tilling, and applying nitrogen (table 1). Certain increase in soil respiration and can have a management practices can induce a temporary negative impact on SOM content. Table 1.—Interpreting management impacts on soil respiration and soil organic matter (SOM) Management Application Short-term impacts Long-term impacts practice Application of Apply at proper Increased respiration when Improved soil solid manure or agronomic rate. Provides manure begins to break structure; increased organic carbon and nitrogen to down; increased fertility and SOM material microbes, increasing their biomass/forage production. content. activity. Use of Crops that have a high Temporary fixation of nitrogen Improved soil quality; crops ratio of carbon to nitrogen during residue breakdown; increased fertility and or cover crops (C:N) produce a high increased soil moisture; SOM content. in rotation amount of biomass. decreased erosion. Leave residue on soil surface to increase SOM. Tillage, such as Mixes the soil, resulting in Released nitrogen and other Decreased SOM annual disking a temporary increase in nutrients and CO2; increased content, soil quality, or plowing oxygen and contact of potential for erosion; and soil fertility; residue to soil, allowing increased rate of reduced diversity of microbes to break down decomposition of residue and soil carbon sources. other carbon sources. (increased bacteria); damaged soil structure. Table 1.—Continued Management Application Short-term impacts Long-term impacts practice Use of crop Leave residue on the Nitrogen temporarily tied up Increased soil residue surface, increasing during breakdown of residue; quality, fertility, and ground cover, to protect increased soil moisture; SOM. the soil. decreased risk of erosion; lowered soil temperature. Application of Provides nitrogen Temporary increased If properly managed, nitrogen (energy), which allows respiration due to increased increased SOM and microbes to break down soil quality; increased
tilling, and applying nitrogen (table 1). Certain management practices can induce a temporary increase in soil respiration and can have a negative impact on SOM content. Table 1.—Interpreting management impacts on soil respiration and soil organic matter (SOM) Management practice Application Short-term impacts Long-term impacts Application of solid manure or organic material Apply at proper agronomic rate. Provides carbon and nitrogen to microbes, increasing their activity. Increased respiration when manure begins to break down; increased biomass/forage production. Improved soil structure; increased fertility and SOM content. Use of crops or cover crops in rotation Crops that have a high ratio of carbon to nitrogen (C:N) produce a high amount of biomass. Leave residue on soil surface to increase SOM. Temporary fixation of nitrogen during residue breakdown; increased soil moisture; decreased erosion. Improved soil quality; increased fertility and SOM content. Tillage, such as annual disking or plowing Mixes the soil, resulting in a temporary increase in oxygen and contact of residue to soil, allowing microbes to break down carbon sources. Released nitrogen and other nutrients and CO2; increased potential for erosion; increased rate of decomposition of residue and other carbon sources. Decreased SOM content, soil quality, and soil fertility; reduced diversity of soil (increased bacteria); damaged soil structure. Table 1.—Continued Management practice Application Short-term impacts Long-term impacts Use of crop residue Leave residue on the surface, increasing ground cover, to protect the soil. Nitrogen temporarily tied up during breakdown of residue; increased soil moisture; decreased risk of erosion; lowered soil temperature. Increased soil quality, fertility, and SOM. Application of nitrogen Provides nitrogen (energy), which allows microbes to break down Temporary increased respiration due to increased If properly managed, increased SOM and soil quality; increased
USDA_NRCS_respiration_guide.docx