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California Polytechnic State University, San Luis Obispo

Series

Food Science and Nutrition

1988

Articles 1 - 4 of 4

Full-Text Articles in Life Sciences

The Estimation Of Free Aluminium And The Competition Between Fluoride And Humate Anions For Aluminium, G. S.P. Ritchie, M. P. Nelson, M. G. Whitten May 1988

The Estimation Of Free Aluminium And The Competition Between Fluoride And Humate Anions For Aluminium, G. S.P. Ritchie, M. P. Nelson, M. G. Whitten

Food Science and Nutrition

Three equations for estimating the concentration of free aluminium, [Al3+], from the activity of free fluoride, (F-), were compared to assess their suitability for estimating [Al3+] in acid soil solutions and in competition studies. We then studied the ability of humic acids to compete with F for Al by comparing the behaviour of the humic acids in the presence of F and Al with that of several carboxylic acids under the same conditions. All three methods of estimating [Al ] were limited in their applicability to acid soil solutions but were uitable for estimating [Al3+] in competition studies ...


A Preliminary Evaluation Of Resin Extractable Molybdenum As A Soil Test, G. S.P. Ritchie Apr 1988

A Preliminary Evaluation Of Resin Extractable Molybdenum As A Soil Test, G. S.P. Ritchie

Food Science and Nutrition

Resin extractable Mo explained 72% of the variation in yield of wheat (Triticum aestivum) grown on ten acid soils as measured by the relative yield of the tops or by the uptake of Mo by the youngest emerged blade.


Phosphorus Leaching In Sandy Soils. I. Short-Term Effects Of Fertilizer Applications And Environmental Conditions, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson, D. M. Deeley Jan 1988

Phosphorus Leaching In Sandy Soils. I. Short-Term Effects Of Fertilizer Applications And Environmental Conditions, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson, D. M. Deeley

Food Science and Nutrition

The consequences of previous as well as current environmental conditions and management practices on the potential for phosphorus (P) to be lost by drainage from sandy soils in the short term (< 1 year) were studied in the laboratory and the field. The potential for P losses by drainage was estimated by measuring soil solution P levels and rapidly released P. Rapidly released P was measured by determining the concentration of dissolved inorganic P contained in filtered (┬Ám) soil solutions after incubating soil at saturation for 15 min at ambient temperature. In the laboratory, sandy soils were incubated with ordinary superphosphate, coastal superphosphate (a granulated mixture of equal parts of superphospate, rock phosphate and elemental sulfur) or lime-superphosphate (a lime-reverted superphosphate with 18% kiln dust) and sequentially desorbed with deionized water. The effects of the extent of leaching, fertilizer type, application rate and the time of contact with the soil on soil solution P levels were investigated. The influence of annual pasture death and summer rainfall on rapidly released P in soils that had been pre-treated by leaching were also investigated.

Phosphorus concentrations decreased logarithmically in the successive supernatants of the sequentially desorbed soils. More P was desorbed from soils incubated with superphosphate and lime-superphosphate than soil incubated with coastal superphosphate. At each level of pre-leaching, the P concentrations in the soil solution increased with increasing time. The level, to which the P concentration in the soil solution increased at each time, decreased with increased extent of pre-leaching. The addition ...


Phosphorus Leaching In Sandy Soils. Ii. Laboratory Studies Of The Long-Term Effects Of The Phosphorus Source, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson Jan 1988

Phosphorus Leaching In Sandy Soils. Ii. Laboratory Studies Of The Long-Term Effects Of The Phosphorus Source, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson

Food Science and Nutrition

Long-term phosphorus (P) losses and gains in sandy soils continuously fertilized with either ordinary superphosphate or coastal superphosphate (a granulated mixture of superphosphate, rock phosphate and elemental sulfur) or previously fertilized with superphosphate were investigated under leaching conditions in columns in the laboratory. The soils were subjected to 10 consecutive cycles designed to simulate the mediterranean weather conditions in the Harvey region of the Coastal Plain of Western Australia. Each cycle consisted of a wet phase during which the equivalent of 850 mm of rainfall was leached through the soil and a drier phase during which the soil was incubated ...