Soil / Cover Crops

Approximately 20% of the nitrogen applied in agriculture is lost through nitrate leaching – with negative consequences for the environment and the economic efficiency of agricultural businesses. An innovative way to counteract this issue is the strategic use of crop species that release biological nitrification inhibitors (BNI). The corresponding investigation was carried out with the support of the European research project Catch-BNI.

Cover crop mixtures can have a decisive influence on the soil and main crop – but how do you create the perfect mixture? Breeding expert Nic Boerboom provides insights into the development of new varieties, their specific characteristics and the challenges of breeding. Find out why well-thought-out combinations of cover crop species offer real added value 
for agriculture.

What can I use companion crops for, what do they do and what do I have to consider when using them in my herbicide management? Prof Dr Verena Haberlah-Korr from the South Westphalia University of Applied Sciences in Soest answers these questions in this article.

The intensity and frequency of extreme weather conditions is increasing. Drought, heat, wind, heavy rain and wetness – these weather effects have a major impact on the soil and are an enormous challenge for agriculture. Dr Norman Gentsch from the Institute of Soil Science at the Leibniz University of Hanover shows how these challenges can be met with the help of various cover crop mixtures using his results from the CATCHY project.

Do I use a single component or a mixture as a cover crop? Are four components in a mixture enough or should there be more? You can find out that there is more than just one correct answer in the summarised results of the CATCHY project.

In this regard, in the CATCHY research project were determined results that are extremely valuable for practical use. Since 2015, individual components have been compared as pure seeds and cover crop mixtures with a black fallow in crop rotation trials.

Nitrogen losses are a major problem in agricultural crop production. Around 20% of the nitrogen fertiliser used get lost in the form of nitrate leaching and causes enormous environmental damage. Stabilising nitrogen in the soil is an efficient way to minimise nitrate losses. Some plant species can even do this on their own. Whether catch crops are also able to stabilise nitrogen and to what extent this can increase the nitrogen efficiency of the subsequent crop is the subject of research in the Catch-BNI project.

The cultivation of catch crops is an important measure for maintaining and promoting soil fertility. High labour peaks and a limited sowing time window often lead to compromises in sowing technique. Therefore, the result suffers. Precise drill sowing can consume too much time, energy and valuable water. It is important to combine resource conservation 
and crop establishment. 

The environmental impact of nutrient leach but also soaring fertiliser prices make it necessary for arable farmers to optimise their nutrient inputs. Cover crops have become a popular extra option in the crop rotation, because they help reduce nutrient losses. Funded by the German Ministry of Education and Research (BMBF), the CATCHY project researches into multiple cover crops and their nutritional benefits for maize as a main crop.

Franz und Marita Grötschl run a dairy farm in the Austrian Burgenland along the Hungarian border. They farm a 65-head herd of dairy cows and their female offspring. Growing their forage on dry and sandy soils, the Grötschls apply rather uncommon methods that defy the extreme weather and soil conditions.

Extreme years like 2018 show that main crops suffer greatly in adverse weather 
conditions. The effects on the plants cannot be prevented, but cover crops are a 
helpful instrument for obtaining resistant plant populations. This is demonstrated 
by studies from the German Federal Ministry of Education and Research (BMBF) 
CATCHY project.

TerraLife® mixes have become an integral part of cover cropping. TerraLife® was launched in 2010 as Germany’s first programme of cover crop mixes designed specifically for crop rotations. The programme was developed over 10 years ago to harness the special benefits of mixes containing different species. The aim was to create a simple cover crop tool for farmers which would improve soil fertility and loosen up the soil between crop rotations. Scientific studies have now confirmed the superior performance of species-rich mixes compared with single crop sowings.

The aim of cover cropping is to improve soil fertility and boost the efficiency of crop rotations. But the choice of cover crop must be tailored to the farm – and rotation system.

Large parts of Germany have struggled for years with very erratic rainfall patterns. Some farmers are now tending to question the usefulness of cover cropping in dry and even semiarid regions largely on the basis of their experience in the dry summer and autumn of 2015. Does cover cropping conserve 
water or squander it?

Farmers have a choice as to which ecological compensation measures they use to meet their greening obligations. According to the German Federal Ministry of Food and Agriculture (BMEL), around 1.37 million hectares of land were designated as ecological focus areas in 2015, of which as much as 930,000 hectares were undersown or sown with cover crops. In weighted terms (factor 0.3) this amounts to around 40% of all greening measures undertaken.

The root system forms the starting point for a plant‘s performance. In the past it has been very difficult for breeders to select plants by root growth, but current research is now shedding new light in this field and creating new opportunities.

The best soils in Europe are in the Kraichgau, in the north west of Baden-Württemberg. A highly erodible covering of loess and a percentage of silt nonetheless pose a challenge for farming. A soil like this suffers from compaction, if, as is the case today, 80% of the land used for agriculture is used in mulch sowing processes. Even growing cover crops, currently consisting of sole crops of phacelia, mustard and oil radish, has no effect on loosening the deep soil. A group of resourceful farmers found an approach to solving the problem in cooperation with the Office of Agriculture, using a variety of cover crop mixtures to loosen the deep soil.

Some 50 specialists from the consultants‘ circles, the state advisory agencies and the Chambers of Agriculture in Lower Saxony, Hessen and North Rhine Westphalia were invited to view the seed breeding station in Asendorf and
then to a discussion forum on soil fertility in Bücken.

In the 1990s, crop rotations were considerably limited by the need to economise and the resulting lack of intercrop cultivation. Meanwhile, intercrops before sugar beets or other spring cultures, such as maize or potato, have become a component of crop rotation. The decisive question now is, which intercrop mix is right for the respective crop rotation and how can it be established well.

Radish Deeptill (Raphanus sativus), also known as “melioration radish” is a plant breeding innovation. The focus was on a strong rooting performance to combat soil compaction during the crucifera selection process.

As a farmer, you don’t like to see your soil – your greatest resource – being washed away as a result of heavy rain. However, extreme weather is unfortunately becoming increasingly common.