UNSIFRAN

Motivation

Silage maize occupies a special position in field forage production for ruminant feeding due to its high biomass yield potential, energy content and good digestibility. There is also a growing interest in maize cultivation in organic farming (ÖL) and the area under cultivation has increased almost tenfold nationwide from approx. 4,500 ha in 2007 to approx. 40,000 ha in 2018.

The particular challenge in silage maize cultivation is the complex weed control, which at the same time inhibits many farmers from getting into silage maize cultivation. Furthermore, there are concerns in the oil sector about silage maize cultivation due to soil erosion problems, which often occur in conventional cultivation systems. Various mechanical weed control strategies have been developed in the past, most of which involve intensive tillage (ploughing, hoeing, harrowing, harrowing, raking) and can therefore increase the problem of soil erosion.

Aims and approach

The general objective is to optimize weed control in silage maize cultivation while at the same time optimizing soil protection. Weed pressure, and thus the need for weed control in silage maize, can be efficiently reduced by growing a suitable preceding crop as a first crop ("winter catch crop"), reducing tillage for maize sowing and reducing row spacing in maize cultivation. Harvesting the preceding crop can lead to an economic advantage of the process.

The project aims to optimize weed control in silage maize cultivation through a preventive approach to crop rotation and cultivation design. To this end, the systemic investigation of a crop rotation element consisting of winter peas in pure seed or in a mixture with triticale or winter vetches in pure seed or in a mixture with rye as preceding crops/first crops and subsequent maize cultivation with reduced tillage or direct sowing as well as with standard (75 cm) and reduced row spacing (37.5 cm) as a second crop is to be carried out.

Innovations and prospects

The following aspects are being investigated in multi-year field trials at three locations:

• Testing the preceding crops with regard to their potential for a preventive reduction of weed pressure in silage maize due to their biomass development.
• Effects of different treatment methods of the first crops: mixed harvesting at the end of May as whole plants or - like the pure seeds - mechanical destruction of the growth with a knife roller; effects on weed dynamics in maize.
• Testing of reduced tillage (after mixed harvesting) for maize sowing and of maize direct sowing after mechanical destruction of the previous crop with regard to weed dynamics in maize.
• Effect of reducing the seed spacing between maize rows to 37.5 cm on weed dynamics in maize.