Calag Archive

Annual teaching with heavy water applications by ponding, with the aid of plastic levees, or use of sprinklers, may be the answer to problems of excess salt accumulation in Coachella Valley vineyards. Trials in a Thompson Seedless vineyard showed marked improvement in vine condition following these special teaching practices. Previous installations of additional tile drains had not corrected this vineyard salinity problem. Salt accumulation in the soil, with resulting vine decline, is the most important current problem facing grape growers in the Coachella Valley.

Cover crops can improve water penetration in orchard soils, as compared with clean cultivation, according to Davis tests. Alfalfa and Hubam clover performed best. Clean noncultivation by use of chemical sprays had an adverse effect on soil surface structure and water penetration in tests at Davis and Fresno. Us of sawdust mulch did not affect water penetration in comparisons with normal cultivation and sod in El Dorado County orchards.

Of 400 samples representative of water resources in California, 25% were found to contain toxic levels of lithium, capable of adversely affecting the growth of citrus and other crops. Water samples with a high lithium content were usually associated with low magnesium and/or a high sodium percentage. Because of the natural occurrences of toxic levels of lithium in irrigation water, as well as possible contamination from industrial uses of lithium compounds, agencies responsible for maintaining water quality standards should also include analysis for lithium along with their routine sampling.

Rapid root growth, stimulated by a plentiful supply of soil nitrogen and high summer temperatures, held the sugar content of beet roots down to 15% or lower during July and August in a 1961 field experiment in Kern County. Enough fertilizer nitrogen should be applied to promote early top growth and prevent any deficiency before mid-May. However, a nitrogen deficiency period of from eight to ten weeks before harvest is essential for maximum sugar production from the roots.

Moisture barriers to limit the movement of water vapor from the fruit may effectively reduce shrivel in nectarines during packing and shipment, if used to supplement good handling methods.

Previous tests have shown that nitrogen applied to California's annual rangeland increases the length of the grazing season by increasing the growth of grass during the winter. However, recent studies at the Hopland Field Station covering a two-year period indicate that growth rate of the common annual grass, soft chess (Bromus mollis), increased very little when the average soil temperature dropped below 45°F. Grass fertilized with nitrogen showed the greatest increase in growth compared with unfertilized grass when the average soil temperature was between 47° and 55°F. When the temperature went above 55°F, the difference between growth of fertilized and unfertilized grass decreased.

Low soil oxygen conditions were found most detrimental to plant growth when air or soil temperatures were high. Test results also emphasized the importance of promoting rapid water intake rates to eliminate prolonged flooding of the soil to get water into root zones.