Synthetic and Inorganic Fertilizers

Synthetic/Inorganic Fertilizers

• Properties are determined by the content of mineral matter or synthetic chemical compounds
• May be in liquid or solid form
• Contain at least one essential plant nutrient, like nitrogen, phosphorus, potassium, secondary macronutrients, and micronutrients
• Nutrients increase the quantity and quality of food crops, flowers, and plants
• High nutrient content results in rapid growth and higher yields

Negative Effects of High Nitrogen Fertilizer Use

• Can make soil acidic, leading to high nitrate accumulation in plants
• The use of fertilizers such as urea (45-0-0) or complete (14-14-14) can result in deficiencies of other nutrients
• The continuous use of synthetic fertilizers alone does not add organic matter, degrading the soil structure
• Excess fertilizer in the soil inhibits the growth of nitrogen-fixing microorganisms

Effects on human health from fertilizers

• Leaching from synthetic fertilizers causes ground water pollution and health problems
• Drinking water with a nitrate concentration greater than 45 ppm can cause methemoglobinemia
• Methemoglobinemia is a disease affecting both livestock and human infants
• Nitrates in food or the digestive system combine with protein to form nitrosoamines, which are carcinogenic
• Synthetic fertilizers contain about 80% ammonia
• Farmers are exposed to ammonia from inhalation of the gas or vapors from fertilizers

Environmental effects of fertilizer

• Nitrogen and phosphorus runoff into streams, lakes, and rivers causes an overgrowth of algae
• Lower oxygen level in water from the death of algae
• Eutrophication occurs from rapid plant growth, increased decomposer activity, and depletion of oxygen

Soil Acidity and Fertilizers

• Excessive chemical fertilizer use in Loo Valley, Benguet Province lowered soil pH to an average of 4.4
• Acid soils are vulnerable to erosion
• Acidity depletes fertility and lowers the amount of essential nutrients in the soil
• Soil microbes responsible for nutrient release are negatively affected

Climate Change and Fertilizer

• Synthetic nitrogen fertilizers like urea and ammonium nitrates become contributors to N2O (nitrous oxide) pollution
• One N2O molecule equals 310 Co2 molecules in its greenhouse effect in the atmosphere
• Synthetic fertilizers contribute to climate change through nitrous oxide (N2O), methane (NH4), and energy used in manufacturing
• An estimated 40% of energy used in the food system is devoted to the production of synthetic fertilizers and pesticides

Organic Fertilizers

• Defined by the Philippines National Standards for Organic Fertilizers (PNS-OF 2013)
• Refers to any product in solid or liquid form that has undergone substantial decomposition
• It can supply available nutrients to plants with a total Nitrogen (N), Phosphorus (P), and Potassium (K) of 5 to 7 percent
• May be enriched with Microbial Inoculants and naturally occurring minerals
• Similar material with a total Nitrogen (N), Phosphorus (P), and Potassium (K) of 2.5 to less than 5% is called COMPOST or Soil Conditioner
• Natural fertilizers that provide necessary nutrients for plants
• Nutrients release gradually from organic matter
• Improves:
  • physical
  • chemical
  • biological properties of soil

Advantages and Disadvantages of Organic and Synthetic Fertilizers

• Table 4.1, Cosico 2011

Quality Standards

• Philippines National Standards for Organic Fertilizers (PNS-OF) of 2008 are revised by the Bureau of Agriculture and Fishery Product Standards (BAFPS)
• Should meet quality standards before sale
• Should protects farmers and buyers from poor quality
• The need to follow recommended procedures and meet standards is critical

Meeting Qualities

• Organic fertilizers for sale should have qualities presented in Table 4.2.
• Addition with synthetic fertilizers is prohibited
• Has a presence of pathogenic microorganisms and infective parasites is prohibited
• Heavy metals above allowable limits are prohibited
• Table 4.2 Draft: Quality standards for solid organic fertilizers (PNS-OF 2013).

