Addition of glucose or/and nitrate significantly increased denitrification activities throughout the profile for all soils, suggesting that both bioavailable carbon and nitrogen were limiting factors of denitrification in these grasslands soils.
The K(h) decreased with increasing tensions, K 60) and K(120) were only 8.4 and 0.89%, respectively, of K 30) for the vegetated surfaces, and were about 30 and 8.7%, respectively, of K 30) for both rock fragment covered surfaces and bare soils, suggesting that pores in the 0.5- to 1-mm diameter range dominate flow under unsaturated conditions.
In contrast to prediction, deeper, low-C soils were more similar to high-C remnant prairie soils than to low-C agricultural soils, suggesting that carbon is not the primary control on soil microbial community composition.
The application of faecal matter biochar enhances yield and tissue nutrient concentrations of lettuce in two contrasting soils, suggesting that faecal matter biochar could be used as an effective fertilizer for lettuce production at least for two growing cycles.
Porous sand-sized particles resembling pumice grains were also observed in some soils, suggesting that conventional particle size analysis and clay interpretations may not adequately describe surface related behaviors.
We also found a correlation between microbial abundance and age-since-agricultural abandonment in ex-arable/non-native-cultivated soils suggesting that non-native plant effects accumulate over time.
This effect, however, was only observed in live soils, suggesting that AC effects were microbially mediated and not caused by direct allelopathy.
Furthermore, QST was correlated with environmental distance (climate and soils), suggesting that these environmental variables are related to the selective pressures in each population.
Principal Component Analysis of the DGGE patterns, right panel) indicated, except for rhizosphere samples BDV4-S5 and BDV4-S1, a higher similarity among the rhizospheres collected from different stations than among the bulk soils suggesting that the rhizosphere acts as a selection factor that tend to uniform bacterial diversity independent from the soil type.
