Article taken from the Farm Contractor & Large Scale Farmer, written by Andy Collings
For an increasing number of arable farmers, black grass has become an almost unbeatable grass weed which, despite their best efforts has continued to flourish over ever greater areas. Compounding the problem is the reduction in the number of chemicals available to control it and, in large areas of the UK, it is becoming resistant to chemical control.
Short of fallowing, extensive use of glyphosate and a move to a spring cropping regime, it would appear that in some extreme cases there little else that can be done to halt the progress of this pernicious, costly, yield sapping weed.
Or is there? Agrovista and Bayer CropScience are currently running Project Lamport which, taking place in Northamptonshire, is a five-year rotational project aimed at developing new ways to control black grass that still enable combinable crops to be grown. Included in the program is discovering weather the use of autumn sown cover and companion crops – and their integration with wheat and oilseed rape crops – can help to suppress black grass.
“It’s a comprehensive project which has 14 different rotational systems incorporating winter and spring cropping, new initiatives including traditional fallows and hybrid rye production for AD plants.” Says Mark Hemmant, Agrovista’s technical manager. “We aim to develop new systems that go beyond the present techniques such as stale seed beds, delayed drilling and increasing seed rates. This is crucial if we are to prolong the activity of Atlantis and contribute to other herbicide stewardship.”
He adds that all the systems used will be evaluated against traditional winter wheat/OSR rotations and the end of the project will see all the plots being drilled with winter wheat to assess the degree of black grass control that has been achieved - and provide a comparison of the costs expended on each plot.
A key and perhaps novel feature then, of Project Lamport is the use of cover crops – the timing of sowing, how they are sown and the plant species used within the seed mixtures.
For this latter detail, the project is using seed mixtures developed by French company Jouffray Drillaud. Interesting to note that in France – as in Germany – it is illegal to leave land bare during the winter with farmers required to plant a cover crop if the land is destined to be drilled in the spring.
“This is to ensure valuable nitrogen and other soil nutrients are not leached away,” says Jerome Vasseur, the company’s commercial manager. He points out that in an average winter, a cover crop’s take up of soil nutrient can prevent up to 36kg/ha of N being lost along with significant amounts of PK and Calcium Oxide, magnesium and sulphur.
But there are other benefits to be gained through using cover crops, he insists. These include better weed control due to the cover crop colonising the ground and preventing space for weeds to flourish, and an improvement of soil structure. Different plant types have different rooting systems – some are strong and go deep while others work closer to the surface – with the result being an improvement in soil drainage and the creation of good rooting territory for following crops.
“Cover crops can also provide increased biodiversity,” he says. “Early flowering plants provide food for pollinators and some cover crops also have a positive effect on the development of plant diseases, such as take-all due to an interruption in the life-cycle of the soil born fungus.”
All of which would seem to add up to a convincing argument. But there are cover crops and there are cover crops, and to get the best results it’s necessary to use plants which have been bred specifically for this purpose.
Mr Vasseur outlines the main characteristics required. “Plants need to have a low carbon to nitrogen ratio (C/N ratio) which is an indicator of how quickly they will release nitrogen when they are mineralised back into the soil,” he explains. “Black oats, which is one of our most used varieties, has a C/N of 12 which is very low and releases its N quickly as a result. Mustard’s C/N is rated at 30 and is rather slow to deliver but slowest of all is straw which can actually remove soil nitrogen from the soil to help it mineralise.”
He adds that plants should also have rapid growth, be early in producing flowers before winter sets in, produce ample green matter, be complementary to legumes and be frost sensitive.
This last requirement is interesting in that being susceptible to frost means that the plants are killed without anyone having to spend money on herbicides to do the job – in a mild UK winter this might not be the case.
But back to Project Lamport. A recent visit to the site was to see a mixed bag of results. While some plots set out to compare the degree of black grass control in respect of drilling dates and the spraying programme implement as a result – Grafton winter wheat sown in the third week of September was compare with Graft sown in the second week of October, for example – it was the plots using cover crops which were perhaps the most thought provoking.
System 3’s plot, for example held a crop of spring wheat which had been direct drilled into a sprayed-off September drilled cover crop mixture of purple vetch and deep rooting Tabor clover. The cover crop had been sown on the 3rd September and it was sprayed off on the 1st and 13th March with glyphosate before a Great Plains Spartan drill planted spring wheat on the 17th March.
According to Mr Hemmant, direct drilling into the sprayed off cover crop wants to be a clean affair with minimal disturbance of the soil – this helps to prevent the surfacing of fresh, as yet, non-germinated black grass seed.
This cover crop/spring wheat plot was repeated using an alternative seed mixture of black oats and red vetch – a mix known in the Jouffray Drillaud portfolio as Chlorofiltre 26.
Also on the trial plots was the company’s Chlorofiltre ST – a Panache oats and Tone Rye mixture.
“Although it’s early days, I’ve been impressed with the way cover crops have held back the development of black grass in spring-sown crops,” he says. “Sown in autumn the cover crop provides control during autumn period, dries out the soil and improves soil structure. Direct drilling in the spring then prevents the creation of a seedbed for black grass to germinate in – these are interesting times.
