Water and Carbon Cycle fieldwork at Magdalen Farm Centre, Dorset
This fieldwork unit is taught almost entirely on the 130 acres of land owned by the Magdalen Farm Centre. It can serve both as an introduction to the topics or can be used to revise the topic together with providing plenty of opportunities for students to design and collect data for their non-examined assessments.
The organic farmland varies in underlying geology, soil type, texture and depth, relief and agricultural use providing a mosaic of variables when measuring parts of the hydrological cycle (such as infiltration, surface runoff and interception) and carbon storage in both soil organic carbon and biomass of trees. The farm is within the catchment of the River Axe which flows along the northern boundary of the farmland.
The unit starts with a discussion of sampling rationale and methodology for practical infiltration experiments across the farm. The resulting data is then used to teach a variety of descriptive statistics (central tendency and dispersion) plus graphical skills (triangular and dispersion graphs). These numerical and graphical skills will then be practised when handling the data from further practical experiments in surface runoff, soil characteristics and interception.
The intended outcome of this part of the unit is for students to be able to quantify various stores and flows within the hydrological system. This enables students to plan how the farm can be managed to maximise flood resilience.
Our unit focuses on calculating the potential carbon storage capacity of Magdalen Farm in terms of soil organic carbon and in tree biomass. We demonstrate how soil organic carbon can be calculated by the loss-on-ignition method and then students apply their knowledge of sampling methodology and techniques to collect soil samples. The samples are collected from fields under different organic management regimes plus a control sample from a neighbouring non-organic farm. The samples are prepared and analysed in a small soil lab on site. We also demonstrate methods of calculating organic carbon stored in trees. Magdalen Farm has a variety of small plantations of varying ages and so it is possible to create a graph showing potential carbon storage over time.
The intended outcome of this part of the unit is for students to be able to calculate the potential carbon storage of various land uses, crops and management techniques on Magdalen Farm.
Magdalen Farm Centre
Fieldwork on the Carbon and Water Cycles provides a huge variety of investigations for the NEA. Some example titles are:
is there a correlation between soil texture and infiltration rate?
can variations in interception rate under different types of trees be attributed solely to mean leaf area?
is slope angle the sole determinant in how much surface runoff occurs once a soil is saturated