Soil Algae Aims to Improve Soil Quality through Algae Cultures
Authors: Samreen Tariq, Areej Ashfaq and Ayesha Asif
Algae is not just for bodies of water anymore. “Twenty percent of the microbial biomass in natural, healthy soil is algae, but many farmers only monitor and maintain bacteria and fungi.” said, group of researchers. The study aim is to highlight the importance of soil algae that can be the beneficial for farmers to increase the fertility of soil for productivity rather than traditional agricultural practices. So, that farms may improve the health of their soil and boost production by algae cultures.
Soil algae live on the surface of soil. There are 2000 species of microscopic soil algae are known blue-green, green, yellow-green and diatom algae. Some blue-green algae fix atmospheric nitrogen (Gollerbakh et al., 1969). The major roles and functions of algae in soil are that it maintains the soil fertility, especially in tropical soils, adds organic matter to soil when they die and thereby reducing and preventing soil erosion (John et al., 2017). Algae fix nitrogen, improve soil fertility, and play a significant role in plant succession. It is also found that algae present on soil increase organic matter, nitrogen and stabilizes it. This promotes germination of seeds and growth of other microorganisms (Agha et al., 2020).
In laboratory cultures of large surface samples, occasional cells and spores of algae which do not multiply actively in soil are favored by the altered pH, higher calcium carbonate content or the fluid culture medium. After a few days, those forms which first predominated tend to disappear, being replaced by others, generally more common and less fragile (Shields et al., 1964). Algal production in outdoor ponds is relatively inexpensive. The nutrient medium for outdoor cultures is agricultural-grade fertilizers instead of laboratory-grade reagents. At present, large-scale commercial production of microalgae biomass (Andersen et al., 2005).
Pakistan is a developing country and depends on agriculture. It is one of the countries consuming very large amounts of nitrogen per unit area. There are estimates that the use of nitrogen fertilizers will continuously increase. Pakistan is a country where rice is the second staple food and it is grown in many areas of the country, particularly in Punjab and Sindh. Some current practices of algal cultures are BGA synthesize and liberate auxin and amino compounds which stimulate the growth of plants, used particularly in rice crops. Whereas the amount of nitrogen fixed by the BGA under field conditions ranges between 15–80kg/ha according to the algal species, fertilization, soil, and environmental conditions (Rehman et al., 2015).
Algae plays an important role in community succession by increasing biodiversity in soil (Starks et al., 1982). At early succession, the biomass of microalgae increased in soil but decreased at later stage, due to presence of lichens, mosses, and vascular plants (Song et al., 2014) (Hu et al., 2003). Algae with high reproduction rate can produce large amount of biomass and cultivation systems play an important role in it. Open pond production systems are cost efficient and require less maintenance than bioreactors for algal biomass production. Microalgae generate more biomass in less time. They can grow on low economic value lands and utilize more carbon dioxide and nitrogen while agricultural crops require fertilizers, for biomass generation and utilize less carbon and nitrogen from the environment (Rajvanshi et al., 2020). Algal growth increases the carbon and nitrogen input in soil (Zaidi et al., 2018).
Nitrogen fixing blue green algae play role in nitrogen accumulation of soil. They grow in tropical regions and common in paddy fields. It is vigorously used as green manure in rice fields for favorable effects. Soil algae, blue green algae or Cyanobacteria contribute about 20–30 kg N ha −1 season −1 as well as organic matter to the soil which is useful for the economically weak farmers who are unable to invest on costly chemical nitrogen fertilizer. Thus, algal cultivation is much favored over traditional agricultural practices (Manzoor et al., 2015).
In Pakistan, microalgal biomass is used as biodiesel in different areas of the country. The first attempt to produce biodiesel from algal biomass in Pakistan was carried out by Khola et al., Pakistan possesses plentiful algal flora because of rich saline habitats and diverse water (Metting et al., 1981). Yet, it is not used as Bio stimulant or biofertilizer for increasing the productivity of crops in Pakistan. Production of algal blooms are due to suitable temperature and solar illumination widespread in different areas of the country. Geographically Pakistan lies in the world’s greatest solar insulation area, receiving high intensity of solar radiations due to favorable climatic conditions (Issa et al., 2014). So, these conditions suggest that cultivation of algal biomass is possible in Pakistan and as biofertilizers to increase the productivity of crops in Pakistan.
Soil conditioners are chemically biologically prepared substances that are used for the nourishment of soil which essentially helps in the growth of various plants. They are somehow different from the soil fertilizers. Fertilizers only supply nutrients to the soil but on the other hand, soil conditioners enhance the physical, chemical, and biological health of the soil. Algal soil conditioners increase aeration, water holding capacity, nutrient viability to the soil due to which the texture of soil and its quality also get improved which supports vegetation. They are effective as they improved the soil property and soil growth (Rehman et al., 2015).
Pesticides, insecticides, and herbicides influences the growth of soil algae. The influence can be variable with inhibition and stimulation of growth or no effect on growth. Microalgae have the bio stimulant and biofertilizers properties which attracts agrochemical industries. Microbial biostimulant and microbial biofertlizer increases the agriculture sustainability in crop production. They are environmentally friendly and cost-effective alternatives to the fertilizers, crop protection products and plant growth regulators. Bio stimulants are derived from organic materials that stimulate the growth and the development of several crops under both optimal and stressful conditions. Biofertilizers contains living organisms that improve chemical and biological soil properties, stimulating plant growth, and restoring soil fertility through natural substances present in them. Microalgae extracts have greater importance in crop production as MBS and MBF. Agrochemical companies are now including microalgal extracts in the formulation of innovative MBS and MBF. These extracts showed beneficial effects like increased nutrient uptake, induced tolerance to the abiotic stresses and improves crop yield and quality (Ronga et al., 2019).
Conclusion
Soil algae plays an important role in enhancing the fertility of soil. It is also beneficial for farmers for increasing productivity as well as cost efficient. Soil Algae, specifically blue-green algae or cyanobacteria is also capable of pulling nitrogen from the air and converting it into usable nitrogen within the soil. It eliminates the cost of nitrogen fertilizers by farmers, for agricultural use. The added algae increase soil biodiversity, organic biomass, and the total humus found in soil, all good things for farmers keen to produce in healthy soils.
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