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ECOLOGY OF SOIL BIODATA AND ITS ROLES IN BIODEGRADATION

CHAPTER ONE

INTRODUCTION

Background to the Study

The importance of soil and the functions it performs are unquestionable. Soil is a living entity that needs to be maintained and managed in a sustainable way. Soils are highly complex systems, both literally in that they are constituted of vast range of constituents that show great spatial heterogeneity across some ten orders of magnitude, and in the more formal construct of complexity science (Ritz 2008). Factors that contribute to effective soil fertility, i.e. the production function, are diverse and concomitantly complex (Gregorich & Carter 1997; Mader et al. 2002). However, it is apparent that the soil biota contribute substantially to effective soil functioning from many perspectives (Bardgett 2005), including the basis and maintenance of sustainable agricultural fertility (Kibblewhite et al. 2008).

The soil biota can be conceived of as the 'biological engine of the earth' (Ritz et al. 2004) driving and modulating many of the key process that occur within soils. The biomass typically only constitutes a small proportion of the total mass of soils, but has a hugely disproportionate effect upon soil functions. For example, Jenkinson (1977) appositely describes the biomass, which is predominantly microbial in constitution, as the "eye of the needle through which all organic materials must pass". However, the soil biota consists not just of the microbes but of a myriad of larger multi-cellular organisms, and the entirety interacts via series of complex food-webs (Van der Putten et al. 2004). Microbes function as primary decomposers and biochemical transformers at the core of such webs, and larger organisms provide higher-order ecosystem services such as organic matter comminution, decomposition, and ecosystem engineering. 

It is important to take an holistic systems viewpoint when attempting to understand the complex interactions in the soil which affect the soil biota. For example, the addition of fertilizers can have direct impact on the soil biota, but also can have an indirect influence via the plant and the two are inextricably linked (Murray et al. 2006). Whilst the mineralogy, physics and chemistry of the soil system provides the context, and sets the boundaries in which the soil biota operates, the unique feature of the biota is that it is adaptive to changes in environmental circumstances, which occur by processes of natural selection, in ways that the abiotic systems of the soil are not (Kibblewhite et al. 2008). This has important implications for the way in which soil systems function, and the ways they can be manipulated and managed. 

Whilst the emphasis on the production function is to maximise yield, and this was historically perceived as the primary goal for agriculture, it is becoming increasingly recognised that the production function has to be reconciled with provision of other ecosystem goods and services to avoid degradation of the wider environment and detriment to society. Given the imperative to produce sufficient food to support a global population currently projected to exceed 8 billion by 2030 (FAO 2006), this is an extremely challenging task. 

Agricultural systems can be classified within a conceptual space that varies in many factors that include the origin of energy sources, nature and intensity of fertiliser use, complexity, biodiversity, cultural tenets, etc. These can be broadly categorised, for example, as a spectrum of industrial – integrated – organic – biodynamic, accepting this is not an entirely comprehensive list. However, it is important to move away from some of the more extreme caricatures of these different approaches to production, to recognise the spectrum of practices adopted, and to avoid presenting “conventional” and “sustainable” farming as opposites, incapable of being mixed (Shennan 2008). When environmental problems occur with agricultural production they usually hinge around poor management, and not the mode of agriculture per se (Trewavas 2004). In essence, the soil biota underpins five key ecosystem services that are fundamental to agricultural productivity, viz. carbon cycling, nutrient cycling, soil structural integrity and dynamics, biotic regulation and mutualism. Agricultural systems utilise or circumvent soil biota to differing degrees depending where they fall in the management spectrum above. Industrial agriculture, for example, typically substitutes services provided by the soil biota in other systems by industrially-derived substitutes such as inorganic fertilisers, synthetic biocides and ploughing. This distorts the natural balance of the ecosystem and may compromise the output of other environmental services (Kibblewhite et al. 2008). If production is taken as the sole aim of the system, then it can be seen as ‘efficient’, but there is likely a trade-off with other ecosystem services being compromised, such as water storage and biodiversity.

The aims of this review are to briefly explain how soil biology operates with respect to production function, and to explore potential strategies for the management of the soil biota to maximise outputs whilst minimising inputs and impacts on delivery of other ecosystem goods and services.

Statement of the Problem

The challenges surrounding the ecology of soil biodata and its roles in biodegradation are inherently interconnected, and addressing them collectively is essential for a comprehensive understanding of this field. One key challenge is the scarcity of comprehensive soil biodata encompassing various microbial, fungal, and invertebrate species present in different soil ecosystems. This shortage of data hampers our ability to comprehend the intricate ecological interactions driving biodegradation processes.

This data deficiency is closely tied to the broader issue of biodiversity impact within soil ecosystems. The extent to which biodiversity influences biodegradation efficiency remains uncertain, and understanding how changes in