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Why Nutrient Management Planning Is So Important For Farmers

In week 6, the final of the Teagasc Waterford/Kilkenny Sustainability Series, Deirdre Glynn, ASSAP advisor advises on implementing a Nutrient Management Plan which can optimise economic return from nutrients used to produce a crop, while reducing the negative impact of nutrients on the environment

In the video below, Nigel Kennington, Teagasc Dairy Advisor, Kilkenny gives an overview as to why Nutrient Management Planning is so important for farmers

Implementing a Nutrient Management Plan

This can optimise economic return from nutrients used to produce a crop, while offering farmers the opportunity to reduce the negative impact of nutrients on the environment. Improving soil fertility to recommended levels will allow for increased nutrient use efficiency and a reduction on the reliance of chemical fertiliser whilst improving overall productivity on the farm.

On most farms nutrients are recycled from the soil to the crops, to the animals and returned to the soil as organic manure. Nutrients also exit the farm by way of soil erosion, nitrate leaching, phosphorus runoff and gaseous emissions such as ammonium volatilization; these are an inefficient use of resources but also have a negative impact on water quality. Especially where the farmer needs to purchase nutrients to compensate for those leaving the farm.

Planning helps to optimise the use of farm nutrients, maintain and improve soil health, reduce excessive nutrient build up and lessen environmental risks. Each farm has a unique nutrient status based on soil type, soil structure and quality, topography, crop rotation, nutrient input, residual nutrients with manure and chemical fertilizer inputs accounted for.

Successful Nutrient management

This requires good record keeping, regular soil sampling, good crop management and following through on the advice specified by your consultant. Soil samples should act as a guide for building a soil fertility programme.

Recent Teagasc research shows that 90% of fields sampled in Ireland are sub-optimal for either pH, phosphorus (P) or potassium (K) or a combination of nutrients. Sustaining a pH between 6.3 and 6.5 on grassland mineral soils regulates nutrient availability and supports biological processes (5.5 pH for peat soils). In grassland soils high in Molybdenum, it is important not to raise the pH above 6.2 as this can induce copper deficiency in animals.

Soil test results indicate nutrient levels in the soil, allowing a farmer plan accurate nutrient applications if needed (no P on index 4 soils). In addition to the cost savings by only applying the required fertilizers, losses and environmental problems associated with the movement of soil nutrients off farm can be minimized.

Research has shown that nitrogen (N), P, and K fertilization efficiency may be increased considerably when soil pH is within the adequate range. P levels on the farm are set according to a farms crop requirements, stocking rate and soil test P levels. Deficient index 1 & 2 soils require building up while index 4 soils require drawing down towards an optimum index 3 balance. Lime and P management go hand in hand. Application of P on acidic soils is not cost beneficial as it becomes locked up and unavailable for plant uptake.

Correcting pH

Correcting the pH with lime applications (grassland soils ≥ 6.3 and arable soils ≥6.5) will improve the efficiency of applied P in manures and fertilizers. There is a compulsory adoption from 2020 of a farm liming programme for derogation farmers where applicable on as part of their nutrient plan.

Nitrogen: Nitrogen (N) is a nutrient needed for plant growth, free draining soils are very susceptible to nitrate (NO3) leaching as it is very mobile and can be leached into groundwater if not managed properly.

The 2 main sources of N used on Irish farms are CAN and Urea. There are N losses as nitrous oxide from CAN and ammonia from Urea under certain soil and weather conditions that promote N loss.  Urea treated with a urease inhibitor (NBPT / 2-NPT) reduces both ammonia and nitrous oxides losses helping to reduce their impact on both air and water quality. Low Emissions Slurry Spreaders (LESS) retains an extra 3 units of N per 1,000 gals of slurry than the splash plate. As well as lower ammonia-N emissions LESS technology allows farmers to spread on higher covers so increasing the spreading window to target fields with low soil test P and K indexes.

Test your soil, form a nutrient management plan and most importantly follow the plan

Spread the right nutrient at the right time in the right place at the correct rate


If you missed the any of the previous articles & videos in the Sustainablity Series you can view them below: