Potential carbon sequestration and nitrogen cycling in long-term organic management systems

Abstract

The fertility and soil health of organic agroecosystems are determined in part by the size and turnover rate of soil carbon (C) and nitrogen (N) pools. Our research contrasts the effects of best management practices (BMP) (reduction in soil disturbance, addition of organic amendments) on C and N cycling in soils from two field sites representing five organic agroecosystems. Total soil organic C (SOC), a standard measure of soil health, contains equal amounts of biologically and non-biologically active C that is not associated with release of mineral N. A three-pool first-order model can be used to estimate the size and turnover rates of C pools but requires data from a long-term incubation. Our research highlights the use of two rapid C fractions, hydrolysable and permanganate (0.02 M) oxidizable C, to assess shifts in biologically active C. Adoption of BMP in organic management systems reduced the partitioning of C to the active pool while augmenting the slow pool C. These pools are associated with potentially mineralizable N supplied by residues, amendments and soil organic matter affecting the concentration and release of mineral N to crops. Our data show that minimizing disturbance (no tillage, pasture) and mixed compost additions have the potential to reduce carbon dioxide emissions while enhancing slow pool C and or its turnover, a reservoir of nutrients available to the soil biota. Use of these rapid, sensitive indicators of biological C activity will aid growers in determining whether a BMP fosters nutrient loss or retention prior to shifts in total SOC.

Responses of Soil Labile Organic Carbon to a Simulated Hurricane Disturbance in a Tropical Wet Forest

“…Permanganate oxidizable carbon was revealed as a more sensitive fraction of the soil organic carbon [58], and soil LOC was believed to be an active component to trigger increases in soil MBC [59,60]. In our study, soil LOC was significantly related to soil MBC (Table 3).…”

Compost Legacy Down‐Regulates Biological Nitrogen Fixation in a Long‐Term Field Experiment

“…2). Others have observed legacy effects of compost and cover crop management that enhances soil C and N pools, including under organic management (Bhowmik et al, 2017), and under biological management in a nearby long-term study (Grandy and Robertson, 2007). In our study, consequences of this organic matter pool build up were observed, including a reduced rate of BNF observed in plants grown in IC+ plots, in each of the 3 yr of the study.…”

A Review on the Current State of Knowledge of Growing Conditions, Agronomic Soil Health Practices and Utilities of Hemp in the United States

“…For generations, animal manures and composts have been identified as soil builders because of their enormous impact on improving soil health [84,85]. The nutrient content of animal waste varies depending on different factors like feed source and type, animal age, handling and storing techniques, temperature, and moisture content.…”

“…It has been reported that hemp is naturally adapted to using mammalian manure, e.g., horse manure as fertilizer, and it can also efficiently employ stocks of livestock manure [78]. Composting of manure is a process that is recommended because it enhances the quality of manure and has been reported to improve soil health properties [85]. Chicken, horse, and cow manure are recommended to undergo composting before usage to decrease the likelihood of pathogens.…”