A Systems-level Case Study of Conservation Agriculture in the UK
Collins, J. (2025) A Systems-level Case Study of Conservation Agriculture in the UK. Doctoral thesis, Harper Adams University.
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Abstract
Conservation Agriculture (CA) is an agricultural system designed to manage agroecosystems for improved and sustained productivity by conserving and enhancing soil quality and biota (FAO, 2014; Page et al., 2020). This thesis presents the results of a three-year case study that evaluated the effects of the transition to CA in comparison to Conventional Agriculture (CON), conducted using a systems-level methodology in Shropshire, UK. Throughout the experiment, the agronomic plan varied considerably between the experimental treatments, with the CON treatment using significantly higher quantities of fungicide and insecticide active ingredients (kg ha−1), and the CA treatment using significantly higher quantities of herbicide active ingredients (kg ha−1). Despite this, the total quantity of pesticide active ingredients applied did not differ significantly between systems. Regarding nutrient inputs, the CA treatment applied significantly less nitrogen (N) fertiliser (kg ha−1), aided by both crop rotation choices and the use of foliar N. Although crop yield variability was high in both systems, no statistically significant differences were found between the treatments in overall crop yield (t ha−1). Soil nutrient availability (phosphorus (P), potassium (K), magnesium (Mg), and total N) increased under CA, suggesting improved nutrient cycling and retention. However, CA significantly increased soil bulk density and led to a significant decline in soil microarthropod diversity; however, no significant differences were identified in individual ecotypes or total earthworm abundance between the treatments. In terms of farm management operations, CA required significantly less machinery operational passes ha−1, machinery operational time ha−1, and fuel usage ha−1, identifying clear operational benefits to farmers from CA adoption in terms of labour and machinery expenditure. This resulted in significantly reduced expenditure on machinery operations and crop applications, whilst not statistically compromising revenue or gross margin compared to CON. Agronomic risk assessment using the Danish Pesticide Load Index identified significantly higher potential environmental risks in CA. The main driver of this was a significantly higher environmental fate load in the CA treatment, due to higher usage of herbicide active ingredients. No significant treatment differences were observed for the ecotoxicity or human health risks of the pesticide agronomic plans. The findings of this study demonstrate that the transition period of CA presents both opportunities and challenges for farmers. While it can reduce inputs and operational costs, it may increase reliance on herbicides and require careful management of soil health to achieve the best outcomes. As a knowledge-intensive and context-specific system, CA demands a high degree of local adaptation. Therefore, future research should focus on multi-disciplinary and multi-stakeholder methodologies, such as Farming Systems Research, to support farmers and agronomists in managing and adapting CA to suit local conditions.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Divisions: | Agriculture and Environment (from 1.08.20) |
| Depositing User: | Miss Anna Cope |
| Date Deposited: | 04 Nov 2025 16:55 |
| Last Modified: | 04 Nov 2025 16:55 |
| URI: | https://hau.repository.guildhe.ac.uk/id/eprint/18272 |
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