Aquarius

Background and Objective

The objective of partial area specific irrigation is to reduce and to better comply with environmental goals by considering the local heterogeneity of soil and the plant population as well as the project related inputs, here water and energy.

Partial area specific management, or rather, irrigation, requires detailed information on the heterogeneity of fields, in order to adapt to the levels of irrigation required for local soil conditions. Conventional methods (soil probes and subsequent laboratory analyses) are however too expensive and too time consuming. For this reason quick, destruction-free methods should be available to calculate the needed information.

The harvest yields were drawn in for an evaluation of the area specific technology in order to understand the influence of differentiated water inputs and to make an economic statement on the topic.

Target Group

Water protection consultants;  farms; public decision makers; water authorities and scientific research agencies.

Approach

In order to build a strategy for partial area specific irrigation, first an application card and the determination of management zones was needed. The path to application cards goes from the farm soil map, assessment of the electrical conductivity (EM 38, Veris) and the extraction of soil samples for punctual determination of the soil water storage capacity. The technical implementation in the project takes place with circular irrigation equipment. A special nozzle control with a magnetic valve was installed.

Data and Methods

First information for the partial area specific irrigation can be found in the farm soil map. This information is too general to be used for the partial area specific application card. As the next step, EM 38 equipment was used to scan the areas. For the electrical conductivity measures (EC) the area was traveled over in 5 m strips and each measured EC value was ordered into a GPS value. Here the measurements extended to a soil depth of 150 cm.

A picture of the soil differences in dependence of the conductivity emerged after the measurements were evaluated.

In this conductivity card, the areas were classified into three management zones according to the different EC values of the soil. In the zones, 24 monitoring points were determined and soil samples were taken at each point to determine the field capacity and the wilting point. The water balancing took place according to the strategy of partial area irrigation. That means that the management zone which first reached a soil moisture content of 50% nFK is driven to and subsequently irrigated to a moisture level of 80 % of the nFK.

To monitor the daily implementation point, an irrigation controller model AMBER from DWD was used to measure the climatic irrigation balance. The five day advance calculation of water needs made further targeted irrigation use possible.

Results

Since the Aquarius project ended on June 30, 2012, only two test harvests could be carried out during the entire study period. In 2010 the study crop was sugar beets and in 2011 potatoes. The study crop in the year 2012, winter wheat, could not be included due to the very early end of  this project.

In  the two test years and considering the technical and financial input in this project, under the given irrigation levels, no economic advantage could be found. With the equipping of the circular irrigation machine for partial area specific water distribution, new knowledge could be gained that is well suited to transfer to similar applications in other countries with high irrigation use. The linkage of soil moisture sensors to control the differentiated irrigation level must be seen critically. The range of measurement values is too large. Furthermore, the soil moisture measurements are expensive and labor intensive. Controlling according to climatic water balance is recommended.

From the perspective of the question on the implementation of partial area specific irrigation in agricultural crops, it was necessary to carry out a continuation of the irrigation experiments in the Project Klimzug Nord.