculture Reference
In-Depth Information
Since Chapter 3 we have been working with parts per million. In order to write a
fertility Rx for our soil or growing media we need to convert ppm into the units per
area or volume we wish the final Rx to be written in.
The table below shows the amount of minerals that we have calculated need to be
added, converted to weight per unit area for both the metric and pounds/acre
systems.
Mineral
Amount
Needed PPM
Kg/ha
Kg/100 m
2
(Kg/ha ÷ 100)
Lbs/Acre
Lbs/1000 ft
2
Lb/ac ÷ 43.56
Calcium
300
600
6
600
13.77
Magnesium
48
96
0.96
96
2.20
Potassium
89
178
1.78
178
4.09
Sodium
13
26
0.26
26
0.60
Phosphorus
78
156
1.56
156
3.58
Sulfur
69
138
1.38
138
3.17
Boron
1.34
2.68
0.027
2.68
0.06
Iron
39
78
0.78
78
1.79
Manganese
34
68
0.68
68
1.56
Copper
7.13
14.28
0.143
14.28
0.33
Zinc
0
0
0
0
0
Recall that we are working with the upper 2 million kilos of 1 hectare of land, or the
upper 2 million pounds of 1 acre. One millionth of that mass is 2 kg /ha or 2
lbs/acre.
Kg per Hectare to Kg per Are
One hectare is 10 000 meters
2
(100m x 100m). 1/100
th
of that is 100 m
2
, an area
of measure also known as an
are
(pronounced 'ar'or 'air'in English).
100 ares = 1
hectare.
This makes the
conversion from kg/hectare to kg/are
simple: just
move the decimal point 2 spaces to the left.
Sulfur needed: 138 kg/ha = 1.38 kg/are.
(1 Are = 100 m
2
= 1076 sq ft)
