In episode two of the Healthy Soils for Sustainable Cotton webinar series, Dr. Jennifer Moore-Kucera links soil biology to soil health by increasing our understanding of the three functional groups for soil organisms, the soil function activities performed by soil organisms, biological hot spots, and biodiversity in this deep-dive into the relationship between soil health principles and soil biology. Soils host vast numbers, mass, and diversity of organisms.
Soils are often referred to as the most biologically diverse ecosystem on Earth and comprise over 25% of the Earth’s biodiversity. In about an acre of healthy soil, there is roughly 20,000-30,000 pounds of biomass, with 10,000-20,000 of this comprised just of microbes like bacteria and fungi. The biomass of two and a half acres equates to about 20 cows. The life-force below our feet interacts in phenomenal ways to bring the soil functions that are critical to agricultural productivity.
There are three soil organism functional groups that perform in an interactive and complex web-like manner: the ecosystem engineers, biological regulators, and biochemical engineers. All three are involved in carbon cycling, and decomposition of plant and animal residues. When these soil organism functional groups are in balance and working together, they contribute to ecosystem resiliency that allows the ecosystem to bounce back after a disturbance like a flood or drought as well as resist the negative impacts of these disturbances. Soil organisms are critical to helping support overall agricultural sustainability and our food security.
In farming systems, the environment where most soil organisms perform best are those where the conditions are just right. This depends on soil’s pH, temperature, water, and oxygen conditions, as well as food sources. In a biological hot spot, microbial activity can be 10 to 1,000 times greater than in an adjacent area. A highly functioning soil will support all the biological hot spots: the root zone (rhizosphere), litter layer (detritusphere), earthworm and root channels (drilosphere), pore spaces (porosphere), and aggregate surfaces (aggregatusphere).
These hot spots are all integrated and do not work in isolation of each other. Microbes help plants deal with stress, including stressors such as temperature, waterlogging, soil toxicity, drought, insects, pests and pathogens, and nutrient limitations (Confirmed benefits of crop probiotics on plants, Source: http://www.uq.edu.au/research/impact/....
We can influence and optimize the interactions of the soil microbiome through crop rotation; cover cropping; 4R fertilizer management (right rate, right source, right placement, right timing); and environment management to minimize stress. So how do you manage for soil biology? Maximize the presence of plants to manage for hot spots. Minimize disturbance, such as through a no-till practice, to support the biology that builds aggregates and creates pore space. Keep soil covered for habitat protection. Optimize biological nutrient cycling to help form biological hot spots and a diverse population. Optimize plant-microbe interactions to build plant defense, nutrient cycling, and access to water.
These can be achieved by following the soil health principles of minimizing disturbance and maximizing soil cover to protect soil aggregates and organic matter; and maximizing the presence of continuous living roots and maximizing biodiversity to feed and fuel soil biology (Modified from USDA-Natural Resources Conservation Service ‘Principles for High Functioning Soils’ fact sheet, Source: https://www.nrcs.usda.gov/wps/portal/....
Dr. Moore-Kucera is the Climate Initiative Director at American Farmland Trust, where she directs the “Farmers Combat Climate Change” Initiative and oversees efforts to develop state-level policies and programs in U.S. Climate Alliance states. The Farmers Combat Climate Change Initiative helps farmers, ranchers, and landowners play a role in reducing the growing threat of climate change while also increasing food production, improving soil health, and protecting farmland for future generations. Dr. Moore-Kucera is an adjunct faculty in the Crop and Soil Science Department at Oregon State University.
The Healthy Soils for Sustainable Cotton webinar series will allow viewership and participation in soil health training for cotton producers who were unable to attend the training field day workshops or advanced trainings. The goal of the project is to quantify, expand and verify the productivity and environmental benefits of the soil management systems used by cotton producers. Healthy Soils for Sustainable Cotton is supported through the generosity of the Wrangler® brand, the VF Corporation Foundation, and the Walmart Foundation.
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