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Psychological disorders in rheumatoid arthritis: a growing consensus?

1990; BMJ; Volume: 49; Issue: 10 Linguagem: Inglês

10.1136/ard.49.10.808

1468-2060

Peter A. Creed,

Psychosomatic Disorders and Their Treatments

Beneficial management practices (BMPs), including nutrient management plans and reduced tillage, have been assessed at a subwatershed and watershed level to examine their impacts on nutrient export, economic opportunity cost, and producer incomes. In assessing nutrient effects on crop production, a crop-specific yield function was estimated. The linear and quadratic nitrogen (N) fertilizer terms were found to have correct signs, with a positive linear relationship, and were significant for major crops grown in the South Tobacco Creek (STC) Watershed. Crop response to phosphorus (P) occurred only for wheat ( Triticum aestivum L.). Nutrient application rates within the STC Watershed were generally within provincial recommended rates; however, data shows an increasing trend in the application of N in wheat, canola ( Brassica napus L.), barley ( Hordeum vulgare L.), and oat ( Avena sativa L.) production over course of the study. Nutrient export parameters at the field scale (4 to 5 ha [10 to 12 ac]), subwatershed scale (210 ha [519 ac]), and watershed scale (7,700 ha [19,000 ac]) were compared to production inputs. At the field scale, in a paired watershed study, N exported was not significantly related to the N applied. The relationships between P exported and P applied and conservation tillage management practices were statistically significant. At a larger subwatershed, the export of P from the subwatershed was significantly influenced by the volume of flow of water runoff and previous year P application. The export of N was only influenced by volume of flow but not by N application. For the STC Watershed, applied N did not affect N export. Assessment of P export found that the conversion to conservation tillage practices increased the P export. The opportunity value of the lost nutrients for the 210 ha (519 ac) subwatershed averaged about C$5.50 ha −1 y −1 (C$2.23 ac −1 yr −1 ), while on the paired subwatershed, the average loss was C$4.50 ha −1 y −1 (C$1.82 ac −1 yr −1 ) on a conventionally managed field and C$2.75 ha −1 y −1 (C$1.11 ac −1 yr −1 ) on a field under reduced tillage. For the entire STC Watershed, the export of nutrients represented a loss of opportunity of C$6.80 ha −1 y −1 (C$2.75 ac −1 yr −1 ) or about 7% of annual fertilizer cost. Assessment of STC manure-applied data on an annual basis shows that the hauling and application of hog manure from 1998 to 2006 was generally more expensive than the nutrient value of the manure; however, in recent years, due to the increase in the value of commercial nutrients, the nutrient value of hog manure exceeds the cost.