Soil sampling: You can reduce your fertiliser bill this spring. How? By making the best use of soil nutrients and available slurry, to grow good crops of grass for silage and grazing.
Fields have not received inorganic fertiliser since mid-September or had slurry applied from mid-October. It is therefore the ideal time to soil sample them, before slurry or fertiliser is applied. As phosphate and potash are recycled by grazing cattle, apply slurry to land that is used for silage, targeting fields low in phosphate and potash. This makes best use of the soil and slurry nutrients and helps avoid nutrient shortfalls on silage ground where there is greatest demand.
Soil sampling augers and bags are available from your local DARD Direct Office. Sample each field and if the field is more than four hectares test each four hectare block in the field. If testing a grass field walk in a ‘W’ pattern taking at least 25 core samples with the 75 mm auger at regular intervals, placing these in a bucket as you move through the field. Avoid sampling headlands, dung pats or areas around gates and water troughs. Mix the samples in the bucket thoroughly before putting 300 g of mixed soil in a sample bag.
Write your name, field name and farm survey number on each bag. The cost per sample is £8.40 including VAT and is usually paid by cheque made payable to Yara UK Ltd. Don’t forget to return the soil auger when you leave your soil bags at your local DARD Direct Office.
Effective use of slurry
You should receive the results of the soil samples within the week and your local Development Adviser can help you interpret them. Your results can be put into the DARD Online Services Crop Nutrient Recommendation Calculator to calculate specific field requirements whilst keeping within nitrates and phosphorus regulations.
The optimum index of 2 for phosphate and 2- for potash maximises grass yield from the most economic use of slurry and fertiliser. Applications of phosphate or potash as slurry to soils with higher indices are not cost effective.
At Greenmount the policy is to spread slurry on first cut silage areas. An application of 33 cubic metres per hectare (3000 gallons per acre) of cattle slurry in February/early March supplies all the required phosphate and potash for first cut silage and approximately the same nitrogen (N) for grass growth as two 50 kg bags of 27 per cent N.
Take account of N in slurry when deciding how much N fertiliser to apply for first cut later in the spring. There is unlikely to be a yield response to applying a total of more than 120 kg of N per hectare for first cut. If you use a trailing shoe or shallow injection system to apply slurry you will almost double the efficiency of nitrogen use giving a saving of another two bags of 27 per cent N fertiliser per hectare.
Typical February performance
Good milk from forage performance is critical at current milk price. The typical performance from the Co Armagh farms I work with is: (see table).
Increase efficiency by targeting concentrate feeding to cows in early lactation. Feed cows calved before mid-December to yield. Feed at 0.45 kg per litre above the TMR M+ for the cow’s previous seven day average yield. Keep an eye on yield, milk quality, cow condition and dung composition.
Call into your local DARD Direct Office now to book an auger for immediate sampling or to discuss improving feed efficiency.