Technical Yearbook 2024

It was found that when the organic carbon-to-clay ratio is <1:13, it cannot be used successfully as a single indicator to measure soil health. 2. Long-term effects of compost on soil health and yield of winter wheat in a semi-arid environment in Logan, VSA This long-term study evaluated the long-term effect of a one-time, broadcast large-amount compost application. In 1994, 50 tonnes/ha of compost (consisting of cattle manure and straw) was applied once on an organic wheat farm with sandy soil. The biggest benefit was obtained from the plant-available phosphorus and nitrogen. Carbon content and aggregate stability also improved. Although the rainfall decreased drastically over the past 30 years due to climate change, the yield is still 38% higher. This increase in yield can be attributed to the increase in carbon and increased nutrient availability, as well as improved soil respiration due to microbial change, soil temperature and soil moisture. 3. Inter-laboratory proficiency tests and the reliability of soil laboratory measurements worldwide: the case of GLOSALAN “Carbon credits” is a buzz term which has been widely used of late, but there is still uncertainty around the accuracy and type of analyses of laboratories worldwide, especially those in developing countries. In order to monitor the accuracy of soil laboratories worldwide, the Global Soil Laboratory Network (GLOSOLAN) was established in 2017, which forms part of the United Nations’ Food and Agriculture Organisation. This organisation sends the same replicas of soil samples to laboratories and evaluates the results using a Z-score which is determined by a standard deviation, and also offers the laboratory assistance to improve its accuracy. This initiative lends more credibility to carbon credits and helps to set up the use thereof in the industry. 4. A framework for the establishment of soil health targets and threshold values Soil health is a key effort to reverse soil degradation, but it has to be quantifiable in some way. To determine these targets and threshold values, the soil type, climate, land-use, management, history and other factors must be considered, standardised and then developed into a policy. Through consultation with stakeholders and considering the available knowledge and theory, the following was determined as a possible framework for the formulation of targets and threshold values: • Fixed values based on research: certain soils should have certain values. • Fixed proportions of natural reference values: everyone should choose their own value. • Values based on the existing ranges: the problem with

FIGURE 1. Global aspects influenced by soil security.

During the first main theme, the focus was on global soil management and the effect of humankind on the productivity of soil, as soil is critical to the functioning of the planet. While there is presently a strong worldwide focus on climate change, a similar prioritising of soil has been left behind. Humankind has had a destructive effect on soil – when the history of soil is considered, more damage has been inflicted than improvements made. This phenomenon is possibly a bigger issue than climate change, because soil security and climate change go hand in hand. Soil must be placed at the front and centre of the earth’s sustainability. As suggested in Figure 1, soil has an enormous influence on water security, climate change, food security, energy security, human health, biodiversity, the ecosystem and the environment. To prove this statement, ask yourself the question: will soil still play a meaningful role in food production 100 years from now? From the presentations which stretched over three days, I would like to highlight and share aspects of the following 10 studies: Complete abstracts and references are available via the following link: https://drive.google.com/file/ d/1mcbITzR1wfY1b4vLAaceHAyg_y_K3vzq/view. 1. Is the organic carbon-to-clay ratio a reliable indicator of soil health? In the European Union, a proposed soil monitoring law is being implemented to measure soil-carbon losses as an indicator of soil health. The observation points are set out by the LUCAS soil survey in combination with other data sets like soil classes, climate zones and archive carbon data.

120

TECHNICAL YEARBOOK 2024