Fertilisers in Solution

Keywords: Solution fertilisers, Fluid fertilisers, Fertiliser development.

Introduction:

Fertilisers in solution have been used in the UK for a number of years by growers of vegetable and other horticultural crops. Potassium nitrate was probably the first salt to be used in this way. Since the war, with the development of sprinkler and trickle systems of irrigation, the practice has extended. Soluble salts are introduced at some point in the irrigation water and applied as a ‘rain’ over crop and soil, or released on to the soil at a controlled rate near the plant. Nitrogen, phosphorus, potassium and magnesium salts, alone or in combination, where this is possible, are being applied apparently successfully by these methods.

In areas where there is a need for irrigation and a suitable water supply is at hand, nutrients are being applied through sprinkler irrigation systems to brassica, sugar beet, grass and other farm crops. Nitrogen is the main nutrient added and sources such as urea, ammonium nitrate, potassium nitrate and sodium nitrate are used.

Sometimes, solutions of urea alone or urea plus magnesium sulphate are sprayed on to fruit trees but mostly as a first-aid measure to deal with a deficiency that is difficult to correct otherwise. Manganese and copper and occasionally potassium are applied as foliage sprays where deficiencies are troublesome.

Recently, dilute solutions of ammonia have been applied from spraying machines on to grass, cereals, kale and other farm crops, and aerial applications of urea solutions have been tried.

There appears to be no record of fertilisers in solutions being injected into the soil in this country on a field scale.

The total amounts of plant nutrients applied in solution must be very small compared with the total tonnage of fertilisers applied to crops and grass in the UK, which was estimated to be 291.3 thousand tons N, 385.8 thousand tons P₂O₅, and 305.4 thousand tons K₂O for the year ended June 30^th, l956. The proportion as liquid fertiliser might increase considerably, however, if fertilisers were to become more generally available that were particularly suitable for application in liquid form, and machinery for applying solutions to crops were developed at the same time.

It is the purpose of this paper to examine the possibilities with liquid fertilisers on soils and crops in this country. Since experience with them is so limited much use has been made of American sources of information where liquid fertilisers are well-established and developing fast. Application to the soil or to crops and soil will be considered, but not foliar nutrients.

Dr N H Pizer MSc, PhD, FRIC, National Agricultural Advisory Service, UK.

42 Pages, 9 tables, 28 references.