Markförbättring och odlingsanpassning på lågavkastande jordar

In 1980 and 1981 four field experiments were laid out within the project "Soil improvement and adaption of cultivation practices on low yielding soils". The project was carried out in co-operation between four divisions of applied research and field experimentation at the Agriculture University. The divisions involved were Agricultural Hydrotechnics, Crop Rotation Science, Soil Management and Soil Fertility and Plant Nutrition. The field trials were mainly considered as observation trials due to the lack of replicates. All the trials had a similar design. In one direction soil improvement treatments were laid out and across those, the special treatments of the different divisions (see Figure 1). Three of the trials were laid out on silty clay soils (Finnbo, Igelsta & Bryngelsrud) and one trial on a gyttja soil (Kurö). The results from the soil improvement part of the trials showed that deep cultivation in general had a negative effect on the silty clays and no effect on the gyttja soil. Mixing organic material into the topsoil had a positive effect on both soil types. The nutrient content of the organic material used was quite high, which makes it hard to distinguish between the soil physical effect and the nutrient effect. Plowless cultivation was successfully tested on the silty clays. Liming with burnt lime (CaO) had a positive effect in some cases but not in others. Nitrogen fertilization had a general effect on the yield level but did not give any distinct results in combination with the soil improvement measures. Ley in the crop rotation had in general a large positive effect on the yield level. An absence of ley in the crop rotation could to some extent be compensated for by the mixing of organic material into the topsoil