For an increasing number of arable farmers, black grass has become an almost unbeatable grass weed which, despite their best efforts has continued to flourish over ever greater areas. Compounding the problem is the reduction in the number of chemicals available to control it and, in large areas of the UK, it is becoming resistant to chemical control.
Short of fallowing, extensive use of glyphosate and a move to a spring cropping regime, it would appear that in some extreme cases there little else that can be done to halt the progress of this pernicious, costly, yield sapping weed.
Or is there? Agrovista and Bayer CropScience are currently running Project Lamport which, taking place in Northamptonshire, is a five-year rotational project aimed at developing new ways to control black grass that still enable combinable crops to be grown. Included in the program is discovering weather the use of autumn sown cover and companion crops – and their integration with wheat and oilseed rape crops – can help to suppress black grass.
“It’s a comprehensive project which has 14 different rotational systems incorporating winter and spring cropping, new initiatives including traditional fallows and hybrid rye production for AD plants.” Says Mark Hemmant, Agrovista’s technical manager. “We aim to develop new systems that go beyond the present techniques such as stale seed beds, delayed drilling and increasing seed rates. This is crucial if we are to prolong the activity of Atlantis and contribute to other herbicide stewardship.”
He adds that all the systems used will be evaluated against traditional winter wheat/OSR rotations and the end of the project will see all the plots being drilled with winter wheat to assess the degree of black grass control that has been achieved - and provide a comparison of the costs expended on each plot.
A key and perhaps novel feature then, of Project Lamport is the use of cover crops – the timing of sowing, how they are sown and the plant species used within the seed mixtures.
For this latter detail, the project is using seed mixtures developed by French company Jouffray Drillaud. Interesting to note that in France – as in Germany – it is illegal to leave land bare during the winter with farmers required to plant a cover crop if the land is destined to be drilled in the spring.
“This is to ensure valuable nitrogen and other soil nutrients are not leached away,” says Jerome Vasseur, the company’s commercial manager. He points out that in an average winter, a cover crop’s take up of soil nutrient can prevent up to 36kg/ha of N being lost along with significant amounts of PK and Calcium Oxide, magnesium and sulphur.
But there are other benefits to be gained through using cover crops, he insists. These include better weed control due to the cover crop colonising the ground and preventing space for weeds to flourish, and an improvement of soil structure. Different plant types have different rooting systems – some are strong and go deep while others work closer to the surface – with the result being an improvement in soil drainage and the creation of good rooting territory for following crops.
“Cover crops can also provide increased biodiversity,” he says. “Early flowering plants provide food for pollinators and some cover crops also have a positive effect on the development of plant diseases, such as take-all due to an interruption in the life-cycle of the soil born fungus.”
All of which would seem to add up to a convincing argument. But there are cover crops and there are cover crops, and to get the best results it’s necessary to use plants which have been bred specifically for this purpose.
Mr Vasseur outlines the main characteristics required. “Plants need to have a low carbon to nitrogen ratio (C/N ratio) which is an indicator of how quickly they will release nitrogen when they are mineralised back into the soil,” he explains. “Black oats, which is one of our most used varieties, has a C/N of 12 which is very low and releases its N quickly as a result. Mustard’s C/N is rated at 30 and is rather slow to deliver but slowest of all is straw which can actually remove soil nitrogen from the soil to help it mineralise.”
He adds that plants should also have rapid growth, be early in producing flowers before winter sets in, produce ample green matter, be complementary to legumes and be frost sensitive.
This last requirement is interesting in that being susceptible to frost means that the plants are killed without anyone having to spend money on herbicides to do the job – in a mild UK winter this might not be the case.
But back to Project Lamport. A recent visit to the site was to see a mixed bag of results. While some plots set out to compare the degree of black grass control in respect of drilling dates and the spraying programme implement as a result – Grafton winter wheat sown in the third week of September was compare with Graft sown in the second week of October, for example – it was the plots using cover crops which were perhaps the most thought provoking.
System 3’s plot, for example held a crop of spring wheat which had been direct drilled into a sprayed-off September drilled cover crop mixture of purple vetch and deep rooting Tabor clover. The cover crop had been sown on the 3rd September and it was sprayed off on the 1st and 13th March with glyphosate before a Great Plains Spartan drill planted spring wheat on the 17th March.
According to Mr Hemmant, direct drilling into the sprayed off cover crop wants to be a clean affair with minimal disturbance of the soil – this helps to prevent the surfacing of fresh, as yet, non-germinated black grass seed.
This cover crop/spring wheat plot was repeated using an alternative seed mixture of black oats and red vetch – a mix known in the Jouffray Drillaud portfolio as Chlorofiltre 26.
Also on the trial plots was the company’s Chlorofiltre ST – a Panache oats and Tone Rye mixture.
“Although it’s early days, I’ve been impressed with the way cover crops have held back the development of black grass in spring-sown crops,” he says. “Sown in autumn the cover crop provides control during autumn period, dries out the soil and improves soil structure. Direct drilling in the spring then prevents the creation of a seedbed for black grass to germinate in – these are interesting times.