Final theses and project work to be assigned

Background

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

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

The input variables for calculating the irrigation requirement are: the usable field capacity (nFK) of the soil, the crops grown and the climatic water balance of the vegetation period. The area under consideration (the whole of Hesse/individual catchment areas) is defined in the course of the work. Precise and close coordination of the method with supervisors is important. Input data for the calculations are available. It is advantageous to be familiar with the scripting language R or to have some experience with it. Processing large amounts of data by hand is more strenuous.

Part 2: Implementation

Determination of the nFK on the basis of the soil area data and the climatic water balance of the vegetation period as the difference between precipitation level and calculated evapotranspiration and, if available, allocation of individual fields according to the crop cultivation of the INVEKOS information. The data are requested.

Part 3: Calculation of the pot. Irrigation quantity

The aim is to perform calculations on a 5x5km² grid for different climate scenarios in order to calculate irrigation amounts 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 for simplification: study and develop an understanding of the R scripting language. Input/output and vectorized processing of data.
• Review of the necessary data (soil, climate data, land use).
• Dealing with and gaining an understanding of the pedological information in a soil map.
• Development of a concept for calculating the average irrigation requirements of the past 30 years and the forecast.
• Calculation of the irrigation quantity 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

Starting date: immediately

Background:

Aggregate stability and tendency to siltation are important parameters for determining the physical soil quality. The silting of soils is based on a rapid disintegration of aggregates or a sloughing of particles on the aggregate surface. Different methods are used both in the field and in the laboratory to measure both parameters. The aim of the work is to determine the degree of agreement between the two methods.

Part 1: practical implementation

The siltation tendency of soil samples is determined using a simple field test at different water contents. The aggregate stability is determined on air-dry samples using wet sieving. Furthermore, the texture of the samples, if still unknown, will be determined.

Loamy samples with known aggregate stability are already available for the work. In addition, the range of soil types in the area of clays and silts is to be extended by taking samples from Frankenhausen.

Part 2: Evaluation

The results of the siltation tendency are evaluated under the aspect of the influence of the aggregate size, the soil water content and the texture. A reproducible field method is to be derived from the results, taking into account the variability of the water content. The degree of agreement between the two methods will be determined using correlation analyses.

Notes

This work is not bound 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

Starting date: immediately

Background:

In the practical research network, various tillage measures are being tested after intercropping to minimize N leaching. As part of a study, the influence of two selected tillage measures after intercropping on the sludgeability of the soil and soil structure development is to be investigated.

Practical implementation:

For this purpose, the tendency of the topsoil to silting will be investigated from mid-February 2024 in the variants with tillage in winter (1st variant plow and 2nd variant newly developed ridger). The investigations serve to illustrate possible effects of the low soil cover between tillage and sowing of the summer crops or crop closure. An assessment of the structural development of the topsoil under the different systems is to be carried out using spade diagnostics in the summer after harvesting the main crops.

Timing of the work:

Sampling 1: February 2024 (assessment of the silting tendency)

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

Sampling locations and logistics

The practical farms on which trials were established were 8 organic farms in Hesse. The trials were carried out in quadruplicate using the farmers' own equipment, accompanied by the scientific team. The team is able to join the sampling during the N-min sampling in February and the final harvest in July/August (led by Johanna Hoppe).

Note

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

Information on the practical 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)

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