Temporal Variability of Selected Properties of Loessial Soil as Affected by Cropping

Abstract

Quantification of the relationships between short‐ and long‐term variability of soil properties is needed to understand the effects of cropping on soils. These relationships were studied in four adjacent fields of a Typic Albaqualf or a Typic Glossaqualf which included a prairie and three fields that had been cropped for 3, 14, or 32 yr. The fields were sampled monthly from March 1989 to March 1990. Soil samples were collected at depth intervals of 0 to 5 cm and 5 to 10 cm at each sampling time. The statistical model assumed that the fields studied represented a random sample of fields from a large population. One of the ways in which these fields differ is in cropping duration. Field and sampling time variabilities were treated as random effects in a mixed model including soil depth. We defined the variability among fields as long‐term and the variability among sampling times within a field as short‐term. Statistical analyses indicated that the soil properties vary with cropping, depth interval, and sampling time within a year. The highest ratio of long‐ to short‐term variability (r) was found to be 26 with total C, and the lowest ratio was 0.52 with saturated hydraulic conductivity (Ksat). Values of r for most of the soil properties examined ranged between 1.7 and 2.8 and tended to be higher in the first depth interval. The large estimated standard errors for these ratios indicated that even though r was greater than 1.0, the long‐term variability was not statistically significantly greater than the short‐term variability at α = 0.05.

Variability of Hydraulic Conductivity Due to Multiple Factors

“…Other possible reasons could be the arrangement of macropores, three dimensional infiltration and restrictions to flow by the membrane (Reynolds et al, 2000). (Scott et al, 1994). (Reprinted with permission from Soil Science Society of America) Table 9.…”

“…For example, Scott et al (1994) studied short-and long-term variability of K s in four adjacent fields located in Arkansas, USA. One of the fields was under prairie while other three cropped fields had mostly been in a rice-soybean rotation for either 3, 14, or 32 years (Scott et al, 1994). The fields were sampled monthly from March 1989 to March 1990.…”

“…3. Scott et al (1994) defined the variability among fields as long-term and the variability among sampling times within a field as short-term. Table 10.…”

“…During the years when the field was disked, the monthly trends of K s changed. Scott et al (1994) reported that the relatively high K s during June and November 1989 was due to the unstable, loose aggregation of the soil due to tillage.…”

Influence of Mediterranean shrub species on soil chemical properties in typical Mediterranean environment

“…Owing to the wide range of variation in soil moisture and temperature regimes, one important consideration is the time-dependent dynamics of soil chemical properties, which can change in a short-term span (one year or less) or under long-term perspective (4).…”