Article taken from Agronomist & Arable Farmer Magazine
Agrovista is acknowledged as a leader in cover crop research and development, helped by a network of trials sites across the UK that allow it to test species and mixtures across a wide range of conditions When it comes to establishment after a cover crop, particularly where grass weeds can be an issue, time spent setting up a drill is essential.
As well as major research sites at Lamport and Maidwell in Northamptonshire and Stoughton in Leicestershire, Agrovista has several more locations across the UK to extend its range of work and experience with cover crops. These additional sites allow variations in climate, soil type and weed pressure to be understood and taken into account when discussing agronomic issues with clients. They also provide a valuable insight into how different mixtures perform under a range of management programmes in different parts of the country, ensuring customers are supplied with the right mix for the job. Given the bewildering array of cover crops on the market, Agrovista maintains there is a real need for such research to deliver clarity. Cover crops are being sold to cure all sorts of problems, but impressive-sounding claims often have little basis in fact. Agrovista’s current range includes unique varieties of the black oat Avena strigosa to ensure there is no volunteer carry-over and to allow easy kill of the cover crop. This powerful and extensive rooter produces plenty of green cover to help build organic matter. It provides the base for most cover crop mixtures Agrovista currently recommends. Berseem clover is supplied as a specific variety for early germination and maximum root impact. It has performed well in mixtures aimed at helping grass-weed control, and its powerful roots can quickly help repair damage. Vetches, which can count towards EFA, have proved effective at mopping up excess nutrients and providing a shallower layer of fine roots to condition the surface layer and boost organic matter. Oilseed radish and phacelia are just two other species under test. This article provides a glimpse and an update of Agrovista’s innovative crop work, especially in grass-weed control and soil management, around the UK.
WESTERN REGION
Location: Shrewsbury
Grass weeds: brome and ryegrass
Following crop: two types
This site was established to show the potential of using cover crops for soil structuring, nutrient capture and to assist in the control of problem grass-weeds such as bromes and ryegrass. A range of mixed species based on black oats with berseem clover or vetches with some single species of black oats or berseem clover and a non-cereal mix of Asian radish and phacelia are being evaluated, together with The aim is to place the seed into the soil at the correct depth with the least amount of disturbance, to minimise germination of grass-weed seeds, so disc drills have become preferable for this job. Row spacing is an important consideration and while close spacing is preferable for crop competition, too close will result in increased soil disturbance, so aim for 125-150mm. The growing cover crop has been conditioning and restructuring the soil profile; all the drill needs to do is place and cover the seed at the correct depth then gently firm the soil around the seed, taking care to minimise soil disturbance. This requires a change of mindset as the resulting seedbed can often look particularly scruffy compared to the norm. For cultivator drills such as the Väderstad Rapid, lift the system disc and following harrow clear of the soil, remove track eradicators (LGP tyres and correct pressures will help) and, if possible, lift the bout markers also. It is essential that disc coulters are not badly worn and that seed coulters are in the raised setting, allowing the leading edge of the disc to cut the slot for the seed. Both Claydon and Dale have now developed a low-disturbance option for their drills specifically for use with cover crops. For strip drills, again, lift all soil-engaging components clear of work and rely solely on the seed coulters to place and cover the seed. Operators must be prepared to decrease forward speed to minimise soil disturbance, 8- 10km/h rather than 12-14km/h. Seedbed conditions are far more important than date of spring drilling. The cover crop tends to hold moisture at the surface. Go when too moist and excessive slot smearing may result. If the seed is covered and well consolidated, giving good seed to soil contact, then rolling won’t be required. However, if in doubt, rolling with worn Cambridge rings as opposed to more aggressive breaker type ring rollers is preferable.
NITROGEN
Our R&D programmes will look at seedbed fertiliser applications. We are investigating the implications other application methods and nitrogen timings on stimulating grass weed germination.
