Organic and Mineral Fertilizers
Organic and Mineral Fertilizer: Differences and Similarities.
Fertilizers are materials that are applied to soils, or directly to plants, for their ability to supply the essential nutrients needed by crops to grow and improve soil fertility. They are used to increase crop yield and/or quality, as well as to sustain soils’ ability to support future crop production.
Mineral fertilizers are produced from materials mined from naturally occurring nutrient deposits, or from the fixation of nitrogen from the atmosphere into plant-available forms. Mineral fertilizers generally contain high concentrations of a single, or two or three, plant nutrients.
Organic fertilizers are derived from plant matter, animal excreta, sewage and food waste, generally in the form of animal manure, green manure and biosolids. Organic fertilizers provide essential nutrients needed by crops, generally containing a wide variety in low concentrations. They also play an important role in improving soil health.
Organo-mineral fertilizers combine dried organic and mineral fertilizers to provide balanced nutrients along with soil health improvements in a long-lasting, easy-totransport and store form.
Organic and Mineral Fertilizers Are the Same to Plants .
Mineral and organic fertilizers contain nutrients in different forms. Ultimately, however, because plants can only take up nutrients in their mineral form, the original fertilizer source makes no difference from a plant nutrition standpoint. No matter what the source, all nutrients are used in exactly the same way by plants with the same effect.
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Mineral Fertilizers: Feeding the World.
Today, it would be impossible to feed the planet without mineral fertilizers. The nitrogen produced by the Haber-Bosch synthesis process for mineral fertilizers is vital for producing large crop yields. Scientific research published in 2008 estimated that the lives of nearly half of the world’s population (48%) are only made possible by Haber–Bosch produced nitrogen. (Erisman et al., 2008)
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Organic Fertilizers: Feeding the Soil.
Organic fertilizers increase soil health, supporting carbon capture and plant growth. Soil organic matter (SOM) has a strong influence on the overall health of soil and its beneficial functions. By introducing soil organic carbon that helps build up SOM, organic fertilizers stimulate microbial activity, improve soil structure and increase both its water-holding and cation exchange capacity. This can reduce soil erosion and degradation, improve nutrient retention, act as a buffer against soil acidification and limit nutrient losses into waterways. Increased SOM also increases soils’ capacity to capture carbon.
Mineral Fertilizers: Providing Precise, Plant Ready Nutrients When Needed.
By offering concentrated, consistent, precise, accessible and easily transportable and storable nutrients, mineral fertilizers have a variety of beneficial properties that organic fertilizers alone cannot supply:
Standardized Nutrient Content
Mineral fertilizers are made with standardized and concentrated amounts of specific nutrients, allowing farmers to consistently give optimal nutrient doses to crops. The amount can even be precisely adjusted to meet the varied nutrient needs of small areas within a field, ensuring that an entire crop gets the right nutrient quantities for maximum yields. Mineral fertilizers can contain up to 820 grams of nitrogen, 620 grams of potassium and 550 grams of phosphorus per kilogram, over 20 times more than organic fertilizers usually contain.
Constant Variation
Organic fertilizers, on the other hand, have variable nutrient content that changes over time. To get an accurate idea of nutrient levels each batch would need to be tested. Relying only on organic fertilizers may not be sufficient to consistently give plants the right amount of nutrients they need at the right time for optimal growth and health. There is also a greater risk of applying excessive amounts of certain nutrients, which can damage plant and soil health and negatively impact the environment.
Table 1. General nutrient content values of crop residues and poultry and livestock manures (Adapted from Barker et al. 2000).
Readily Available to Plants
The nutrients in mineral fertilizers are formulated to be readily available to plants, absorbed either directly through their roots or leaves. As a result, they can be applied at just the right time they are needed for the most efficient uptake during a plant’s growth cycle, for example by micro-dosing during planting, minimizing nutrient losses to the environment while maximizing their efficiency.
Slow, Inconsistent Release
Storage and Transport
Limited Lifespans
Due to being quite volatile, organic fertilizers generally need to be used soon after production and are difficult to store for long periods. Manure, for example, produces anaerobic decomposition resulting in methane emissions when stored and should be applied to fields as soon as possible. Organic fertilizers are also bulky and difficult to transport. As such, their supply can be seasonal, limited or entirely unavailable to farmers without local sources.
Slow- and Controlled- Release and Stabilized Fertilizers.
Several additives and treatments have been developed to modify the availability of nutrients in mineral (and even some organic) fertilizers. These include ‘slow-release fertilizers’ that break down gradually to release plant available nutrients (e.g. methylene urea), ‘controlled-release fertilizers’ that are physically encapsulated in a protective coating (e.g. polymer-coated fertilizers), and ‘stabilized fertilizers’ that slow N cycling in the soil (e.g. fertilizers treated with urease and/or nitrification inhibitors). All these products aim to extend the release of the nutrients from mineral fertilizers to better match crops’ requirements.
Mineral and Organic Fertilizers: The Perfect Combination.
When it comes to using organic and mineral fertilizers there really need not be any competition. Using a combination of the two has been scientifically proven to be the best solution for maximizing plants yields and sustaining healthy soils with the greatest ability to sequester carbon in agricultural soils. Within IPNM, both types of fertilizer have a complementary role to play. Mineral fertilizers supplement the nutrients provided by organic fertilizers with concentrated, consistent and plant accessible nutrients. Organic fertilizers provide beneficial SOM that improves soils’ health (including fertility, structure, water retention capacity and biological activity), and ability to sequester carbon.
Integrated Plant Nutrient Management: Increasing Productivity and Food Security on Existing Land.
Based upon agricultural research findings across numerous countries and diverse agroecological zones of sub-Saharan Africa, for example, a consensus has emerged that the highest and most sustainable gains in crop productivity per unit of nutrient are achieved from mixtures of mineral and organic fertilizers.