Making Our Own Fertilizers

• Organic agriculture promotes self-sufficiency
• Commonly regarded farm wastes such as animal manures, crop residues, rice straws, cut weeds, and leaves of multi-purpose trees can be used as raw materials
• Microbial inoculants may be added to hasten the decomposition process
• Should consider the raw materials and production process

Raw Materials and Fertilzers

• The use of guano and natural rock deposits such as dolomite, limestone and rock phosphates is restricted
  • Possible depletion of natural resources
  • Concerns of environmental sustainability
• Risk of accumulation of trace elements and heavy metals after prolonged use
• Prohibited:
  • human excreta
  • Chilean nitrite
• Animal manures are good fertilizers with high contents of:
  • macro nutrients (N,P,K)
  • micro nutrients (boron, manganese, cobalt, copper, zinc and molybdenum)

Composting Method

• A mixture of organic raw material is left to decompose under controlled conditions
• Produces a stable end-product (organic fertilizer or soil conditioner)
• A basic procedure for small-scale composting (Zamora, 2009; Cosico 2011):
  • Choose a shaded area that will provide protection from heavy rains
  • Avoid direct sun exposure
  • Gather raw materials and pile them in alternate layers
  • Pile should be about 50-80cm high
  • Wet each layer to provide adequate moisture
  • Optimum moisture content is about 50-60%
  • Cover the pile to retain moisture
  • Build heat in the compost pile to kill disease-causing organisms or pathogens and weed seeds.
  • Turn over or mix the pile with a spading fork after 3-4 weeks to aerate the pile
  • Repeat this after every 3-4 weeks. Turning or mixing the pile provides aeration and removes methane gas.
  • The compost would be ready for harvest in 3-4 months
  • The composting process can take a longer time if the heap does not have enough moisture and aeration

Enhancing the composting process

• Add a single microbial inoculant such as Trichoderma to enhance the composting through rapid decomposition
• Farmers use Multi-strain inoculants to hasten the composting process
• Multi-strain inoculants:
  • Effective Microorganisms (EM)
  • Indigenous Micro-Organisms (IMO)
  • Fermented Plant Extracts (Fermented Plant Juice (FPJ) and Fermented Fruit Juice (FFJ)

Modified Composting Method: Vermicomposting

• Vermicomposting uses earthworms
• The worms' excreta is called "vermicast"
• Vermicast:
  • high in nitrate
  • high available forms of phosphorus
  • high in potassium
  • high in calcium
  • high in magnesium
• Bacteria and actinomycetes are over six times greater in vermicast than in the soil

Fermentation

• Fermented Plant Extracts are more popularly called Fermented Plant Juice (FPJ) and Fermented Fruit Juice (FFJ)
• Referred to as Foliar Fertilizer
• Contain little amounts of N, P, and K – too little to qualify as fertilizers
• Contain secondary macro and micronutrients needed by plants for growth
• Fermented extracts has been analyzed

Microbial Inoculants for Supplements

• FPJs and FFJs are like liquid organic fertilizers, the microorganism improves the effect
• During 2nd meeting of the PNS-OF Technical Working Group, those products as “organic plant food supplement”
• Other extracts:
  • Fish Amino Acid (Fish Emulsion)
  • blood meal
  • bone meal
  • seaweed extracts

Microbial inoculants

• Biologically active products with beneficial bacteria, algae, and fungi.
• Useful in:
  • decomposition of organic residues
  • nitrogen fixation
  • nutrient availability to plant roots
• The microorganism colonizes the rhizophere around the plant root hair
• Can improve plant growth or availability of nutrients
• Sometimes called biofertilizers
• Biological products developed at:
  • national Institutes of Biotechnology and Microbiology (BIOTECH)
  • Institute of Biological Sciences (UPLB)
• Bio N, MykoVAM and Biogree are known examples

Using Organic Fertilizers

• The method of application and timing is of value
• Should be applied to critical stages of plant growth:
  • seedling
  • vegetative
  • fruiting stage
• Incorporate into the soil 1-2 weeks before the stage of critical crop growth
• Liquid Organic Plant Food Supplements are usually diluted with water (3-5% by volume)
• Follow specific recommendations in their labels to ensure strict microbial inoculants