| 原文摘要 | Soilless culture of plants in containers involves a restricted root system and a reduced root zone volume when compared with soil-based production. While details related to this are covered in Chapter 2, Soilless Production Agriculture, and Chapter 14, Growing Plants in Soilless Culture: Operational Conclusions, it is important here to note that under these conditions the physical and chemical properties of the growing medium must be such as to provide adequate storage of water and nutrients for the plant whilst maintaining good aeration. Historically, materials such as locally available soils were used to grow plants in pots and containers. Often, organic materials such as manures and composts were used to supplement the inorganic base materials, improving water retention and airspace as well as offering nutritional benefits. Many formulations of combinations of soils with organic materials, notably peat and manures, are reported in the 19th century articles in magazines and elsewhere (Anon, 1874), and even a few reports exist of growing media containing exclusively organic materials (Anon, 1830). The scientific studies of Lawrence and Newell (1939) in England on development of standardized growing media of consistent pH, absence of pathogens, pest and weeds, and without nutritional imbalances (the so-called John Innes composts) recommended the inclusion of 25% organic matter in the form of moss (sphagnum) peat. However, their media required the acquisition and sterilization of good-quality loam soil, and difficulties in obtaining such loam and cost of its sterilization led to its popularity declining among professional growers post-1950. In the United States during the 1950s, growing media principally based on peat were developed at the University of California (Baker, 1957). Further studies in Germany (Penningsfeld and Kurzmann, 1966) and Ireland (Woods and Kenny, 1968) showed that peat alone could form the basis of growing media. Peat use in horticultural growing media then expanded rapidly. In the early part of the 21st century, growing media used commercially in many parts of the world are prepared mainly from peat along with other organic materials: the major exceptions being mineral wool substrates used for glasshouse crops such as tomatoes, cucumbers, and pepper. |