Chemical Fertilizers and Their Impact on Soil Health

Soils provide important ecological services for the maintenance and survival of life. Soil health management is critical to maintaining biodiversity and ensuring sustainable agricultural production. Soil health is regulated by soil properties, namely physicochemical and biological properties. Modern agriculture relies heavily on chemical fertilizers. These are inevitable threats to agriculture. Nonetheless, they remain an important tool for global food security. As sustainable agriculture becomes a global goal, the ill effects of chemical fertilizers cannot be ignored. Fertilizers play a vital role in increasing crop yields and soil fertility. There are many kinds of chemical fertilizers, such as nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer. The use of fertilizers not only increases crop yields, but also alters the physicochemical and biological properties of the soil.

However, the continued use of chemical fertilizers is responsible for the decline in soil organic matter (SOM) content as well as the decline in agricultural soil quality. Excessive use of chemical fertilizers will cause soil compaction, reduce soil fertility, pollute air, water and soil, and reduce important nutrients and minerals in soil, thereby causing harm to the environment. Single application of chemical fertilizers leads to weak microbial activity in the farming system. Continued use of chemical fertilizers alters soil pH, increases pests, acidifies and soil crusts, which leads to loss of organic matter and humus, reduction of useful organisms, stunted plant growth, and even contributes to greenhouse gas emissions. Due to their long-term persistence, these undoubtedly damage soil health and thus affect soil biodiversity.

Disadvantages of chemical fertilizers

Improper use of fertilizers can damage soil and plant health. The main disadvantages are as follows:

1. Some artificial fertilizer elements can disturb soil properties.

2. Artificial fertilizers become expensive for farmers.

3. It enhances nitrate emissions.

4. Insufficient crop growth, leading to crop yield reduction.

5. Crops are often damaged by insufficient water supply, especially in areas with little rainfall.

6. When nitrogen fertilizers are applied in the field, only the bacteria that are already present can convert nitrogen into nitrate.

7. Due to the lack of organic matter, it destroys the structure of the soil.

8. Soil-dwelling organisms that make the soil fertile, such as earthworms, can also be destroyed by improper application.

9. Nitrogen fertilizers are toxic to both animals and humans.

Effects of Chemical Fertilizers on Soil Health

1. Soil quality

Soil quality has deteriorated due to increased application of chemical fertilizers, especially urea, potassium chloride and superphosphate (SSP), as a means of increasing agricultural production. Because soils are major reservoirs of reactive nutrient types, their comprehensive management is critical to address global food security challenges and reduce environmental nutrient losses that can affect water and air quality. There are multiple risks to soil health: soil compaction, acidification, erosion, pollution, salinization, and loss of organic matter, all of which affect the loss of P and N to water and air.

2. Physical and chemical properties of soil

Management of soil nutrients is critical to maintaining good soil quality and the continued productivity of nursery systems. Fertilization affects the amount of N and C in soil by changing soil structure, soil organic N and C composition and soil aggregates. Continuous use of chemical fertilizers has clear effects on the biochemical properties of soils, resulting in changes in microbial populations. Due to the continuous use of fertilizers in different crops such as corn, wheat and others, the nitrogen (N) content, SOC, moisture, pH and nutrients available to microorganisms in the soil are constantly changing.

3. Soil enzyme activity

The activity of various soil enzymes, such as alkaline phosphatase, dehydrogenase, protease and ?-glucosidase, is an important indicator of soil fertility and microbial activity. Long-term application of chemical fertilizers has no positive effect on microbial biomass and dehydrogenase activity, while organic fertilizer has a positive effect on this. In addition, copper, a common pollutant in soils due to excessive use of pesticides and fertilizers or irrigation, adversely affects the activities of soil dehydrogenases.

4. Soil compaction

Reduced use of organic fertilizers, use of heavy machinery, continued use of chemical fertilizers, and constant tillage to consistent depths can all contribute to soil compaction. Additionally, soil compaction can lead to problems such as insufficient aeration, excessive soil strength, poor drainage, erosion, runoff, and soil degradation. These changes lead to decreases in permeability, hydraulic conductivity, and groundwater recharge.

5. Effects on soil biota

Soil microbial activity is an important component of soil health. Bacteria, fungi, protozoa, algae, and viruses make up the soil microbial community and form an important part of the agricultural ecosystem. Soil biodiversity is a cornerstone of global food security and also affects agricultural biodiversity, including plant and animal resources. The effects of chemical fertilizers on microbes in the soil can be beneficial or detrimental, depending on the time period considered, the quantity, quality and method of fertilization. Continued use of pesticides and fertilizers disrupts the functional and structural properties of soil microbial populations while creating nutrient imbalances in soils. Application of phosphorus fertilizers regularly reduces mycorrhizal fungi, but the strength of the effect depends on the species of fungi involved and the amount of phosphorus available to the plant.

Conclusion

The use of chemical fertilizers is seen as a technique required in agriculture. Long-term application of chemical fertilizers has adverse effects on soil physical and chemical properties and biological properties. Chemical fertilizers destroy the major soil species and structural and functional diversity of microorganisms. Fertilizers should be applied in a timely and appropriate amount. First, the soil should be carefully diagnosed and then fertilized. The chemical composition and structure of the soil should be known and the most effective fertilizer should be chosen. There should be the most appropriate method of handling. Otherwise, it will lead to loss of financial resources.