The addition of manure
and fertilization plus heavy cropping tends to
increase the acidity of the vegetable plot. Never
lime each year as a matter of routine –
if you are following the standard crop rotation
plan then lime only the land which is to be used
for brassicas. This means that the land is limed
every 3 years.
There is no need to guess the correct amount of
lime to use these days. A simple pH kit will tell
you the degree of acidity, and this reading plus
the type of soil in question determines the application
rate. This will be between ½ - 1 ½
lb per sq yard (250-750g per sq m) – the
experts recommend ground limestone rather than
hydrated lime. If you don’t want to go to
the trouble of testing, use ½ lb per sq
yard (250g per sq m).
Timing is all important. If organic matter has
not been added to the soil, sprinkle the lime
over the freshly-dug surface – do not incorporate
into the surface. If manure has been added, postpone
liming until February. Lime likes to be alone,
and that applies to fertilizers as well as manures.
Feeding should take place either a month before
or after the application to the soil surface.