Cover crop effects on spring soil water content and the implications for cover crop management in south coastal British Columbia
Soil water content in the spring is an important factor in making decisions on cultural operations. A 2-year study was conducted to determine the effects of fall planted cover crops on spring soil water content dynamics and to relate the water content to cover crop management in terms of field trafficability. Each year, cover crops were planted at two planting dates in the fall, late August and late September on a loamy, mixed, mesic Humaquept on the Fraser River delta, south coastal British Columbia. Treatments were bare (control), wheat, rye and spring barley. Soil samples were collected at approximately bi-weekly intervals beginning in early spring to determine soil water content. Plant samples were also obtained late in the spring to determine C:N ratio. Treatments affected soil water content differently at each sampling date. No differences in soil water content at depths 20�40 and 40�60 cm were observed. Critical soil water content value for trafficability was determined to be 0.32 kg kg-1. Cover crops attained critical C:N ratio of 31.7:1 when the soil water was still above the critical value. The results suggest that terminating the cover crop growth in the spring could best be done by either mowing or spraying the cover crops as opposed to incorporation in order to minimize compaction since the critical C:N ratio for net mineralization is achieved when the soil is still too wet.
The effects of green manure and NPK fertilizer on the growth and yield of maize ( Zea mays L ) in the mount Cameroon region
This study was carried out in the Mount Cameroon region to evaluate the effects of green manure and fertilizer on the growth and yield of maize. There were eight treatments: Calliandra prunings, Calliandra prunings + fertilizer (60kg/ha NPK), Gliricidia prunings, Gliricidia prunings + fertilizer, Senna prunings, Senna prunings + fertilizer, fertilizer only (120 kg/ha NPK) and control. Results showed that biomass of prunings in the first pruning was highest in Calliandra (5314kg/ha) and this was significantly different from those of Senna (2909kg/ha) and Gliricidia (2112kg/ha). Nitrogen input from the prunings was highly significant (P<0.05) in Calliandra prunings (217 kgN/ha) and least in Gliricidia species (69.0kgN/ha). Maize grain yield in the different treatments was not significantly different in the first and second planting seasons. The highest grain yield during the third cropping season was observed in Calliandra + fertilizer (4696kg/ha) and least in control (3332kg/ha). It was also noted that nitrogen uptake was highest in plots supplied with fertilizer only and lowest in control. Weed biomass was highest in control and in plots supplied with fertilizer only. Soil chemical changes after three cropping periods showed variable changes in treatments. There was decrease in bulk density in plots supplied with Calliandra prunings.
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.