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Sustainable weed management: development of techniques to balance biodiversity benefits with retention of yields - AR0408

Description
Overall objective: to test the potential for managing weeds that contribute to biodiversity in the crop without reducing economic sustainability (ie. controlling damaging weeds and retaining those with biodiversity benefits). Such techniques could be applied to whole fields, part fields or headlands/field margins.
The work aims to meet the general MAFF goal of minimising pesticide use. Specifically, it addresses the objective in the ROAME A to ‘provide a better understanding of weed-crop competition and population dynamics.... to support rotational approaches to weed management that are both economically sustainable and reduce environmental impact’. There is evidence that weed control practices and changes to other aspects of crop agronomy have caused a decline in biodiversity as evidenced by a reduction in farmland birds. This project will explore the possibilities of redressing this decline by a more integrated approach to weed management. Project PN0940 has recently clearly identified weed species that are of benefit to birds and invertebrates but are not (often) a major threat to crop productivity. The project concentrates on these species.
The research will aim to answer the question ‘is it possible to manage weeds to meet biodiversity targets, without appreciably jeopardising profitability, and how do you do it? Experiments will be carried out to investigate how to use the information from the related programmes ‘the biology and population dynamics of weeds’ and ‘modelling arable crop:weed dynamics and competition’ to manage weeds in a more environmentally beneficial way. Work will be done to explore alternative methods of achieving this:
a) Autumn germinating species of biodiversity value;
i) Identification of appropriate treatments to control aggressive species whilst retaining desired ones,
ii) Exploitation of the potential to control dense patches whilst leaving less dense areas, utilising patch spraying technology
iii) Utilisation of appropriate doses of herbicides and/or mechanical weeding to suppress weeds so that they do not reduce yields, whilst retaining their ability to benefit wildlife
b) Spring germinating species of biodiversity value:
i) study of the possibilities for encouraging spring emerging species (with clear benefits for biodiversity) in winter sown crops, without jeopardising yields,
ii) benefits of spring cropping (no research planned as already known that this has biodiversity value)
The results of this work can be used directly, through meetings and articles in journals and the press, to influence weed management approaches on farms. It can also be used indirectly through the MAFF-funded SAPPIO LINK Weed Management Support System project, which will provide a ‘vehicle’ for the introduction of these less intensive weed management systems for growers of the major UK crop – winter wheat.
Objective
Overall objective: to test the potential for managing weeds that contribute to biodiversity in the crop without reducing economic sustainability (ie. controlling damaging weeds and retaining those with biodiversity benefits). The following species have already been identified as being ‘beneficial’ for biodiversity: fat hen, knotgrass, chickweed, annual meadow-grass, scentless mayweed and groundsel. The work will concentrate on these weeds and primarily on autumn sown crops.

Autumn germinating species of biodiversity value
1) Tactical use of herbicides and mechanical weed control: (ADAS/IACR/SRI)
to establish the feasibility of managing weeds by selecting appropriate herbicides (or other weed control technique) to eliminate competitive weeds, whilst retaining those of biodiversity value. Work to include studies of the practicability of applying herbicides on a spatially selective basis to reduce high density patches, whilst retaining plants on areas where densities are lower. (this diverges from guidelines being developed for ‘normal’ patch treatment of weeds)

2) Manipulation of weed competitive effects (ADAS/IACR)
to investigate the possibility of using sub-lethal herbicide treatments and/or mechanical weeding to suppress the growth of target species, so that biodiversity value is retained but yield losses are reduced. Assess impact on viable seed production.

Spring germinating species of biodiversity value
3) Stimulation of spring weeds in winter wheat: (ADAS/IACR)
to explore the possibility of using a tine weeder in spring to stimulate the emergence of weeds, that would be of environmental benefit.. To assess success both in terms of plant numbers and seed production. Check consequences for subsequent crops.

4) Benefits of spring cropping
As it is already quite well established that spring cropping can have biodiversity benefits, this part of the programme will simply aim to collate and summarise available information on these benefits.
Project Documents
• Final Report : Sustainable weed management: development of techniques to balance biodiversity benefits with retention of yields   (2744k)
Time-Scale and Cost
From: 2001

To: 2005

Cost: £443,644
Contractor / Funded Organisations
Rothamsted Research (BBSRC)
Keywords
Arable Farming              
Crops              
Farming              
Natural Resource Use              
Sustainable Farming and Food              
Sustainable Production              
Weed Control              
Fields of Study
Arable Crops