First cuts are now in and for the
second year in a row there seems
to be a pleasing quantity of it.
Early indications from the analysis
seem to indicate that qualities
are better than last year which
should make feeding this
winter a little less challenging.
We all welcome better than average yields but it is worth remembering that with large crops there is an associated increase in
o take of nutrients especially P and K. A tonne of grass silage at 30% DM will contain approximately 2 kg of Phosphate (P2O5)
and 7 kg of Potash (K2O). This has been removed from the soil reserves and will need replacing at some point. If we say that, on
average, silage yields have been up 10% for the past 2 years, then this would mean an extra 3 tonnes or 6kg (12 units) of P and
21kg (42 units) of K above the normal o take of 30kg (60 units) of P and 105kg (210 units) of K (assuming a modest 15t/acre).
The principle of managing soil nutrients is very much like managing cow condition. When you have it right then you can
maintain high yields by drawing on these reserves, but, if condition is low at calving, then the yield will be compromised
even if you feed the animal well during that lactation.
Late summer or autumn applications of top up P and/or K along with Calcium and some trace
elements will work very well in this situation especially when combined with targeted slurry or FYM
applications which will be high in Potash. Where slurry has been used in this way it is well worth
looking at balancing with a Phosphate containing a high Calcium content to help forage and
soil quality and aid Nitrogen e¤ ciency at tail end. A Sulphur component could also provide
bene ts in terms of autumn disease susceptibility.