Grow grass as catch crop without reducing your maize yields

Grass sown as a catch crop beneath maize helps maintain your soil and your nitrogen levels – and it does so with no loss of yield.

Why sow grass beneath maize?
When maize crops mature in late summer and early autumn, they take in fewer nutrients. That is when you risk losing precious nitrogen to the ground water below. But not if you have a well-established catch crop of grass beneath your maize. Grass reduces nitrogen loss and provides a level of erosion control after your maize harvest.

Which grasses are best?
Many grass species struggle in the shade cast by maize. Others grow well, but at a cost: they reduce the yield of your main crop. So we set out to find grass species that grow well beneath maize without harming the crop. After three years of trials in Denmark, researchers have isolated three grass species that fit the brief. They are perennial ryegrass, cocksfoot, and tall fescue.

The researchers also identified the time and method of grass seeding that produces the best outcome.

Timing and method
Timing your grass catch crop is essential for success. Sow too early, and you hold back the development of the maize or restrict your ability to use chemical weed controls. But if you sow at either of the times identified below, you should have excellent results:

  • Sow your grass at the time of the second weed control, typically when your maize has 3-4 leaves


  • Sow at the time of the third weed control, when your maize has 7-8 leaves

Undersowing grass as a catch crop beneath maize

Which species to sow, and when to sow them

Recommended grasses Best sowing times: when maize has…
Tall fescue, cocksfoot 3 to 4 leaves
Late perennial ryegrass, cocksfoot, tall fescue 7 to 8 leaves

The simplest way to sow is by broadcasting with a simple electric spinner. But this approach risks low germination levels because the seed rests on the soil surface. You get better results if you follow up with a light harrow or row tiller. Or you could try row seeding at a distance of 18-20 cm from the maize crop. At this distance the grass germinates well and competition with your maize is limited.

Create your EU Environmental Focus Area
Reforms to the EU's common agricultural policy encourage farmers to create Environmental Focus Areas (EFAs). One way to create an EFA (which must cover 5% of the arable land) is to establish spring-sown grass as a catch crop beneath your main crop – which includes maize.

Click here to read more about maize undersown in maize.