Nutrient-balance assessments are valuable tools for delineating the consequences of farming on soil fertility. Various approaches and methods for different situations have been used in the past. This bulletin presents a state-of-the-art review of nutrient balance studies. It brings out the evolution of the approaches and methods, provides for comparisons among them, features the improvements made, and highlights remaining issues. This analysis will be useful in further development of the assessment methodologies as reliable tools for devising time-scale soil fertility management interventions.

This open access book highlights concepts discussed at two international conferences that brought together world-renowned scientists to advance the science of potassium (K) recommendations for crops. There was general agreement that the potassium recommendations currently in general use are oversimplified, outdated, and jeopardize soil, plant, and human health. Accordingly, this book puts forward a significantly expanded K cycle that more accurately depicts K inputs, losses and transformations in soils. This new cycle serves as both the conceptual basis for the scientific discussions in this book and a framework upon which to build future improvements. Previously used approaches are critically reviewed and assessed, not only for their relevance to future enhancements, but also for their use as metrics of sustainability. An initial effort is made to link K nutrition in crops and K nutrition in humans. The book offers an invaluable asset for graduate students, educators, industry scientists, data scientists, and advanced agronomists.

Using data on three countries in sub-Saharan Africa, this report compares macro- and microlevel approaches to determine soil nutrient balances with an innovative mesolevel approach. It highlights the added value that a mesolevel approach can provide in terms of its usefulness to mesolevel stakeholders in articulating and targeting scale-specific soil fertility enhancing measures, and its validity as an entry point for policy-makers and private-sector intervention. Contains numerous color figures and tables.

Nitrogen is indispensable to all life on Earth. However, humans now dominate the nitrogen cycle, and nitrogen emissions from human activity have real costs: water and air pollution, climate change, and detrimental effects on human health, biodiversity, and natural habitats. Too little nitrogen limits ecosystem processes, while too much nitrogen transforms ecosystems profoundly. The California Nitrogen Assessment is the first comprehensive account of nitrogen flows, practices, and policies for California, encompassing all nitrogen flows—not just those associated with agriculture—and their impacts on ecosystem services and human wellbeing. How California handles nitrogen issues will be of interest nationally and internationally, and the goal of the assessment is to link science with action and to produce information that affects both future policy and solutions for addressing nitrogen pollution. This book also provides a model for application of integrated ecosystem assessment methods at regional and state (subnational) levels.