Publisher Summary This chapter reviews the cycling of nutrients within pasture soils. The major emphasis is on the central role of the grazing animal in influencing soil fertility, particularly in the dung and urine patches. In addition, the progress is reviewed that has been made in modeling the cycling of nutrients in pasture systems. Nutrients are partitioned differently between dung and urine, with K being excreted mainly in urine; P, Ca, and Mg are excreted principally in dung and N and S are excreted in both forms. Nutrients returned in excreta can be in inorganic and organic forms, depending on the particular nutrient being considered. For some nutrients (e.g., P and S) significant mineralization of ingested organic forms occurs during passage through the animal, whereas much of the N is excreted in the readily available organic urea form. From the present knowledge of the major nutrient inputs and losses for the grazed pasture system and an understanding of the pathways of nutrient flux within the system and some key measurements, simple mass balance nutrient models for various pasture systems can be constructed. Such simple models have been used to calculate site-specific maintenance fertilizer requirements of pastures based on the amount of nutrient required to replace losses in the soil (e.g., through fixation and leaching) and losses by animal transfer and in animal products.

Nutrient cycling and soil fertility in the grazed pasture ecosystem

This memorandum documents the updates implemented in EPA’s 2020 Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHGI) for gathering and boosting (G&B) stations. Additional considerations for G&B were previously discussed in memoranda released November 2019 (Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2018: Updates Under Consideration for Natural Gas Gathering & Boosting Station Emissions),1 October 2018 (Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates Under Consideration for Natural Gas Gathering & Boosting Emissions),2 and April 2019 (Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates to Natural Gas Gathering & Boosting Pipeline Emissions).3

Inventory of U.S. Greenhouse Gas Emissions and Sinks

Common agricultural practices such as excessive use of agro-chemicals, deep tillage and luxury irrigation have degraded soils, polluted water resources and contaminated the atmosphere. There is increasing concern about interrelated environmental problems such as soil degradation, desertification, erosion, and accelerated greenhouse effects and climate change. The decline in organic matter content of many soils is becoming a major process of soil degradation, particularly in European semi-arid Mediterranean regions. Degraded soils are not fertile and thus cannot maintain sustainable production. At the same time, the production of urban and industrial organic waste materials is widespread. Therefore, strategies for recycling such organic waste in agriculture must be developed. Here, we review long-term experiments (3-60 years) on the effects of organic amendments used both for organic matter replenishment and to avoid the application of high levels of chemical fertilizers. The major points of our analysis are: (1) many effects, e.g. carbon sequestration in the soil and possible build-up of toxic elements, evolve slowly, so it is necessary to refer to long-term trials. (2) Repeated application of exogenous organic matter to cropland led to an improvement in soil biological functions. For instance, microbial biomass carbon increased by up to 100% using high-rate compost treatments, and enzymatic activity increased by 30% with sludge addition. (3) Long-lasting application of organic amendments increased organic carbon by up to 90% versus unfertilized soil, and up to 100% versus chemical fertilizer treatments. (4) Regular addition of organic residues, particularly the composted ones, increased soil physical fertility, mainly by improving aggregate stability and decreasing soil bulk density. (5) The best agronomic performance of compost is often obtained with the highest rates and frequency of applications. Furthermore, applying these strategies, there were additional beneficial effects such as the slow release of nitrogen fertilizer. (6) Crop yield increased by up to 250% by long-term applications of high rates of municipal solid waste compost. Stabilized organic amendments do not reduce the crop yield quality, but improve it. (7) Organic amendments play a positive role in climate change mitigation by soil carbon sequestration, the size of which is dependent on their type, the rates and the frequency of application. (8) There is no tangible evidence demonstrating negative impacts of heavy metals applied to soil, particularly when high-quality compost was used for long periods. (9) Repeated application of composted materials enhances soil organic nitrogen content by up to 90%, storing it for mineralization in future cropping seasons, often without inducing nitrate leaching to groundwater.

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Long-term effects of organic amendments on soil fertility. A review

A critical review on inhibition of anaerobic digestion process by excess ammonia.

