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Silage and Fertiliser

Now is the optimum time to consider your second cut fertiliser application plan. It is important to ensure you have the right type and quantity of product available to guarantee a healthy yield and good quality grass.

Nutrients required for 2nd Cut Silage (4 tonnes/ha grass DM)

Nutrient Nitrogen (N) Phosphorus (P) Potassium (K)
Kg/ha (Units/ac) 100 (80) 14 (11.2) 100 (80)

Large quantities of nutrients are removed when taking out a crop and will need to be replaced. The above are maintenance rates only for P and K, and additional P and K will need to be addressed in your overall fertiliser plan for the year. Note; the ratio of P:K is 1:7 in the above table which is the same ratio in cattle slurry. It is for this reason; the advice is to recycle the cattle slurry onto silage fields. However, with higher temperatures, nitrogen is less efficient than that applied in the spring and a large proportion will be lost during summer spreading even with the LESS system, especially on bare ground. It is best advised not to spread slurry in these current dry conditions. Increased utilisation can be achieved by waiting on rain to build soil moisture.

Below is a recommend guide, however when determining a slurry and fertiliser regime for second cut, remember you must know your offtakes or silage crop requirements. It is best to get your advice from your local advisor.

Option 1.

1500 gallons of good quality cattle slurry + 3.5 bags of Target Fertilisers; 24-2.5-10 + S per acre. The slurry needs to be high quality of 7% DM and not diluted. Allow the slurry to wash into soil prior to inorganic fertiliser application.

Option 2.

2500 gallons of cattle slurry (7% DM) + 2 bags of UreaMax+S per acre.

Option 3.

In the absence of slurry, use 4.5 – 5 bags of Target’s 15-3-20+S per acre.

Impact of taking out surplus grass in paddocks as baled silage:

Depending on your farms grass covers, it is best to wait for more rain before making the decision to take your paddocks surplus grass out as baled silage. It is important to note that surplus grass in a paddock taken out as silage bales can equate to half the nutrient offtake of your first cut silage and this is often overlooked. A cover of 2000Kg DM/ha taken out in bales, will add to a maintenance requirement of 5 kg P/ha and 50 kg/ha of K. This will need to be replaced at some stage during the season.

Testing for free nitrates and sugars

It is important to calculate your Nitrogen usage for your silage crop to determine your cutting date and to ensure not to cut grass with high free nitrate levels. The typical rule of thumb is that in ideal conditions, grass will utilise 2 units of Nitrogen per day (e.g. applied 80 units then cutting date is in 40 days.)

It is beneficial to talk to your advisor or co-op to carry out a grass sample analysis for ‘Free Nitrates’ and sugars to prevent cutting grass with excessive nitrates and to guarantee a good fermentation in the ensiling process, be it in the pit or as baled silage.

The ‘Free Nitrates’ represent the Nitrogen fertiliser that was applied to the crop that has subsequently not yet been converted into protein. When this level is above 1500 mg/Kg in a fresh weight sample, the silage can potentially go into secondary fermentation when ensiled and significantly reduce its feed value. Sugar content should be between 3 – 4 % in a fresh weight sample or 10 – 12% in a dry matter sample. Higher sugars will result in improved silage preservation and fermentation. To achieve high sugar levels, mow silage fields in early afternoon when sugar content is at its highest in the grass leaf. Allow for a short wilt of 24 hrs to bring DM content to around 30%.

For your nitrate and sugar analysis test, results are usually obtained in 1-2 days from the lab. If the Nitrogen level is high, it is best to delay your cutting date a further 3 – 4 days, depending on your results.

Summer Grazing

It has been well documented and researched that grazed grass is the most cost-effective feed and it should be utilised to the maximum in the diet. Soil temperatures are 3 – 4 degrees above average and with sufficient moisture, grass growth will increase. At the moment, soil moisture is low in most parts of the country especially in the East, where moisture deficits are now at 70-80 mm.

Grass growth rates are very variable, running from as low as 40kg – 70 Kg/ha/day, in some parts of the country. Frequent paddock walking and grass measurement is especially important. The aim is for pre-grazing yields of 1400/1600 Kgs/ha, which will give a good leafy sward and a low level of stem.

Continue to apply nitrogen following each paddock grazing at the rate of 25 – 30 units/acre. Sulphur is important in protein production and increased nitrogen use efficiency and is wise to apply at a low level this time of year. Products of choice include SuperCAN (27N 4S), UreaMax (46N) or UreaMax + S (38N 7S). If your soil index is lower than 3, it is wise to use an NPK + S product and in this case consider using Target Fertilisers; 27-2.5-5 + S or 24-2.2-4.5 + S.

To view our full range of fertilisers for grassland, click here.

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