Deep Topsoil Research Articles

The chronology of anthropogenic soil formation in Orkney

Abstract Anthropogenic deep top soils in Orkney, formed by the process of ‘plaggen’ manuring, are dated by their association with settlements of known cultural age and by radiocarbon. On the basis of these methodologies, the initiation of deep top‐soil formation is dated to the mid to late Norse period. Possible reasons for the initiation of deep top‐soil formation include the introduction of the ‘plaggen’ manuring technique by monastic settlement and the need to sustain increasing population levels. Formation of these soils continued until the late nineteenth to early twentieth centuries when new methods of maintaining arable soil fertility were introduced.

Restoration of Grassland After Magnesian Limestone Quarrying

(1) The chemical and physical properties of Magnesian Limestone waste strongly suggested that successful restoration to grassland would require large additions of nutrients, and also organic matter to improve its texture. (2) Greenhouse experiments and field trials with commercially available seeds mixtures and amendments such as fertilizer, softwood bark, peat, topsoil and sewage sludge indicated that a combination of complete (NPK) fertilizer and an organic material are likely to be the most effective in giving satisfactory establishment and sustained growth. There was a linear relationship between growth and fertilizer, suggesting that very heavy fertilizer applications (up to 2000 kg ha-' of a balanced complete NPK formulation) could be most effective. Treated sewage sludge (at 38 t ha-') with added potassium was shown to be an alternative, being more effective than complete fertilizer at 900 kg ha-'. (3) Legumes, considered to be important because of their nitrogen accumulation potential, were found to respond markedly to complete fertilizer (at 600 kg ha-') but not to inoculation. Growth in the absence of fertilizer was negligible. (4) A comparison of different species both in pure stands and in mixtures indicated that Agrostis stolonifera L., Festuca rubra Gaud., Dactylis glomerata L., and the legumes Lotus corniculatus L. and Trifolium repens L. were likely to be the most effective in long-term reclamation. (5) These findings were confirmed in an 11-year trial, showing that permanent low maintenance grassland can be established on Magnesian Limestone wastes without recourse to deep top soil coverings.

Effect of soil type and depth on crop production

SUMMARYTopsoils from eight different soil series were substituted for the local soil in three arrangements involving two depths of topsoil and either local or sand subsoils. A rotation of crops was grown with uniform annual N, P and K treatments for 24 years. A peaty soil produced the highest yields of grain, straw and grass, presumably because it released more N than the mineral soils, but an average yield of swedes. No mineral soil consistently produced higher yields of all crops and, although there were some significant differences, the variations in yield were generally relatively small. The deep topsoil consistently produced the highest yields. Topsoil with sand subsoil gave the lowest yields of grain, straw and swedes but not of grass.All the crops on the peaty soil had higher concentrations of P in the dry matter than those from the seven mineral soils. Crops and herbage on the Laurencekirk and Foud-land soils had consistently slightly higher P concentrations than those on the other five mineral soils. Compared with the amounts applied, the crops removed considerably more K but only 45–68% of the P. There were large differences in the proportion of the P residues extractable by acetic acid from the different soil series.The depth of topsoil was at least as important as soil type in determining yield, and the results support the use of soil depth as one of the main factors used in the Land Capability Classification for Agriculture.

The formation of deep topsoils in Orkney

AbstractThe Soil Survey for Scotland, in their mapping of the soils in Orkney, identified a deep top phase of the Bilbster Series. This soil is distinguished by having a topsoil usually in excess of 75 cm and it occurs almost exclusively on the Mainland of Orkney, especially in the west round Marwick and Skaill Bays. An anthropogenic origin to this soil is proposed and the present study is designed to investigate the particular processes of formation which have led to the increase in soil depth. Results from transect and grid surveys indicate how the soil is thickest adjacent to old farms. The historical literature suggests a wide range of possible inputs from seaweed and calcareous sand to turves after they had been used as bedding for cattle. Analytical results support the last process as the dominant one and an accumulation rate of c.1 mm/yr is proposed.

Economics of Grassland Farming in the Cornbelt

ONSIDERABLE interest within the past few years has been focused on an area of agriculture commonly referred to as grassland farming. A plausible reason for this development is that over the years forages have not received the same degree of emphasis as other crops.1 Some persons are even willing to go so far as to say that with somewhere near equal attention to forage crops a new frontier in agriculture will be opened up-that within this frontier lies the key to the greatest potential in agriculture, today. History shows that new frontiers are usually surrounded by glamour and propaganda. In Michigan, we feel that much of the present day publicity concerning grassland farming is grossly overdone. The problem is nothing more than the age old problem of farm management with emphasis on forages. The remainder of my remarks will be directed with this vein of thought in mind. In organizing a farm, we recognize that soil characteristics of the land pretty much determine or set the limits for the minimum amount of grass which should be included in a cropping program. Generally, this minimum is referred to as being the least amount of grass required to maintain soil fertility and crop production. As one might expect, this limiting factor may vary greatly from farm to farm. Between the corn belt and those farms located elsewhere, even larger differences may be anticipated. In Michigan on a large number of our farms where the land is less fertile and rolling, the percentage in grass may be 35 to 40 more as compared to only 20 to 25 per cent on corn belt farms. It is even suspected that on the best corn belt farms, having deep level top-soil subject to little erosion, the proportion necessary in grass may be approaching zero. For such farms, it may possibly be more economical to supply nitrogen from the bag (commercially) than to attempt to provide it by growing legumes. It is generally agreed that on a good share of our farms there is a possible range over and above the minimum of grass where other characteristics besides soil characteristics play a major role in deciding the best propor-