Article taken from Agronomist & Arable Farmer MagazineNew cover crop research by Agrovista aims to provide much-needed guidance for growers
Agrovista is expanding its cover crop trials programme to provide a series of blueprints to help growers choose the right mixture for the job.
“Given the bewildering array of cover crops on the market, there is a real need for clarity,” says Agrovista technical manager Chris Martin. “Cover crops are being sold to cure all sorts of problems including poor soil structure, resistant weeds and nutrient leaching. They are often backed by impressive sounding claims, which have little basis in fact.
“There is very little research being done. It’s not unusual for some mixtures to have six to eight species in them, when one or two would do a better job.”
Correcting poor soil structure will be a key focus of the trials. “we are looking at several different cover crops and their agronomy to assess their ability to raise organic matter content and improve structure, bringing our soils back to life again using roots rather than iron,” says Mr Martin.
Problem Grass Weeds
Until now, Agrovista’s main focus with cover crops has been in helping to control problem grass weeds, using over wintered mixtures to condition and dry heavy soils to allow spring wheat to be drilled relatively early into seed-beds. “This has shown to be one of the most effective ways of controlling black grass and other problem grass weeds such as Italian ryegrass and some bromes while maintaining a profitable, high yielding, wheat based rotation,” says Mr Martin.
These mixtures must allow grass weeds to germinate and grow along with the cover crop, as control is achieved when the cover crop is sprayed off before drilling, he explains.
Some of these species and varieties will also perform well where soil improvement is the primary aim, he believes. For example, the late flowering black oat (Avena stigosa) is a very powerful rooter that will push through compacted soil layers while producing plenty of green cover to help build organic matter. It is slow to establish to allow grass weeds to germinate, but also grows rapidly later in the autumn to produce plenty of biomass, says Mr Martin.
“We will continue to test various cereals but we think the black oat is the cereal of choice in both situations. Pound for pound it produces a very big root, much more extensive than rye and triticale.”
Berseem clover is another plant that has performed well in mixtures aimed at helping grass weed control.
“It has roots like jackhammers – it is amazing how quickly these can help repair damage,” says Mr Martin. “We are trialling a host of different species as soil improvers and nutrient retainers.” “Berseem clover scavenges nutrients very effectively, before being killed off by heavy frosts. Nutrients are then released back into the soil to become available to the crop. “Many countries, including France, stipulate that cover crops must be established over winter on land that would otherwise be bare. It probably won’t be long before we have to as well,” he adds. “Berseem clover could be a very cheap solution.”
Vetches have also proved effective at mopping up excess nutrients and providing a shallower layer of fine roots to condition the surface layer and add biomass to boost organic matter.
Potential soil improvers
Radishes and phacelia are also being investigated as potential soil improvers. “We avoid radishes in mixes aimed at black grass control, as they tend to leave holes that can encourage flushes in the spring,” says Mr Martin.
“But they can do a very good restructuring job, though they are expensive – we need to see how they compare with berseem clover.”
Phacelia is a vigorous rooter that also provides plenty of green manure to build organic matter, though it does need to be established much earlier than other species, he adds.
Cover crop seed treatments are also being assessed, including inoculations of mycorrhiza, a symbiotic fungus whose fine mycelia can access phosphate beyond the reach of plant roots, says MR Martin.
“This increases uptake by the plant and holds soil particles together, reducing the risk of soil erosion. This cuts the risk of phosphate pollution, which has become a key focus of the Water Framework Directive.”
Agrovista’s cover crop research is taking place at sites from the Midlands to the Scottish Borders, including Newcastle University’s Cockle Park, where much of the scientific research will be carried out. “These sites cover a range of different soil types and climates to ensure we get the right mix for the job,” says Mr Martin.
Agrovista is expanding its cover crop trials programme to provide a series of blueprints to help growers choose the right mixture for the job.
“Given the bewildering array of cover crops on the market, there is a real need for clarity,” says Agrovista technical manager Chris Martin. “Cover crops are being sold to cure all sorts of problems including poor soil structure, resistant weeds and nutrient leaching. They are often backed by impressive sounding claims, which have little basis in fact.
“There is very little research being done. It’s not unusual for some mixtures to have six to eight species in them, when one or two would do a better job.”
Correcting poor soil structure will be a key focus of the trials. “we are looking at several different cover crops and their agronomy to assess their ability to raise organic matter content and improve structure, bringing our soils back to life again using roots rather than iron,” says Mr Martin.
Problem Grass Weeds
Until now, Agrovista’s main focus with cover crops has been in helping to control problem grass weeds, using over wintered mixtures to condition and dry heavy soils to allow spring wheat to be drilled relatively early into seed-beds. “This has shown to be one of the most effective ways of controlling black grass and other problem grass weeds such as Italian ryegrass and some bromes while maintaining a profitable, high yielding, wheat based rotation,” says Mr Martin.
These mixtures must allow grass weeds to germinate and grow along with the cover crop, as control is achieved when the cover crop is sprayed off before drilling, he explains.
Some of these species and varieties will also perform well where soil improvement is the primary aim, he believes. For example, the late flowering black oat (Avena stigosa) is a very powerful rooter that will push through compacted soil layers while producing plenty of green cover to help build organic matter. It is slow to establish to allow grass weeds to germinate, but also grows rapidly later in the autumn to produce plenty of biomass, says Mr Martin.
“We will continue to test various cereals but we think the black oat is the cereal of choice in both situations. Pound for pound it produces a very big root, much more extensive than rye and triticale.”
Berseem clover is another plant that has performed well in mixtures aimed at helping grass weed control.
“It has roots like jackhammers – it is amazing how quickly these can help repair damage,” says Mr Martin. “We are trialling a host of different species as soil improvers and nutrient retainers.” “Berseem clover scavenges nutrients very effectively, before being killed off by heavy frosts. Nutrients are then released back into the soil to become available to the crop. “Many countries, including France, stipulate that cover crops must be established over winter on land that would otherwise be bare. It probably won’t be long before we have to as well,” he adds. “Berseem clover could be a very cheap solution.”
Vetches have also proved effective at mopping up excess nutrients and providing a shallower layer of fine roots to condition the surface layer and add biomass to boost organic matter.
Potential soil improvers
Radishes and phacelia are also being investigated as potential soil improvers. “We avoid radishes in mixes aimed at black grass control, as they tend to leave holes that can encourage flushes in the spring,” says Mr Martin.
“But they can do a very good restructuring job, though they are expensive – we need to see how they compare with berseem clover.”
Phacelia is a vigorous rooter that also provides plenty of green manure to build organic matter, though it does need to be established much earlier than other species, he adds.
Cover crop seed treatments are also being assessed, including inoculations of mycorrhiza, a symbiotic fungus whose fine mycelia can access phosphate beyond the reach of plant roots, says MR Martin.
“This increases uptake by the plant and holds soil particles together, reducing the risk of soil erosion. This cuts the risk of phosphate pollution, which has become a key focus of the Water Framework Directive.”
Agrovista’s cover crop research is taking place at sites from the Midlands to the Scottish Borders, including Newcastle University’s Cockle Park, where much of the scientific research will be carried out. “These sites cover a range of different soil types and climates to ensure we get the right mix for the job,” says Mr Martin.