Establishing Cover Crops

Key Considerations when Establishing Cover Crops

• TIME OF DRILLING
  Many of the species require reasonable soil temperatures and day length. Drill immediately after harvest, ideally most cover/ catch crops should be drilled by the end of August to give sufficient biomass and rooting.
  
  
• DRILLING RATES
  The quantity of seed required for a good cover will vary with the types of species included within the mix in relation to seed size, plant architecture and drilling date. The target seed number for a diverse species mix drilled in early August would be 150 – 200 seeds per m2. Higher seed rates, 250 – 350 seeds per m2 with a diverse mix within an established cover cropping system have shown to provide greater soil health benefits.
  
• SOIL MOISTURE LEVELS
  Good seed/soil/moisture contact is required to get quick emergence of the mixtures. Soil moisture needs to be conserved and ideally minimal soil disturbance should be considered during the sowing period.
• SOIL NUTRIENTS
  To achieve a well grown cover crop, early nutrition in the form of nitrogen is required, depending on previous cropping soil N reserves and if there is a high level of straw residue, approx. 20-30 kg of N/ha will be required to aid establishment.
  
• PREVIOUS CROP
  An important consideration particularly if there are high levels of straw residues; cover crops could be held back and overall level of establishment will be disappointing.
  If following winter barley, then removal of the barley straw would be useful, if not the straw and chaff residues need to be evenly distributed prior to drilling. Very good establishment of cover crops has been achieved behind pea and bean crops, also after a fallow situation.
• PESTS
  Slug pressure needs to be assessed following the previous crop. If the pressure is high then slugs need controlling before establishing the cover crop. Pea and bean weevil can cause serious problems for the vetches and clover species, if the pressure is high and insect activity is causing damage, the appropriate insecticide should be used.
• ESTABLISHMENT TECHNIQUE
  Cover crops need good soil structure and a workable soil to achieve maximum growth. Soil compaction needs to be addressed both for the cover and also for the following crop, therefore subsoiling should be completed if required.
  A subsoiler with a tine that stops large amounts of surface disturbance should be considered; again loss of soil moisture is an important consideration. Broadcasting seed 7 -10 days before harvest is an option to achieve earlier establishment and spread work load, but only if the soil structure is good, the correct species mix is used and an even spread pattern can be achieved.