Why Garden Organically
By: John Ross, Rivenrock Rocks, http://www.rivenrock.com
There are many people who garden organically for many different reasons. Chief among these are the various philosophical reasons such as a desire to live in harmony with the Earth. Living within one’s means so to speak, and attaining a balance in the garden.
I garden organically because of these reasons, and also because to me it seems easier ultimately. I grew up learning both organic and conventional methods, and have gradually switched over to wholly organic because when the soil is properly prepared and fed, it will in turn feed the plants in a way that will reduce insect and disease problems, and reduce weeding and watering chores. Every hour I spend mulching and composting probably saves me a couple hours of weeding and other work.
A properly compost amended soil will have good air and water penetration as well as good water retention. The high air flow within the soil will reduce rot and disease problems. But the high water retention will result in reduced watering chores as well as ensuring a steady supply of water to the plant when it needs more moisture.
How does compost perform this seemingly ‘too good to be true’ task? It all is due to the unique properties of compost, that is it’s high surface area. In short, water clings to the surface of soil particles such as clay and sand.
Clay particles are very thin wafer-like particles that stack like cards on a table. This is why clay soils are so hard to get wet, the water likes to roll off the surface, and has a hard time overcoming the soil chemical and physical resistance and sink into the soil. But once it becomes wet, it’s high surface area causes it to be resistant to drying, in addition it’s tight packing features cause the airflow between the particles to be nearly non-existent resulting in reduced drying by airflow. There is one benefit to the high water holding capacity of clay though, it means that the nutrients in the soil which are water soluble are not going to be taken away by water easily and transported beyond the reach of the roots.
A sand soil is very difficult to keep wet due to the fact that sand particles tend to be of a rounded or jagged shape, and they do not fit tightly together, this results in a smaller surface area that does not hold much moisture, also the loose soil texture causes massive amounts of air to flow between the particles, this airflow can wick much moisture from the soil particles. Sandy soils have the additional ability to loose moisture through them during periods of high irrigation and rainfall. This moisture going quickly through the soil and into the groundwater can take with it many of the soluble nutrients that were in the soil either naturally or by being added.
So there you have the major types of soil, sandy and clayey. Most soils are some extreme of one or the other, or a mixture to one degree or another of both. Now the big question is, how does compost make such a large change in either type of soil? Well, imagine a tiny piece of compost, residue of some type of animal or plant that has rotted to a great degree, this high carbon state of being results in a very porous material, it may have many many holes all through it, this feature gives it a very very high ration ot surface area to which water will cling, this means that compost can hold many times it’s own weight in water. Picture if you will, a sponge as the compost, oh yes, you can pour much water into a semi moist sponge, it’s open and cellulose structure makes it capable of absorbing much water.
Think if you will of the flat platelets of clay particles, laying flat on a table top. When water is poured over them it runs off the surface. Now if you took the sponge, tore it into many smaller pieces and lifted the clay particles and put pieces of the sponges between them you will have a surface physically lifted up and made more ‘fluffy’ and able to readily accept water. This lifting action will result in greater airflow and quicker water acceptance. Using this method the compost will ensure less water runoff and wastage, quicker water acceptance and greater airflow and reduced rot. The good benefits of clay are retained though, the soils will not tend to run water through it too fast to be absorbed, and digging compost in a shovel depth or two will not cause the water to run beyond the root area overly quickly taking vital nutrients.
The sandy soil is likewise helped by compost. Picture sandy soil as marbles in a bag, when water is poured into the bag it will quickly run through the marbles. The compost if pictured as a torn up sponge placed between marbles makes it easy to see how it would trap much water. The high surface area of the compost dug into the sand will trap much more of the soil moisture than would be trapped by the sand alone. Also the overly high airflow rates of the sandy soil is reduced by the compost wedging itself between the sandy particles. Water is retained by the compost along with many of the water soluble nutrients.
Now compost can do all these things and more, it can help to reduce weeding chores due to the fact that it loosens soil so well. When you pull on a small weed it will come out easier because the soil is loosened by the compost.
When you walk on the soil it will be a little less likely to pack down tightly because of the springy action of the sponge like compost.
The compost will cause a reduction in the amount of soil erosion. Clay soils will accept more moisture and reduce erosive run off. Sandy soils will be held a bit tighter together and cause a reduction in wind erosion.
So with all these benefits it is easy to see why an hour of composting saves several hours of other types of work