Importance of soil preparation

Press, 15 September 1976, Page 13

Importance of soil preparation

Probably the most important single aspect of a successful home vegetable garden is the preparation of the soil, but unfortunately that is quite often the one thing which is not given the care it both needs and deserves.

I Nowhere in the garden does the soil get more abused and misused ll'/.ri in the vegetable plot. Constant cultivation and intensive growing means the healthy organic life of almost any soil becomes used up and burnt out, along with most of the essential plant foods. So, the first step to be taken with the onset of spring is to do something about replenishing the soil’s reserves before sowing any seed. Remember, vegetables grown in rich, fertile soils are tastier, more nutritious, less prone to disease and produce greater yields more quickly than if planted in soils which are impoverished. There are many different types of soil in this country but generally most will need a decent dressing of lime — probably every year and certainly every second year. Acid soils of heavy,

stiff clay need an annual dressing of about 250500 g per square metre, while lighter. sandier soils (which tend to use up plant food more quickly) will benefit from more frequent, lighter dressing of about 100200 g per square metre. Agricultural lime in its various grades is the thing to use. Some home garden limes contain extra trace elements which are particularly useful if minor mineral deficiencies are suspected. Liming improves the physical structure of heavy clay soils by a process known as flocculation. It makes it more porous, easier to cultivate and it will change a sour, acid soil into one which is sweeter and more chemically healthy for plants. Making the soil sweeter also encourages the organic life therein. Millions of micro-organisms are stimulated into even greater activity which consequently improves natural fertility. This in turn improves the soil’s organic health. The organic, or humus, content of the earth needs constant care and attention.

Those rich in humus require the absolute minimum of cultivation and are able to withstand wet or dry conditions more effectively. Many organic materials, such as compost, peat moss, seaweed, straw, leafmould, animal manure etc, are suitable for building up soil humus but this really needs to be a continuing process and not necessarily confined to the spring months. One word of. caution about the use of organics. As a general rule avoid sowing root crops such as carrots and parsnips where fresh organics have been worked in.

These particular vegetables do not take too kindly to such a situation and finish up with distorted and deformed roots. Building up plant food reserves of nitrogen, phosphorous and potash (designated N.P.K. on bags and fertiliser) is also important. The simplest way to ensure these major, foods are in plentiful supply

during the months ahead is to apply a base dressing of a general purpose fertiliser containing the three in roughly equal proportions. Phosphate tends to become locked and unavailable in many New Zealand soils and as a rule it is a good idea to apply about IOOg (two or three good handful) per square metre each year. Serpentine superphosphate is

best as it also contains magnesium and is nonburning. More often than not during late winter — early spring, soils tend to become very wet and waterlogged. An important rule is not to work such soils. Cultivating wet soil causes it to clog up and it will later prove verydifficult to turn into a fine seed bed.

A further point about waterlogged soil is that it spells disastei for germinating seeds, which may rot and die if the ground is wet and cold In fact rather than sow in adverse conditions lust because the calendar saxs it's spring, it is far better to wait a few weeks. Quite often later sown vegetables easily catch up with those sown a few weeks earlier anyway.