Nitrogen is a crucial nutrient for crops. Its concentration in the soil is very low, which often leads to nitrogen deficiency in plants. One of the methods to enhance nitrogen levels in the soil that has garnered significant attention is the use of nitrogen-fixing microorganisms from the atmosphere.
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Nitrogen-fixing microorganisms applied in crops |
In the soil environment, microorganisms participate in the transformation of organic matter, fix nitrogen to enrich the soil with nitrogen, accumulate auxins that stimulate plant growth, and synthesize vitamins such as thiamine, nicotinic acid, and biotin. Radiation technology is being implemented to create various substrates capable of fixing nitrogen-fixing bacteria and microbial preparations for the cultivation of some common crops in Da Lat.
Some products, such as modified starch, C-grafted-AAm, and C-grafted-AAc, have been researched for their water retention and fertilizer-holding properties, serving as artificial substrates to maintain activity and cultivate microbial biomass, preventing adverse effects on their life processes during storage, preservation, or when directly applied as fertilizers or in soil.
Currently, scientists have identified several bacterial species capable of fixing nitrogen, including: Rhizobium, Beijerinskii, Clostridium, and Azotobacter.
The Da Lat Nuclear Research Institute has chosen Azotobacter as their research subject. Azotobacter does not have the ability to assimilate humic substances; it can only thrive in soil rich in easily assimilable organic matter. Azotobacter effectively assimilates the products of cellulose degradation.
Master Nguyen Duy Hang from the Radiation Technology Department at the Da Lat Nuclear Research Institute stated that one of the important criteria for materials to absorb microorganisms is their water swelling capacity. The water swelling capacity of the grafted material plays a vital role in absorbing and maintaining the activity of the bacteria. The radiation dose also affects the water swelling capacity of the grafted material (C-g-AAm). At high radiation doses, the water swelling capacity decreases. The swelling capacity of these substrates ranges from 59 to 98 times.
An important characteristic of bacterial-absorbing materials used in agriculture is their biodegradability, which does not pollute the soil environment. Field tests in Lam Dong have shown that C-grafted-AAm has a strong degradation capability in the soil environment. Under the influence of the microbial and fungal systems present in the soil, C-g-AAm is broken down into smaller molecules (CO2, H2O). After 20 days, the hydrogel material lost 52% of its weight. This rapid degradation occurs because C is a biodegradable polymer that is easily degraded by the soil microbial system, leading to a significant breakdown of C-grafted-AAm.
When investigating the effects of the biological nitrogen-fixing preparation on the growth and development of sweet mustard and ground strawberry plants, it was also observed that the Azotobacter bacterial preparation had a pronounced effect on the growth and development of the plants compared to the control group.
