What is regenerative agriculture? In week five of this 12 part series, we’ll consider this indicator of an ecologically healthy farm system: increasing nutrient cycling. This explanation relies heavily on the very cool, open-source online textbook website created by Rice University. Read the entire chapter here: https://cnx.org/contents/s8Hh0oOc@13.7:1KV9fus6@9/Biogeochemical-Cycles. All images credit: work by John M. Evans and Howard Perlman, United States Geological Survey (USGS).
Nature produces no wastes. Everything gets used by something else. Mineral nutrients are cycled through ecosystems and their environment. Of particular importance are water, carbon, nitrogen, phosphorus, and sulfur. All of these cycles have major impacts on ecosystem structure and function.
Water from the land and oceans enters the atmosphere by evaporation or sublimation, where it condenses into clouds and falls as rain or snow. Precipitated water may enter freshwater bodies or infiltrate the soil. The cycle is complete when surface or groundwater reenters the ocean.
Carbon dioxide gas exists in the atmosphere and is dissolved in water. Photosynthesis converts carbon dioxide gas to organic carbon, and respiration cycles the organic carbon back into carbon dioxide gas. Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized. Volcanic activity and, more recently, human emissions bring this stored carbon back into the carbon cycle.
Nitrogen enters the living world from the atmosphere through nitrogen-fixing bacteria. This nitrogen and nitrogenous waste from animals is then processed back into gaseous nitrogen by soil bacteria, which also supply terrestrial food webs with the organic nitrogen they need.
In nature, phosphorus exists as the phosphate ion. Weathering of rocks and volcanic activity releases phosphate into the soil, water, and air, where it becomes available to terrestrial food webs. Phosphate enters the oceans in surface runoff, groundwater flow, and river flow. Phosphate dissolved in ocean water cycles into marine food webs. Some phosphate from the marine food webs falls to the ocean floor, where it forms sediment.
Sulfur is an essential part of the amino acid cysteine and is involved in the formation of proteins. Sulfur dioxide from the atmosphere becomes available to terrestrial and marine ecosystems when it is dissolved in precipitation as weak sulfuric acid or when it falls directly to Earth as fallout. Weathering of rocks also makes sulfates available to terrestrial ecosystems. Decomposition of living organisms returns sulfates to the ocean, soil, and atmosphere.
The cycling of these elements is interconnected. For example, the movement of water is critical for the leaching of nitrogen and phosphate into rivers, lakes, and oceans. The ocean is also a major reservoir for carbon. Thus, mineral nutrients are cycled, either rapidly or slowly, through the entire biosphere and from one living organism to another. Understanding these cycles and their inter-relatedness enables us to make good choices about the ways we choose to farm.
CSA (Community Supported Agriculture) Shares
This is the final pick up week for 2018 shares! Here is what we plan to include in this week’s CSA shares:
See you at the farm!