“Only well-established crops lead to optimal N-fixation”

The farm situated in the Weser hills is one of 31 pilot project farms in North-Rhine Westphalia. It practices a non-inversion cultivation system and has provided trial fields for the last three years on which the impact of various environmental specifications and requirements in regard to nutrient removal, soil erosion, soil fertility, yield performance etc. have been investigated. In this context different catch crop mixtures have also been used. Catch crops have always been part of the Schmeinks’ crop rotation. However, before the “greening era” it has mainly been single catch crops like turnip rape and forage rye.

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Here winter hard components are important

Many fields are on hillsides prone to soil erosion and also in the floodplain of the river Nethe so that besides vigorous growth winter hardiness is a decisive criteria for variety choice. Only with a winter hardy crop both erosion protection and nutrient fixation can be ensured up to drilling time of the main crop.  Through the trials attention was called on the mixture viterra® universal winter that contains an equal amount of phacelia and westerwolds ryegrass and 10 % black oat.

Junior boss Markus Schmeink explains why he thinks that this composition is beneficial to the farm:” In normal years at first the quick growing phacelia dominates. This crop mobilises soil fixed phosphorous. The crop grows vigorously and when phacelia and black oat freeze off the ryegrass fixes the nutrients and prevents soil erosion throughout the winter. Additionally the fields can be travelled easily in February for slurry application. The intensive rooting of the mixture improves soil bearing capacity so much that the difference is still noticeable when harvesting maize.

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Forage rye has also a save place

Within the crop rotation forage maize – winter wheat – winter barley, catch crops follow barley. On the better sites forage rye is still grown. “The variety Protector has been reliably high yielding on these sites for many years”, says Klemens Schmeink pleased. The mixtures are found on weaker sites following barley. Their stubbles are cultivated twice. After cultivating, the catch crop mixture is drilled between the 20th and the 25th of August at a seed rate of 35 kg/ha. The only fertiliser application is carried out with fermentation residues from the biogas plant. They are usually applied before catch crop drilling and partly also with trailing shoes into established crops. A disc harrow, a stubble cultivator and a total herbicide are used in order to kill off the mixture. “Only in very dry years is it possible to live without Glyphosate. However, even then the risk would be immense”, regrets Markus Schmeink. “It is necessary to consider the consequences of the loss of Glyphosate should it fail its approval. We definitively do not want to return to ploughing.” The agricultural department has also picked up this thought and plans trials in the coming years accordingly.

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Water usage of the catch crop mixture is unproblematic

Due to the lack of water after drilling in 2016 the crops’ growth vigour was unsatisfactory. The crop is catching up now but in the case of an early winter the foliage density will fall short of previous years. This circumstance will not have any effect on erosion control and soil trafficability because the crop had already been dense at the end of October. However, N-fixation cannot be optimal due to the lower bio mass available.

Nonetheless, the Schmeinks don’t see the water usage of catch crops as a problem for the following maize. “The reduction in soil moisture loss through a good ground cover by the mixture outweighs the crops’ own water usage. Even in dry years no problems have ever occurred with the following main crop. Certainly, the non-inversion cultivation system and the better soil structure contribute accordingly.  Maize is less prone to drought on unplouged land”, says Klemens Schmeink convinced. “It’s different with forage rye which needs a lot of water and therefore is not grown on light land.”

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Nutrients from organic matter are especially effective

Due to intense crop observations Markus Schmeink established the following theory:
The nitrogen placement is often too early available and can be lost under unfavourable conditions. “Nitrogen fixed in organic matter is better available to the plants. Building up soil organic matter and maintaining soil humus content is also very important in intensive maize and cereal crop rotations. Nutrient supply is more efficient as fertiliser can be saved and nutrient leaching reduced.

Undersowing grass in maize is another measurement to build up soil organic matter. This system has been carried out on some fields already for the second time. However, it is emphasised that undersowing is not due to greening requirements which are already fulfilled elsewhere. Undersowing was especially convincing in continuous maize and when timing is too tight for catch crops. “Too early drilling has to be avoided in any case. In contrary, there is no such thing as too late. It doesn’t look very pretty after the maize harvest but grass re-establishes quickly as soon as light and water are available”, explains Markus Schmeink. “In spring time the field is very early accessible.”

Summary Catch crops are important to the farming system independent of greening requirements or water conservation acts. One urgent advice given from the Schmeinks’ to anybody who is interested in catch crop mixture cultivation: “If you want take advantage of these mixtures the catch crop cultivation has to be done properly. The main crop can only profit if the catch crop is well-established resulting in an optimal N-fixation, sufficient erosion control and deep rooting. Just to do the minimum in order to comply with the greening requirements achieves nothing.”

Dr. Anke Boenisch and Klaus Schulze Kremer

Farm details: Farm Schmeink (Brakel): Pilot project farm of the agricultural department of North-Rhine Westphalia to implementing the water framework directive 850 mm/yr, 140–200 m a.s.l. Crop rotation: Maize –winter wheat – winter barley 30/40 to 89/90 soil points (German soil quality rating, fields range from very low to very high) 140 ha including 20 ha grassland (solely for biogas production) Biogas plant with 320 kW 800 pigs for fattning

Status: 27.12.16