Reasons you need to know why people should appreciate the true value of organic fertilizer in Agriculture.
By Rebecca Cagmat PHD
The term “Organic” has come to be associated with many things over the last few years, including movement, processes, substances, and products, particularly fresh produce. But it originally referred to the chemistry of the element carbon, which can be
found in food, ﬂowers, fragrances, and the tissues of all living things, including human beings.
Organic agriculture, according to IFOAM (International Foundation of Organic Agriculture Movement), includes agricultural systems that promote environmentally, socially and economically sound production of food fibers and bio-fuels. On the other hand, organic farming is a form of agriculture that relies on techniques such as crop rotation, green manure, compost, and biological pest control. It does not allow the use of pesticides, inorganic fertilizers, GMO (genetically modifed organisms), antibiotics, and growth hormones.
ORGANIC FERTILIZERS – Organic fertilizers are sources of nutrients of plant and animal origin, or living things. It also refers to a soil amendment derived from plant and animal sources that contains nitrogen, phosphorus, and potassium—the three fertilizer elements. It can also be of microbial origin. It is the required organic input in organic forming.
Some examples of plant materials that can be applied as fertilizers are grass clippings, legume cover crops, green manure cover crops, leaves, rice straw, and corn stalks. Organic fertilizers are also made from industrial waste like sugarcane bagasse, coffee pulp and shell, sawdust, and seaweeds.
Plant-based fertilizers have lower nutrient content but have more biomass (organic matter than can be used as fuel). Plant parts that cannot be decomposed easily, such as woody parts whose component is mainly lignin, are not a good source of fertilizer nutrients. However, these form the bulk of humus, which remains in the soil for a longer period, maybe a
thousand years. It acts more as a soil conditioner that promotes aggregation, enables it to hold more water, and makes the soil more porous.
Fertilizers from animal sources are manure, urine, and animal byproducts such as blood meal, fish meal, and bone meal. Fertilizers from animal products have a higher population of microbial decomposers and higher nutrient content, and decompose faster compared to plant materials. These organic fertilizers may be applied fresh, dried, or processed.
Other materials that can be considered as organic fertilizers are bio-fertilizers. Bio-fertilizers are materials containing living microorganisms. These can be applied to seeds, plant surfaces, or as decomposers. Bio-fertilizers are supposed to promote growth by increasing supply or availability of nutrients to the host plant. Some examples of biofertilizers available in the Philippines from UPLB-BIOTECH (UPLB-National Institute of Molecular Biology and Biotechnology) are the following:
1. Biogroe: a plant growth promoter for vegetables and ornamentals
2. Bio-N: a microbial-based fertilizer that supplies nitrogen and enhances growth of rice, corn, and vegetables
3. Brown Magic: contains effective growth enhancers and provides for bio-control of root diseases of various orchid species
4. Bio-Green: bioorganic fertilizers from industrial waste with the fungus Trichoderma and nitrogen fxing bacteria
5. Bio-Quick: composting inocula containing the fungus Trichoderma
6. Bio-Fix: an enrichment inoculant
7. Mykovam: a soil-based biofertilizer for fruit trees, agricultural crops, reforestation species, and ornamentals
8. Nitroplus: a nitrogen supplement for legumes such as peanut, sitao, soybean, and mungbean.
9. VAM Root Inoculant: promotes growth of agricultural and horticultural crops, trees, and ornamentals
Organic fertilizers may be prepared and applied in various ways; each has distinct benefts and limitations.
Manure may be applied fresh by broadcasting or incorporation into the soil. Crop residues may also be directly applied, provided it is cut to a suitable length. The quality of crop residues and manure as fertilizer may be enhanced by composting. Composting is the process by which organic materials are decomposed by microorganisms. The product is compost, and this can be applied as fertilizer or soil conditioner.
The raw materials for composting are kitchen refuse, crop residues, and farm manure. Industrial waste products may also be used as a raw material for composting, such as sugar
cane bagasse, coffee grounds, rice and peanut hulls, and meal. Although there are a number of composting technologies, an awareness of the conditions necessary for this biological process to proceed is a must to generate compost of superior quality. Gaining popularity as decomposers are earthworms. However, the substrate and growth conditions are more exacting.
BENEFITS OF ORGANIC FERTILIZERS – Organic fertilizers contain all the 17 essential nutrients taken up by the plants from the soil. It is present in their biomass. When used as feed or food by animals, the nutrients will be present in their waste. When applied as fertilizers it is a valuable nutrient source for plants.
Organic fertilizers are biodegradable and the decay process can only be brought about by soil microorganisms. The process releases the nutrients in a form that can be absorbed by plant roots. Thus, organic fertilizers can be considered as slow release fertilizers. They are less likely to be subject to leaching and loss in gaseous form.
Another important advantage of organic fertilizers is its impacton the environment. It is a solution to problems of waste disposal. Crop residues and byproducts (including farm animal waste products) may be processed into compost. This can generate employment and provide an additional source of income for farmers. Application of this fertilizer can recycle the nutrients back to the farm from which it was removed. The materials are renewable and therefore more sustainable.
A very important beneft of organic matter fertilizer is that it gives the soil favorable physical properties. No amount of inorganic or synthetic fertilizers can result in such benefts. It is only organic matter that can promote aggregation. The primary particles of sand, silt, and clay are ‘cemented’ by the byproducts of decay and form bigger particles called aggregates. Well-aggregated soil is more porous, less compact, and can hold more water. Thus the soil is not prone to erosion. Organic matter maintenance is an important soil conservation practice.
However, organic matter is not a cure-all soil amendment. There are a number of limitations to using organic over inorganic materials. Organic fertilizers have variable compositions and low nutrient content. The nutrient composition of organic fertilizers depends on the organic materials used. Crop residues with low nutrient content such as rice straw and corn stover should be combined with animal manure to hasten decomposition and increase the nutrient content.
Since decomposition is a biochemical reaction, it is dependent on optimum conditions for the growth and activities of the microbial decomposers. As a result, the nutrients are not immediately absorbed by plants, unlike inorganic fertilizers.
This story appeared in Agriculture Monthly’s May 2017 issue.