wastes, and other materials.
Peat, aka peat moss, has been a standard organic
source. It is still the same good product as in the
past, but may occasionally contain weed seeds or
pathogens, depending upon method of harvesting.
Peat decomposes more slowly than most other organic
sources and thus may give its effects comparably longer.
Animal manures have for years been among the best
organic sources. While providing organic matter they
can also be a good source of plant nutrients. Partially
decomposed “old manure” is a good source of organic
matter but inferior to fresh manure in plant nutrients.
The fear of “burning” with fresh manure is easily offset
by applying less of the better product. Unfortunately
manure may contain numerous weed seeds, including
those of noxious weeds.
When purchasing manure, inspect carefully
for unwanted problems. One, garden centipedes
(symphyllans) introduced into a soil can cause
tremendous damage for years to come by feeding on
plant roots. It’s best to avoid manure stored for any
length of time on the ground. Older manures are more
likely to come with these problems.
Organic materials high in lignin, such as wood
products, straw, grass hay, and hulls, can deplete soil
nitrogen during their decomposition. Supplemented
nitrogen, supplied by a fertilizer relatively high in
nitrogen, will correct the deficiency. Wood products
take up to four years of decomposition for the
“softwoods”—pine, fir, spruce, etc.—before a nitrogen
balance is reached in the soil. Hardwoods—oak, maple,
beech, etc.—take about half this amount of time for
decomposition. This is usually not a problem with
peat since it naturally contains some nitrogen, or with
composts, leaf mold, manures, and other such sources.
Dealing With Sandy Soils
A truly sandy soil will feel gritty when rubbed
between the fingers. Most sandy soils have at least a
little clay and silt in them, but insufficient amounts of
clay, especially to hold nutrients and water. Structure of
sandy soils may be either loose or, with an insufficient or
“wrong” amount of smaller particles and organic matter,
hard and crusty and impenetrable to water when dry.
They are inherently low in plant nutrients and good tilth.
Sandy soils can be much improved by “diluting” with
good soil and/or organic matter. The amendment(s)
should be thoroughly worked into the top six or more
inches of the soil, as deeply as possible.
It is wrong to assume that a sandy soil is well drained.
If the sand is underlaid by a compacted layer, drainage
can be a serious problem.
Generally, in sandy soils fertilizer should be applied
in lesser amounts but more frequently to avoid loss by
leaching and contaminating ground water. This is more
important with water-soluble inorganic than with organic
fertilizers.
Soil Testing
Testing your soil is a good way to determine the
pH (acidity or alkalinity), need for pH correction,
and nutrient content of your soil, with suggestions. A
good soil sample for testing is a composite of samples
taken throughout your garden, then thoroughly mixed
together when sufficiently dry by pouring back and forth
from one clean bucket to another. Follow all instructions
of the testing laboratory to which you will submit your
soil sample. One thing you will not learn about your soil
from the test is the soil’s texture; that is, if it is a clay,
clay loam, loam, etc. A few labs, however, can make a
texture test for you for an additional fee.
Generally Speaking
Organic matter will do as much, or more, to improve a
given soil than most any other practice. Worked deeply
into the soil, its effects can often be seen for years to
follow. The only real “downside” in using organic matter
is the nitrogen imbalance that high lignin materials can
present, and the potential for insect, weed, and disease
problems of some organic sources. Seldom do the
problems outweigh the benefits.
Keep in mind that working a soil when it is excessively
wet or when excessively dry should be avoided. When
too wet the soil structure is broken down, causing
puddling or “plastic remolding.” When too dry, the
soil is ground or pulverized into dust, also causing a
breakdown of structure. In between lies a rather narrow
range of wetness for optimal cultivation of the soil.
Improve your soil—make it enjoyable and watch your
garden grow!
d
Fall 2018 AIS Bulletin 47