Thursday, 29 October 2015

Fertiliser for Growth in a Grassland System

I'm sure you know that Ireland has a massive ability to grow grass, at least a third higher than the European average.  In fact over 80% of the agricultural area is dedicated to grassland, hence the name 'The Emerald Isle'.  But did you know that most soils (up to 90%!) are below optimum fertility for grass production?  Addressing this issue is central to maximising grass production as outlined at the recent Teagasc Soil Fertility Conference in Clonmel. 
Mark Plunkett of Teagasc highlighted a number of key messages from the day:
1.      “65 to 70% of dairy and drystock grassland soils respectively are below the optimum soil pH 6.3 for optimum grass production”;
2.      "Soil testing is the starting point for good fertiliser planning an essential requirement to maximise grass production annually”;
3.      “Maintaining soil pH close to the optimum 6.3 for grassland mineral soils will ensure soil the availability of soil P for plant growth and development”;
4.      "Sulphur containing fertilisers should be applied routinely to all grass silage swards in spring to prevent yield losses worth up to €100/ha/cut”;
5.      “Urea is a less expensive and a viable N source for grassland.  It produced similar yields to CAN when applied throughout the year, particularly at low rates.  Farmers could consider having urea on hand throughout the growing season and applying shortly before rainfall to minimise ammonia loss risk”;
6.      "The slurry hydrometer is an effective tool to measure the nutrient content of liquid manures and to determine its fertiliser value”;
7.      "Grass-clover swards increased grass dry matter production levels by 2.9t/ha compared with grass only, regardless of N fertiliser application rate”;
8.      “On average 1,000 gallons of pig slurry is equal to one 50kg  bag of 19-7-20 (N-P-K)”;
9.      “There is significant nutrient lock up especially on soils with high clay contents and low soil pH levels. Correcting soil pH based on lime advice as per the test soil report will increase the availability of soil P”.
A large number of speakers addressed a wide variety of topics relating to soil fertility research and practical application.  The full conference proceeding is available here.