Final and project work to be assigned

Background

Irrigation demand in agriculture is expected to increase as a result of climate change. The Department of Soil Science is involved in two projects in which the irrigation demand is determined. The aim is to quantify the present and future irrigation demand for Hesse/selected regions in Hesse. This is to be done either on the basis of a) the Geisenheim irrigation control(link), b) the DWA leaflet 590 (link) (German Association for Water, Wastewater and Waste e. V.), or c) according to FAO CropWat(link) can be determined. This results in the possibility of three student theses, which can be worked on in parallel or in groups.

Part 1: Planning - Definition of the model area and required variables, acquisition of data

Input variables for the calculation of the irrigation demand are: the usable field capacity (nFK) of the soils, the cultivated crops and the climatic water balance of the growing season. The definition of the considered area (whole Hesse/individual catchments) is done in the course of the work. A precise and close coordination of the method with supervisors is important. Input data for the calculations are available. It is an advantage to know the scripting language R or to have some experience with it. Processing larger amounts of data by hand is more strenuous.

Part 2: Implementation

Determine nFK based on soil area data and growing season climatic water balance as the difference between precipitation depth and calculated evapotranspiration and, if available, allocate individual plots by crop from INVEKOS information. The data have been requested.

Part 3: Calculation of the pot. Irrigation Quantity

The goal is to perform calculations on a 5x5km² grid for different climate scenarios to calculate irrigation amount for common crops.

Tasks (preliminary)

• Reading and appropriation of the selected method (a) Geisenheim irrigation control(link), DWA leaflet 590(link), FAO CropWat(link)
• Optional to facilitate: employment and development of an understanding of the R scripting language. Input/output and vectorized processing of data.
• Sifting through necessary data (soil, climate data, land use).
• Engaging with and gaining an understanding of the soil information in a soil map.
• Developing a concept for calculating average irrigation needs over the past 30 years and forecasting.
• Calculation of irrigation amount for a 5x5m km² weather cell and the selected soil and crop.
• Visualization of the results using appropriate software. Here again R + of the package "grammer for graphics" (ggplot2) is very suitable.
• Transfer of the results including a description of the data (metadata).

General information:

Supervisor: Prof. Dr. Tobias Weber

Examiner: Prof. Dr. Tobias Weber

Start date: immediately

Background:

Aggregate stability and sloughing tendency are important variables for recording physical soil quality. The sloughing of soils is based on a rapid disintegration of aggregates or a sloughing of particles at the aggregate surface. Different methods are used to record both quantities, both in the field and in the laboratory. The objective of this work is to determine the degree of agreement between the two methods.

Part 1: practical implementation

The sloughing tendency of soil samples is determined using a simple field test at different water contents. Aggregate stability will be performed on air-dry samples using wet sieving. Texture, if still unknown, will also be determined on the samples.

Clayey samples with known aggregate stability are already available for the work. In addition, the soil type spectrum in the area of clays and silts is to be extended by sampling Frankenhausen.

Part 2: Evaluation

The results of the siltation tendency will be evaluated under the aspect of the influence of aggregate size, soil water content and texture. The results will be used to derive a reproducible field method taking into account the variability of water content. The degree of agreement between the two methods will be determined by correlation analyses.

Notes

This work is not tied to a specific processing period.

General Information:

Supervisor: apl. Prof. Dr. Christine Wachendorf (c.wachendorf@uni-kassel.de)

Examiners: apl. Prof. Dr. Christine Wachendorf and Prof. Dr. Tobias Weber

Start date: immediately

Background:

Different tillage measures after intercropping to minimize N leaching are tested in the practice research network. Within the scope of a student research project, the influence of two selected tillage measures after intercropping on soil siltability and soil structure development will be investigated.

Practical implementation:

For this purpose, the tendency of the top soils to silt up will be investigated from mid-February 2024 in the variants with tillage in winter (1st variant plough and 2nd variant newly developed heap cultivator). The investigations serve to show possible effects of the low soil cover between tillage and sowing of the summer tillage or stand closure. An assessment of topsoil structure development under the different systems will be made using spade diagnostics in the summer after the main crops are harvested.

Timing of work:

Sampling 1: February 2024 (assessment of siltation tendency).

Sampling 2: July-August 2024 after harvest of the main crop (spade diagnosis).

Sampling locations and logistics

The practical farms where trials were established were 8 organic farms in Hesse. The trials were established in 4-fold repetition with the farm's own technology by the farmers accompanied by the scientific team. There is a ride along with the team to the sampling during the N-min sampling in February and to the final harvest in July/August (lead Johanna Hoppe).

Note

The work can also be extended to a master's thesis (e.g., by adding the variants with spring turn-over) or be carried out jointly by 2 students.

Info about the practice research network: https://www.pfn-hessen.de/portfolio-item/projekt-umkreis/

https://www.pfn-hessen.de/

General information:

Supervisor: apl. Prof. Dr. Christine Wachendorf (c.wachendorf@uni-kassel.de)

Examiner: apl. Prof. Dr. Christine Wachendorf and Johanna Hoppe, FG FÖL