The potential of alternative forage crops

These are specifically suited to carrying store lambs or ewes over the winter months. A range of brassica crops can be grown for grazing, including forage rape, hybrid brassicas, stubble turnips and swedes. However, the most suitable crop will depend on when it is planted, the expected yield and the type of sheep that will graze it.

Stubble turnips may be more suited for adult ewes, which are better able to scoop the turnip from the ground and make full use of the crop. However, farmers should avoid grazing broken-mouthed ewes on turnips, as these animals may struggle to eat them. Forage rape and other grazing brassicas can produce between 3t and 6t DM/ha. Crops edging towards the higher range are generally those planted in early July and having received additional fertiliser.

For tillage farmers considering establishing forage brassica crops for grazing, a degree of caution is required. This reflects the risk of clubroot and its potential implications for crops such as oilseed rape. Tillage farmers must also ensure that any forage crop is established and managed in accordance conditionality. To establish a good forage crop, there are a few factors to consider. The crop has to be grown on good free draining land. Growers must also decide on when the forage is grazed? They cannot be accessed by stock once they head out and flower due to the presence of toxins.

Forage crops grown on arable farms offer a number of advantages. They can be a low cost winter forage solution; they are an excellent break-crop for grass reseeding as it helps reduce pest such as leatherjackets and slugs. There is potential for high dry matter yields when the crops is sown as recommended. Brassica crops have a lower dry matter compared to grass at 12-14%, have a higher crude protein than grass silage and are low in fibre. There are also a number of potential disadvantages to be considered.

A wet winter could lead to soil structure damage and possible run-off if not managed well. Hence the importance of growing alternative forages in a good free draining and not a hilly field where there is the potential of runoff. The field may lost from the grazing rotation for 9-12 months.

AFBI reserach

An Agri-Food and Biosciences’ Institute (AFBI) research team is to investigate the potential role of alternative forages within livestock production systems. The work will centre on eight farms across Northern Ireland.

Forage-S is a three-year study which will look at how a mix of grasses and alternative forages perform under different weather and environmental conditions found on Northern Ireland farms, compared to perennial ryegrass monocultures. The alternative forages include legumes such as white and red clover and herbs such as chicory and plantain.

The project, which is being run in collaboration with the College of Agriculture, Food & Rural Enterprise (CAFRE) and AgriSearch, will investigate how soil type, weather and field management affect sward establishment and productivity over the lifetime of the project. Forage-S will involve a diverse range of farms, including upland and lowland sites: AFBI Hillsborough’s research farm, and CAFRE’s Greenmount site and Hill Farm Centre at Glenwherry, Co Antrim. The other sites have been selected for their specific location, soil type and weather conditions. Funded by the Department of Agriculture, Environment and Rural Affairs (DAERA), the study will include farms in counties Fermanagh, Derry, Antrim and Down.

The project is led by Dr David Patterson and Dr Aurélie Aubry from AFBI Hillsborough and also involves scientists from AFBI’s Newforge and Crossnacreevy research sites.

Dr Patterson commented: “Forage-S aims to provide empirical evidence of alternative forages establishment, biomass yield, herbage quality and persistency in contrasting Northern Ireland soil/climatic environments. The work will be undertaken in a fully replicated study over three years, comparing sward productivity on eight farms spread across Northern Ireland. In due course the data from the farms will be integrated into a simulation platform, using the AFBI GrazeGro growth prediction model, to provide geographically explicit predictions of alternative forage production and herbage quality of the contrasting sward types and their associated uncertainty.”

Dr Patterson has confirmed that the results will be presented to farmers, in collaboration with CAFRE and AgriSearch, to help them make better decisions about managing their grassland in different farming situations across Northern Ireland.

Recent years have also confirmed a growing interest in grassland famers establishing crops of red clover.

David Paterson again: “Red clover can fix up to 200kg of nitrogen per hectare from the air on an annual basis. Crops have the potential to produce up to 15t of dry matter per hectare, again ion a dry matter basis. High animal intakes and comparable levels of animal performance can be achieved while the growth profile of red clover will act to improve soil structure. This level of clover output is achieved on the back of up to four silage cuts in the same season.”

