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This new online seminar series from the University of California, Agriculture and Natural Resources, with support from the California Department of Water Resources, brings timely, relevant expertise on water and drought from around the UC system and beyond directly to interested communities.
Assessing water quality for Southern California agriculture typically revolves around the total salinity of the water, its total dissolved solids (TDS), and the toxic ions boron, sodium and chloride. Salts are necessary to plants, because it is in the form of diluted salts that all nutrients are taken up by plants- the macro and micronutrients plants extract from the soil. High salinity leads to water imbalance problems much as if the plant were not getting adequate water. A toxicity problem is different from a salinity problem, in that toxicity is a result of damage within the plant rather than a water shortage. Toxicity results when the plant takes up the toxic ions and accumulates the ions in the leaf. The leaf damage that occurs from both toxicity and salinity are similar in that it causes tissue death known commonly as "tip burn." The damage that occurs depends on the concentration of the ions in the soil water around the roots, the crop sensitivity and crop water use, and the length of time the crop experiences the ions. In many cases, yield reduction occurs. Because crops can not excrete salts the way humans do, salts gradually accumulate in a plant. As a result plants need a higher water quality than humans do.
Much study in many countries has gone into evaluating water for crop use. Some of these studies have been on the effects of salts on soil characteristics. Generally, as sodium concentration increases, a soil will lose its aggregation, eventually leading to poor water infiltration. Many more salinity and toxicity studies have been done on plants themselves. Not all crops are equally tolerant of salinity and toxicities, and in general most plants respond to salinity and toxicities in a similar fashion. If a plant is intolerant of salinity, it will be intolerant of chloride, sodium and boron. Most annual crops are less sensitive to salts than tree crops and woody perennials, although symptoms can appear on any crop if concentrations are high enough. The reason for greater sensitivity for perennial crops is that the tree is sitting in the ground absorbing salts for a longer period than the lettuce plant that is harvested 3 months after planting. Furthermore, deciduous trees like walnut shed their leaves each winter, so they can handle salinity better than evergreens like citrus and avocado.
To manage salinity and toxicities, water management is the key. Depending on water quality, an excess of water will be applied to the soil to leach the previously applied salts away from the root zone. The poorer the water quality, the more excess water is applied.
Selecting a less sensitive crop is also an alternative when dealing with poor water quality. Some barley varieties can handle salinity similar to ocean water. Barley nets a grower $400 an acre, avocados $9,000 and $25,000 if the market is right for strawberries. Avocados are salt sensitive, so are strawberries and lemons and cherimoyas and star fruit and blueberries and raspberries and mandarins and nursery crops. We grow these because with our climate, very few other places can grow them and they return enough money for a grower to stay in business in an area where land, water and labor are expensive. We really don't have much in "alternative crops" to grow here.
Along with drought there are also concerns about water quality which has all kinds of weird units that area actually convertible. Here's a little guide for the principle water quality components and their conversions.
Common ions in water: calcium (Ca2+), magnesium (Mg2+), sodium (Na1+)
sulfate (SO42-), chloride (Cl-), carbonate (CO32-), bicarbonate (HCO3-), boron (H3BO3)
Measured as parts per million (ppm) or milligrams per liter (mg/l), which are interchangeable , or milliequivalents per liter (meq/l). A milliequivalent is the ppm of that ion divided by its atomic weight per charge.
Example: Ca2+ with atomic weight of 40 and a solution concentration of possibly 200 ppm. Ca2+ has two charges per atom, so it has a weight of 20 per charge. 200 ppm divided by 20 = 10 meq of calcium for a liter of water.
Total Dissolved Solids (TDS): measure of total salts in solution in ppm or mg/L
Electrical Conductivity (EC): similar to TDS but analyzed differently.
Units: deciSiemens/meter(dS/m)=millimhos/centimeter (mmhos/cm)=
1000 micromhos/cm (umhos/cm).
