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Improving Nutrient Efficiency on Tillage Farms - Mark Plunkett

Reducing the impacts of high input costs on Tillage Farms

Over the last 12 months fertiliser prices have continued to increase to unprecedented levels never seen before. Indications at present are that fertilisers will remain high for the remainder of 2022. This is due to energy costs and the conflict between Russia and Ukraine. These regions are major suppliers of all major nutrients (N, P, K & S) and poses concern for 2023 especially with potassium supplies.

Over the last number of decades tillage systems have evolved to more specialised tillage farms with the absence of livestock enterprises. Tillage farms are now very dependent on artificial fertilisers (N, P K & S) to supply major plant nutrients during the growing season. These systems have been very successful in producing high crop yields coupled with a high levels of management. For example from more diverse crop rotations to more precise fertiliser applications with combine drilling of phosphorus with modern and more rapid establishment systems. Today presents a whole new challenge to maintain current crop yields and margins while managing higher costs such as fertilisers / fuel and possibly fertiliser supply issues in the year ahead.

Getting more out of each kilo of applied N, P & K must be the aim to help control input costs. This very much starts with improving soil health which is the foundation to good crop productivity. Healthy soils will retain and recycle more nutrients during the growing season and help meet peak nutrient demands at key crop development.

Bio-Based Fertilisers

Where organic manures are available they will supply valuable organic matter which will feed soil biology and improve soil health. Over the last 4 years an EU project (Nutri2Cycle) investigating the recycling and nutrient profiles (N, P & K) of a range of bio-based fertilisers for tillage crops. Bio based fertilisers such as dairy processing sludge / cattle slurry / poultry manure etc…are compared to a conventional chemical fertiliser programme. Results to date show that bio based fertilisers can produce similar yields to a standard chemical fertiliser programme. With high fertiliser prices these alternative local nutrient sources provide a great opportunity to supply N, P & K, and valuable organic matter to continuous tillage soils at lower costs. Crops tested to date are maize, spring wheat, winter oilseed rape and winter wheat in 2022. Figure 1 below shows spring wheat yields in 2020 for the different bio based fertilisers + balanced chemical fertilisers compared to chemical fertiliser only. Spring wheat grain yields ranged from 4.6 (unfertilised) to 9.8t/ha (Pig slurry separated). Fertiliser costs for the 100% chemical fertiliser was €670/ha which is higher compared to a combination of bio based fertilisers and chemical fertiliser options ranging from €325 to 542/ha while no yield difference found between them.


Figure 1:- Spring wheat grain yields for bio based fertilisers and balance chemical fertiliser programmes compared to chemical fertiliser only.