Ny teknik för kombisådd

Abstract: The use of combi-drilling during spring tillage has become very common in southern Sweden in recent years. Combi-drilling leads to fewer passes on the field and better plant nutrient utilisation. An example of a combi-drill is the Väderstad Rapid, which is very widely used in spring tillage in southern Sweden. The Rapid has separate fertiliser and seed coulters, which means that the draught requirement is relatively high. It thus requires large, heavy tractors, which compact the soil and are comparatively expensive to buy and run. A few years ago the Finnish combi-drill Tume Nova Combi came onto the Swedish market. This machine places the seed and fertiliser using the same coulter, with the fertiliser placed just below the seed. The risk with placing the fertiliser so near the seed is that it can lead to a relatively high salt content in the vicinity of the seed, which can result in lower yields. In this work, we evaluated the Tume Nova Combi combi-drilling method and compared it with the conventional combi-drilling method in the form of Väderstad Rapid. The work comprised three sub-sections: 1. An overview of the literature on combi-drilling in Sweden 2. A practical field experiment in which we used Tume Nova Combi and Väderstad Rapid to combi-drill malting barley. The results were evaluated by counting plant emergence in experimental plots drilled by the two different combi-drilling methods. 3. An interview survey of farmers with experience of Tume Nova Combi. We found that there were significant differences in emergence of malting barley between the two combi-drilling methods at the Lönnstorp Experimental Station in the very dry spring of 2005. Tume Nova Combi, which places the fertiliser near the seed, gave a somewhat lower emergence (around 15% less) than the Väderstad Rapid. The poor plant emergence was probably due to the fertiliser burning off some of the seed. Furthermore, the effects of high salt concentration in the immediate vicinity of the seed may have been particularly large in this experiment, since only 5 mm of rain fell between drilling and emergence.