Peas look set for whole-crop silage
By Robert DaviesWales correspondent
SPRING peas are already showing good potential for whole-crop silage in a trial which also includes spring-sown beans and lupins.
Six varieties of peas and three each of beans and lupins have been grown at Harper Adams University College, Shropshire, in a trial supervised by NIAB regional trials manager Mark Sheridan.
Crops were planted at the same time in one field. The project will provide comparisons of in-field performance, feed value and growing costs when harvested for whole-crop.
"There is tremendous interest in high protein crops, but we have limited information on the nutritional quality of different varieties," says Francis Dunne of Oliver Seeds, the trials sponsor. "The species have all been drilled at the recommended seed rates and depths. Fertiliser, herbicide and fungicide use has followed national recommendations.
"We are monitoring pests and disease, measuring height at harvest, lodging, fresh yield and dry matter. All costs are recorded and there will be the fullest possible analysis of protein and starch quality, as well as yield."
Harvesting started when the first pea variety reached the hard rubbery stage and the lower haulm leaves started to senesce. Combin-ing rather than forage pea varieties were chosen to reduce lodging. All were standing well when cut.
"It is already clear that spring peas have potential for whole-crop silage. They can be undersown with grass because they stand up and light can get through. Peas are also harvested early enough for grass to use the nitrogen it fixes and produce autumn grazing or a late silage cut."
However, securing arable aid for peas grown for whole-crop complicates management. "The crop does not qualify for arable area aid unless 10% barley is included to make it arable silage. This complicates herbicide treatment and harvest timing."
Lupin varieties will be harvested next, he adds. The trial has shown wide differences between lupin varieties. One Danish bred variety lodged badly, but the other two look good.
"It will be interesting to compare yields and protein quality of these two. In the field, it seems that Wodgil from Western Australia has done well."
The three spring bean varieties will be harvested last. DM figures are expected to be lower than the 25-30% for peas or lupins.
John Bax, of Biotal, adds that pulses are low in sugar at harvest and high DM silage made from them is susceptible to aerobic spoilage. But suitable biological additives are available to boost favourable initial lactic fermentation and inhibit yeasts and moulds.
"Grass silage is becoming expensive and quality cannot be guaranteed, whereas whole-crop varies little from season to season," says Mr Bax.
Mr Dunne is keeping an open mind about the potential of pulses on trial. "It is important to consider the cost of producing protein on UK farms." *
• Peas, lupins and beans grown.
• All spring-sown.
• Quality and cost monitored.
Whole-crop peas could have a future in providing home-grown protein, believe John Bax (left), Francis Dunne and Mark Sheridan.