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| The Potash Development Association |
|
Contents |
| Background |
| Survey of commercial fodder beet crops |
| Methods |
| Measurements |
| Results |
| Removal data from other countries |
| Pratical consequences |
| New typical values |
| Recommendations |
Fodder Beet - P & K offtake |
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Removal data from other Countries
A literature search produced some data specifically on fooder beet from other countries which endorse the survey finding that P content of roots is similar in fodder and sugar beet but that K content is considerably higher in fodder roots. The actual levels are similar to those found in the survey.
| kg/t fresh roots |
P2O5
in roots
|
K2O
in roots
|
||
 |
||||
|
Fodder beet
|
Sugar beet
|
Fodder beet
|
Sugar beet
|
|
| Latvia 1 |
0.7
|
0.7
|
4.2
|
2.5
|
|
||||
| Slovak 1 |
0.9
|
0.9
|
3.8
|
2.4
|
|
||||
| Poland 1 |
0.9
|
0.9
|
4.6
|
2.2
|
|
||||
| Germany 2 |
0.9 a
0.7 b |
1.0 |
5.0 a
4.5 b |
2.5
|
|
||||
| Denmark 3 |
0.7
|
0.7-1.0
|
3.2
|
2.3-3.5
|
|
||||
| UK 4 |
0.8
|
0.8
|
1.7
|
1.7
|
1 Source : M Shepherd ADAS, data from the EU funded
"MAINTAINE" project (CT-98-0108)
2 Source : K Orlovius K+S KALI GmbH. Germany standards
3 Source : IFA World Fertilizer Use Manual. Carl Pederson LIK
data.
4 Source : PDA leaflet Phosphate & Potash removal by crops.
UK standards
a Vars with higher dry matter
b Vars with lower dry matter
Practical consequences
Phosphate and potash recommendations should be calculated to maintain available soil nutrient reserves at a level at which crop growth and yield will not be adversely affected by that nutrient. This is a maintenance policy which therefore requires the replacement of the amount of nutrient in the crop which is removed from the field. Where tops are grazed in situ with livestock, nutrient may be re-distributed across the area but it is virtually all returned and therefore need not be included in the replacement calculation.
These studies indicate a greater removal of potash by fodder beet in practice than existing standards allow for. For a typical 60t/ha crop (25t/ac) the maintenance recommendation using existing standards would be 100 kg/ha potash whereas this study indicates that it should be 240kg/ha. If not recognised, this under-replacement would result in an erosion of soil fertility. In practice this shortfall may be hidden because of the use of generous applications of FYM/slurry but the use of manures should be monitored to make best use of this valuable resource rather than used to excess on a limited crop area.
New typical values
Following this study new typical values for phosphate and potash content of fodder beet should be adopted as follows :
|
Phosphate
kg/t roots |
Potash
kg/t roots |
|
 |
||
| Roots only |
0.6
|
4.0
|
|
||
| Roots & tops |
1.7
|
7.5
|
New recommendations
Total nutrient requirements should be based on the replacement of nutrient removed (maintenance levels) adjusted according to the field soil P and K Index. Fertiliser recommendations are calculated after deducting nutrient contribution from any FYM/slurry applied.
| Maintenance requirements (kg/ha) | |
|
|
| Phosphate | Root yield (t/ha) x 0.6 (kg/t) |
|
|
| Potash | Root yield (t/ha) x 4.0 (kg/t) |
| Soil fertility adjustments (kg/ha) | |||||||
|
soil index
|
|||||||
|
0
|
1
|
2-
|
2
|
2+
|
3
|
4
|
|
|
|||||||
| Phosphate |
M+50
|
M+25
|
M
|
M-50
|
Nil
|
||
|
|||||||
| Potash |
M+50
|
M+25
|
M
|
M-25
|
M-70
|
Nil
|
|
Example: Typical 60t/ha crop on soil P index 2 and K index 1 requires 60 x 0.6 = 36 kg/ha P2O5 and 60 x 4.0 +25 = 265kg/ha K2O
Further information
More details on the fertilisation of fodder beet can be found in :-
PDA leaflet 16 "Fodder Beet - Fertiliser Requirements" by
Dr A P Draycott & J D Hollies
MAFF Fertiliser Recommendations RB209 7th edition 2000.
NB. The recommendation figures in this edition are not updated
to the new typical values now agreed.