Getting the best from oilseed rape

Farm advisory group Masstock uses a number of “Smart Farms” dotted around the country to compare various crop husbandry practices.

This year oilseed rape specialist Philip Marr has set up a field-scale trial to assess the merits of three OSR establishment methods at the company’s Brotherton Farm near Pontefract, Yorks.

One of Philip’s key tips is to make a sub-soiler pass before planting OSR.

He argues that most farms will be performing the operation at some point in the rotation and doing so ahead of rape maximises the crop’s rooting potential.

OSR can really exploit an open seed-bed and its root structure is such that the soil is left loose for the following crop.

Top Tips for OSR establishment
– Avoid using one variety across farm, choose types to suit seasonal conditions and to spread harvest time pressures.

– Minimise seed rates. Aim for about 60 seeds per sq m which should equate to 40 plants per sq m in spring. E.g. Lioness @ 2.5kg/ha and Caracas @ 3.7kg/ha.

– Be aware of variety thousand seed weights and adjust seed rates accordingly. E.g. 1kg Lioness = 232,000 seeds; 1kg Caracas = 158,000seeds.

– Score seedbed conditions on the day. Increase or reduce seed rates accordingly.

– Attribute costs per tonne rather than per acre/hectare. That way expenditure can be instantly compared with crop returns.

– Consolidation is key – rolling won’t do any harm if it rains but could be the difference between crop failure and success in a dry year.

Consequently each of the Masstock plots was subsoiled.

In addition the whole area was rolled to ensure moisture conservation.

The cost of these passes is included in the final figure.

The first plot received a fairly conventional but intensive cultivation regime.

It had two passes with a set of heavy Simba discs and the seed was drilled with a Kuhn power-harrow combination.

For the second technique an Opico HE-VA Disc-Roller disc/press combination with Variocast seeder-unit was employed.

On the third plot a Variocast seeder-unit piggy-backing on the sub-soiler was used to drop seed in a band behind each soil-loosening leg.

OSR Establishment technique
. Establishment method Subsoil, disc x 2, power-harrow/drill, roll Subsoil, disc/press/seed, roll Subsoil/seed, roll
Cost £130/ha £75/ha £48.25/ha
Advantages – stubble incorporation
– consistent establishment
– consistent 12.5cm (5in) row spacing
– high speed
– seed-to-soil contact
– minimal disturbance in stony conditions
– low cost
– moisture conservation
– minimal weed seed disturbance
-utilises existing sub
-soiler pass
Disadvantages – high cost- time consuming- weed seed disturbance – unnecessary pass if sub-soiling- variation in seed depth- weed seed disturbance – slower output- untidy finish
GAI* on ?10th Mar? 1.4 1.5 2
NB – Costings from Nix Farm Management Pocketbook 2005. *GAI measured by collecting green leaves from 1sq m of crop. This is then weighed and multiplied by a factor of 0.8. Generally if GAI = 1, total leaf area = 1sq m. At early growth stages GAI closely correlates with root development.

Clearly the first technique proved most expensive and the final one cheapest. But that is not all that needs to be considered.

Germination rates, light interception capabilities and of course the final yield all need to be compared.

We’ll be following the trial through the growing season.

First up, we kick off with measurements of the canopy area – Green leaf Area Index (GAI) – as temperatures begin to rise and plants prepare for the spring growth spurt.

GAI scores are highest in the subsoil only plots because seed was dropped directly behind the subsoiler leg, allowing the tap root to quickly establish itself straight down into the loosened slot.

This means that the plants are able to gain access to nutrients (mainly nitrogen) more effectively.

In the other establishment plots, (GAI 1.4 and 1.5) the roots are smaller and found nutrition more difficult to obtain.

We’ll return to the trials for an update as plants reach stem extension – late April/early May.

Did you know?

  • 60% of seed is produced in the lower third of the canopy. Therefore light interception to the lowest pods needs to be maximised. Well spaced, branched plants will achieve this best.
  • Minimising seed rates at the Brotherton Smart Farm has brought average OSR yields up to 5.8t/ha. Yields of up to 7.2t/ha (2.9t/acre) were recorded last year.