in this research, several chemical extractants and modified olsen methods were studied in 25 surface-calcareous soils (0-30 cm) for determining available phosphorus (p) for corn (zea mays l.) plant. in this experiment, the highest correlation was obtained between extracted p by olsen and colwell methods (nahco3-extractable p) and dry weight of corn shoot (r =0.67 and 0.75, p

By Thomas Olsen, MD, PhD The calculation of IOL power in an eye that has undergone corneal refractive surgery is not a straightforward task. However, if you understand why the calculation may go wrong, you will have a fair chance of getting a good result using modern technology. It is important to understand that the calculation errors of post-LASIK eyes are the sum of the traditional errors pl...

Soil phosphorus (P) fertility arising from historic P inputs is a major driver of P mobilisation in agricultural runoff and increases the risk of aquatic eutrophication. To determine the environmental benefit of lowering soil P fertility, a meta-analysis of the relationship between soil test P (measured as Olsen-P) and P concentrations in agricultural drainflow and surface runoff in mostly UK s...

In this research, several chemical extractants and modified Olsen methods were studied in 25 surface-calcareous soils (0-30 cm) for determining available phosphorus (P) for corn (Zea mays L.) plant. In this experiment, the highest correlation was obtained between extracted P by Olsen and Colwell methods (NaHCO3-extractable P) and dry weight of corn shoot (r =0.67 and 0.75, p

Repeated application of manures to agricultural soils could cause the accumulation of phosphorus (P) in soils. However, it is unclear if manure P can behave similar to P in soluble fertilizers in accumulation Olsen-P (0.5 mol L-1 NaHCO3 at pH 8.5) in soils. A long-term wheat-maize rotation experiment was conducted to investigate the effects of repeated application of manures on P accumulation i...

abstract in this study, p critical level for corn plant (zea mays l.) was determined using pbc in 25 combined soils samples from different fields of east azerbaijan province. to calculate the pbc, current soil p test methods such olsen,colwel, soltanpur and schowab, kelna2 and iron impregnated strips as a quantity factor (q) and the methods of soluble p measurements such as distilled water, cal...

The spatial and temporal stability of soil test values is important to the use of soil testing for nutrient management. A study was conducted to evaluate the spatial and temporal stability of soil test phosphorus (P). Five sites ranging in size fiom 9.1 to 10.8 acres were soil sampled in the same locations in a 60 X 60 ft. grid either three or four times over a two year period. Bray 1 -P values...