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Nutrients in agroecosystems: Rethinking the management paradigm

Author
Drinkwater, L. E.; Snapp, S. S.
Abstract
Agricultural intensification has greatly increased the productive capacity of
agroecosystems, but has had unintended environmental consequences including degradation of
soil and water resources, and alteration of biogeochemical cycles. Current nutrient management
strategies aim to deliver soluble inorganic nutrients directly to crops and have uncoupled carbon,
nitrogen and phosphorus cycles in space and time. As a result, agricultural ecosystems are
maintained in a state of nutrient saturation and are inherently leaky because chronic surplus
additions of nitrogen and phosphorus are required to meet yield goals. Significant reductions of
nutrient surpluses can only be achieved by managing a variety of intrinsic ecosystem processes
at multiple scales to re-couple elemental cycles. Rather than focusing solely on soluble,
inorganic plant-available pools, an ecosystem-based approach would seek to optimize organic
and mineral reservoirs with longer mean residence times that can be accessed through
microbially- and plant-mediated processes. Strategic use of varied nutrient sources, including
inorganic fertilizers, combined with increases in plant diversity aimed at expanding the
functional roles of plants in agroecosystems will help restore desired agroecosystem functions.
To develop crops that can thrive in this environment, selection of cultivars and their associated
microorganisms that are able to access a range of nutrient pools will be critical. Integrated
management of biogeochemical processes that regulate the cycling of nutrients and carbon
combined with increased reservoirs more readily retained in the soil will greatly reduce the need
for surplus nutrient additions in agriculture.
Date Issued
2005-06-14Subject
Agroecosystems; nutrient cycling; coupled biogeochemical processes; plant species functions; microbial community structure; microbial community function
Type
book