Search

Soil science students are required to apply knowledge from a range of disciplines to unfamiliar scenarios to solve complex problems. To encourage deep learning (with student performance an indicator of learning), a formative assessment exercise was introduced to a second-year soil science subject. For the formative assessment exercise, students were required to prepare a draft of a critical review of a current topic in soil science, and then (following guidance from staff members) provide feedback to each other through a peer assessment exercise. In contrast to expectations, the formative assessment did not appear to improve overall student performance in this task based upon their grades for this task. Furthermore, despite being given an exemplar and attending a workshop where tactics for searching the scientific literature were discussed, this did not increase the likelihood that students would cite studies from the scientific literature when conducting their critical review. Regardless of these observations, the students were positive and appreciated the feedback they received through the exercise. This study demonstrates the need to ensure that feedback is effective and enables students to identify their weaknesses and modify their work accordingly. (Contains 4 tables.)

• Land use change from pasture to forest did not increase in soil carbon over 19 years. • Land use change from pasture to cropping decreased soil carbon. • Soil carbon under reforestation increased at 3 t/ha/y. • Soil carbon ranged between 47 and 108 t ha−1 to 0.5 m depending on land use. • Carbon pools were dominated by humic organic carbon (~50%). Changes in land use affect the soil organic carbon (SOC) stocks and pools. This is currently of great interest as soils are a major pool of carbon in the biosphere and can sequester atmospheric carbon. This study investigated the effect of pasture conversions into reforestation or cropping land on SOC, humic organic C (HOC), particulate organic C (POC) and resistant organic C (ROC) stocks, and soil nitrogen, to 0.5 m depth using mid infrared spectroscopy and combustion analyses. The ten study sites in south east Queensland, Australia were cleared of native vegetation to pasture decades earlier and were more recently (6–19 years ago) converted to either forest plantations (eucalypts) or cropping land. The SOC was significantly affected by land use and site location. Conversion of pasture to forest plantation had no significant effect on SOC compared to pasture up to 19 years since reforestation, but SOC increased slightly with plantation age at a rate of 3.03 t ha−1 per year. Conversion of pasture to cropping land significantly decreased SOC. The stocks of SOC ranged from 47.0 to 107.6 t ha−1. The HOC pool contributed the most towards the total SOC, and ranged from 17.7 to 67.8 t ha−1 across all sites. The POC pool ranged from 2.1 to 17.8 t ha−1 and the ROC pool varied between 5.3 and 22.3 t ha−1. The total SOC stock determined by MIR was closely related to SOC determined by dry combustion analysis. Soil N was significantly affected by land use and location, but trends were not consistent. On pasture sites, total N was higher likely due to fertiliser applications and total N ranged between 3.7 and 15.0 t ha−1 across sites. In summary, conversion of pasture to forest plantation had no significant effect on SOC stocks and different soil carbon pools over 19 years in the subtropical climate of south east Queensland. [ABSTRACT FROM AUTHOR]