Asutuskeskuksien orgaanisen jätteen käyttö kasvinviljelyssä

Authors

• Toivo Rautavaara

DOI: https://doi.org/10.23986/afsci.71286

Abstract

Reporting on conceptions to date regarding the significance of organic matter in the soil, the author presents a biologico-dynamic view on plant production; soil fertility i. e. its ability to produce both qualitatively and quantitatively the best crops at a minimum of cost is primarily determined by its biological condition, varying in accordance with the composition and the succession phases of the biotic community (biocoenose) of the humus. This biocoenose of the humus has a twofold activity: the production of organic matter and its decomposition. If man ignores this perpetual circulation by harvesting his crop and by administering only mineral salts to the plants direct, the biocoenose loses its equilibrium and is destroyed. The result is the disappearance of top soil, erosion, and the degeneration of plants, animals and man. This can only be averted by providing the biocoenose of the humus with sufficient quantities of such organic matter that the biocoenose can use as source of carbohydrates and other nutrients. The quantity required varies in the different climates and conditions. A part of it is obtained as the waste of crop, primarily roots. According to Sauerlandt (38) and Salonen (37), the author states, if the objective is to replace annually with equal quantities of organic matter the amount lost from the biocoenose in the form of the crop, clover is the only plant cultivated in Finland that leaves an adequate amount of root stock in the soil. Cereals and particularly root vegetables and greens leave far too little of it, fruit trees and berry bushes less still. The deficit can be replenished by correctly prepared cattle manure containing enough straw. But in the neighbourhood of towns and villages, where mainly intense gardening is practised, the amounts of manure available are grossly inadequate. The best source of organic matter in such conditions is the refuse of population centres, containing mainly paper, food waste and ashes. Its composition makes this waste ideal nutrition for the fungi, actinomycetes and bacteria which play the main part in the humus. They require the carbohydrates offered to them in readily digestible form, as by the cellulose in paper. The population in towns and other centres of population in Finland totals 1,640,000, producing approx. 300 million kg dry waste annually. Approx. 1 million people live in areas furnished with sewage facilities. The N, P and K salts contained in wet and dry waste are alone very valuable; at the same time, mineral fertilisers were imported to Finland 1949 to the value of 2,110 million marks. At the moment dry waste from all Finnish towns is taken to dumps, but in Helsinki for instance no dumps will be available within a reasonable distance in 3 years, for which reason an incinerator has been planned. At their meeting of November 24, 1949. the Helsinki Horticultural Society decided to request the Municipal Administration to alter their resolution. At their annual meeting of March 20, 1950, the Association of Horticulturists adopted a resolution demanding the Goverment to initiate investigations and to supplement the items on disposal of refuse included in the Act on Public Health. After a review of the uses of dry waste in the different parts of the world, the author comes to the conclusion that the high wages paid in Finland do not permit the use of the laborious Indore Method and its variations. But a very simple and both technically and biologically successful method and equipment (Dano) has been invented in Denmark, and the author has studied it in some Danish and Swedish towns. A single slowly revolving drum mixes, reduces, granulates, sorts and empties the waste automatically onto a conveyor belt, untouched by hand, converting it in a few hours into an odourless, porous grey product, very easy and convenient to handle. While fresh this product develops a better and more even heat in nursery beds than horse manure. »Ripe», i.e. fermented in heaps, it is excellent manure and soil improvement matter, increasing the crops of all cultivated plants. If no buyers are found for the product, it can be used as clean soil filling to provide valuable plot land. Aerobic fungi and bacteria increase rapidly in the product, and while stored in heaps its own heat makes it self-pasteurising, and it is therefore absolutely hygienic. In Northern conditions it is obviously the most advantageous method of waste treatment, more so than controlled tipping, not to mention burning which is most expensive of all. Sewage or night soil can easily be combined with Dano compost, as is done e.g. at Karlskoga in Sweden, and in that case too the product is odourless and hygienic. The conclusions of the author are as follows To prevent the disappearance of humus top soil, to reduce the necessity for purchasing fertilisers, to lower the high cultivation costs occasioned by exceedingly high manure prices, and to improve the quality of cultivated products, the tendency should be to treat both dry and wet town and village waste so that it can be utilised in household and market gardens, in agriculture and for the improvement of waste soils. This can be done successfully, with technical and biological advantages employing the mechanical composting method, e.g. Dano convertor equipment.