All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Permanganate Oxidizable Carbon Refl ects a ProcessedSoil Fraction that is Sensitive to Management Soil Biology & Biochemistry P articulate organic C and MBC are important C fractions that refl ect key processes such as nutrient cycling and availability, soil aggregation, and soil C accrual (Wardle, 1992;Six et al., 1998;Wander, 2004). A large number of studies have shown that both POC and MBC are sensitive to changes in management such as reduced tillage, cover cropping and land use (Cambardella and Elliott, 1992;Wardle, 1992;Wander and Bidart, 2000;Grandy and Robertson, 2007). Th is sensitivity has led to wide adoption of these methods in soil science as indicators of change in the soil ecosystem (Wander, 2004;Gil-Sotres et al., 2005;Kaschuk et al., 2010).As informative as POC and MBC are, they are expensive soil measures for most applications outside of a research setting. Although adaptations have been made to streamline the extraction process of POC (Marriott and Wander, 2006a) and MBC (Fierer et al., 2003), these methods remain costly due to the required labor and combustion analyzer to quantify the total C in the extracted fraction. In addition to the cost, there is a large degree of variation on how researchers extract

Perennial grains hold promise, especially for marginal landscapes or with limited resources where annual versions struggle.

Escalating production costs, heavy reliance on non-renewable resources, reduced biodiversity, water contamination, chemical residues in food, soil degradation and health risks to farm workers handling pesticides all bring into question the sustainability of conventional farming systems. It has been claimed, however, that organic farming systems are less efficient, pose greater health risks and produce half the yields of conventional farming systems. Nevertheless, organic farming became one of the fastest growing segments of US and European agriculture during the 1990s. Integrated farming, using a combination of organic and conventional techniques, has been successfully adopted on a wide scale in Europe. Here we report the sustainability of organic, conventional and integrated apple production systems in Washington State from 1994 to 1999. All three systems gave similar apple yields. The organic and integrated systems had higher soil quality and potentially lower negative environmental impact than the conventional system. When compared with the conventional and integrated systems, the organic system produced sweeter and less tart apples, higher profitability and greater energy efficiency. Our data indicate that the organic system ranked first in environmental and economic sustainability, the integrated system second and the conventional system last.

Much remains to be known concerning the complex relationships between specific soil property measurements and overall soil quality. The objective of this study was to advance our understanding of these complex relationships by further developing and applying a systematic method for evaluating the effects of conventional, integrated and organic apple production systems on soil physical, chemical, and biological properties using a modified soil quality index. This index utilizes 1998 soils data from these three treatments. The study used four, 0.14 ha replicates of each of the three treatments in a randomized complete block design. Experimental plots were planted to 'Golden Delicious' apples (Malus domestica Borkh.) in 1994 on a commercial orchard in the Yakima Valley of Washington state. Organic soil management practices included additions of composted poultry manure and bark mulches and the use of mechanical tillage for weed control. Conventional soil management practices included additions of synthetic fertilizers and the use of herbicides for weed control. The integrated system utilized practices from each of the other two systems. Increased aggregate stability, microbial biomass, and earthworm abundance were associated with improved soil quality under integrated management when compared to conventional management in 1998. Organic management resulted in lower soil bulk densities and generally improved biological soil properties compared to conventional management. Few significant differences in soil properties were measured between the integrated and organic systems. The integrated production system received a soil quality index rating of 0.92 (out of 1.00), which was significantly higher than the index rating of 0.78 for the conventional production system; the organic production system received a rating of 0.88, which was not significantly different from the other two systems. The study indicates that a well-developed soil quality index can provide an effective framework for evaluating the overall effects of different orchard production practices on soil quality.

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