International Fertilizer Industry Association (IFA’s Literature)

Crop quality comprises all those properties of the harvested product that contribute to its value to the consumer. These include:

1. external qualities — colour, appearance and grading, 2. compositional qualities all dependent on chemical composition — taste and flavour, energy-value (i.e. calorie content), protein content, biological value of the protein, mineral content, vitamin content, 3. storage and transportation qualities (for storage of varying duration before processing and/or marketing), and 4. processing and cooking qualities. The various properties are not necessarily interrelated. Thus a product which is regarded as having good compositional qualities will not necessarily be of a high quality for processing, and so on. Equally, external factors such as soil, climate and methods of cultivation and postharvest handling will not necessarily affect the different aspects of quality in the same way.

When fertilizer is applied to soil, the nutrients that it contains will in part be taken up by the crop, in part remain in the soil and in part be lost from the soil/crop system by one or more of a number of mechanisms. The relative amounts following these different pathways, and in particular the amount reaching surface or underground water, vary between nutrients and also with soil, climatic and agricultural circumstances.

Soil fertility, upon which plant growth and hence crop yield and quality depend, embraces its content of plant food (nutrients), its organic matter content, its structure, its ability to supply water and its depth. It has been said that fertilizers, though they stimulate crop yield, do nothing to bring about improvement in soil fertility. A few have even said that using fertilizers may cause soil fertility to deteriorate. There are no grounds for such opinions; in fact fertilizers, properly used, are most effective in improving soil fertility, not only as measured by nutrient content but also in terms of the other components of fertility. Further, such improvement is long-lasting.