This is a useful information page on asparagus growing. A month ago, I scattered well rotted manure over the asparagus patch and covered that with mulch, as shown (product of our own mulcher, garden prunings plus waste paper and cardboard). More recently I have scattered blood and bone. While I have done these things in early spring, I also favour fertilising with natural fertilisers during winter. It is true of chemical fertilisers that if applied during the non-growing period, they are lost. But the natural materials are food for worms and worms work closer to the surface in cooler weather and thus we can expect, applying manures, compost and blood and bone when worms are coming to the surface, that it will be consumed and the soil with be loaded with the ultimate plant food, worm castings.
Moisture retention is important in this bed (as in nearly every other plant bed, of course). The keys to moisture retention are:
- mulch... whereas compost breaks down relatively quickly and feeds life, mulch (high carbon levels) breaks down slowly, allows water in and reduces the drying effects of harsh sun and wind,
- high humus content of soil. The wikipedia article on humus and this page by a biodynamic organisation in India are informative. In simplest terms, you seek the development of soil that contains a diversity of life, that incorporates the wonders of micro-crystals of clay (which are arguably the closest thing in inorganic chemistry to organic life), that is naturally moisture retentive and that provides an optimal basis for cation exchange capacity (CEC), inhibiting erosion and moisture and soil value to lower depths, connecting intimately with plant roots. Pick up a handful of good high humus soil and squeeze it; compare with a lesser soil which falls apart and is relatively dry. Add chemical fertilisers to any soil, throw the whole population of humus into unemployment, lose soil variously.