17 August 2001

Plants with room boost winter rape margins

By Andrew Blake

WINTER oilseed rape needs space to produce best yields and margins. That is a key finding from on-farm establishment trials with Apex carried out by Farmer Focus writer and former FW barometer farmer Jim Bullock.

Direct drilling a low seed rate in wide rows after double harrowing produced joint top yield and cost least to grow in his test plots at Mill Farm, Guarlford, Hereford & Worcs.

But sowing early to help the plants smother weeds and resist pigeon grazing is advisable and slug control essential, the work suggests.

The one-acre tramline trials, sown on Sep 6, examined 10 different methods of establishment (see table) costing from £14.80/ha (£6/acre) to £63/ha (£25.50/acre).

The time taken to establish an acre ranged from as little as 8mins to over four times that. All bar plot 9 were sown at 6kg/ha, and only on plot 8 was the straw not removed.

Slug pellets were applied at sowing and again at emergence. "Anything less than this was most unsatisfactory," notes Mr Bullock.

Emergence, with up to 130 seedlings/sq m, was initially best in plots where the soil was inverted (1, 3 and 4), notes Mr Bullock. "But as there was no time to create a stale seed-bed before drilling, these plots required extra sprays to control vast numbers of wheat volunteers and later charlock.

"Plots 5, 7 and 9 looked quite thin all winter but produced good yields. The rape compensated in the spring."

Plots 1, 3 and 4 all lodged in early July. "They should have been drilled at a lower seed rate," suggests Mr Bullock. "The high seed rate in the wide row plot 10 produced a mass of small plants along the row."

Broadcasting produced surprisingly good results despite looking messy all winter. "Its a bit of a risky system. Autumn 2000 was so wet the system worked well, but in a dry year it could be less reliable."

Soil structure in the trial field was good so there was little or no benefit from costly subsoiling. "On poorly structured soils there might be a yield response."

Key conclusion? "If a proper stale seed-bed cannot be achieved, either direct drill or plough," he says. &#42

Ten different methods of establishment

Plot Establishment Time Estab Growing Yield Margin over

method* taken costs costs** (t/ha) estab & growing

(min/ha) (£/ha) (£/ha) costs (£/ha)

1 SS, H, R & DD 78 57 208 3.7 279

2 &#42 x 2, & DD 46 35 143 3.1 274

3 SS, D, R & DD 83 63 208 3.1 245

4 D, R & DD 54 41 208 3.1 190

5 SS, R & DD 68 51 143 3.5 294

6 &#42 x 2 & DD 46 35 143 3.1 274

7 H, B/C, H 20 15 143 3.1 294

8 H, DD (chp str) 31 28 143 3.1 279

9 &#42 x 2 & DD

(wd rws, low rate) 46 35 128 3.7 380

10 &#42 x 2 & DD

(wd rws, std rate) 46 36 143 2.5 185

* Key: SS=subsoil; H=harrow; R=roll; DD=direct drill; D=disc; B/C=broadcast; chp str=chopped straw; wd rws=wide rows (36cm); low rate=3kg/ha; std rate=standard rate (6kg/ha).

** Incl application costs – Six passes for plots 1, 3 & 4, and three for the rest.