Sunday 25 September 2016

Soil fertility testing is the foundation of good farming

Published 25/11/2015 | 02:30

If you don't have a soil test for your farm you don't know what you are dealing with.

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Many farms around the country are in this position and haven't a soil test result for their farms for years, if ever.

Over the last number of years National soil fertility trends have been on the downward slope with only 10pc of farms at the optimum level for pH, phosphorus (P) and Potash (K).

Soil fertility is like the foundations to a house.

It is the basis to which all activities on your farm are dictated by.

If the soil is not in top working order it will not be able to drive the grass or crops on the farm that will lead to poor performance, poor quality grass and fodder, thereby reducing stocking rate and output from your farm.

All of this in the long run will affect the profitability of your business.

Now is an ideal time for you to plan and make decisions regarding fertiliser and manure management strategies for your farm.

Targets

The target levels for pH on grassland are 6.2 to 6.3 and P and K should be at index 3.

At these levels, land will be very responsive to applications of lime and compound fertilisers.

On many farms sub-optimal soil fertility will lead to a drop in output and income if allowed to continue.

It is very important to complete a farm fertiliser plan for your farm to avoid further decline in soil fertility levels.

There are five key steps for effective soil fertility management:

Soil test

The whole farm should be sampled and tested for pH, P and K.

Have one sample for every five to 10 acres.

Take sample in a W shape to get a random sample.

Make sure there is a minimum of 20 cores per sample.

The sample should be taken to a depth of 10cm and during the late autumn to early spring.

Leave at least three months from the last application of fertiliser or slurry

Avoid unusual spots, like where a ditch was removed, feeders, farmyard manure stored.

The cost is small at around €0.50/ac/year

Soil pH and lime

Correct lime status first.

One to two tonnes of lime per acre are removed every five years

Target pH of 6.2 - 6.3 for grassland.

Apply lime as required to increase soil pH up to target, as 60pc of the country has a pH of <6

Apply to bare ground or low grass covers.

Do not apply within six months if on a silage field, as it may affect preservation.

Target P and K Index 3

Aim to have soil test P and K in the target Index 3 in all fields, only 25pc of soils are at index 3

Low index fields will have less productivity and they will require additional fertiliser.

Index 3 soils only require maintenance levels of fertiliser to replace crop off takes.

Slurry and organic manures

Use the resources on your farm.

Most of the value is in the P and K.

Spread slurry and farm- yard manures on low P and K index soils.

Spread as much as possible in the spring to maximise availability of Nitrogen.

Timing doesn't have as big effect on P and K as N

Balance the land with fertiliser

Choose a fertiliser that is well balanced to make up the crop requirements.

The nutrient in the shortest supply will determine the yield

Have N, P, K and S in the correct ratios.

Gordon Peppard is the programme advisor for the Teagasc Green Acres programme email: godon.peppard@teagasc.ie

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