2.2 ROLES AND DESIGN CONSIDERATIONS IN AB WASTES

SOLID PHASE, LIQUID PHASE, GASEOUS PHASE

SOIL PHASES

SOLID PHASE

Consists of minerals (gravel, sand and silt) and organics (humus, plant and crop residues)

Nutrients depends on biological, chemical and physical makeup.

LIQUID PHASE

It is called as soil solution. It consists of water with dissolved minerals and nutrients.

Oxygen and carbon dioxide can also dissolved in the soil solution.

GASEOUS PHASE

It occupies the pore space that is not filled with water.

Nitrogen, oxygen, water vapor, and carbon dioxide are the primary gases from the air and living organisms.

Filtration

It is the capture and subsequent degradation of manure solids in the soil matrix.

It reduces bio-stimulants as phosphates and nitrates as phosphates and nitrates, provide long-term storage of heavy metals, suppress pathogens, and degrade pesticides

Biological degradation

The physical properties of the soil such as temperature, moisture oxygen supply, pH, and nutrients affects the microbial growth and metabolism.
Decomposition of organic material on waste its reduces impact on polluting air and water bodies.

Chemical reactions

It includes ion exchange, adsorption, precipitation, and complexation.

Ion exchange

includes cations and anions wherein the positivelty/negatively charged particles of waste is exchanged with soil particles and organic materials.

Adsorption

occurs when the ions are attached to soil surface

precipitation

occurs when soluble compounds is deposited in soil voids.

Complexation

is the interaction of metals with soil organic matter and some oxides and carbonates, resulting in the formation of large, stable molecules.

Mineralization

occurs through physical, chemical and biological conversion of waste into inorganic forms making them available to plants
Inorganic materials released during this process are the essential plant nutrients (N, P, K), macronutrients and micronutrients, salts, and heavy metals.

Organic waste mineralization

is a process where microbes digest organic waste to convert into inorganic or more stable organic materials.

Cation Exchange Capacity (CEC)

The ability of the soil to hold nutrients and release them through chemical reactions for plant uptake
MANURE - increase CEC

pH

A measure of the level of acidity or alkalinity in the soil. It is essential for plant nutrition, growth and soil’s biological and chemical activity

MANURE - Keep pH in normal levels

Bulk Density

Amount of solid particle weight per volume of such mass of soil. It reflects the level of porosity (void space in the soil that can be filled by air or water) and compaction of the soil. Compacted soils (higher bulk density) have less porosity, lower air content, lower water infiltration, and poor plant growth.
MANURE - reduce bulk density

Earthworms Population

Earthworms help accelerate biomass decomposition, nutrient cycling and building a better pores system for water infiltration and retention.

MANURE - Increase soil biological activity

Microbial Biomass Carbon and Microbial Respiration

Laboratory measurement used as an indicator of the microbial abundance in the soil. Both are directly related to the general biological activity, which influences the nutrients availability for crops and the generation of the substances that act as a “glue” to help build more stable soil aggregates

MANURE - Increase soil biological activity

Animal manure

is an example of a waste by-product that can be used as a plant nutrient.

Filtration, Biological degradation, Chemical reactions, Chemical reactions

SOIL-MANURE INTERACTION

PLANT-SOIL SYSTEM

The roots of the plants absorbs the nutrients of soil which includes both macronutrients and micronutrients.

Macronutrients

are the building blocks for plant growth which is required in large quantities. It includes nitrogen, phosphorus, magnesium, and potassium. Nitrogen, phosphorus, magnesium, and potassium are nonmineral class of macronutrients.

Micronutrients

are elements required for balance growth of plants which constitute in less than 1% of its dry weight. Essential micronutrients includes boron (B), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), molybdenum (Mo), chlorine (Cl).

Soil

provides anchorage to roots thereby stabilizing plants.
The spaces among soil particles provides oxygen and water needed by plants.

Vegetative cover

prevents soil from erosion and drought.

An analysis of the waste material

Heavy applications of waste can cause elevated levels of nitrates

Animal manure releases ammonia gas upon drying.

Applying manure at rates based on nitrogen requirements

The soluble salt content of manure and sludge is high

After prolonged application of manure, the soil electrical conductivity should be tested

Too much application of manure will lead to toxicity

Sewage sludge is not recommended to tobacco

Organic materials or manures are normally applied uniformly across the field

Legumes, such as alfalfa, peanuts, and soybeans, benefit less by manure and sludge additions

Surface application on the soil surface around fruit trees

Well composted manure

Well composted manure

APPLICATION CONSIDERATIONS OF AGRICULTURAL WASTE

Groundwater

provides water supply for human consumption. It provides drinking water entirely or in part for as much as 50% of the global population and accounts for 43% of all of water used for irrigation.

It is a source of recharge for lakes, rivers, and wetlands.

is recharged naturally by rain through infiltration and deep percolation.

Major aquifers are being depleted as population grows due to its demand. Recharge is also impeded by human activities including paving, development, or logging.

Pollution degrades the quality of groundwater and poses a threat to human and ecological health.

• pesticides and fertilizers

• livestock wastes

• antibiotics

• silage effluents

• processing wastes from plantation crops

Common source of groundwater contamination in agriculture

nitrogen and phosphorus

Animal manure has significant amount of

nitrate

Excessive — consumption can cause methemoglobinemia (“blue baby syndrome”), certain cancers, and adverse reproductive effects

phosphorus

Excessive — consumption can cause problems with bones

Pathogens

that contaminates groundwater such as various bacteria, viruses, and protozoa causes different outbreaks.

heavy metals

from agricultural wastes such as arsenic, fluoride, mercury, and lead, also contaminates groundwater.

Proper storage and treatment of manure

Clean water diversion to prevent

Composting

Pasture space should be adequate

Feedlots must regularly scraped and collection systems must be properly designed

PREVENTING ANIMAL WASTE FROM REACHING GROUNDWATER