The term “simple farmer” is rather misleading. In actuality, farmers are far from simple, and hold complex skill sets that are based on agronomic, horticultural, biological, environmental, and technological competencies. At Cool Planet, we recognize farmers, growers, and green industry professionals as scientists and land stewards. Farming, growing, and landscaping doesn’t just require skill and experience, it implores an intricate understanding of different organic processes and scientific concepts. One of these concepts that we know is particularly important is leaching, which threatens your crops’ and plants’ nutrient supply and your soil’s structure.
The term “leaching” refers to an agricultural process in which a liquid, typically water, percolates through the soil and drains it of soluble minerals, chemicals, and/or nutrients. Leaching affects some soils more than others depending on factors like its soil structure and external environment. No matter what kind of soil you’re dealing with, you will want to limit leaching so that your soils retain crucial nutrients and the general integrity of its composition.
A high water-retention capability is a key characteristic of great soil, but even the best dirt can only hold so much before it has to drain excess moisture. As this excess water moves downwards through the soil, its flow dislodges particles and dissolves soluble chemicals, particularly phosphate and nitrate. Nitrogen deficiencies will lead to poor plant growth, so you want to make sure to limit the amount of nitrogen that is lost due to leaching.
Leaching is a natural process, and as long as rainfall isn’t excessive, broken down organic material will replenish your soil’s nutrient deficiencies. There are ways, however, to minimize leaching so that your soil is flush with nutrients.
During spring and summer, nitrate doesn’t reach groundwater because of the low rainfall and high evaporation that occurs during those seasons. After harvest, however, rainfall increases, driving rainwater and the soluble nutrients it picks up along the way down towards the ground water. Growing catch crops in the offseason can help to avoid excess leaching during this period.
It’s important to keep in mind that adding more nitrogen and phosphorous to your fertilization routine can provide greater nutrient availability to plants, but the fertilizers can also increase the amount of soluble chemicals running off into the groundwater. What can be done to limit leaching, so that naturally occurring nutrients are retained in the root zone? By focusing on strengthening your soil’s ability to retain the necessary nutrients rather than increasing the number of potential particles that can be leached.
By building soil organic matter land stewards can optimize naturally occurring soil performance characteristics that limit leaching. To date when we talk about methods to improve Soil Organic Matter (SOM) levels, which is the amount of plant and animal residues, the substances synthesized by the soil organisms, that are found in the soil we usually focuses on no-till and cover crop practices. No-till, or zero tillage farming, is when a farmer grows crops year after year, without disturbing the soil through tillage. No-till farming practices can help reduce erosion, improve the soil’s retention of organic matter, and support its cycling of nutrients. Retaining carbon in the soil helps to mitigate the amount of greenhouse gasses released into the atmosphere by keeping carbon ‘locked’ in the soil. Cover crop farming is when a grower plants a crop to protect their soil after harvesting their cash crop. Cover crops help reduce erosion and their residue becomes an additional source of fertility for the soil.
It’s great to see an increase in the acres of American farmland using cover crops and no-till practices. This is a step in the right direction to limit leaching and will aid in the development of a robust food system that can feed our increasing population. However, if we want to make additional environmental and productivity gains, especially in regards to mitigating the leaching of nutrients, it is time to consider a third strategy and tool when trying to improve SOM levels – a strategy that is proven and becoming more widely commercially available: adding Soil Organic Carbon (SOC).
One form of SOC, called recalcitrant, also known as fixed carbon, is mostly delivered to the soil as biochar. Recalcitrant carbon can be added to soils as an amendment to improve the structure of the soil, aiding in water infiltration and retention and nutrient efficiency by helping to hold nutrients in the soil column.
Cool Terra is a recalcitrant, or biochar-based, carbon soil amendment that can help growers improve soil health and subsequently mitigate leaching occurrences. It’s expansive surface area and porosity adds structure to the soil and its high ionic exchange capacity holds nutrients in the root zone longer. By incorporating Cool Terra into the root zone of specialty fruit and vegetable crops, permanent crops, broad-acre row crops, landscapes, turf, and more areas, growers and land stewards can establish a solid foundation for plant growth and revitalize key soil performance characteristics that can limit the soils tendency to leach nutrients.
Creating healthier soils by adding a soil organic carbon material like biochar-based Cool Terra can provide a tangible, and immediate benefit to farmers, growers, and society at large. Specifically, university and independent 3rd party field trials have shown that the incorporation of biochar can have a positive impact on crop yield and plant quality.
Limiting leaching by optimizing soil performance characteristics doesn’t just boost the quality of your crop yield—it also makes your farming practices more sustainable and community-friendly. If you’re using artificial fertilizers or pesticides, water can drain harmful chemicals from your soil and carry them through groundwater and into nearby sources of water that are used by your community. When nitrates get into people’s drinking water, it poses health risks that can be lethal to infants.
As the levels of phosphorous and nitrogen in bodies of water rise due to leaching, they start to serve as food to algae, causing growth in algae cultures throughout your community’s lakes and river. High levels of such algae can make it dangerous to come into contact with the water. This poses threats to the delicate ecosystem within your natural community, which are difficult to reverse.