1. Definition of “Soilless culture”
To know the meaning of soilless culture and its system can result in choosing appropriated planting form. There are many words for in Thai language such as soilless culture, water culture with nutrient essence, nutrient solution planting, substrate culture with nutrient solution, and planting with root suspended in nutrient solution.
Whatever it called, this planting without soil could be described in 2 manners by planting system which interpret from English Language as “Soilless Culture” and “Hydroponics”

1.1 Definition of “planting without soil” from “Soilless Culture” is the growing of plants that imitate soil- base gardening by using many kinds of growing media as for example inorganic substance, organic substance and synthetic substrate. In this system, plant can grow in growing media by obtains nutrient solution which mixed from water and essential nourishment from the roots.

Inorganic substrates are
(1) Natural material such as sand, gravel, pebbles, and perlite.
(2) Heated/ burned material such as backed clay, grain-backed clay, asbestos or rockwool, perlite, and vermiculite.
(3) Leftover material from industrial factory such as brickbat from brick factory, backed clay from pottery factory.

Organic substrates are
(1) Natural material such as fuzz straw, coconut fiber, nutshell and peat.
(2) Leftover material from industrial factory such as bagasse and dregs from sugar factory, leftover material from paper mills.

Synthetic substrates such as foam ship, sponges, and moisture absorbent plastic fiber.

Although we generally call these growing media as substrate but in case of using specific materials it can be called by the name of such materials, for example:
- The cultivation of plant in sand or Sand culture.
- The cultivation of plant in gravel or Gravel culture.
- The cultivation of plant in rockwool or Rockwool culture.
- The cultivation of plant in sawdust or Sawdust culture.

Growers who want to grow the plant without soil from the characteristic of soilless culture must select the growing media to be matched with planting growth.

1.2 Definition of “Planting without soil” from “Hydroponics” is the growing of plants without using growing media (non substrate or water culture) by growing plant in nutrient solution as its roots directly touch with the solution. As the word “Hydroponics” combined from 2 Greek vocabularies, “Hydro” which means water and “Ponos” which mean work, its meaning can be defined as “Water-working” or meaning of The work of water which deliver nutrient solution trough the roots of plants.
            Growers who want to grow the plant in the soilless environment as this Hydroponics meaning need to control the temperature of nutrient solution to mach with the growth of plant.
            Although Hydroponics is not the soil culture as the research and development of scientist but the plant can also grow in other media like sand, gravel, pebbles, providing with nutrient solution that have been developed. Therefore, it can be called as combined word as “Soilless Culture”.

1.3 Advantage of soilless culture
Soilless culture and the circumstance
            Soilless culture is a combination of science and art for gardening anywhere with no limitation for both household consumption and commercial planting. This technique is suitable for gardeners who have small space as apartment and condominium; therefore it can be use for growing plant in such crowed cities like Japan, Taiwan, Netherlands, England and Belgium.
            Moreover, it isn’t complicate for growers who want to grow the plant as hobby or household consumption. Accordingly one can also enjoin and learn the basic of planting as same as normal gardening. However in term of commercial planting, techniques and principals will be added for production control.
            Soilless culture and business production
Soilless culture can be applied to many kinds of plants; the complexity depends on the kind of plant: vegetables, flowers, leave plants, climbing plants, and perennial. For business production, short-lived plants are more popular as shown in table 1.

Table 1: The examples of plants that can apply soilless culture

1.4 The difference between Soil culture and Soilless culture

                Typically, factors of plant growth are weather (Sunshine, temperature), water, and food elements from soil, water, and air (Oxygen, Hydrogen, and Carbon dioxide). In addition, pH of soil is related to food element absorptions of roots above soil.
                The disadvantage of soil-based planting is that the soil usually lacks of necessary food elements i.e. the characteristics of soil (soil structure, nutrients, pH) are not the same because it depends on area. Accordingly, it is hard to improve the quality of soil, and leading to high cost of improvement. Such problem leads to the non-consistent productivity.
                For soilless culture, plants absorb solutions called nutrient solution that consists of essential nutrient for plants. The solution can be directly absorbed because its EC and pH are all time adjusted to be appropriate for plants. In fact, there is no difference between the anatomies of roots for these two planting systems as shown in figure 1.
                For soil culture, “Soilless Solution” which is in soil and water comes from the decomposition of inorganic and organic substances. For soilless culture; on the other hand, plants absorb “Nutrient Solution” that is from the dissolution of chemistry fertilizer in water called “Plant Nutrient Solution”. Both Soilless solution and Nutrient solution that are touched by roots will be absorbed for plant growth.





Table 3: Advantages and disadvantages of soilless culture

2. Nutrient and Nutrient solution

For soilless culture, the main factor of plant growth is the Nutrients that are the raw grow media in growth process. For example, Photosynthesis uses carbon dioxide (CO₂) as a raw in grow media associate with sunshine and chlorophyll to produce carbohydrate and oxygen.
                Nutrients used in Photosynthesis is Carbon (C) from carbon dioxide and Hydrogen, oxygen from water (H₂O). In addition, chlorophyll consists of Nitrogen (N) and Magnesium (Mg). We can classify nutrients by the quality plant needs. The quality of nutrients is necessary for plant growth. Beside, we must concern the environment. If we fill insufficient or Excessive nutrients, it will not grow well.

                In addition, there may be other nutrients that are necessary for plant growth such as Iodine (I), Silicon (Si), and Sodium (Na), but they are not called essential  elements for plant.

Form of nutrients that plant uses, and the problem from getting in appropriate nutrients

Plant gets Nutrients in form of Ion, gas, or chelate as shown in table 4.1.  Problems of plant getting insufficient or Excessive quantity of nutrients are shown in table 4.2.

Table 4.1: Forms of essential elements that are absorbed to roots and their functions.

Adapted from Megel, K. and B.a. Kirby. 1987 Principles of plant nutrition, 4^th Ed, International Potash Institute. Beme, Switzerland. With permission

Table 4.2: Reactions of plant when it gets insufficient or Excessive quantity of nutrients.