What are Amendments?
An amendment is any material added to a soil to improve its physical properties, such as water retention, permeability, water infiltration, drainage, aeration and structure. The goal is to provide a better environment for roots. To do its work, an amendment must be thoroughly mixed into the soil. If it is merely buried, its effectiveness is reduced, and it will interfere with water and air movement and root growth. Amendments are also excellent for lightening clay or rocky soil, adding substance to sandy soils and adjusting Ph.
Amending a soil is not the same thing as mulching, although many mulches also are used as amendments. A mulch is left on the soil surface. Its purpose is to reduce evaporation and runoff, inhibit weed growth, and create an attractive appearance. Mulches also moderate soil temperature. Organic mulches may be incorporated into the soil as amendments after they have decomposed to the point that they no longer serve their purpose.
There are two broad categories of soil amendments: organic and inorganic. Organic amendments come from something that was alive. Inorganic amendments, on the other hand, are either mined or man-made. Organic amendments include sphagnum peat, wood chips, grass clippings, straw, compost, manure, biosolids, sawdust and wood ash. Inorganic amendments include vermiculite, perlite, tire chunks, pea gravel and sand.
Organic amendments increase soil organic matter content and offer many benefits. Over time, organic matter improves soil aeration, water infiltration, and both water- and nutrient-holding capacity. Many organic amendments contain plant nutrients and act as organic fertilizers. Organic matter also is an important energy source for bacteria, fungi and earthworms that live in the soil.
** Information from the Colorado State University Extension
N-P-K refers to the ratio of important elements in a fertilizer or soil amendment.
Nitrogen (N), Phosphorus (P), and Potassium (K), each of these being essential in plant nutrition.
Nitrogen helps plants grow quickly, while also increasing the production of seed and fruit, and bettering the quality of leaf and forage crops. Nitrogen is also a component of chlorophyll, the substance that gives plants their green color, and also aids in photosynthesis.
Phosphorus, also a key player in the photosynthesis process, plays a vital role in a variety of the things needed by plants. Phosphorus supports the formation of oils, sugars, and starches. The transformation of solar energy into chemical energy is also aided by phosphorus, as well as is development of the plant, and the ability to withstand stress. Additionally, phosphorus encourages the growth of roots, and promotes blooming.
Potassium, the third essential nutrient plants demand, assists in photosynthesis, fruit quality, the building of protein, and the reduction of disease.
An easy way to remember which is important in different stages of growth is :
N-P-K = ROOTS- SHOOTS- FRUITS
Soil pH defines whether your garden is composed of acidic soil, alkaline soil or somewhere in between. Assuring that your garden soil pH is in the proper range for the plants you’re growing is important. pH is basically the measurement of Lime ( calcium) in your soil.
On the pH scale, which ranges from 0 to 14, 7 is neutral – neither acid nor alkaline. Anything less than 7 is acidic. And the lower the number, the more acidic, anything above 7 is alkaline, and the higher the number, the more alkaline.
The pH of your soil is substantial in regards to the growth and health of your plants. It determines whether the nutrients will be readily available to the plant roots. If your plants require a large uptake of a given nutrient, but your soil pH makes that nutrient less available to the plant, you’ll have problems. The reverse situation can also occur, since certain elements are toxic to some plants.
We suggest having your soil tested every year BEFORE you add amendments.