The history of mineral for the rejuvenation of soil goes back as far as the beginnings of agriculture itself. While Liebig’s law of limiting factors may well have been a few millennia in the future, the early tentative farmers were quick to learn the potential qualities of alluvial soil for increasing yields of their crops.

With the spread of agricultural practises and the change from nomadic to sedentary lifestyle came the first real population explosion; this in turn drove a need for even more food production putting the earths soils under increased pressure.

While it may well have been the early farmers of the Fertile Crescent that had sowed the seeds of the agricultural revolution, it was their slash and burn cousins from densely forested northern Europe that developed the science of plant nutrition that we take for granted today. The use of animal manures had been prevalent by the middle ages but it was the development of the rotational system, whereby fields were left fallow at first then later planted with legumes, which cultivated the emergence of plant chemistry. Once that technique was discovered, it became possible to keep certain types of crops and fields under almost continuous cultivation, producing two and three harvests a year. The rotational system brought with another population explosion, which in turn facilitated the ushering in of the industrial age.

The process of fixing nitrogen is a notoriously difficult process and before the 20th century is was the sole realm of bolts of lightening and a few hardy bacteria. During that period many people had been working on methods of artificially fixing nitrogen but it was the development, by two enterprising Germans, of the Haber-Bosch process that finally made the the production of synthetic ammonia commercially viable. While this technological breakthrough would have enormous long-term ramifications for the biosphere it had the short-term effect of facilitating Germanys ability to remain in the war.

Now, at the beginning of the 21st century we find our humble planet home to an estimated and growing population of six and a half billion people. The global industries that have grown around this burgeoning population such as agriculture and our own business of horticulture are finding themselves becoming increasingly more dependant upon the use of artificial fertilizers.

Driven by our insatiable appetite for cheap goods, high profits and quick turnover, research and development abound. Ireland, with its relatively small horticultural industry a large number of projects have been undertaken over the last ten years to develop more efficient means of nursery crop production. A large proportion of the research has been undertaken by Teagasc and has been focused upon comparable growth performance between liquid feeding and conventional control release fertilizers systems (CRFS). The use of CRF has proliferated within the industry because of its ease of application, the relatively quick turnover of container crops and limited legislation governing nursery practises. While the practise of bulk buying supplies of peat pre-mixed with CRF has obvious short-term benefits, research has show that this generic approach can result in significant loss of nutrients into the environment. And while our northern European colleagues embrace and apply the latest research findings we have been very slow to implement change. The greatest barrier to effective introduction of alternative methods, such as the closed system, has always been economic pressure and while there are a number of grant schemes in operation the costs of implementation remain prohibitive.

The economic losses incurred through nutrient loss to drainage water are currently absorbed within the industry, the environmental damage resulting from our open systems and the spectre of the nitrates directive and the Water Quality Framework will surely spur much change over the coming years.

Have you wondered how you might become more precise or proficient with irrigation and nutrient applications? Irrigation and fertilizer are controllable costs, but until you examine some of the factors that affect the efficiency of applying water and nutrients, and make necessary adjustments, you might not be controlling those costs to your maximum benefit. Listed below are 13 important management strategies regarding container plant irrigation and nutrition. Implementing any one of these management strategies could reduce your production costs or result in other benefits such as a reduction in water and nutrients lost from containers.

Uniformity of Water delivery.
Lack of uniformity and control of water delivery is one of the primary causes of inefficiency in nutrient management. Excessive irrigation can lead to leeching and run off while under watering can result in lack of mineral uptake. Both results are effectively negative in economic and environmental terms. Determining if an irrigation system is working effectively can be achieved in a number of ways, a visual observation of rotational speed, angle of water, droplet size can isolate specific problems with sprinklers while recording the time to fill the same size bottle in a number of locations is a convenient method for testing uniformity.
 
Plant water requirement.
Another significant factor in nutrient loss is inappropriate plant groupings. Nutrient savings can be made when plants which have similar requirements are placed together and where water delivery to those groups is controlled. Container size should also figure in deciding on specific plant groupings, as larger containers will require more water than smaller ones.

Container spacing and temperature.
Containers and plants of the same size should be placed in as close proximity to one another as possible as a diversity of pot size and large spacings can result in an increase in water loss of up to 50%. Orientation of planting beds and their relative exposure to the elements will have a significant impact on plants ability to uptake and utilise nutrients.

Container design.
Research has shown that squat containers have a greater ability to retain water than the more conventional upright ones. The result of the use of more squat containers will be an increase in the duration between waterings.

Closed or open systems.
While the expense of implementing a closed system may seem a huge cost in today’s climate we have an environmental responsibility that will, if not taken up voluntarily, be forced upon us through legislation.

Substrate properties.
The pressure being put upon our finite peat bogs is enormous. It is somewhat ironic that the driving force behind research into peat alternatives is the UK market. In the coming years we will see change in the primary substrate that we utilise and we will again have to revise irrigation and nutrient techniques to suit. For now we can reduce the leeching fraction by careful monitoring of the water holding capacity of given plants and containers.

While uptake of new research findings has been relatively slow in Ireland some nurseries are being to see the benefits of incorporating integrated potting machine, liquid feed CRF systems. While a large initial investment may be required the subsequent control can result in improved plant performance, reductions in nutrient loss and positive environmental benefits, all of which translate into more cash in our pockets.

For those wishing to investigate this subject further a wealth of information awaits you.

Research and information in Ireland
Teagasc, Head Office, Oak Park, Carlow
Tel: +353 59 917 0200: Fax: +353 59 918 2097
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http://www.teagasc.ie
Web based liquid feeding research http://www.teagasc.ie/research/reports/horticulture/4461/eopr4461c.htm

Popular liquid feeding operating systems in Ireland.
http://www.dosatron.com

For purchase and installation of liquid feeding and irrigation systems, contact.
Mr. Paul Kunkels. Irritec Ltd, Lissenhall, Swords, Co. Dublin. Tel: 01 - 840 4033 Mobile: 088 - 277 4230.