Fertilizer Optimization for Sustainable Agriculture: Needs, Current Strategies and Future

Successful management of agricultural nitrogen (N) during crop growth has major implications for food supply, energy and environment. Need for N during crop growth is not a linear function. As an example, for corn growth, the need for N is S-shaped (sigmoid) during the growing stage, which suggests that for optimum use of the fertilizer, continual adjustment of the amount of fertilizer as the plant is growing is necessary. The most common practice is to add extra fertilizer, well beyond what the plant needs, even though the extra fertilizer results in significant environmental damage. Sustainable practice would balance crop productivity and profitability with negative environmental effects. The challenge for developing sustainability is to meet the N requirements of the growing crop with fertilizer, as well as timing of irrigation and additives application, proper dosing, and related management actions during a crop season. In this review article, we begin with the role of fertilizers in ensuring food supply for the burgeoning human population. Soil parameters, including soil biochemistry, determine the transformation of N in the fertilizer to nutrients suitable for plant uptake. There are several options for applying fertilizer to soil, and this has a bearing on the fertilizer fate. We examine current methods and technologies that farmers can use to optimize fertilizer use, keeping abreast of the temporal dependence for N needed for a growing crop. The widespread adoption of technologies for sustainable agriculture is lacking. Why such strategies are not being used extensively and a discussion of what is needed to enhance fertilizer optimization concludes the article.