Close up Fields now for Quality Silage in May

By John Galvin, B&T Drystock Adviser, Teagasc Galway/Clare

How can you close what has not been opened you may ask; and that is most likely the scenario most farmers find themselves in.

With 28% more rainfall than the long term average at Athenry weather station so far this year, the majority of the soils in the county are waterlogged and facing into another Met Eireann named storm (Storm Kathleen), it is questionable if it is either sane or appropriate to be discussing the topic of silage making. Yes, there are still large numbers of stock still in sheds and grazing has not gotten into second gear and indeed it is a common sight to see large trailers of bales being transported on our roads with the winter feeding period going long into extra time. However plans must be put in place immediately to replenish the much depleted silage stocks on many farms.

Quantity and Quality

Every farmer should carry out a simple fodder budget to work out the silage requirements for their farm based on based on planned stock type and numbers to be wintered and the no. of months housed.  Suckler cows, 0-1 year old’s, and 1-2 year old’s consume 1.4, 0.7 and 1.3 tonnes of silage per month respectively. On a 20 cow farm + followers housed on the 1^st November and let to grass on the 1^st of March gives a silage demand of 272tonnes/340 bales.

Quality silage is key in reducing the feed costs associated with cattle rearing in a suckler beef system. Dry matter digestibility (DMD) is one of the key measures of quality with protein also being very important especially in growing cattle. See table 1.below for silage quality guidelines for different types of livestock.

Table 1. Silage Quality Guidelines

Cutting Date

Ideally silage should be cut and harvested in the first half of May as grass digestibility decreases by 2-3% units per week from mid-May onwards. A leafy sward with little or no stem will typically give a 75-80 DMD silage, whilst a grass crop with seed heads emerged will normally be as low as 65 DMD. Silage crops need to be walked regularly to monitor growth stage and ground conditions. In my experience farmers can get too hung up about the requirement to have a crop closed for a minimum of 7 weeks due to nitrogen levels. There needs to be a greater focus on bringing the harvest date forward to the 2^nd/3^rd week of May.

Fertiliser

First cut silage has a requirement of 80 units of Nitrogen (N), 16 units of Phosphorous (P), 80-90 units of Potassium (K) and 15 units of Sulphur(S) per acre. Ideally 3000 gallons/acre of cattle slurry would fulfil most of these needs with only 1.4 bags of Pro-Urea + S per acre required in chemical fertiliser. However this year with little or no pre-grazing carried out, poor ground conditions and high grass covers, the time for achieving all of the pre closing best practice measures is quickly diminishing. In this scenario the crop requirements will have to be supplied by chemical fertilisers in agreement with the farm P allowances depending on soil analysis results. If there is no P allowance just spread the required N + S + K and put out the slurry after harvest. If covers are very high during fertiliser application a good option would be to reduce the N rate to 50-75% and bring the cutting date forward to reduce the risk of the crop heading out and lodging occurring thus increasing the chances of producing a quality feed. This puts the field in a great position to close early for a second crop.

In summary here are a few key points to focus on when aiming to harvest quality silage;

• The key influence of quality in silage is firstly pasture quality, silage can only be as good as the quality of the pasture being harvested (Ryegrass Vs Old Pasture)
• Stage of growth of grass at time of cutting (just before seed heads start to appear)
• Graze off dead butt tightly prior to closing
• Do not overload the crop with nitrogen especially old pastures with limited yield potential and un-grazed fields – it delays cutting date and causes lodging risk
• Ensure not to mow too bare – this risks bacterial contamination
• Try to mow in late afternoon, when both the sugars and dry matter levels of the grass are at their peak
• A fast wilt of 24-48 hours depending on mower type and weather conditions is best
• Avoid delay in harvest especially as there is a 7-9% quality penalty associated with lodged crops

Aiming for the big June cut is false economy, it costs the same to harvest poor quality silage as good quality silage, and this combined with a performance penalty of 50-60kg per weanling in the absence of meal supplementation thus further increasing wintering costs.

Anecdotal evidence from previous fodder shortage surveys suggest that the farmers that delayed their first cut the longest had the largest fodder shortages. Remember late first cut silage means losing out on the May/early June growth rates for second cut crops.

Let’s hope the age-old saying “April Showers Bring May Flowers” still holds true and good times will follow after what has been a very prolonged winter.