Type of soil
There are different types of soil and not all are created equal when it comes to crop production. In general, darker soils are better because they contain a lot of organic matter. They have more minerals and vitamins available than other types of soil, and that’s why they can grow more food per acre. Clay and silt soils are generally better for crop production because they have small particles, which means water is less likely to escape, keeping the soil moist and fertile.
Salinization is the process of salts and other chemicals found in water accumulating in the soil over time. Many land plants, including most crops, cannot grow in saline soil. Lands have to be carefully managed to prevent salinization. The solution is flushing the soil with lots of water.
Strong winds, grazing, and ploughing are often responsible for the lifting of soil, mostly from arid and dry lands. The dust particles can travel long distances depending on weather conditions, contaminating not only the air humans and animals breathe, but also crops with bacteria and fungi spores. The dust particles may also contain heavy metals, insects, pollen, and radioactive materials.
Bacteria are the most common kind of pathogenic organisms in soil. Most types of fungi in soil absorb nutrients contributing to the decomposition of dead organisms. But only about 300 out of 10,000 bacteria found in soil can make their way into food and be seriously harmful to humans. Viruses are sometimes introduced into the soil through sewage waste and can survive. Viruses that cause conjunctivitis, gastroenteritis, hepatitis, polio, aseptic meningitis, or smallpox have all been found in soil and later in food.
The diversity of contaminants in the soil has increased significantly over the last decades due to urbanization and rapid industrialization. Some of the biggest sources of heavy metals in the soil are livestock manure, irrigation with wastewater or polluted water, pesticides, and phosphate-based fertilizers. Once the heavy metals are absorbed, beneficial soil insects, invertebrates, and small and large mammals are all affected. Greenhouse vegetables have been found to contain high amounts of heavy metals such as lead, copper, and cadmium. Accumulating too much of certain heavy metals can lead to poisoning.
Organic farming has grown in popularity, even though organic foods are more expensive. Sales of organic foods nationwide were up nearly 6% in 2018 to a record $47.9 billion. Growing food organically means less pollution and using less water, which results in less soil erosion and increased soil fertility. These foods are also better for human health because they don’t contain pesticides, growth hormones, or antibiotics, and they have a higher content of important nutrients.