Establishment

Establishment

1. Factors affecting germination

   • Soil structure and bulk density
   • Soil moisture
   • Nutrient availability
   • Oxygen availability
   • Soil temperature

2. Plough based

   • Sterile broam does not persist therefore plough is good control method

3. Conservation Tillage VS Plough (SAC, 2006)

   • Disease risk
     • take all and eyespot may reduce but fusarium and other foliar diseases may increase
     • Take-all good soil structure allows crop to out grow disease, influenced main by rotation. Assuming soil structure is good and volunteers are controlled, there is a reduction in the severity of take-all. if min till becomes compacted and grass weeds not controlled it will be come a problem
     • Common eyespot- Expected that disease would increase, however the opposite was observed. Thought that antagonists are greater in higher levels of trash
     • Fusarium- increase in disease where disease levels were highest
     • Greater risk from ergot as they only survive one year and are not buried
     • Phoma in OSR increases as inoculum resisdes in trash
   • Grass weeds and volunteer crops are a problem due to difficulty in control but broad leaf tend to reduce (SAC)
     • Grass seed can germinate on soil surface. Leaving these weeds on the soil surface reduces their chance of becoming persistent.
       • Stale seed bed
     • Grass and cereal volunteers have very little dormancy and readily emerge in reduced tillage systems but some can persist in seed bank for 1-3 years. Black-grass 2-3 years, wild oats 12+ years, and OSR up to 9 years.
     • Most seeds germinate in the top 1-5cm of soil. Cleavers and Oats can germinate from 10-15cm or more regardless of soil disturbance of not, so are less effected from establishment technique
     • Broad leaf weeds have dormancy and will become part of the seed bank if ploughed down. In reduced tillage systems seed numbers depleat in surface soil as long as weeds are controlled
     • Perennial weeds such as common couch and creeping thistle rely on underground rhizomes/stolons for spread which could be encouraged by min-till
     • Herbicide resistance could increase as strong selection pressure apposed to the mixing/diluting effect of ploughing
   • Pests
     • Increase in beneficial insects such as predatory ground beetles and parasitic wasps as plough kills a proportion, leading to better control of slugs and aphid over several seasons
     • Slug populations increase, but partly overcome by the increase in predators,, slug traps recommended with metaldehyde where necessary
     • Aphids -BYDV may increase if volunteers and grass weeds are not controlled as they harbour aphids , green bridge
       • less aphids on CT due to more predators (spiders) and less visual cues (Kendall et al,1995). More straw, less aphids as less contrast of green tissue against dark soil. and therefore less flying aphids
         • Less aphids in autumn results in less aphids at heading and a lower infection of BYDV meaning less insecticide required
           • higher yields in CT and in strawed plots
   • Cost (adapted Morris et al)
     • Plough £80-£115- 65-100 mins
     • Deep non inversion £65-£80- 45-70 mins
     • Shallow non inversion £60-65-24-59 mins
     • Direct Drilling £22-£32 -20-30mins
   • Environmental
     • Reduces run off 48% and sediment loss by 68% (Holland,2004)
     • soil stability, reduces run off and therefore pollutants within. e.g. nutrients, pesticides and silt
     • Aquatic ecosystems- rainfall infiltration, replenishment of water sources, maintain moisture in top soil level reducing need for irrigation
     • eutrophication reductions,
       • nitrate leeching can be higher as proportion of water moving through the soil is greater.
         • earth worm dramatically increase in CT, creating macropores and greater filtration of water
       • phosphate
     • Greater reliance on herbicides in CT
     • improved soil biodiversity- increased nutrient recycling, improved soil structure and suppression of crop pests and diseases
     • Seed eating birds increase and ground nesting birds

4. Herbicide efficiency

5. Yield (Kennedy)