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Catch crop for Samuel!

September 22, 2021

The benefits of crop rotation have been well known and used for generations. Our forefathers where doing this continually and it would be quite common for a livestock farm to plough the farm yard manure (FYM) down into the soil to prepare for planting potatoes, then harvest them in September or October, followed by planting winter barley or spring barley, then back into grass in the Autumn or Spring of the following year.  This rotation not only allowed the farmer somewhere to go with the FYM but also helped to reduce the weed burden in the following crop especially after potatoes.  It also improved soil structure, drainage, soil fertility and thus productivity. 

The move away from growing crops on livestock farms due to the changes in farm business structure and efficiencies of scale, has led to the continuous growing of grass on many farms.  However in recent years there has been somewhat of a revival in growing some winter forage crops which have the added benefit of extending the grazing season.

Samuel Knox, who farms outside Broughshane has just recently sown forage rape, following a crop of spring barley.  The barley was harvested at the end of August, yielding 7.5ton/ha. It will be crimped and used to feed store cattle over the winter which will greatly reduce the farms meal bill, the barley straw will be used to bed young calves.

Instead of trying to get a full grass reseed completed in September and getting very little benefit from it until the spring, Samuel wanted something that was quite easy to establish even in September. He required a crop that was quick growing, a quality feed for young cattle and that will help reduce fodder demand in November and December.  Forage Rape ticks all these boxes and is more flexible than kale in that it can be sown later in the year.

The method used was quite simple yet effective.  The barley was sprayed with glyphosate 12 days pre harvest on the 19th August, FYM spread post-harvest, then power harrowed twice, rolled, forage rape seed sown with a seed cultivator at a rate of 6.25kg/ha and rolled again on the 4th September.  As the seed is very small, there is a danger of planting it too deep and thus killing it as it doesn’t have the energy reserves to make it to the surface. Planting the seed at the surface level or no deeper than 10mm is the key to success and the seed rate needs to be at least 6kg/ha. Lower seed rates can lead to the plant having thicker stalks which are of less nutritional value than the leaf.    Forage rape, like all brassicas responds well to good soil fertility and particularly nitrogen and phosphorus.  The crop is also prone to sulphur deficiency so it is recommended to apply 25kg of sulphur (SO3)/ha to the seed bed.

Once the crop is well established, in about 10-12 weeks, Samuel plans to gradually introduce light store cattle and use an electric fence to control and maximize crop utilisation.  The fence will be moved daily and each strip will be long and narrow to allow all cattle to feed at once and avoid wastage of the crop.

By sowing forage rape Samuel should benefit from having a few extra weeks of forage available for young cattle plus a saving on demand for silage.  He feels however that his biggest benefit comes through the soil getting a boost, from increased organic matter, improved soil structure and fertility and a reduced weed burden in the following spring grass reseed. 

The other benefit mentioned by Samuel to Stephen Flanagan, his local CAFRE Beef and Sheep Development Adviser is that by extending the period that his cattle are outside grazing means less slurry to store and less to apply in the spring.  This helps lower the amount of ammonia produced on the farm.  The widely branched root system of the forage rape not only reduces soil compaction but by increasing the gaps between soil aggregates enhances the speed of nutrient infiltration, hence reducing ammonia emissions from the urine and manure produced by grazing animals.

This is a win win for both Samuel’s farm and the environment. The other farmers in his Business Development Group will be monitoring the forage rape closely and will want to hear how Samuel’s stock are performing on it.

The BDG Scheme is funded by the Department of Agriculture, Environment and Rural Affairs and the European Agricultural Fund for Rural Development.