Organic Growing?
There is a lot of interest at present in 'organic' farming, driven by an understandable concern for the environment and a wish to eat healthy food. The debate can though sometimes cloud the fact that conventional farming also has a very real concern for these issues. There is a great deal of interesting and important research aimed at finding solutions to the problems associated with growing food on a large scale.
Within our own greenhouse we are able to grow a crop of tomatoes without, in general, any use of herbicides or pesticides. In fifteen years we have only had to spray twice. We can achieve this control by virtue of the advanced growing system which enables us to control the conditions for plant growth closely, enabling us to grow strong and healthy plants - healthy plants have excellent resistance to disease. Occasionally we get minor infestations of white fly or red spider, and these we can control by introducing predator insects into the crop which eat the pests.
In the hydroponic system that we use people are often struck by the absence of soil. Many assume that this should lead to a watery and tasteless final product. This is a natural reaction, and stems from a misunderstanding about how plants grow. Plants do not eat soil. Soil is a complex substrate which holds the water and minerals that a plant needs in order to grow. Of all the dry matter in a plant only 10% comes from the soil, consisting of trace elements such as potassium, calcium, zinc etc. The rest of the dry matter is synthesised from thin air and sunlight, by the process of photosynthesis. This is a truly remarkable process in which carbon dioxide from the surrounding air is transformed into organic compounds within the plant leaf in a matter of seconds.
Plants in a properly managed water culture are able to develop in an entirely normal way. The water contains the nutrients normally found in the soil, and a strong root system is able to take up water, or nutrients, as required. Photosynthesis proceeds as normal. The plants are no more 'watery' than a plant grown in soil.
On the other hand the soil is not simply a passive substrate. It is also teeming with microbial activity which allows for close symbiotic relationships to develop between the plant roots and the surrounding nutrient supplies. Nutrients are often available in forms that first require to be broken down by bacteria before the plant can take them up, and in general this symbiosis is of great value for plants. In hydroponic systems it is now possible to introduce microbes to the root zone so that this activity, not normally associated with water cultures, can proceed as normal. But even without this the plants do not simply take up water in an uncontrolled fashion. Experience shows that the plants take up what they need, resulting in a balanced and healthy plant that can produce fruit of exceptional quality.
All farming consists of growing specially selected hybrid plants in unnaturally dense populations. It is not a natural activity, but has always been a major modification of the environment for the purpose of feeding people. The ethos that we feel is most helpful for the future of agriculture can perhaps be summed up by the search for 'best practice farming'. Many researchers and farmers are engaged in finding the most efficient and friendly methods for producing crops - but this does not necessarily mean adopting the philosophy espoused by the organic movement, which only represents one very particular approach to the problem.