Fertilizer Issues Primer

 What are fertilizers?

Think of fertilizers as plant food. Fertilizers are combinations of the nutrients that plants must have to grow, in a form they can use. The primary nutrients in fertilizers needed in the largest quantities are nitrogen (N), phosphorus (P) and potassium (K), which are often combined into an NPK blend. The secondary nutrients, sulfur (S), calcium (Ca) and magnesium (Mg), are needed in smaller amounts for normal plant growth. Micronutrients are also needed but in even smaller quantities. Micronutrients include boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni) and zinc (Zn). People require the same nutrients. These plant nutrients can be supplied through organic fertilizers such as plant residues or livestock manure, or mineral fertilizers, which are chemically processed to meet crop needs.

Plants generally need more nitrogen than phosphorus or potassium. Nitrogen is contained in chlorophyll, the factory of photosynthesis, and colors leaves green; nitrogen is the major component of most fertilizers. Phosphorus is the engine in the photosynthesis process that transports energy. Potassium helps plants fight stresses and disease and grow strong stalks.

Most nitrogen in mineral fertilizers is drawn from the air – which is 80 percent nitrogen – through an industrial process, and then highly pressurized to convert the nitrogen to ammonia. The ammonia is then converted to various nitrogen-based fertilizers, such as granular urea and liquid ammonia. Phosphorus, potassium and most secondary or trace nutrients are mined from underground deposits.

All plant nutrients, whether found in organic or mineral fertilizers, are the same, but mineral fertilizers have the advantage of concentration, and nutrients can be blended to meet specifications. Thus, mineral fertilizers can be better “targeted” to meet the nutritional needs of specific plants and soils. Organic fertilizers often contain a wide range of nutrients, including micronutrients, and generally help to improve soil health; yet the use of organic fertilizers alone are insufficient to secure food production.

Suggested editorial topics: “Plant Nutrients are People Nutrients, Too”; “Nutrients from the Air”; “A Perfect Blend: Nourishing the World with Fertilizers”


Why do we need fertilizers?

As plants grow, they absorb and deplete ("scavenge" or “mine”) nutrients from the soil. Farmers harvest those same nutrients when they harvest crops. Fertilizers, whether mineral or organic, nourish the soil by returning essential mineral nutrients.

It is a biological fact that plants require about 1.0 kilogram (kg) of nitrogen to produce 50 to 75 kg of grain. Our atmosphere is about 80 percent nitrogen. Some plants, primarily legumes, live in symbiosis with bacteria that “fix” nitrogen drawn from the atmosphere. This natural process fixes enough organic fertilizer nitrogen to produce an absolute maximum of about 2 to 2.5 tons of grain per hectare. To produce more grain, the plants must have more nitrogen from mineral fertilizer sources. Plants must also have phosphorus, potassium and the other (secondary and micro) nutrients. Most soils in the world contain insufficient amounts of these minerals and must be supplemented by fertilizers to prevent stagnation or cessation of production.

Suggested editorial topics: “How Much Fertilizer is Required to Feed the World?”; “Healthy Soils Mean Healthy People”


How have fertilizers benefited the world?

About half of the world’s population is alive today because of increased food production fueled by mineral fertilizers. Fertilizers and other inputs (improved seed and crop protection products) give the industrialized countries inexpensive food. For example, the average U.S. farm feeds about 150 Americans for a year, with a balance to export worldwide. U.S. citizens spend only about 10 cents of each dollar on food, so they have 90 cents for other things. Most rural families in Africa spend as much as three-fourths of their income on food. Little is left for necessities such as education of children and health care.

The Green Revolution – which generated dramatic increases in food production in Asia and Latin America – occurred because of higher crop yields. These yields were made possible through the use of improved seeds and inputs, particularly mineral fertilizers. The Green Revolution is credited with feeding more than one billion people in Asia alone. The far lower increases in food production in Africa have been gained primarily by bringing marginal land into production, which further threatens Africa’s endangered wildlife and ecosystems and keeps poor people poor and food insecure.

The late Nobel Laureate Dr. Norman Borlaug, often called the “father of the Green Revolution,” has called improved seeds the “catalysts that ignited the Green Revolution” and mineral fertilizer the “fuel” that powers it.

Suggested editorial topics: “Fertilizers Keep How Many People Alive?”; “The Green Revolution: Its History and its Legacy”


Isn’t it true that fertilizers can be detrimental to the environment?

Poor management of plant nutrients – whether as organic amendments or mineral fertilizers – can cause the loss of some nutrients to the environment, where they can upset the balance of natural ecosystems. Nitrogen may also volatize – be lost as a greenhouse gas that affects the atmosphere. But if a farmer uses appropriate agricultural practices, the crop will absorb most applied fertilizer.

Using too few crop nutrients also has devastating environmental effects. In the 1930s – before mineral fertilizers were widely used – nutrient depletion was widespread on many agricultural lands in North America. The result was the “Dust Bowl” era, with its extensive wind erosion and massive dust storms.

Africa today faces a soil fertility crisis. African soils are losing at least $4 billion worth of soil nutrients yearly. Three-fourths of the farmland in Sub-Saharan Africa is plagued by severe nutrient depletion, and 46 percent of the African continent suffers from desertification. African farmers desperately need Integrated Soil Fertility Management (ISFM) practices that include organic and mineral fertilizers to bring life back to the depleted soils, and to feed the continent’s inhabitants.

If production on existing farm land is not intensified, African farmers will continue to bring marginal land into production – further threatening humans and nature.

Suggested editorial topics: “Balancing Fertilizer Use, Environmental Stewardship and Feeding the World”; “Africa’s Soil Fertility Crisis: What’s Being Done