Soil Chemical Analysis

The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

2006 IPCC Guidelines for National Greenhouse Gas Inventories

http://www.tinread.usarb.md:8888/tinread/fulltext/lal/soil_structure.pdf

Soil structure and management: a review

https://www.ipcc-nggip.iges.or.jp/public/gpglulucf/gpglulucf_files/0_Task1_Cover/Cover_TOC.pdf

Good Practice Guidance for Land Use, Land-Use Change and Forestry

The emission of greenhouse gases (GHG) during feedlot manure composting reduces the agronomic value of the final compost and increases the greenhouse effect. A study was conducted to determine whether GHG emissions are affected by composting method. Feedlot cattle manure was composted with two aeration methods--passive (no turning) and active (turned six times). Carbon lost in the forms of CO2 and CH4 was 73.8 and 6.3 kg C Mg-1 manure for the passive aeration treatment and 168.0 and 8.1 kg C Mg-1 manure for the active treatment. The N loss in the form of N2O was 0.11 and 0.19 kg N Mg-1 manure for the passive and active treatments. Fuel consumption to turn and maintain the windrow added a further 4.4 kg C Mg-1 manure for the active aeration treatment. Since CH4 and N2O are 21 and 310 times more harmful than CO2 in their global warming effect, the total GHG emission expressed as CO2-C equivalent was 240.2 and 401.4 kg C Mg-1 manure for passive and active aeration. The lower emission associated with the passive treatment was mainly due to the incomplete decomposition of manure and a lower gas diffusion rate. In addition, turning affected N transformation and transport in the window profile, which contributed to higher N2O emissions for the active aeration treatment. Gas diffusion is an important factor controlling GHG emissions. Higher GHG concentrations in compost windrows do not necessarily mean higher production or emission rates.

Greenhouse gas emissions during cattle feedlot manure composting.

Carbon and N losses reduce the agronomic value of compost and contribute to greenhouse gas (GHG) emissions. This study investigated GHG emissions during composting of straw-bedded manure (SBM) and wood chip-bedded manure (WBM). For SBM, dry matter (DM) loss was 301 kg Mg -1 , total carbon (TC) loss was 174 kg Mg -1 , and total nitrogen (TN) loss was 8.3 kg Mg -1 . These correspond to 30.1% of initial DM, 52.8% of initial TC, and 41.6% of initial TN. For WBM, DM loss was 268 kg Mg -1, TC loss was 154 kg Mg -1 , and TN loss was 1.40 kg Mg -1 , corresponding to 26.5, 34.5, and 11.8% of initial amounts. Most C was lost as CO 2 with CH 4 accounting for <6%. However, the net contribution to greenhouse gas emissions was greater for CH, since it is 21 times more effective at trapping heat than CO 2 . Nitrous oxide (N 2 O) emissions were 0.077 kg N Mg -1 for SBM and 0.084 kg N Mg -1 for WBM, accounting for 1 to 6% of total N loss. Total GHG emissions as CO 2 -C equivalent were not significantly different between SBM (368.4 ± 18.5 kg Mg -1) and WBM (349.2 ± 24.3 kg Mg -1 ). However, emission of 368.4 kg C Mg -1 (CO 2 -C equivalent) was greater than the initial TC content (330.5 kg Mg -1 ) of SBM, raising the question of the net benefits of composting on C sequestration. Further study is needed to evaluate the impact of composting on overall GHG emissions and C sequestration and to fully investigate livestock manure management options.

Xiying Hao

Papers

Greenhouse gas emissions during cattle feedlot manure composting.

Carbon, nitrogen balances and greenhouse gas emission during cattle feedlot manure composting.

Effect of grazing intensity on carbon and nitrogen in soil and vegetation in a meadow steppe in Inner Mongolia

A review of composting as a management alternative for beef cattle feedlot manure in southern Alberta, Canada

Distribution of sulfamethazine, chlortetracycline and tylosin in manure and soil of Canadian feedlots after subtherapeutic use in cattle.