Soil Use and Management Supplement: Soil Fertility in Organically Managed Soils
Format:
Main Description
This Special Issue compares soil fertility in soils farmed organically and conventionally, and examines whether the current concept of soil fertility adequately encompasses both these systems. The papers presented are part of several DEFRA and SEERAD funded projects, involving scientists from a range of backgrounds. Organic Farming has been proposed as a solution to problems associated with inputs of chemical fertiliser and pesticide, taking an ecological approach to nutrient supply and crop protection. However, it too sets environmental, human health, economic and production challenges that require co-ordinated research to be fully addressed. Organic producers seek to manage the rotation as an integrated whole, and central to this integration is informed management of soil fertility. But careful soil management is not the sole preserve of organic farmers; so is there anything that is qualitatively different about soil fertility on organic farms? The issue begins by describing the nature and practice of organic farming with the aid of a review, and an exploration into how organic growers use a range of management practices to maintain and improve soil fertility, follows. Subsequent papers examine the key components of soil fertility by combining comprehensive review with information from new or recent research. A comparative study of nitrate leaching from farms managed conventionally or organically is the subject of a further contribution. The final paper examines important aspects of nutrient pools and nutrient transformations, drawing together the findings of the previous papers in reaching a definitive answer to the question of the adequacy of the current concept of soil fertility.
Professor Ken Killham
President of the British Society of Soil Science
Main Contents
Papers in this supplement:
Managing soil fertility in organic farming systems. C A Watson, D Atkinson, P Gosling, L R Jackson and F W Rayns
Is the productivity of organic farms restricted by the supply of available nitrogen? P M Berry, R Sylvester-Bradley, L Philipps, D J Hatch, S P Cuttle, F Raynes and P Gosling
This paper reviews information from the literature and case studies to investigate whether productivity in organic systems is restricted by the supply of available N during the major phases of crop growth. Organic systems have the potential to supply adequate amounts of available N to meet crop demand through the incorporation of leys, N rich cash crop residues and uncomposted manures. However, this is seldom achieved because leys are only incorporated once every few years and organically produced crop residues and manures tend to have low N contents and slow mineralization rates. N availability could be improved by delaying ley incorporation until spring, applying uncomposted manures at the start of spring growth, transferring some manure applications from the ley phase to arable crops, preventing cover crops from reaching a wide C:N ratio and better matching crop type with the dynamics of N availability.
Nitrate leaching from organic farms and conventional farms following best practice.
C Stopes, E I Lord, L Philipps and L Woodward
A review of farm-scale nutrient budgets for organic farms as a tool for management of soil fertility.
C A Watson, H Bengtsson, M Ebbesvik, A-K Lψes, A Myrbeck, E Salomon, J Schroder and E A Stockdale
On organic farms, where the importation of materials to build/maintain soil fertility is restricted, it is important that a balance between inputs and outputs of nutrients is achieved to ensure both short-term productivity and long-term sustainability. This paper considers different approaches to nutrient budgeting on organic farms and evaluates the sources of bias in the measurements and/or estimates of the nutrient inputs and outputs. The paper collates 88 nutrient budgets compiled at the farm scale in nine temperate countries. Overall, the data illustrate the diversity of management systems in place on organic farms, and suggest that used together with soil analysis, nutrient budgets are a useful tool for improving the long-term sustainability of organic systems.
A comparative study of the microbiology of soils managed under organic and conventional regimes. D Shannon, A M Sen and D B Johnson
Managing soil organic matter - implications for soil structure on organic farms.
M A Shepherd, R Harrison and J Webb
Comparisons of earthworm populations and cast properties in conventional and organic arable rotations.
J Scullion, S Neale and L Philipps
Soil fertility in organic farming systems - fundamentally different?
E A Stockdale, M A Shepherd, S Fortune and S P Cuttle
