Diverse forage mixtures to optimise ruminant animal production, nutrient use efficiency, environmental impact, biodiversity and resilience

Lead Research Organisation: Rothamsted Research
Department Name: Sustainable Soils and Grassland Systems

Abstract

Growth and supply of pasture is the most cost effective way to feed sheep and cattle. Pasture is comprised mainly of ryegrass, or ryegrass mixed with white or red clover, with the total amount of pasture produced dependent on the climate, management, soil, and amount of fertiliser used. Ryegrass and clover thrive in a moist, cool environment, but these 'optimal' conditions are occurring less often due to an unpredictable and changing climate. Both drought and soil water-logging reduce the amount of forage that can be grown, which affects farm productivity and, ultimately, increases the cost of producing UK 'home grown' milk and meat.

There are a number of essential nutrients that plants need for growth. Most of these nutrients are supplied through the soil but others such as nitrogen (N) are lacking for many plants and therefore need to be added in the form of a mineral fertiliser. Mineral fertilisers are expensive to produce through reliance on oil, and are detrimental to the environment through their production and contribution to soil nitrous oxide emissions and pollution of waterways.

A solution to these concerns is through the use of a greater diversity or variety of forage plants. The more plant species in an ecosystem the healthier, more robust and resilient it is to changing environments. Diverse mixtures containing drought-tolerant and flood-tolerant plants can provide a source of high quality feed in the face of erratic weather patterns, above and beyond that of typical climate-specific pastures. These diverse plants include legumes which reduce the need for mineral fertilisers because they provide an excellent source of N for pastures due to their ability to convert or 'fix' unusable atmospheric N gas. As a result this improves soil fertility, forage production, and enables N to be better utilised at the animal and farm scales. This, combined with reduced methane emissions from livestock fed diverse forage mixtures can reduce the carbon footprint of milk and meat production. These benefits however, can only be achieved with greater farm uptake of such forages.

The ultimate aim of this project is to achieve high yields of good quality forage for livestock production whilst having a positive and long term impact on the environment. We envisage that this can be achieved by utilising diverse forage mixtures that have the potential to be productive during more challenging climatic scenarios, as well as improving N use efficiency, compared to ryegrass or ryegrass/clover pastures. The project will include a series of agronomic and 'on farm' evaluations of the performance of diverse forage mixtures, formulated for fertility building, resilience, and drought tolerance. Diverse mixture formulations will be based on our previous research and industry needs, and compared to conventional ryegrass and fertiliser. The forage treatments will be compared across a range of environments over multiple seasons in the southern UK and their feeding value for livestock and effects on N utilisation will be measured in a series of nutrition studies with growing cattle. The results will be integrated using existing farm scale models of nutrient balance and ecosystems services to determine the overall benefits of diverse swards in terms of nutrient cycling and the wider ecosystem, and the results disseminated through participatory workshops. The research outcomes from this project will deliver rapid, high impact results for increasing on-farm sustainability in terms of livestock production systems, soils and the environment.

Technical Summary

In the face of climate change and unpredictable seasonal events, mineral nitrogen (N) inputs must decrease, and forage yield and quality must be more resilient to variable weather patterns. There is concern about the poor persistency of ryegrass and the need for improved herbage quality and quantity in variable climates. There is increasing awareness of the role of species-rich plant communities in reducing environmental impact and having positive consequences for agricultural productivity. Diverse plant communities are expected to utilise available resources more efficiently than monocultures due to species-niche complementarity and positive interspecific interactions. Manipulation of plant species richness found that the most diverse mixtures, on average, achieved a yield benefit of +77%, compared with monocultures. Further, reliance on mineral N inputs has been reduced by exploitation of N fixation from legumes, with grass-legume mixtures containing 40-60% legume and receiving 50 or 150 kg/ha/yr fertiliser N achieving similar yields as grass monocultures fertilised with 450 kg N/ha/yr.

The objective of greater sustainability, biodiversity, and resilience of livestock production will be achieved here through the harnessing of forage mixtures that have the capability to be more productive under variable climates, require less N fertiliser due to reliance on N-fixation capabilities, and contribute to greater N use efficiency at animal and farm scales, compared to swards typically grazed in the UK. Forage treatments will be based on agricultural and environmental requirements, and developed and performance tested in different areas of the UK. Agronomic characterisation, utilisation and feed value for livestock, on-farm uptake and performance, and resilience and recovery to drought and water stressors will be investigated. Information will be integrated into models to provide farm and national scale assessments for efficient, productive and sustainable agriculture.

Planned Impact

Please refer to the main application.

Publications


10 25 50
 
Description Designing Forage Mixtures Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact Approximately 20 participants including farmers, nutritionists and other specialists took part in a workshop to discuss the advantages and disadvantages of different forage mixtures with the aim of informing the project as to the most suitable mixtures to be assessed on the research and commercial farm sites. An overview of the project was given as introduction and there was discussion regarding the purposes of growing forage mixtures and the wider animal health and environmental benefits that they may give and whether there was a trade off with productivity. Barriers to uptake of more diverse forage mixtures was also discussed. Several of the participants expressed an interest to be more involved in the project (e.g. to host a farm trial) and to be kept informed as theh project progresses.
Year(s) Of Engagement Activity 2016