DEVELOPING STANDARDISED COMPOSTS FOR TOMATOES
John Innes seed and potting composts (1) are widely used as standard propagating media by tomato research workers. These composts were also used in the early studies at Kinsealy. However, lack of uniformity, problems in stacking and the difficulty in obtaining suitable loams for John Innes composts forced us to investigate the potential of other materials as a basis for composts. Horticultural moss peat is a light, uniform, almost sterile medium which is readily available in Ireland. Moss peats have a high cation exchange capacity and compared with mineral soils have a high pore volume and consequently a high air and water capacity (2). These characteristics ensure that the nutrients added are available to plant roots and that the root zone is adequately supplied with oxygen. There is no danger of overwatering once drainage is provided. Laurie (3), commencing in 1928, grew a range of annual plants in 1 : 1 mistures of sand and peat and Baker et al (4) following exhaustive studies later developed the UC system for producing healthy container-grown plants in peat sand mixes. There are five basic UC mixes of sand and peat in the following proportions (percent by volume): 100/0, 75/25, 50/50, 25/75 and 0/100. The most commonly used UC composts in California(4) are (sand/peat) 75/25 and 50/50. Suggested uses for the 100 percent peat compost were in cultivating azaleas, gardenias and camellias (4). Publication of the UC Manual 23 in 1957 stimulated interest in peat sand mixes and in 1959 Downes and Brickley (5) studied the use of a 75 peat, 25 sand mix for propagating tomatoes. They found it necessary to modify the UC formula and to add trace elements. Their work led to the development of the UCEE* compost which gave excellent results as a tomato propagating medium. This was an important advance in the quest for a standardised factory-made compost. It was an asset both to the experimenter and the commercial grower. However, Downes and Brickley developed this compost for maincrop tomatoes. Since then the Irish tomato season has been considerably extended and some early growers doubted the suitability of the UCEE compost for plants grown under poor light conditions following a mid-November sowing. It was at this point that the work on the development of standardised seed and potting composts began at Kinsealy. Studies carried out since then are described.
Woods, M.J., Browne, H.K. and O'Hare, J.J. (1968). DEVELOPING STANDARDISED COMPOSTS FOR TOMATOES. Acta Hortic. 7, 181-185