Forage Maize – Has it a Place on Your Farm?

The recent rises in fertiliser and fuel costs will have a dramatic effect on the costs of forage production for next winter. Estimated cash-cost of producing the main forages this year are shown in Table 1.  The cash-cost includes cultivation, contractor, seed, fertiliser, herbicide and additive costs.  

Table 1.  Estimated Cash-Cost of Production for Alternative Forages (2007)

(DM = Dry Matter)

A 3-cut silage system can be expensive due to the low yield of grass for the third cut and the high harvesting costs per tonne.  A two cut system with the after-grass used for grazing is more economical.  Whole-crop winter wheat and forage maize can be produced at a similar cost to grass silage on a two cut system.  Given current high cereal prices a number of farmers are considering that it may be more economic to combine the winter wheat and use the grain as part of the concentrate diet.  Forage maize can be a cost effective alternative forage for producers to consider where the farmer can be assured of achieving a good yield and consistently high dry matter and starch quality.

In a variable climate typical of Northern Ireland it is difficult to consistently produce high quality grass silage, defined as >11.5 MJ ME/KG DM, >25% DM, and >13% crude protein.  Forage maize can produce forage of consistent quality throughout the pit and has proven a useful complement to medium/poor quality silage.  The benefit is most significant where a high quality crop is harvested; >30% DM, >30% starch – see Table 2.  If this quality is not achieved and yields of only 10–11t DM/Ha obtained then maize is an expensive crop offering little value to the dairy cows winter diet.

To achieve these quality targets in Northern Ireland, an early maturing and high yielding variety has to be grown on a site with as long and warm a growing season as possible.  The Ontario Heat Unit (OHU) is used as a measure of the warmth and longevity of the maize-growing season in the Province.  For the current early maturing maize varieties to mature sufficiently in our climate, 2500 OHU must be recorded during the season.  

Table 2.   Effect of Maize Maturity on Cow Performance

(1:3 DM mix Maize:Grass + 10KG Concentrate)

(Phipps et al, 2000)

Total cover degradable polythene mulches can be used to protect the crop at sowing.  These mulches raise soil temperatures by about 3°C allowing earlier sowing and faster plant growth.  The net effect of using a plastic mulch is earlier flowering, by up to 15 days, and increased yield by up to 4t DM/ha.  Most of this yield increase is due to a higher proportion of grain (starch) – an increase which more than covers the extra costs associated with this technique.  With the use of polythene mulches, maize growing becomes viable in areas recording over 2300 OHU.  The map identifies areas of the Province where this target could be met and maize production considered.

United producer Brian Hanna of Vow Road, Ballymoney, was one of the first producers in North Antrim to grow Forage Maize, starting in 2002.  Brian had been interested in growing the crop for a number of years but knew the Bann Valley was a marginal area for production (orange area on the map).  However, having noted the success of the crop when grown under plastic in Myroe, in 2001 he decided to try the crop on his own farm.

With six years experience growing and feeding the crop, Brian is confident that maize has an important role in the management of his 170 cow Holstein herd.  He has consistently produced high quality crops.  The main varieties grown in recent years have been Justina and Benecia – to ensure that these later maturing varieties produce a high quality crop Brian tries to the sow crop in early April.  If poor weather delays planting to late April – early May an earlier maturing variety such as Goldcob is used.

After the first two years experience Brian found that the crop was much poorer on the compacted areas around gateways and head-rigs, which received extra trafficking when spreading slurry and harvesting.  Sub-soiling of these areas is now normal practice.  This is proved to be very effective.

To reduce the risk of wind-blow with the plastic due to rubbing against hard clumps of soil, Brian is careful to plant into a fine, fresh, seed-bed.  The field receives two to three runs with the power harrow before sowing.  The final run is made just in front of the drill so that the small soil clumps are not dried out before sowing.

Brian is content that maize has been a profitable alternative in the past and will be even more so in the future.  At worst it reduces the risk of making poor quality silage and at best adds significant intake potential and starch to diets.  “It improves my milk from forage” says Brian, “and at the current price of concentrates that is my way to improved profit”.

Brian Hanna (right) discusses the quality of this seasons maize silage with author William McCulloch