Articles
INFLUENCE OF CATCH CROPS IN ASPARAGUS ON THE YIELD AND THE NITROGEN DYNAMICS OF SOIL
This applies especially to asparagus, which takes up nitrogen from the soil only from end of June to beginning of October.
In the other months of the year, nitrogen is liable to leaching.
In order to achieve N-fixation in autumn, specific catch crops are grown between the asparagus rows, at a spacing of at least 1.80 m.
Under the conditions of the Rhine Valley, sowing of oil radish took place in mid-August.
At this time of sowing, the oil radish can still develop and effectively fix nitrogen.
The effect of oil radish on the nitrogen balance in the course of the year, and on the development of asparagus was tested on two soils with different organic matter content (0.3 % and 1.4 %, respectively). The oil radish died with the ocurence of frost in late autumn.
At the end of winter, the plant material was worked into the soil.
By means of catch crops, the Nmin residue can almost be halved in autumn in top soils with higher organic matter content.
The mineralisation of catch crops began in January and the Nmin content reached higher values than in top soils without catch crops.
At the location with a lower organic matter content, the oil radish produced less plant mass and nitrogen fixation was less effective.
Under drought conditions, the development of catch crops can be improved by sprinkler irrigation, in order to ensure a high N-fixation.
First yield results indicate advantages of these methods for the production of first class quality asparagus spears.
However, total yield is slightly decreased.
A conclusive statement can only be reached after further harvest years.