Moisture Regimes and Morphological Characteristics in a Hydrosequence in Central Massachusetts

Abstract

Moisture regimes and associated soil mottling patterns were investigated over a 2‐y period in a Paxton‐Rainbow‐Ridgebury‐Scarboro hydrosequence in central Massachusetts. Changes in physical conditions in these coarse‐loamy fragipan soils were monitored with well points, tensiometers, soil temperature probes, and redox potential electrodes. Well‐drained soils appeared uniformly brown, reflective of a generally strongly oxidized environment. They also showed the greatest seasonal fluctuations in soil temperature ranging from 0 to 23°C. Matrix colors of highest chromas (6 or higher) occurred in the moderately well‐drained (MWD) soils where reducing and oxidizing environments coexist within the profile at some time during the growing season. Prominent ferrans and albans in the 2Cx horizons of MWD soils were related to sustained groundwater levels, although higher water tables often occurred for periods too short or too cold for development of strongly reducing conditions. The characteristics grey streaking patterns of fragipans were best expressed in the 2Cx horizons of MWD soils and can be attributed to reducing environments during periods with soil temperature above biologic zero when conditions are wet but unsaturated. Significant translocation and leaching of iron occurred in the somewhat poorly drained soils, as evidenced by olive‐grey matrix colors. Channel neoferrans and some neoalbans indicated that a reducing environment may persist within the B2 horizon long after it has become unsaturated. Lowest chroma colors in this hydrosequence was found in the very poorly drained soils where perennial conditions of saturation or near saturation exists up to the soil surface resulting in the strongest reducing environment and least fluctuations in seasonal temperatures.

Using CO2 Efflux Rates to Indicate Below-Ground Growing Seasons by Land-use Treatment

“…There were many consecutive days with soil temperatures at 15 cm below 5°C when appreciable CO 2 efflux was measured and when water was within 30 cm of the surface (Burdt 2003). These results indicate that even though low soil temperatures may inhibit biological and microbial activity, the redox depletions and concentrations found in wet flats soils may form or have formed during January to March saturation and reduction events, as reported by Pickering and Veneman (1984), Groffman et al (1992), and Megonigal et al (1996).…”

“…In effect, the frost-free days approximates the above-ground growing season but may miss periods of biological activity in the soil, indicated by soil CO 2 emissions above a background level. Pickering and Veneman (1984) measured soil temperatures along a forested toposequence in Central Massachusetts and reported that poorly drained soils supported microbial activity even during winter months, while microbial activity in the better drained soils was undetectable. Soil temperatures at 50 cm stayed above 5°C in the better drained soils from April to mid-November, outside of the frost-free days growing season.…”

Redoximorphic Features as Related to Soil Hydrology and Hydric Soils

“…Endosaturation is defined as continuous saturation to a depth of 2 m from the top of the water table. The above relations focus on the depth at which saturation occurs but do not directly suggest duration or frequency of saturation (Veneman and Pickering, 1984;Soil Survey Division Staff, 1993;Veneman et al, 1998;Ticehurst et al, 2007). Veneman et al (1998) summarized the general morphologic relations to drainage class.…”

Redox effects on resin extraction of herbicides from soil1

“…The relative sum of these niches determines momentary redox status that for well drained arable soils is usually \ 400 mV [2,3]. Whenever the oxygen flow into soil is less than the oxygen demand, the number and volume of the anaerobic environments increases and the overall redox potential decreases.…”

“…Whenever the oxygen flow into soil is less than the oxygen demand, the number and volume of the anaerobic environments increases and the overall redox potential decreases. Such a change occurs in flooded and wetland soils where redox values of less than − 100 have been recorded [2,4,5].…”