Ny teknik för kombisådd
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.