August 19, 2015
Latest wholecrop rye for AD trials show importance of matching variety to farm conditions
Wholecrop rye is confirming its particular potential as an anaerobic digestion (AD) feedstock in the latest production trials at Agrii’s Brotherton iFarm in North Yorkshire; especially so wherever forage maize production is impossible or unreliable.
An average fresh weight yield of 48 t/ha at 32% dry matter was recorded from heavy land trials with seven advanced hybrid varieties from three leading European breeding programmes, delivering an average 12.9 t/ha of Volatile Solids (VS) for energy production.
Together with significantly lower production costs than higher energy-producing forage maize or energy beet, valuable methane production synergies with both, very fast spring growth and high yield stability under marginal conditions – courtesy of powerful rooting and cold tolerance – this confirms the crop’s value in AD feedstock mixes.
Volatile Solid dry matter production differences of more than 1.5 t/ha (13%) between the highest and lowest output hybrids, however, underline the importance of matching varieties carefully to farm conditions.
“At 13.8 t/ha, the highest output variety in our trials, Helltop yielded almost a tonne more Volatile Solids dry matter than the mean,” pointed out trial co-ordinator, Philip Marr. “Its vigorous early growth habit and relatively fast leaf development speed suited early October sowing on the farm’s heavy ground especially well. These characteristics also made it highly competitive with the resistant ryegrass that has always caused such problems locally.
“That’s not to say that several of the other varieties wouldn’t have done as well, if not better, than Helltop if sown earlier, on lighter land or where there was less grass-weed competition. More than anything else, the performance differences we’re recording in our Agrii research programme show just how important it is to choose the right variety for the conditions.”
In Philip Marr’s experience, soil type and drilling date should be the first considerations in wholecrop rye variety choice for AD. As well as fast autumn development for crops sown beyond September and on heavier ground, he advises growers to look for varieties that tiller well and are aggressive with grass weeds. Varietal resistance against the main disease threat, brown rust, should also be borne in mind, together with stem stiffness, to minimise both fungicide and PGR need.
“The greatest possible tillering is essential with wholecrop rye,” he stressed. “While later drilling gives valuable flexibility for autumn grass weed control, just like wheat it also reduces tillering. Increasing the seed rate can, of course, compensate. But we’ve found a free-tillering ability and rapid leaf development is invariably the key to the most cost-effective performance if drilling is delayed or the ground is on the heavy side.
“Whenever you drill, it’s important not to put the seed any deeper than around 2cm as rye has a considerably weaker coleoptile than either wheat or barley.
“We find around 200 kg N/ha with balancing sulphur in three spring splits is about right for the crop,” suggested Philip Marr. “Because rye grows away very much earlier than most in the spring, though, it’s crucial to get the first 50-60 kg/ha N on as early as possible to avoid starving it and compromising tiller numbers, crop biomass and, as a result, yield.
“Early PGR application – from GS28 – is a useful way of thickened without shortening the crop unduly. A second PGR with the single fungicide spray may be valuable too. But there should certainly be no need for a third, even with less stiff-stemmed varieties.
“Important for the greatest energy production too is harvesting at the right time,” he added.
“In hot, dry weather there may only be a 4-5 day window in which to hit the optimum
32-36% DM that gives maximum sugar availability for the digestor.
“Produced in the right way, we’ve found wholecrop rye is an excellent complement to maize silage or energy beet for AD. Just like cereals, I can’t stress strongly enough the importance of growing the right variety for your conditions and matching agronomy carefully to it for the most cost-effective energy production.”