The Teagasc/Irish Farmers Journal BETTER Farm Beef Challenge spring walks have passed, signalling just how quickly the year is moving on. On Thursday 4 April, Maurice Hearne welcomed around 100 people to his mixed suckler, beef, sheep and tillage farm in Dunmore East, Co Waterford. The following Thursday, 11 April, Ricky Milligan hosted a similar crowd on his suckler calf-to-beef and tillage holding near Naas, in Co Kildare. In this article we present some of the key learnings.

First-cut silage

Given the time of the year, a strong emphasis was placed on growing silage crops at both walks. The main points of advice were around closing up and fertiliser application. Table 1 details the effect of cutting date on silage quality and yield, and on the subsequent animal intake and liveweight gain.

Farmers seeking high-quality silage should be targeting a cutting date before 1 June. However, because yield is compromised in a strive for quality, farmers should also consider the type of stock they are carrying over the winter.

Weanlings and beef animals will need high-quality silage, but dry cows can make do with lower quality, thus allowing a higher yield to be obtained at cutting.

After picking a target cutting date, target close-up needs to be determined.

Fifty days is the length of time a silage crop will take to grow in normal growing conditions. Once closed, getting crop nutrition right is paramount. Figure 2 shows the nutrient requirements for first-cut silage, based on the soil index.

Remember to take note of the N volume applied. A silage crop will utilise around two units/acre of N daily. If 100 units/acre is applied, the crop can’t be cut for 50 days.

Grassland weeds

Grassland weeds are evident in a lot of swards subjected to severe drought stress last summer. In Kildare, Shay Phelan, crops specialist with Teagasc, explained: “Weeds are opportunists, the seeds are in the soil all the time. They’re just looking for sunlight and the correct conditions to grow.”

With grass under severe pressure last summer and with swards grazed bare, weeds got the opportunity to germinate.

Once established in the sward, weeds can have a significant financial impact on a farm. “Firstly, think of the price of nitrogen, think of the price of P and K. The weeds are using up those nutrients, they are competing with the grass and they are costing you money,” Shay explained. “Weeds are also reducing the performance ability of animals grazing the sward. Output targets are far less achievable.”

According to Shay, an integrated weed management approach is best: “Gone are the days where the answer is a can of spray. Grazing management, topping, alternating grazing and silage should come first. A herbicide should be the last option.”

Grazing ground tightly this spring may be enough to choke out the weeds once again. However, where spraying is required, the best time to spray is when the weed is young (definitely before it produces seed heads) and when growth is good (to maximise herbicide uptake). Despite usually being more expensive, longer-acting herbicides were recommended.

Soil fertility

Farmers at both farm walks were guided through five steps to building soil fertility:

Step 1 – soil test

A soil test should be carried out at least every five years but, in cases where swards are being pushed hard, every three years is ideal. Testing will provide a phosphorous (P), potassium (K) and pH analysis of the soil.

Step 2 – soil pH

Optimum soil pH is between 6.3 and 6.5. Where pH is maintained close to the optimum range, an increase in grass DM production of at least 1t/ha/year can be achieved.

This has subsequently been calculated as a €105/ha benefit or a return of €4 for every €1 invested in lime. Lime can be spread at any time of the year but single applications should not exceed 7.5t/ha.

Step 3 – P and K

Farmers should aim for grassland P and K indexes of three and four. Soils at index three or four for P and K, compared to index one, can grow an extra 1.5t DM/ha annually. Building P and K levels is a long-term task which will require P and K to be applied at maintenance, plus build-up levels.

Step 4 – slurry

The majority of the nutritional value in slurry is in K (69%) and P (19%). For this reason, P and K should be used primarily for low-index soils. Every 1,000 gallons of slurry provide five units/acre P and 30 units/acre K. The timing of spreading has no effect on the availability of P and K. Nitrogen in slurry will range from three to six units/acre per 1,000 gallons depending on weather conditions. In monetary terms, 1,000 gallons of cattle slurry is worth between €20-€25.

Step 5 – balance

Soil fertility is only as strong as its weakest link, so the nutrient that is in shortest supply limits grass yield. Compound fertilisers should be used as a balancer to target nutrients which need building.

Sulphur is one thing to consider. Although there is no test for it, 30% of Irish soils need it. Grazing ground should get about 20kg/ha (16 units/acre) of sulphur annually.