Most moderately- to well-stocked farms have at least four and possibly six rounds of fertiliser out by now.

Based on stocking rate (kg/ha organic N), Table 1 shows the recommended quantities of N that should have been applied to grassland swards by the end of July.

To get your head around the kg/ha organic N value, look at Table 2. For example, two suckler cows and two calves per hectare would give a stocking rate of 178kg/ha organic N (2.4LU/ha).

A heavier stocking rate of 3.3LU/ha on the grazing ground (three suckler cows and three calves) is right up at the 250kg/ha organic N mark.

Summer approaches

In reality, however, the quantity of N spread this year to date may not be as high as what was recommended. Obviously it has been an exceptional year for grass in most parts of the country and the need for N fertiliser was reduced.

Some farmers still used their planned quantities of N fertiliser and, combined with the strong growth, were able to build up large buffer-stocks of fodder. Others chose to limit N spreading as a means of cutting costs on farms.

Both are valid approaches, but my preference would have been the first option – “grow the grass when the growing is good”.

I also spoke to a lot of people that were spreading N after every grazing, but in small amounts, as a means of maintaining grass quality during the summer. This tactic worked well too.

Autumn requirements

Table 3 now adds on to the spring and summer N requirements for grassland shown in Table 1 and details the autumn N requirements of grass swards.

Across all farms, the final application should be about 20-30units/ac of N. The most common approach is a blanket application.

Soil temperatures stay quite high in September and grass responses per kg N of between 10-15kg DM/ha have been recorded under good growing conditions.

In terms of timing, moderately stocked farms should aim to spread one good application sometime in August/early September. I would be aiming for mid-August so it will act as a good boost for building grass in the back end but it will also avail of better N response rates than early September.

Higher stocked farms should be looking at getting two applications out in the back end. If this was front loaded at the end of July, then you probably don’t need to give the final application until late August/early September.

Remember, as part of the Nitrates Directive, 15 September is the deadline for all chemical N application.