Technical Yearbook 2024

this approach, is how do you quantify agricultural soil against veld or new soil? This information can be used to develop a framework for the most suitable target or threshold values for the wine industry. 5. Cover cropping for soil health: does diversity matter? A case study in Reading, UK Organic matter supports soil health. To accumulate organic material, it is necessary to place organic additions into the soil like animal manure, compost, cover crops, crop residues and root exudates. These additions offer several benefits, like improved water and nutrient retention, soil structure, aggregate stability, microbial biomass and water infiltration. To establish soil health, the following five principles can be followed: • Limit disturbance and cover the soil surface. • Keep living roots in the soil. • Bring animals into the system. • Build diversity into the system. Not all organic matter is the same. Raw organic matter promotes nutrient mineralisation and water retention. Organic matter protects the aggregates and helps with soil structure and aggregate stability. Mineral-associated organic matter assists with the retention of nutrients and carbon storage. Establishing cover crops is one way to bring organic matter and diversity into the system. In this study, monoculture crops were compared to a mixture of the same combination of monoculture, including sunflower, radish, clover and buckwheat. After three years there was no difference in soil carbon for mixtures compared to that of the monoculture. Where residues of the mixture were spread or placed on the soil surface, it led to greater microbial assimilation of carbon and mineral-associated carbon. It was also observed that the chemical (sorption) and physical (aggregate) properties of the soil protected the stable carbon (dead microbe network). 6. Seasonality and sensitivity to land use are critical factors for soil health assessment in a Mediterranean climate A study from a Mediterranean climate in Israel found that environmental factors pose major scientific challenges and in summary showed that, when crops experience stress, it is the ideal time to test for soil health. 7. Spatial patterns of historical crop yields reveal soil health attributes in US Midwest fields This research shows that yield stability maps provide valuable insights about soil-organic carbon and soil health. Yield maps were used over consecutive seasons to divide blocks into four sections, namely unstable, low to stable, medium to stable and high to stable. Composite samples

were taken and each zone was analysed with the use of the Solvita soil health test. The outcome of the research shows that the differences in yield were influenced by the climate, topography and soil. There was also a direct correlation between higher soil-organic carbon and soil health matrixes in statistically separate regions. The unstable and low-to-stable areas had compact soil layers or shallow soil on steep slopes. 8. SoilBio analysis: a sensitive, calibrated and simple assessment of soil health for Brazil This study was performed in the Cerrado region in Brazil across approximately 200 million hectares. In line with worldwide concern over soil health, Brazil adopted the SoilBio analysis in July 2020. Together with routine soil samples, two key enzymes are also analysed, namely arylsulfatase and beta-glucosidase. These analyses can be collected on farm level and have three functions: • Nutrient cycling (arylsulfatase and beta-glucosidase). • Nutrient storage (organic matter and CEC). • Nutrient supply (routine soil analyses). With 20 years of research data on arylsulfatase and beta glucosidase, it was observed that these enzymes play a role in soil function and show a correlation with other microbial indicators for soil health. The analyses, which are accurate, consistent and affordable (USD35 per sample), can also be performed on soil which has been air-dried. The protocol is the same as for the routine soil analyses. The concept is that soil with high arylsulfatase and beta-glucosidase activity stores more water, has a lower phytonematode population, shows better nutrient absorption, as well as fruit quality, and has a higher potential for bioremediation. 9. Isolating the effects of soil-physical properties on fruit composition: a case study in Maryland, USA This study was performed on Albarino Clone 1 grafted onto 101-14 Mgt which was planted in 2013. The only variation in the block was the topsoil depth, which varied between 0 to 38 cm. The vineyard management was also adjusted to create a balance between the vegetative growth of shallower and deeper soils. The remarks were as follows (see Figure 2): • The colour of the juice far left is that of bunches which grew on deeper topsoils, and on the right clusters which grew on thinner topsoil. • The deeper topsoil produced denser bunches and higher titratable acidity. • The thinner topsoil produced looser bunches and lower titratable acidity. • Grapes grown on the thinner topsoil made a better quality wine.

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TECHNICAL YEARBOOK 2024