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Can conservation agriculture compete with conventional agriculture commercially?

Primary Supervisor: Dr Simon Jeffery, Crop & Environmental Science

Secondary supervisor: Professor Karl Berhendt

PhD project title: Can conservation agriculture compete with conventional agriculture commercially?

University of Registration: Harper Adams University

Soil degradation is one of the greatest challenges facing us today. Conservation agriculture is proposed as a means of reducing soil degradation associated with food production. It aims to work with the biology of soils to support crop production, as opposed to conventional agriculture, which often aims to maximise crop yields despite the soil biota rather than because of it. Conservation agriculture is predicated on no-till management practice with direct drilling of seeds to achieve minimal disturbance of the soil combined with cover crops and the return of crop residues to the soil. The aim is to disturb the soil and its biology as little as possible, while feeding the biology to enable it to do the work that traditionally the plough and agrochemicals would otherwise do. Indeed, Charles Darwin referred to earthworms as “Nature’s Plough” as far back as 1881. Furthermore, conservation agriculture’s practice of residue return and cover crops, works to protect the soil from erosion while the cover crops grow and function, and to provide food for the soil biology during decomposition while the main crop is growing. This can reduce the need for artificial fertilizers, and the higher levels of soil biodiversity can reduce the pest and pathogen load and so reduce the need for spraying pesticides.

There is an increasing interest in conservation agriculture within the UK, as evidenced by the fast growth of “alternative” agricultural shows such as Groundswell and The Real Oxford Farming Conference. However, some research has suggested that conservation agriculture cannot compete with conventional practices when it comes to profitability. A highly cited meta-analysis (Pittelkow et al., 2014) reported that, on average over 610 studies, conservation agriculture produced yields that were between 2 and 10% less than conventional agriculture. The issue with this study in defining the benefit of adopting a conservation agriculture based system is that about half of the studies included in the meta-analysis were from studies over 1 or 2 years. These showed negative yield effects on average, which were no longer present by Years 3 to 9. This shows that to identify the true benefit of such systems, experiments and their economic analysis need to consider the short and long term implications (Pannell et al., 2013).

Experiments comparing systems need to run for at least 3 years to allow sites to pass through the well reported transition period. As such, this proposed project, at 4 years, would be sufficient to overcome these initial yield penalties, if observed. Additionally, previous experiments have been confounded by agronomic practice. In an effort to keep all of the variables as similar as possible, apart from the exclusion of tillage and/or the return of residues, the agronomy for both conventional and conservation agriculture plots have often been kept standardised. While minimising the variables that change within an experiment may be good science, this is not realistic of the real world situation where the agronomic requirements of the two systems may vary considerably.

This project aims to take a systems-level approach, pitting the two agricultural management systems against each other in a replicated and randomised experiment in which the agronomy is specifically designed for each system by professional agronomists with expertise in each management practice. This project will then investigate the impacts on soil health through looking at the below ground community, both at the macro and micro-scales, as well as impacts on water flow, soil erosion, greenhouse gas emissions, and carbon footprints of the two management systems. The costs and returns will also be monitored and used to analyse the economics, risks and externalities of the two systems. Combined, these approaches will allow an objective investigation into the potential environmental and economic benefits of conservation agriculture for UK farmers and society.

BBSRC Strategic Research Priority: Sustainable Agriculture and Food: Plant and Crop Science

Contact: Dr Simon Jeffery, Harper Adams University