Calag Archive

Important losses to beekeepers—and to agriculture in general—have been caused by certain pesticides appearing on the market during the last few years.

Commercial Easter lily forcers frequently have finished plants that are too tall. Shorter plants can be obtained by forcing at lower than the usual night temperature of 60°F. However, such plants—forced at low temperature—need a long forcing period and bloom in June rather than during the Easter season.

Most commercial olive growers in California apply nitrogen to their orchards annually, although the response of the trees seems to be different in the various olive districts, probably because of the influence of such factors as soil type, topography, and amount of rainfall.

Accuracies of soil moisture measurements obtained with recently developed neutron equipment are comparable to those associated with conventional sampling procedures.

Fertilizer urea is considered—usually—to resemble nitrates in its mobility in soils because it is not strongly retained by soil colloids and appears to move freely in the soil solution. However, when added to a soil, urea is converted to ammonium carbonate, and when nitrogen is in the ammonium form it is leached only slightly. The downward movement of urea in soil and the possibility of leaching loss are dependent on the rate of hydrolysis—the conversion of urea to the ammonium form. The hydrolysis is accomplished through the activity of enzymes, present in all agricultural soils, although the rate of conversion varies somewhat among different soils. The accompanying table shows that in four soils the equivalent of 200 pounds per acre urea nitrogen was hydrolyzed to ammonia in two days, and in two of the soils there was virtually no urea remaining after one day. Thus there would be movement of urea nitrogen for only a day or two—or in some soils, only a few hours—because it would be converted to the ammonium form.