21,178 research outputs found
Impact of watercress cultivation on river water quality: progress report for the period, January - December 1987
The objective of this short project progress report is to investigate the possible water quality implications of modern watercress growing practices. Chalk receiving watercourses are usually of high supply, amenity, game fishing and fish farming value. Any headwater pollution load, therefore, needs characterising and quantifying. Two sites of watercress farming were studied in 1986-87 and nutrient levels examined. Different approaches of watercress farmers in Dorset and Hampshire are summarised
Environmental aspects of soil phosphorus testing
peer-reviewedSoil phosphorus testing in Ireland uses Morgan’s reagent from samples taken to 10 cm
depth for agronomic recommendations. However, its suitability as an environmental
indicator has been questioned in terms of sample depth and extraction solution. Seven
grassland sites were sampled to depths of 2, 5 and 10 cm and extracted for Morgan’s
P, the standard agronomic test, as well as iron-oxide impregnated paper strip P (FeOP),
calcium chloride extractable P (CaCl2-P) and water soluble P (WSP), all proposed
as environmental soil tests. Extractable soil P decreased with increasing sample depth,
as did variances in each test, such that, 2 cm samples had highest concentrations and
variances. The current standard sample depth (10 cm) was linearly related to corresponding
data from samples taken to 2 and 5 cm, indicating that surface soil P can be
consistently estimated from the current standard depth. When soil tests were compared
with dissolved reactive P (DRP) in overland flow collected from two field sites,
certain soil tests were better indicators of P loss than others. The relative difference in
Morgan’s P values at the standard sample depth (10 cm) was reflected in the relative
difference in P loss between the two sites. Average values of DRP collected from two
sites ranged from 0.032 to 0.067 mg/l at the low P site and 0.261 to 0.620 at the high P
site. Average DRP values from the high P site and maximum DRP values from the low
P site were simulated using water-soluble P extraction at water to soil ratios 5 to 250
l/kg. In this study, Morgan’s P to 10 cm gave a good indication of the relative difference in DRP loss between the two sites
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