The role of plants in protecting our soil?

Role of plant roots

Plant roots do not just take up water from the soil but they secrete various compounds into the soil. These compounds include a whole range of organic substances including protein, sugar, long-chains of sugars or polysaccharides, and even DNA. Collectively these organic substances are called root exudate. Another part of this root exudate are cells, which actively detach themselves from the root and continue to grow, and secrete root exudates for up to several months. These cells along with the main root exudate form a complex network, which modifies the surrounding soil making the local environment more suitable for plants to proliferate. These organic substances have a variety of functions within the soil, from defending the root from invading pests and disease to increasing the availability of nutrients. The secreted polysaccharides from roots, which are collectively referred to as root mucilage, lubricate the roots so that they can penetrate through the soil so that they can access water and nutrients from the soil below. These secreted polysaccharides are derived from a mixture of plant cell debris from burst root cells, and active secretion by living cells.

Secreted polysaccharides cause soil to clump

Secreting these polysaccharides comes at a great cost to the plant. These secreted polysaccharides use up to 60% of the energy generated by plants through their leaves; during the commonly known process of photosynthesis. The exact functions of these secreted polysaccharides other than to lubricate the roots remains uncertain. However, the latest research has demonstrated that these polysaccharides secreted by many plants, particularly crop plants such as wheat can cause soil to clump. This may seem counter-intuitive as when roots bury down into the soil, soil clumping would increase the work plants need to undertake to bury further down into the soil. Soil clumping to roots can increase the uptake of water from soil, nutrients and can help plant roots to form critical relationships with soil dwelling bacteria and fungi, which helps plants to access the viral nutrients for them to grow.

Plants adapt their environment

As plants cannot move when their environment becomes hostile like us, plants must adapt. One way plants do this is by secreting polysaccharides into the soil so that they can adapt the soil’s local environment to their needs. Plants are remarkable clever in the ways they can modify their environment and surrounding life, for instance, plants produce seed in order to spread their genetics similar to us having children. For seeds to be produce by many plants, plants require the aid of animals such as bees to pollinate flowers. Plants also produce fruits to cover their seeds in order for animals to eat them, and spread their genetics by animals carrying them within their stomachs until animals eventually deposit them in their dung. When you think about it, we as humans produce millions of tonnes of fruit for us to consume. You could say that plants to a degree control us in the way they needs us to spread their genetics. For plants to produce fruit that will successfully spread their genetics, they produce fruit that are suited to our desires such as sweetness, colour or texture. In summary, without plants we cannot eat, clothe ourselves, produce medicines and so on. Plants are crucial for all life on the land, and for most of the products that we know and consume.

Significance of secreted polysaccharides

These secreted polysaccharides are available in an industrial form. These equivalent polysaccharides to the secreted polysaccharides of plant roots can also cause soil to clump. These commercial polysaccharides could be used as a soil conditioner, which would prevent soil from eroding. Additionally, these polysaccharides could make the soil’s environment more suitable for plants, thus making them an ideal substitution for inorganic fertilisers, which have a negative large scale impact on the environment. These inorganic fertilisers also pollute many water sources, including rivers and lakes, causing the collapse of many aquatic ecosystems around the world. These secreted polysaccharides have the vast potential to increase global crop yields at a greater efficiency compared to traditional fertilisers, and without the negative impact on the environment and ecosystems. These polysaccharides have also been demonstrated to be secreted from early land plants suggesting that they played an important role in forming the Earth’s first soils. Soil is viral for plant growth, and many millions of other species, that support all land-based ecosystems including our own civilisation. These secreted polysaccharides may have played a role in clumping early soil particles, which modified the environment to suit early plants. This led to the modern day environments that we commonly recognise and enjoy.

Summary

Secreted polysaccharides may initially seem unimportant at first glance but they may have played a vital role in the development of the first soils, and helping plants to access the resources that they require for their growth. Many people do not think that plant roots play an important role as they are hidden by soil but they play a crucial role as outlined in this article. 

Potential Implications

This research may have both ecological and agricultural implications. From this research secreted polysaccharides have been demonstrated to increase soil aggregation. By increasing soil aggregation, soil which has suffered from over-cultivation and soil erosion could be regenerated. Regenerating degraded soil would increase land productivity, and would protect areas of ecological importance by reducing the demand for deforestation. Growers could alter the amounts of polysaccharides released from crops to manipulate the relationship that plants have with beneficial fungi and bacteria. This could increase crop yields without genetic modification, long-term sustainability of crop production, and increase crop resilience against climate change.