Soils Health

The foundation of sustainable agriculture is soil fertility, a term that encompasses:

• the soil’s nutrient content,
• the amount of soil organic matter (SOM),
• the soil structure,
• its pH balance, and
• the presence of microorganisms.

Most soils lack at least some plant nutrients, and growing crops remove nutrients from the soil. Soil nutrients must be replenished when removed and supplied when deficient.
Traditional methods for restoring soil fertility, which entail long fallow periods and shifting agriculture into new areas, may contribute to deforestation, given current pressures on land use. Although historically relevant, these practices no longer suffice to meet the needs of the current and future population levels.

Organic sources of nutrients
Organic sources of nutrients provide fewer nutrients than most people think (and these are not necessarily in plant-available forms), but they are usually excellent for improving other aspects of soil fertility.
The main nutrients in most fertilizers — nitrogen, phosphorus and potassium — come from the land and the air. They exist in crop residues, manure and waste but their plant available forms are not abundant enough for the level of agriculture needed to produce food, feed, fibre and bioenergy to more than 7 billion people.

Inorganic sources of nutrients

Inorganic sources ("manufactured" fertilizers) contain only plant-available nutrients and therefore have no direct influence on soil structure or on the presence of microorganisms. This is why agronomists generally consider it optimal to use both organic and inorganic sources together, a technique called Integrated Plant Nutrition Management (IPNM).

Soils Degradation

Erosion and desertification

When soils are not replenished after every harvest with the necessary micro- and macronutrients it needs, it becomes gradually depleted and less fertile, thus more prone to environmental problems, such as erosion and desertification.

Whereas in the developed world, excess application of fertilizer and manure is sometimes blamed for damage to the environment, the low use of inorganic fertilizer is one of the main causes for environmental degradation in Africa.

Bationo, Alliance for a Green Revolution in Africa (AGRA)

Desertification is the degradation of land in arid, semi-arid and dry sub-humid areas, primarily caused by human activities and climatic variations. Although other regions, mostly in Asia and Latin America, are also concerned, the most dramatic examples of desertification are found in Africa, where declining soil fertility is linked to declining agricultural productivity.
Managing soil fertility helps in several ways. High levels of soil organic matter improve water retention. Furthermore, fertile soils can support a more vigorous crop cover, which can help prevent erosion that contributes to desertification.
Improving land productivity is necessary to manage soils and the land. By enhancing farmers' access to improved technology and inputs, especially credit and mineral fertilizers, they can best steward their soils and land and improve their livelihoods.
Farmers will be more successful if they learn to combine locally available organic resources and mineral fertilizers to build up soil fertility and to improve fertilizer use efficiency.

Soil degradation in Africa

Low use of fertilizers is one of the main causes of environmental degradation in Africa. Intensification is needed to feed growing populations, but it must be done in a way that uses soil nutrient and water resources efficiently and that relieves pressure on forests and other fragile lands.

Farmers in sub-Saharan Africa have traditionally cleared land, grown a few crops, then moved on to clear more land, leaving the land fallow to regain its fertility. But population pressure now forces farmers to grow crop after crop, ‘mining’ the soil of nutrients. Africa loses an estimated $4 billion worth of soil nutrients yearly, severely eroding its ability to feed itself. This has led two former World Food Prize Laureates to call this situation a 'catastrophe'.

Olusegun Obasanjo, former President of Nigeria

Solutions need to provide timely and affordable access to agricultural inputs (fertilizers, improved seeds, crop protection products, etc.), credit facilities, infrastructure and market opportunities. Successful approaches have entailed building farmer capacity by:

• forming cooperatives and teaching business skills,
• credit and insurance schemes for farmers, retailers and wholesalers,
• vouchers to purchase inputs from private-sector dealers,
• providing market and agronomic information through the internet and mobile phones,
• and multi-stakeholder public-private partnerships around specific agricultural development corridors.

Integrated Soil Fertility Management (ISFM)

There is a common misconception that supporting the use of manufactured fertilizers means opposing the use of organic sources of nutrients. Nothing could be further from the truth.
In fact, most agronomists agree that optimal nutrient management entails starting with on-farm sources of nutrients and then supplementing them with manufactured fertilizers.
The integration of organic and inorganic sources of nutrients should also be seen in the context of overall crop production, which includes the selection of crop varieties, pest control, efficient use of water and other aspects of integrated farm management.
Manufactured fertilizers and organic sources of nutrients can, and should, be used in a complementary fashion.

Organic Fertilization

Organic farming is a farming system that promotes, among other practices, the use of organic fertilizers (manure, compost, crop residues). Organic matter is an essential component of healthy soils, and all sound farming practices integrate and allocate available organic materials to maintain or improve soil fertility. Although inorganic sources of nutrients are often called "manufactured" or "chemical" fertilizer, all of these nutrient forms exist in nature and are a vital part of the natural cycles that provide plant nutrition.

What are the limitations for a global adoption of organic farming?

• Volume : In many countries, particularly in developing countries, the availability of organic sources of fertilizers is simply insufficient for crop needs. Because organic fertilizers are low in nutrient content, high application rates are needed to meet crop nutrient requirements. The nutrient content, composition and release rate of organic fertilizers is variable and unpredictable and, therefore, it is extremely difficult to ensure a timely and steady supply and the correct balance of all the essential elements for healthy plant growth.
• Availability- In most regions with low agricultural productivity or with limited livestock production there is a lack of organic matter. Yields are not sufficient to produce crop residues that can be recycled for compost and farms do not have enough livestock to produce manure. These farms are caught in a vicious cycle where their soils become less productive and in turn less nutrients and organic matter are available to improve soil fertility.
• Competition- In other regions with good productivity rates, organic sources of nutrients may be used for competitives uses, in particular energy production, and thus cannot be used for crop nutrition purposes.
• Food safety- Organic sources of nutrients are not subject to the same level of safety control as mineral fertilizers. Heavy metals, toxins and bacteria may be present, in particular in manure. It is imperative that food safety standards look in detail at the significant pathogen risks posed by organic fertilizers, as shows by E.Coli outbreaks in organic food products in the US and in Europe traced back to improperly composted organic nutrient sources.

Combining organic and mineral fertilizers is the best strategy

Independent scientific studies show that combining inorganic and organic sources of plant nutrients is a beneficial option for the crop and soil system and hence can be of great benefit to both farmers and the environment. Integrated organic and inorganic nutrient sources can improve soil fertility, enhance soil organic matter content and limit both nutrient and soil losses. This integrated plant nutrition approach is an appropriate strategy for effective and responsible plant nutrition. IFA advocates for:

• The removal of scientifically unjustified requirements imposed by organic farming guidelines on agronomically effective and economically valid inorganic fertilizers. Since guidelines for organic farming practices are not necessarily science-based, it should be clearly specified that the justification for not allowing some inorganic fertilizer sources is for marketing purposes only and not for food or environmental safety reasons.
• Sound science as the basis for food and environmental safety standards, applied equally to all fertilizer sources used to supply nutrients for food production.
• Uniform descriptions of available nutrient content for all fertilizer products, whether of organic or inorganic origin.