ISSN:
1475-2743
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract. The transfer of suspended sediment (SS) and phosphorus (P) in overland flow from 30 m2 field plots receiving either nil, surface-applied or incorporated manure (slurry) were monitored to determine the vulnerability of land cropped to continuous forage maize to diffuse pollutant transfer in winter runoff. In the absence of slurry, P export was dominated by particulate forms, with up to 1 t SS ha−1 and 0.75 kg total P ha−1 collected from an individual storm event. Background concentrations of P in soluble (〈0.45 μm) form were large (c. 0.5 mg L−1) by eutrophication standards due to the previous build-up of soil P, and largely independent of SS concentrations. Largest P exports (representing up to 23% of the slurry P applied) were measured when dairy slurry (3–13% dry solids) was surface-applied. The P mobilized from the slurry accounted for up to 60% of total plot P export, with the majority occurring in a soluble bioavailable form during the first storm event. Initial P concentrations in runoff were in proportion to the amount of slurry P applied and significantly lower where rainfall was delayed after application. In one year, splitting the slurry application (3 × 10 kg ha−1) reduced total P export by 25% compared to a single surface application (30 kg P ha−1). In two years, incorporation of slurry, either by ploughing, or by tine cultivation, reduced the amount of overland flow by 50%, and the amount of P export by up to 60%, compared to the surface-applied slurry treatments. Timeliness of slurry spreading to avoid periods of wet weather and simple cultivation of maize fields after harvest are practical and effective options to minimize SS and P transfer in land runoff from maize fields. The results also draw attention to the need to grow maize, and apply slurry to fields with a low P loss risk.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1475-2743.2003.tb00276.x
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