Spring cereals have a much shorter season with a faster establishment, leaf and tillering development phase, before moving into the stem extension phase. Early nutrition is essential so aim to apply up to 50% of planned N in the seedbed to maximise early growth to establish full ground cover for light interception and early weed competition. Demand for nutrients will accelerate as biomass develops.
SEED RATES
Newer varieties of spring cereals are capable of achieving average yields in excess of 8t/ha but on-farm yields have often disappointed, achieving yields lower than anticipated. Commonly suggested seed rates resulting in plant establishment counts ranging anywhere from 150 to 300 plants/m2 at best are often the cause for poor yields. Recent work of spring wheat seed rates is sparse and seed rates are an area requiring new R&D work. However, limited data would suggest that the aim should be to establish nearer to 400 plants/m2, always recognising that actual establishment achieved for spring sowings can vary considerably. For this reason, particularly later sowings where the plant’s capacity to tiller may be compromised, then much higher seed rates should be considered.
The performance of two spring crop types. The plan is to establish these spring crops across the plots and Agrovista will be looking to see the impact this has on the speed of nutrient recycling from the different cover crops. Despite later-than-planned drilling, the cover crops established really well and grew nicely through October and November. They only required one application of slug pellets on 1st October and no other autumn inputs.
NORTHERN REGION
Location: Doncaster
Grass weeds: black-grass
Following crop: spring barley
The Doncaster regional trial site, courtesy of Robert Atkinson, is well-known for its oilseed rape establishment trials looking at five different establishment techniques, with and without berseem clover as companion plants. A range of cover crops is also being evaluated as part of the national black-grass control programme. The trial follows last year’s work which highlighted huge differences between different stale seedbed preparation techniques on the number of black-grass plants that germinated and were controlled with glyphosate prior to establishing the commercial crop. Despite the success of destroying large numbers of black-grass seeds through stale seedbeds ahead of the following spring barley crop, the fewest black-grass heads were where the stubble had been untouched in the autumn and the spring barley was established with minimal disturbance using a Moore Uni direct drill.
SOUTH WEST REGION
Location: RAC Cirencester
Grass weeds: black-grass
Following crop: spring wheat
The Cirencester site, courtesy of the Royal Agricultural University, compares different cover crop establishment techniques and various cover crop mixtures prior to planting a spring crop where black-grass is a problem. The establishment techniques used were stale seedbed, a ploughed comparison, a non-inversion tillage plot using a Väderstad TopDown and a direct-drilled plot. Each of the establishment areas was split into sections to compare different cover crops mixes based upon black oats, berseem clover, and vetch species. There is also an opportunity to see oilseed rape sown with and without berseem clover as a companion plants nearby, looking at improved establishment of oilseed rape on a heavy site.
EASTERN REGION
Location: Lincoln
Grass weeds: black-grass
Following crop: spring wheat
In conjunction with Farmcare, following high black-grass seed return in the previous crop of winter wheat, the field was ploughed. Various cover crops were drilled on 7th September using a Väderstad Rapid drill. These are being compared with different cultivation methods for stale seedbed creation and captured black-grass (black-grass that is encouraged to grow with a cover crop in the early stages, which will be killed when the cover crop is sprayed off with glyphosate).
Location: Morley, Norfolk
Grass weeds: no
Following crop: sugar beet
On the trial site at Morley Farms a number of cover crops were sown on 30th August, using a KV spring-tine seeder. The intention is to establish the sugar beet crop using strip tillage in conjunction with a Väderstad Tempo precision drill, following the various cover crops as well as autumn stubble. In addition the trials will compare the impact of late winter and spring cover crop destruction dates.
Location: Newmarket, Suffolk
Grass weeds: black-grass
Following crop: TBC
In conjunction with Jeff Claydon, Chlorofiltre N-Structure (black oat and berseem clover) was drilled on 27th August using a Claydon hybrid drill. The comparison treatment on the rest of the field uses multiple passes with a straw rake and TerraStar to encourage black-grass to chit during the autumn.