The Next 200 Years by The Next 200 Years

Author:The Next 200 Years
Language: eng
Format: mobi, epub
Published: 0101-01-01T00:00:00+00:00

our conservative estimate of an increase in production by a

factor of 20 from purely conventional means,)

2. Unconventional or currently "exotic" agriculture

In following the second and third technological avenues,

progress in some unconventional techniques continues and is

assumed to be reasonably—but not outstandingly—success-

ful. It is clear that a technological advance does not neces-

sarily have to be exotic to be dramatic. For example, the

nutrient film technique (see Figure 8), a rather novel and

Figure 8. Nutrient Film Technique

SOURCE: A. J. Cooper, "Soil? Who Needs It?," Vegetable Grower, August 1974, p. 18.

128

THE NEXT 200 YEARS

simple variation of hydroponics, is rapidly coming into use

today.* This technique of growing crops was conceived in the

1960's at the Glasshouse Crops Research Institute in England

and is in practice in some 20 countries today, primarily for

high cash-value vegetables and flowers. The NFT method has

the following characteristics:

1. Capital and operating costs are low; only a waterproof

material, such as polyethylene, is required for gulleys. The

system does not require extensive, rigid, water-tight tanks

or expensive root-support media, as do other kinds of hy-

droponics.

2. Water: f

—Recirculation and the configuration of the gulleys elimi-

nate loss from drainage and evaporation.

—Storage requirements are minimal since plants thrive in

a thin film of nutrient solution (a one-millimeter film has

been found to be sufficient).

3. Fertilizer:

—No nutrients are lost through runoff.

—A low concentration of fertilizer may be used in the

solution; yet a wider range of nutrient concentration is

tolerable than when a solid rooting medium is used.

—Mistakes made in composition of the nutrient solution

can be rapidly rectified via quick adjustment (or replace-

ment) of the solution.

4. Soil-borne diseases:

—Continuous sterilization of the liquid in its flow pipe can

be used to overcome root disease problems.

—Systemic fungicides and insecticides at nonphytotoxic t

concentrations can be used.

—Increased resistance to virus diseases has been experi-

enced, possibly because the root system is not subject to

the abrasions encountered with soil culture.

5. The use of triangular gulleys, acting as a watershed, avoids

the leaching effect of rainfall and permits outdoor farming.

Rocky or saline soils pose no special problems.

* We place a strong emphasis on NFT here not because we believe it

will provide the solution we are seeking, but because it is one of the newer variations of hydroponics that might be developed into part of a solution.

Also, we believe the use of a specific illustration for the a fortiori argument will make the point more vividly.

t Nonphytotoxic means nonpoisonous to plants.

Food: Supplying Demand

129

6. Elimination of drying-out cycles increases average growth

rates.

7. Temperature control of the nutrient solution enables longer

growth periods in both colder and warmer climates.

8. The shallow stream of nutrient solution in the plastic gulley

allows a single thick, continuous root mat to form, provid-

ing a very stable support for plants.

As with most new techniques, there are still some uncer-

tainties: In some instances, root death has occurred, lowering

yields; however, precautions taken in early 1975 to prevent

root death are claimed to have been successful so far. Little is

known about the need for sterilizing the nutrient film, al-

though if necessary this can be done easily at small cost.

There is only limited experience with its use, and most of this

has been for certain high-cash crops.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.