ConversionTDSEC: 640 ppm=1 dS/m= 1 mmhos/cm=1000 umhos/cm
Hardness: measure of calcium and magnesium in water expressed as ppm CaCO3
pH: measure of how acid or base the solution
Alkalinity: measure of the amount of carbonate and bicarbonate controlling the pH, expressed as ppm CaCO3.
Sodium Adsorption Ratio (SAR): describes the relative sodium hazard of water
SAR= (Na)/((Ca+Mg)/2)1/2, all units in meq/l
1.5 feet of water with EC of 1.6 adds 10,000 # of salt per acre
and that same water with 20 mg/l of nutrient will supply 80# of that nutrient/acre
Sea water has ~ 50 dS/m, 20,000 ppm Cl, 10,000 ppm
Irrigation water WATCH OUT- 1,000 ppm TDS, 100 ppm Na/Cl, 1 ppm B
Dothiorella leaf blight which is really a whole range of fungi that cause leaf diseases, along with cankers and wilts goes to many different host plants from citrus to Brazlian pepper to ash to redwood to palm to pittosporum to eucalyptus to pine. Look around, this year you'll see lots of it because it results from water and salt stress.
Images: ash, redwood, avocado, lemon, palm, pistachio, blueberry
California Cherimoya Association Annual Meeting
10 AM, Sunday, April 13, 2014
The Annual Meeting will be held at Hanson Agricultural Center (formerly Faulkner Farms) on the corner of Briggs Rd. and Telephone Rd. in Santa Paula. (14292 W. Telegraph Rd., Santa Paula.) Parking is on Briggs Rd, around the corner
Annual Meeting Admission will be $20. Admission includes:
1. BBQ lunch catered by Sparky's 2. 1 year CCA membership
We need payment by Thursday, April 10, so we know how many meals to order.
Send payment in check, money order, or wampum, (please no Bitcoin) to: Dario Grossberger, 6301 Worth Way, Camarillo, CA 93012. Payment can also be made by PayPal to email@example.com.
9:30 to 10 AM. Arrival and Registration.
10 to 10:15 AM. CCA Business
10:15 to 11:15 AM. Nino Cupaiuolo and Ben Faber will discuss cherimoya pollination.
For good yields and quality cherimoya in California must be hand pollinated. Ben Faber is a UC Cooperative Extension Farm Advisor who for many years has had an interest in cherimoya and has supported the efforts of the CCA. He visited Spain recently and discussed with researchers their work on pruning cherimoya as a way of controlling time of blooming, and therefore also time of harvest.
Nino Cupaiuolo has been a cherimoya grower and CCA member and Officer for many years. He will discuss his pollination procedures and observations made from pollination done last Summer.
11:15 to 11:45 PM. Dario Grossberger will describe efforts to produce a seedless cherimoya
It's not possible to eat a cherimoya and not wonder how one might develop a variety without seeds. Dario Grossberger is a cherimoya grower and current CCA President. There are indeed such efforts under way, and Dario will make a summary of current progress with the seedless cherimoya
11:45 to 12:30 PM. BBQ Lunch catered by Sparky's.
12:30 to 1:30 PM. Scott Van Der Kar will discuss cherimoya pruning
Cherimoya pruning is essential each year to improve cherimoya yield and quality. Scott Van Der Kar is a cherimoya grower, CCA member and Officer, and past CCA President. He will describe how he prunes cherimoya trees.
1:30 to 2 PM. Raj Desai and Dario Grossberger will describe 21 varieties of cherimoya from Spain
Fruit varieties are always of utmost importance to all fruit. California has developed a set of varieties, most of which are in the collection in Irvine. However, Spain made a major effort, and amassed more than 300 varieties in their collection. They agreed to send 21 of these varieties, selected as the most promising, to California for evaluation. Raj Desai, a cherimoya grower, and Dario, each planted an exemplar of each of these varieties in their orchards. They will describe what they have observed to date on the performance of these varieties.