TECHNICAL Fig 6: Calvin cycle phases


Through empowering


young turf professionals with a greater insight and understanding of the key elements and processes, progress will be accelerated


maintain stomatal health, particularly during times of increased stress, will be the most successful in aiding the grass plant to achieve this. Diff ering methods of C fi xation are examples of plant evolutionary change over millennia in response to climatic pressures. In recent decades, biologists have increasingly observed such changes, with one example of this being a decrease in stomatal density in response to elevated atmospheric CO2 levels. It may seem obvious to assume that an increase in the availability of CO2


would


be benefi cial to plants, but the contrary is actually true, with research indicating that once concentration reaches 1000ppm, photosynthesis is in many cases impeded[3] saturation.


This referred to as CO2


Moving the focus of attention below ground, it soon becomes apparent the magnitude of the role that C plays in a functioning growing medium. As noted,


.


photosynthesis enables the conversion of inorganic atmospheric C into organic carbohydrates. A proportion of these are deposited via exudates into the area surrounding root tips, this referred to as the rhizosphere. These providing a source of energy for the microbial community which inhabit this region. The utilisation of these C rich deposits is exemplifi ed by the fact that the average C:N ratio of a soils total microbial biomass is believed to range from 4:1 to 8:1[2]


compounds. These all crucial components to achieving a healthy soil structure. Availability of C compounds in the soil matrix is also an essential building block to enable the process of decomposition. Even the most resistant of OM such as cellulose and lignin is ultimately decomposed by specialist fungi and bacteria. However, when oxygen limiting conditions prevail inhibiting decomposition, resistant OM can result in stable soil C pools persisting for thousands of years. The decomposition process that occurs in a functioning soil is fundamental for achieving equilibrium in the C cycle, with the vast amounts of CO2


released by


. The plant - biota C relationship is very much a mutualistic one. Mucus and discharge from biota act as cohesive binding agents for soil particles, enabling the formation of aggregates (Fig 8). The macro & micro pores that these aggregates provide ensuring porosity, and subsequently the availability of oxygen and water to plant roots. Meanwhile, vast networks of mycorrhizae fungi are eager to exchange nutrients and water with plants for C rich


respiring biota an essential input. Ultimately, this can be recognised as contributing to the restocking of the atmospheric C pool for your grass to utilise. These types of feedback loops are a regular occurrence in the natural world. Soil conditions, particularly water levels, will impact these and the compounds omitted. Saturation of a soil profi le results in denitrifi cation through anaerobic bacteria, with a bi product of this being N2


O. Meanwhile, CH4 is produced from microbes via a process known as methanogenesis


Murrayfi eld Golf Club Fig 7: The physiology of a monocot leaf such as grass 130 PC April/May 2021


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