He concluded: “The downsides associated with red clover include its lack of persistency. It can be difficult to ensile, crops are problematic form a grazing perspective and a four-year break is needed between crops of red clover that are established in the same field. Four years is the optimal period over which a red clover sward will deliver productive yields After that it is a case of moving on to new ground.”

Fodder beet

Fodder bet is a forage option that is now grown on a number of farms in Northern Ireland. But it is expensive to grow. The figure comes in at £2,919/ha, according to the current Teagasc costs and returns figures. As a consequence, tillage farmers should ensure that they have an agreement in place with the end user before sowing takes place. This should outline details on tonnes/hectares to be delivered, quality and payment details. All varieties can be sown from now on. However, yields will be reduced if drilling is delayed into May. Growers can apply lime on plough ground, if required, to reach the target pH value of 7.0.

Fodder beet is a high energy forage that can be grazed in situ or harvested, stored and fed to livestock. Dry matter yields in excess of 18t DM/Ha are achievable. Generally low dry matter varieties will have a larger percentage of the root over ground and are suitable for grazing in situ.

In contrast, high dry matter 'sugar beet' type varieties will have a higher percentage of the root underground. These are harvested, and are capable of high dry matter yields per hectare. Trace element nutrition is a fundamentally important aspect of fodder beef crop management. Boron (B) leaches readily from all soils. This effect is severe in light sandy soils and less so in heavy soils but B application is generally necessary for all beet crops and especially for sugar beet. Boron uptake is severely restricted during periods of drought in all soil types. Thus, even when soil concentrations are above the critical level, B deficiency can still occur in sensitive crops. Where deficiency is likely to occur, a source of B may be included in the fertiliser to supply 3.0 kg/ha of B. Where the soil test results are less than 1 mg/l B, it may be worthwhile to supplement the soil application with one or more foliar sprays.

Manganese (Mn) deficiency (speckled yellows) can occur in beet when the pH is above 7.0. But the issue is more is more likely at pH values above 7.5. However, it has been recorded at pH 6.5 or lower in peats and dark soils with high organic matter content.

Manganese deficiency is controlled effectively by the application of foliar sprays of Mn compounds, e.g. manganese sulphate, Mn-chelate or inorganic formulations. The incorporation of manganese oxide in the seed pellet has proven very successful in preventing early deficiency. It works best when supplemented by a foliar spray at the 4-leaf stage.

Disease control

Disease control is essential in fodder beet to maintain a healthy green leaf canopy and maximise root yield. This can be achieved with well-timed fungicide programmes capable of delivering significant yield responses. Late July to early August is generally the optimum time for fungicide application. Fodder beet remains one of the most important forage crops grown in Ireland, with approximately 10,000 hectares planted each year to provide high energy winter feed for livestock. Crops have generally established and grown well this season, although many are now under increasing pressure from the recent dry weather, particularly on lighter soils.

With forage likely to be in high demand this autumn, protecting fodder beet yield is more important than ever. Effective disease control can significantly increase root yield by maintaining the leaf canopy, allowing the crop to increase root yield well into the autumn. The key fungicide window for most crops is late July to early August, with a follow-up application where required. The first fungicide should be applied at the first signs of disease, rather than waiting until infection is widespread. For crops intended for later harvesting, a second fungicide application 3–4 weeks after the first is often worthwhile where disease pressure remains high.

However, it is important to avoid applying fungicides to crops that are suffering from drought stress. Fungicides are most effective on actively growing plants, so where crops are under severe moisture stress it is better to wait until rainfall allows plants to recover before spraying.

There are a number of key foliar diseases that affect fodder beet crops in Ireland. Powdery mildew is favoured by the current warm, dry conditions and is likely to be the first disease seen in many crops. Cercospora Leaf Spot is, increasingly, becoming the most damaging disease of fodder beet. Warm, humid conditions favour its spread and severe infections can reduce yield by more than 50% if left uncontrolled.