Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/1/2003
Publication Date: 11/1/2003
Citation: Russelle, M.P. 2003. Principles of nutrient cycling in grassland agriculture [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. CD-ROM. Paper No. C06-RUSSELLE400994-ORAL.
Technical Abstract: Nutrient cycling in grassland agriculture differs in crucial ways from nutrient cycling in arable agriculture. Livestock gather forage from large areas and excrete nonutilized nutrients in concentrated patches, resulting in greater heterogeneity of nutrient availability. Spatial variability in nutrient supply affects pasture productivity, composition, and utilization, but can be modified by livestock management and application of fertilizer and stored manure. Under low stocking rates and minimal external inputs, plants rely mainly on nutrients recycled from decaying residues. Composition of nonconsumed herbage and decaying roots affects nutrient release rates and is a function of plant species, stage of maturity, tissue type, and growth conditions. Fauna, such as earthworms and insects, play a critical role in plant residue and dung decomposition. Under intensified pasture management, both the rate and amount of nutrient cycling increases, resulting in higher productivity per unit area, but also greater risk of nutrient losses that impair the environment. Perennial grasslands, however, have inherent capacities to reduce adverse environmental impacts. Furthermore, strategic dietary supplementation of livestock, appropriate grazing management, tactical fertilizer application, injection of manure, variable rate application technology, and other means are available to reduce the probability of undesirable nutrient losses.