Introduction

Traditionally, wildland repair programs emphasized soil modifications to suit the desired species, rather than using adapted species that improve soil conditions. The objective was to rapidly alter soil conditions to meet the requirements of desired plant species by changing the soil's physical, chemical and biological attributes (Table 3.1). Fertilization, liming, and other subsidy-based approaches are effective and have well-developed methodologies (Schaller & Sutton, 1978; Bradshaw & Chadwick, 1980; Bradshaw, 1983; Lal & Stewart, 1992; Munshower, 1994). Few wildlands have the productive potential to finance those subsidies, particularly when they must continue indefinitely. Thus, contemporary approaches are often so expensive that severely degraded wildlands are more likely to be abandoned than repaired (Harrison, 1992). This is particularly true in arid and semiarid environments, where the risks are greater and potential returns are lower.

Soil textbooks often include descriptions of the ‘ideal’ soil. This ideal soil has a loamy texture, granular structure, good fertility, and organic matter content and contains approximately half solid matter and half pore space (e.g., Brady, 1990). The solid mineral component comprises about 45% of the soil volume with the remaining 5% being organic matter. At optimum soil-water levels this ‘ideal’ soil contains equal proportions of air and water in the pore spaces and has physical, chemical, and biological features contributing to plant growth. Most soils are less than optimum, due to inherent properties (parent material, climate, or age) or accelerated (anthropogenic) degradation. While desirable and occasionally achievable as an agricultural objective, this ideal soil is usually neither possible nor realistic as a wildland repair objective.