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Low N grass



Key messages emerging from the project:

  • Nitrogen increases dry matter yield with all species tested
  • The effect of N on quality is less and more variable than yield
  • No consistent significant differences in ranking were identified with perennial ryegrass and timothy varieties with increasing N levels
  • Clover yield were significantly lower when grown in companion with cocksfoot compared to perennial ryegrass or timothy
  • Persistence was higher with higher N levels, which could delay the need for re-sowing
  • The relative performance of varieties selected from the RGCL will be similar under most, lower N, conditions on farms. Dry matter yields (t/ha) from different N levels


Results for perennial ryegrass

100 N 200 N 400 N SE LSD
Year 1 conservation 8.6 11.1 16.7 0.68 1.34
Year 2 simulated grazing 3.8 5.8 10.1 0.52 1.02
Year 3 conservation 5.0 6.8 12.7 0.7 1.39


Mean digestibility values

Management 100 N 200 N 400 N LSD
Year 1 cut 1 (conservation) 74.3 73.4 70.6 1.39
Year 1 cut 2 (conservation) 74.7 74.6 71.1 2.08
Year 2 (simulated grazing) 71.2 71.9 74.4 1.56

Beef & Lamb
Project code:
01 August 2011 - 31 December 2015
AHDB Beef & Lamb
Total project value:
Project leader:


74316 Final Report 2016

About this project

The Problem:

One of the knowledge gaps identified with the Recommended Grass and Clover List (RGCL) system is that the current test protocol uses a large amount of inorganic nitrogen fertiliser (circa 400 kg N/ha) in order to identify varietal differences over a limited number of years. As a result the current RGCL trials represents a high input production system and there is a need to identify varietal characteristics that are of importance in low and zero inorganic N input production systems. The results can then be disseminated to farmers, so that they can be confident of picking varieties that will perform most efficiently in the systems that they operate.

Work recently carried out by NIAB (2004-2006) on limited information suggested that there may be some correlation between Perennial Ryegrass (PRG) variety performance under the current RL system and a low input system, but a very weak correlation under zero inorganic N (organic) production for PRG and White Clover. Overall the data on organic production and low input systems is very limited and we have been unable to draw firm conclusions with which we can provide advice to farmers.


Project Aims:

To test grass and clover varieties from the Recommended Grass and Clover in order to provide advice to farmers on which varieties to use in low and zero inorganic N systems.



On three NIAB sites (Yorkshire, Devon and Shropshire) plots of three diploid intermediate heading and three tetraploid intermediate perennial ryegrasses, and three Timothy varieties will be grown under nitrogen regimes of 100 kg, 200 kg and 400 kg N per ha. The same varieties plus three cocksfoot varieties will also be grown with two types of white clover to see the impact of nitrogen from clover. These trials will be run over three seasons.



The results will be used to investigate if changes to the current testing protocol are needed to reflect lower nitrogen use with the industry. The results will also be used to help producers make mixture selections.