Fertilizer use is a major driver of crop yield. However, a comprehensive understanding of how fertilizers impact the nutritional quality of food crops has been lacking so far. In this first global meta-analysis, a large team of scientists compiled 7,859 data pairs from 551 field experiment-based articles published between 1972 and 2022. The goal was to assess how fertilization affects the nutritional value of a wide range of food crops.
We learn from this excellent analysis that fertilizer application improved nutritional quality — referring to all nutritionally relevant components assessed: carbohydrates, proteins, oil, vitamin C, representative mineral nutrients, and total soluble solids — on average by 12%. The improvements varied by nutrient and crop species, with vegetables being the most responsive. Potassium, magnesium, and micronutrients played important roles in promoting crop nutritional quality, as did the combined application of inorganic and organic nutrient sources. The unique contribution of the latter is, however, difficult to ascertain because nutrient additions in NPK+organic treatments are often larger than in NPK treatments in such experiments.
Across the world, the increase in the nutritional quality of food crops with fertilizer application was greatest in Africa. Generally, crops cultivated in regions with higher temperatures, poor soil organic matter, extreme soil pH, and predominantly sandy soils had smaller increases in nutritional quality upon fertilizer applications.
Overall, these findings provide strong evidence for designing responsible plant nutrition solutions that aim to improve both crop productivity and crop nutritional quality. Such double-benefit thinking should be included in crop- and location-specific fertilizer recommendations and fertilizer products.
