Rain between drilling and emergence can completely compromise crop emergence if a crust forms. In that event, a rapid and determined response is needed to protect emergence and ensure crop survival. Two
trials at Brunnby Research Farm in Sweden showed the importance of always breaking up a crust.

The spring began well at Brunnby and the barley on both fields was drilled on 23 and 25 of April. The foundations were laid for a good harvest. Then came the rain and within the space of 10 days over 50 mm of rain had fallen.

Two types of crust
On soils with a silt component, a crust always develops as a predictable reaction to rain after drilling. Everyone knows that. But few actually know how much yield loss this crust causes, since it is difficult to get reliable measurements. Therefore during an advisory field visit at the beginning of May, the idea arose of measuring the impeding effects of such a crust. Two trials were laid out on different soils. One of these was
a heavy clay with 3.4 % humus.

On this, the crust that developed was brittle and crisp. ‘You could see footprints when someone walked on the soil’, explains Henrik Lillje, crop production advisor for a Swedish agricultural advice service and the initiator of the trials.
The other soil was a poor medium clay with only 1.9 % humus but with a large silt fraction.
‘Here the entire seedbed became a compactcrust’ says Henrik Lillje.

Four treatments
Four treatments were applied in addition to the untreated plot. A Rexius roller with Crosskill rings was used with and without the crust-breaking Double-Knife attachments mounted on the levelling board. In addition, an ordinary NZ cultivator and a converted Wiberg cultivator with three rows of following harrow tines were tested. All treatments were carried out on 15 May and their effects were soon apparent.

‘The trapped seedlings began to grow again when we aerated the soil with some form of treatment’, reports Henrik Lillje. And when the time came to harvest the barley, the summer recovery was apparent in the combine bins in the plots where the crust had been broken. In the trial with the brittle crust, all treatments produced a 14 - 15 % yield increase.
‘The yield outcome was better than we expected. The results show that one should always take action as soon as crusting is suspected’, advises Henrik Lillje.

Crop failure prevented
In the trial with the hard crust, the improvement was huge and the yield increased from the crop failure level to almost a normal level in some of the plots. The conclusion is that it is better to do something than to wait and do nothing at all.
‘The essential thing is to improve gas exchange for the seedlings trapped under the crust’, explains Henrik Lillje.
The best results were obtained with the crust breaking Double-Knife tool, which had to face this stiff challenge in only its first year on the market.
‘The crust-breaker knife is an excellent crust-breaking tool. The advantage with Double-Knife is that it is possible to apply hard cultivation without ripping up the soil because the movement is directed frontwardsbackwards’ comments Henrik Lillje.

Rexius surprising
The NZ cultivator was poorly set up and should have gone deeper, so it did not do itself justice. However, the excellent abilities of the Rexius roller emerged even without the crust-breaking Double-Knife on the levelling board.
‘One pass with the Rexius roller only made faint tracks on the surface but more than doubled the yield!’
The best advice for growers is to always react in some way and to never delay.
‘Always break up a crust – hit it hard with whatever is available on the farm’, concludes Henrik Lillje.