Evaluation of Laboratory-Measured Soil Properties as Indicators of Soil Physical Quality

Abstract

Routine soil analyses provide an approach for assessment and monitoring of soil quality and targeted implementation of management practices, but suitable indicators are mostly undefined. We used three long-term experiments on several soil types where maize (Zea mays L.) was grown under different tillage (no till and plow till), rotation (continuous maize and maize after grass), and harvesting (silage and grain) methods to identify suitable indicators for evaluating soil physical quality. Disturbed and undisturbed soil samples were collected, and laboratory-based analyses were performed for water-stable aggregation, saturated hydraulic conductivity, several pore size parameters, penetration resistance at A = j10 MPa, and bulk density. Sensitivity to management, expense of measurement, measurement consistency, and relevance to critical physical soil processes were used as criteria to evaluate indicator suitability. Indicators varied significantly seasonally and by soil type, and several showed significant differences and trends between management treatments. Small water-stable aggregates (0.25-2 mm) showed the most consistent and significant treatment differences. Bulk density, available water capacity, and air-filled pores at field capacity (PO 9 30) were also related to treatment effects and had low variability. Penetration resistance and effective porosity (PO 9 0.2) were not sensitive to management practices, whereas aeration pores and saturated hydraulic conductivity were too variable to use as indicators. Several indicators measured on undisturbed cores may be predicted from those measured from disturbed samples using pedotransfer functions. Small water-stable aggregates (0.25-2 mm), available water capacity, bulk density, and PO 9 30 appear most promising as indicators for routine evaluation and monitoring of soil physical quality. (Soil Science 2007;172:895-912)

Statistics, Scoring Functions, and Regional Analysis of a Comprehensive Soil Health Database

“…fitted with Teflon capillary microtubing and an adjustable Mariotte-type bubbling tube to control hydraulic pressure (Ogden et al, 1997;Moebius et al, 2007). Approximately 30 g of dry soil aggregates (sieved past 0.25-2.00 mm) were evenly distributed on a 0.25-mm mesh sieve (200-mm diam.)…”

Comprehensive assessment of soil quality for landscape and urban management

“…Therefore, the reliability of the results was questionable due to frequent improper sampling, especially with soils containing coarse fragments. Based on an economic analysis (Moebius et al, 2007), the cost of the standard test was determined to be less than US $50. The optional elemental analysis adds approximately $15 to the cost.…”

“…Some indicators have been shown to have significant within-season variability (Moebius et al, 2007), and soil management practices can be a confounding influence for physical and biological soil indicators. Also, spring sampling is facilitated by favorable soil water conditions (generally near field capacity), and biological assessments benefit from the more uniform conditions following over-wintering.…”

“…The test also includes penetrometer measurements as the only in-field assessment. Although it is widely regarded as an important physical indicator, bulk density was not included because it was found to be imprecise (Moebius et al, 2007) and generally strongly correlated with other physical indicators in the test (and, therefore, mostly redundant). Moreover, the use of ring samplers for bulk density proved to be a serious obstacle with field practitioners and technicians.…”

“…The physical tests were based on standard methodology (Moebius et al, 2007), except for wet aggregate stability, which involved the application of simulated rainfall of known energy (Ogden et al, 1997) to aggregates on sieves. The biological test also mostly involved established methods.…”