Canopies up to sector challenge

22 June 2001

Canopies up to sector challenge

Manipulating agronomy for

the correct plant canopy

structure should help wheat

growers achieve high yields

at low cost every year.

Edward Long explains

how the latest effort to

demonstrate the technology

could save a Notts producer

over £16,000 each year

MORE grain for the same or less outlay is the tempting prospect being demonstrated in a joint ADAS, DTI and HGCA initiative underway on farms across the country this year.

The science-into-practice aim is to show how practical farmers can exploit technology to boost profits. On one demonstration site the method looks set to cut variable costs by £16,800 each year.

"The approach is based on HGCA-funded trials undertaken largely by ADAS in the 1990s," says ADAS Gleadthorpe-based consultant Andy Wells.

"It shows what type of plant architecture should be created by manipulating seed rate, variety, drilling date and nitrogen inputs. There is no blueprint for high yields at low cost, as seasonal factors make it a movable target. But it is a target that can be hit.

"In a good season it is easy to produce a high yield. But the reason for success is often unclear. We aim to show, by a series of Sector Challenges with practical farmers trained to manage the canopy, how to achieve high yield at the lowest possible cost consistently year after year."

John Hollingworth, who has 330ha (815 acres) of wheat on his 777ha (1920-acre) South Farm at Letwell, near Worksop, has one of the Sector Challenge sites on the Yorks/Notts border.

He grows biscuit types Claire and Consort for a local pet food manufacturer and has a yield target of 8.75t/ha (3.5t/acre).

A 16ha field of Consort is the Sector Challenge crop, but a further 121ha in neighbouring fields is also being canopy-managed.

"Canopy management defines the mechanisms of what is needed to make wheat crops more reliable," says Mr Hollingworth.

"By targeting inputs to actual need, efficiency is improved and cost reduced. The secret of success is to be flexible and react to what is happening in the field."

For optimum yield he needs 500-600 heads/sq m. To achieve this he must work back to seed rate.

An early September-drilled wheat tillers more than one put in during mid-October, so less seed is needed. With a 1000-grain weight of 52g and a target of 120 seeds/sq m, 78kg/ha of the farm-saved seed was needed for the early sowing.

For wheat drilled in mid-October 260 seeds/sq m were required to achieve a target of at least 90 established plants by spring.

The min-tilled Sector Challenge crop emerged within a week, and with 100 plants/sq m it was clearly too thick. But it provided a buffer against losses in an autumn of high slug risk.

"The critical time for canopy management is the spring," says Mr Hollingworth. "We look at our crops carefully in late February or early March to assess winter plant loss.

"We count tillers and like to see twice as many as we need for our 500-600 ears, because half of them will be lost by early May. If there are fewer than 1000 tillers early nitrogen is applied to keep them alive."

For best results a canopy with a green area index (GAI) of 6 is required by growth stage 59 (the start of flowering). That means the crop has produced enough green material to cover the ground beneath it six times. Visual guides to assess GAI are available.

The GAI figure is then used to guide optimum N, with 30kg/ha of N being required for each unit of GAI. Nitrogen can be from the bag or soil mineralised reserves.

In February the soil mineral nitrogen (SMN) is assessed. This season there were 79kg/ha, and with 1000 tillers/sq m no early N was needed to top-up soil reserves.

To achieve GAI 6 at GS59, allowing for the SMN and a GAI of 1 in early March, another 140kg/ha was needed from the bag. This was applied on Apr 12 and 30.

"I was not keen to apply it all in one dollop, so opted for two equal splits. It was hard having to wait until GS30 before putting any on, as neighbours were all busy. But mine did not seem to suffer. It was never yellow, though it was obvious it had not been given the early green-up dose that made neighbouring crops looks so lush."

South Farm plants not "stretched" by early N had thick stems so the lodging risk was reduced. In the past, Mr Holling-worth has spent heavily on regulators to keep crops on their feet.

The N cost for this seasons canopy managed Consort and adjacent crops was just £19.44/ha (£48.01/acre). The only pgr, chlormequat, added £2.02/ha (£4.99/acre).

Second wheat on the farm costs at least 25% more, most of the extra due to increased N and pgr needs, and a more expensive eyespot fungicide.

Fungicide applications for the canopy-managed crop are simple and frugal. By early June only a single Mantra (epoxiconazole + fenpropimorph + kresoxim-methyl) treatment costing £16/ha (£39.50/acre) had gone on.

Variable cost projection suggests £123.50/ha (£50/acre) will be spent on the Sector Challenge crop, compared with £174.60/ha (£70.69/acre) last year.

"This is a saving of more than £20/acre on first wheats which over 815 acres adds up to over £16,300. It will be interesting to see what savings are possible when canopy management is applied to second wheats."

&#8226 farmers weekly will revisit the trial site at harvest to check on yield results from the canopy managed crops. &#42


&#8226 Notts/Yorks border.

&#8226 777ha clay to limestone.

&#8226 Wheat, barley, OSR, sugar beet, potatoes.

&#8226 Target wheat yield: 8.75t/ha.

&#8226 Varieties: Consort and Claire.


Rotation Followed oilseed rape

Variety Consort

Area 16ha

Drilling date Sept 4

Seed rate 78kg/ha of farm-saved seed for 120/sq m

TGW 52g

Seed cost £8.84/ha

Emergence 100 plants/sq m

Winter survival 100%

Target population 500/600 ears/sq m

Projected variables £123.50/ha

Variables last year £174.60/ha

Average saving £51.10/ha

Saving on 330ha £16,863

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