Q.1 How early can I apply nitrogen to grassland in Spring? A. Nitrogen can be applied from early January onwards or about 6 weeks before the expected turnout date. The ideal is to apply nitrogen in January as soon as ground conditions allow and there is no heavy rain forecast within 48 hours. This nitrogen will not be leached out of the soil and will be available for uptake when growth conditions improve in February and March. Q.2 How late can nitrogen be applied to grassland in Autumn? A. In general, nitrogen fertilizer applications Q.3 Will heavy rain wash away recently applied fertilizer? A. If there is heavy rain within 48 hours of a fertilizer application significant amounts of fertilizer can be lost in run-off water. If the rain occurs after 48 hours most of the fertilizer will be absorbed onto the soil and won’t go into solution and the risk of loss is greatly reduced. Q.4 How long before cutting should nitrogen be applied to first cut silage? A.Aim to have all nitrogen applied at least 8 weeks before the expected cutting date. This should ensure that there will be at least 6 growing weeks between application of fertilizer and cutting. Q.5 How much nitrogen should I put on a first cut silage crop on fields that were reseeded two years ago? A.Recent reseeds can take up to 110 Q.6 Are there any advantages to splitting nitrogen applications on first cut silage? A.The main advantage of splitting is it gives an opportunity to apply a small amount of nitrogen early in the season while reducing the risk of losses by not applying all the nitrogen early. For example a silage field that is not being grazed in Spring could get 40 units of nitrogen per acre in mid February to take advantage of any early growth and another 60 units in mid-March. If March arrives without the opportunity for an early split it is then advisable to apply all the nitrogen in one split. Q.7 Does frost damage recently applied fertilizers? A. Frost does no damage to recently applied fertilizer. Growth conditions will obviously be very poor during frosty weather and there will be little or no uptake of fertilizer but the fertilizer nutrients will retain their potency for when growth conditions improve. Fertilizer should not be applied to frozen fields due to the risk of run off losses when the thaw sets in. Q.8 When is the best time of the year to apply phosphorous (P) and potassium (k) to grassland. A.This depends on soil fertility and soil type. On peaty soils it is best to apply P and K during the growing season because peat has a poor capacity to retain fertilizer. Potash shouldn’t be applied to sandy soils during late Autumn/Winter as it is readily leached from sandy soils. On non sandy mineral soils where soil fertility is poor (Index 1) it is best to apply a fairly large application of P and K in the Autumn in order to promote tillering and root development. As soil fertility improves (index 2 or better) the timing of P and K becomes less critical but there are time and labour advantages to applying P and K with nitrogen during the growing season. Risk of losses should be less with smaller more frequent applications of P and K during the growing season compared to a large single application out of season. Q.9 When is the best time of the year to apply sulphur to grassland and how much should I apply? A.From May onwards is the best time. 15 units of sulphur per acre is recommended for second cut silage. In very deficient areas apply 15 units of sulphur for first cut as well. 15 to 20 units per acre should be applied to grazing fields preferably in a number of applications. Q.10 How will I know if my fields need sulphur? Q.11 Can there be problems with too much sulphur? Q.12 Can I spread urea in the same year as I spread lime ? As a general rule don’t use urea if lime has been applied that Spring. If lime was applied in the previous back end it should be safe to use urea in the following Spring provided there was sufficient rainfall to wash the lime into the soil. Lime can be applied a week after an application of urea with no increased risk of losses as the urea will have been fixed in the soil and no reaction occurs between the urea and lime particles. Q.13 How late into the growing season can urea be used? Q.14 I normally apply one bag of urea per acre to my silage fields for early grazing. By how much should I reduce the main application of nitrogen for my first cut silage crop to allow for some carry over of nitrogen? Q.15 I spread about 3,000 gallons per acre of cattle slurry to my silage fields in February/early March. How much nitrogen will this slurry contribute to my first cut of silage? Q.16 What is meant by luxury uptake of potassium (K) and how can it be avoided? Q.17 Is there a risk of luxury uptake when large amounts of phosphorous (P) are applied? Q.18 When is the best time to apply lime to grassland? Q.19 How often should I take soil samples and when is the best time of the year to take them? Q.20 What steps can I take to ensure losses of fertilizer to the environment are minimised? A. Apply fertilizer on the basis of soil analysis:
|