Forage Maize – Growing in Northern Ireland
By Mark Scott, Dairying Technologist, Greenmount Campus, CAFRE
The area of forage maize grown in Northern Ireland decreased slightly in 2009. However indications are that this was due to the poor weather conditions around sowing time with seed having been returned to merchants. Year on year the general trend is that the area grown is increasing with the area of maize grown now almost 3500ha. It is essential that those involved in the growing of this crop understand the main factors for success, as a poor forage maize crop is very expensive and not viable.
CAFRE Technology Work
A project looking at several aspects of forage maize was established at Greenmount in 2007 to ensure the best information was available to dairy farmers on the management of the forage maize crop and feeding it to dairy cows. These important aspects of management include:
- Yield and quality achievable
- Sowing date
- Use of plastic
- Supply of nutrients
- Harvest date
In 2009 the forage maize growing cycle was followed on 10 farms located throughout Northern Ireland. Crop details were fully recorded and analysed from soil analysis through to yields and forage analysis.
Yield and Quality
Undoubtedly the greatest factor that should influence the decision whether to grow maize or not is the achievable yield and quality of the forage. Yields measured on farm in 2009 ranged from 6.5 to 14.5 tonnes of dry matter per hectare (t DM/ha). Yields were generally lower than 2008 with the main reason for this being poor weather delaying sowing in May and good weather in early October encouraging early harvest. As a result either one or both of these factors meant lower yields. Ideally the crop should be sown as soon as possible after the middle of April with harvest delayed if possible to the end of October or beginning of November. The effect of yield on the cost of the crop is highlighted in Table 1.
Table 1. Yields achieved on 10 farms in 2009 and associated cost
| Utilisable DM yield (tonnes/ha) | Cash cost (£/tonne utilisable DM) | |
|---|---|---|
| Lowest yield | 6.5 | 139 |
| Average yield | 9.7 | 93 |
| Highest yield | 14.5 | 62 |
Forage quality on project farms however was greatly improved compared with 2008. A combination of better weather around pollination and favourable weather in September and October allowing plants and cobs to mature prior to harvest probably lead to this improvement. Protein levels were down on previous years therefore additional concentrate protein supplementation will be required to balance this when feeding out. If yield and quality are maximised this will drive down the cost per tonne of forage and increase the benefit achieved from feeding forage maize in the diet of dairy cows. Table 2. highlights the reduction in yield and forage quality observed through delaying sowing date by 13 days.
Table 2. Influence of sowing date on yield and forage analysis
| Sown 15 May | Sown 15 May | Sown 28 May | Sown 28 May |
|---|---|---|---|
| DM Yield (t/ha) | 9.0 | DM Yield (t/ha) | 7.0 |
| DM (%) | 30.3 | DM (%) | 20.4 |
| CP (%) | 8.6 | CP (%) | 11.2 |
| ME (MJ/kg DM) | 11.3 | ME (MJ/kg DM) | 10.3 |
| Starch (%DM) | 30.4 | Starch (%DM) | 22.5 |
The quality and yield of the crop sown on 15th May could have been improved further had it been sown at the end of April.
Plastic or no plastic?
The additional cost of plastic mulch will add £230 - £240 per ha to the overall cost of growing forage maize. In most areas of Northern Ireland this cost will deliver a greater financial benefit in terms of yield and quality and is therefore recommended. AFBI research has shown that the use of plastic increases soil temperature by 4.1oC, advances the emergence of the crop by 5-10 days and silking by up to 16 days. However the on farm results from 2009 show that the use of plastic can be wasted through poor management in other areas. From the data it is essential that the crop is sown early and harvest delayed until at least the end of October to ensure the maximum benefit is achieved from the additional investment in plastic mulch. Simply because plastic mulch has been used does not mean the crop can be sown late and harvested early.
Nutrient Management
In the past the land intended for forage maize has been heavily coated with manure and slurry in addition to inorganic nutrients applied at the time of sowing. This practice is likely to have resulted in a significant over supply of nutrients to the plant, which would now under the Nitrates Action Plan (NAP) constitute a breach in cross compliance. The work carried out by CAFRE and ongoing research at AFBI, Crossnacreevy would indicate that the supply of nutrients above the recommendations will not give any increase in crop yield. In the current economic climate these wasted nutrients could be put to better use elsewhere on the farm, reducing overall fertiliser costs. Interestingly, the highest yielding crop in the on farm maize project was grown through application of nutrients according to the RB209 recommendations.
The bottom line – COST
Work on the cost of forages on Northern Ireland dairy farms is reviewed annually by CAFRE Technologists to take account of fertiliser price, contractor charges and other applicable inputs. The results of this review for 2009/10 have shown the cash cost of forage maize (without considering storage and feeding out costs or land charges) to be £905 per ha. Table 1. earlier shows how the yield achieved on farm affects the cost per tonne of dry matter. Poor yields result in very expensive crops and the growing costs cannot be justified and would be much better spent on improving grass swards to produce better quality grass silage.
In summary
- On the 10 CAFRE project farms yields were 7% lower in 2009 than 2008 however quality was improved
- Low protein in forage maize must be balanced through the use of an appropriate concentrate, leading to increased diet costs
- Excess application of nutrients has no positive effect on yields
- In most areas of Northern Ireland plastic mulch will result in a yield and quality benefit but only if the crop is managed correctly in all other aspects
- Sowing as soon as possible after mid April and harvesting late October or early November will improve yields and quality
- Alternative forages such as forage maize only give value for money if good yields and nutritional analysis are achieved
- If you struggle to achieve yield and quality then it is a better investment to improve grassland to achieve better quality grass silage
Jim Fulton (Stockman), Mark Scott (Dairying Technologist) and Michael Graham (Farm Manager) monitor forage maize quality for the Future Herd throughout the winter feeding period to ensure diets are correctly balanced.
