| (6) LIME USE SURVEY |
| Approximately 70,000 soil samples are delivered annually to Johnstown
Castle for lime requirement analysis. The percentage of soils with various lime
requirements are summarised in Table 8. |
Table 8: Percentage soils with varying lime requirements
| L.R. (t/ha) |
0 |
0.1-5.0 |
5.1-10.0 |
10.1-15 |
15.1-20 |
20.1-25 |
>25 |
| 1997 1989 |
11
17 |
31
40 |
34
29 |
18
11 |
4
3 |
1
0 |
1
0 |
|
This table suggests that soils have become more acid in the last 10 years. In 1997, some
42% of soils had a L.R. at or below 5 t/ha. In 1989, some 57% of soils had a LR below 5
t/ha. It is difficult to determine how much can be taken from this table. There is no way
of ensuring that the samples taken represent the L.R. of the country. For instance in
1997, there were less tillage samples than in 1989 (The total area under tillage declined
from 1989 to 1997). A breakdown of the L.R. for tillage and grassland in 1997 is given in
Table 9. Mean lime requirements since 1991 are summarised in Figure 2. Total L.R. has
increased slightly, as has L.R. for both grassland and tillage. |
Table 9: The L.R. for grassland and for tillage crops in
1997
| LR (t/ha) |
0 |
0.1-5.0 |
5.1-10 |
10.1-15 |
15.1-20 |
21.5-25 |
>25 |
| Grassland Tillage |
10
17 |
29
50 |
36
24 |
19
4 |
5
4 |
0.5
0.5 |
0.5
0.5 |
|
Some 67% of the tillage samples had a L.R. of 5.0 or less t/ha, while in grassland only
39% had a L.R. of this magnitude. Only 9% of tillage soils had a L.R. greater than 10t/ha
while in grassland some 25% of samples had a L.R. greater than 10 t/ha. |
| The actual lime used on a yearly basis since 1989 is given in Table 10.
This shows a marked decline lime usage since 1996. There are no data on the amount of lime
being applied to different crops. But the previous data suggests that there is less lime
being used on grassland than on tillage crops. There are 3.4 m hectares of good
agricultural land in the country and we estimate that an annual ground limestone (calcium
carbonate) usage of approximately 1.5 million tonnes would be needed to maintain a
satisfactory level status on these soils. Consumption is falling significantly below
optimum usage. Surely, in a time when nitrogen usage is under scrutiny, the use of lime
should be increasing, rather than decreasing. |
Table 10: Lime usage (1988-1998)
Calendar Year |
Tonnes |
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988 |
750,000*
962,471
1,100,076
1,124,080
612,821
812,045
580,911
716,239
806,900
940,616
885,559 |
* This is an estimated
figure |
|
|