The purpose of this paper is to support the development of so-called good practice guidelines for the estimation of methane (CH 4) emissions from solid waste (SW) disposal for national greenhouse gas inventories. The paper reviews and discusses the emission estimation methods given in the IPCC 1996 Revised Guidelines (IPCC Guidelines), and uncertainty and quality management issues related to the emission estimation. At solid waste disposal sites (SWDS) the degradable organic carbon in waste is decomposed by bacteria under anaerobic conditions into methane (CH 4) and other compounds. The CH 4 emissions from SWDS are important contributors of global anthropogenic CH 4 emissions. The IPCC Guidelines give two methods for estimation CH 4 emissions from solid waste disposal. The IPCC default method is a simple mass balance calculation which estimates the amount of CH 4 emitted from the SWDS assuming that all CH 4 is released the same year the waste is disposed of. The other method outlined in the IPCC Guidelines is the so-called First Order Decay (FOD) method. The FOD method takes the time factors of the degradation process into account, and produces annual emission estimates that reflect this process, which can take years, even decades. The estimates on annual emissions produced by the two methods are therefore not comparable. The FOD method produces better estimates on annual emissions, whereas the IPCC default method has merits e.g. in studies comparing the potential to reduce the CH 4 emissions by alternative waste treatment methods. The use of the IPCC default method and FOD method require as input annual SW disposal data including information on the composition of the waste and on the conditions at the SWDS. The IPCC default method requires this data only for the inventory years, whereas the FOD method requires data for also the past 20-25 or more years. In addition, the rate of degradation for waste disposed at SWDS needs to be determined in the FOD method. The IPCC Guidelines contain default values for most of the data needed in the use of the default method, whereas the guidance and default values needed in the use of the FOD method are insufficient. The uncertainties in the emission estimates produced by both the IPCC method and the FOD method are large in most countries. Even few industrialised countries have good SW disposal data based on weighing of amounts disposed and frequent sampling to determine the composition …

Good practice guidance and uncertainty management in national greenhouse gas inventories

Management considerations for organic waste use in agriculture.

Wood chips and wheat straw as alternative biofilter media for denitrification reactors treating aquaculture and other wastewaters with high nitrate concentrations

Ammonia emissions from swine feeding operations depend on the housing type; animal size, age, and type; manure
management, storage, and treatment; climatic variables; and manure utilization or land application techniques. Techniques
or methods for estimating or quantifying NH3 flux from a source to the atmosphere include nitrogen mass balance,
micrometeorology, flux chambers, models, and emission factors. Of these techniques, emission factors, once established,
provide the most convenience in estimating emissions. However,it is important to understand how a particular emission factor
is determined and whether it accurately reflects a composite or average emission for all the variable conditons. Using an
average ammonia emission factor multiplied by pig inventory to determine a regional or national ammonia emission inventory
may be misleading, especially in the U.S. where existing emission factors were developed using data from swine facilities in
Western Europe. 
Housing, manure management practices, and climate vary among different regions of the U.S. and can be very different
from those in Western Europe. In addition, ammonia concentrations and emission estimations have been determined with a
variety of methods, making it difficult to compare results. To determine representative ammonia emissions from confined swine
feeding operations, it is important that emission factors be specific enough to account for animal type and size, housing
system, manure storage and treatment, land application, and climatic effects. This article describes the strengths and
limitations of emission factors as currently used and provides recommendations for determining realistic ammonia emission
factors for swine feeding operations. Because of the limited nature of the data published in the literature, emission factors
for different animal management systems could not be presented. 
Regulators, consultants, cooperative extension personnel, and other leaders in the agricultural community with interest
in ammonia emissions should be aware of the lack of reliable U.S. data available for calculating accurate emission factors.
The scientific research community should standardize methods for measurement, calculation, and reporting of ammonia
emissions.

Philip W. Westerman

Papers

Management considerations for organic waste use in agriculture.

Wood chips and wheat straw as alternative biofilter media for denitrification reactors treating aquaculture and other wastewaters with high nitrate concentrations

A review of ammonia emissions from confined swine feeding operations

Water treatment and waste characterization evaluation of an intensive recirculating fish production system

Long-term swine lagoon effluent applications on coastal bermudagrass. II, Effect on nutrient accumulation in soil