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 firstname.lastname@example.org.
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.
Ground urban organic material that shows up in great trailers for use in agriculture has simple rules for its use. 1) It should be a material low in contaminants. If you can clearly see golf balls and plastic, send it back. Over time with decomposition it is only going to become clearer because all the organics go away and all you are left with is a mess to clean up. 2) If used as a mulch (applied to the surface of the soil), it should be as woody material as possible, because it is more persistent and lasts longer and the roots which adjust to the mulch layer are less likely to be disturbed. 3) If it is used as a material to be incorporated into the soil IT MUST BE COMPOSTED. This cannot be emphasized enough. With decomposition, gasses such as methane, ethylene and ammonia are released which are all toxic to roots and it heats up, also which is hard on roots- like it burns the heck out of them. This goes for the material used as a mulch, it should be kept at least 6 inches away from tree trunks so that gasses and heat don't burn the trunks. And 4) no organic material should be incorporated into the planting hole, composted or non. This is one of those myths (planting mix in planting holes) that have been foist on gardeners and farmers alike. If it is organic it is good? Any organic material incorporated into a planting hole is going to decompose over time, and then the soil settles, causing voids. Much better to plant into the mineral soil and mulch and let the worms move any nutrients from the organic surface material into the root zone.
And remember that fresh citrus leaves and stems can harbor Asian citrus psyllid. Dry that material out before moving it around so you don't spread the psyllid.
OK! Let's Strategize. There are four steps for everybody to consider, it doesn't matter if you have a backyard lawn and landscape or if you have 700 acres of avocados.
1. Maintenance: Irrigation System and Cultural Practices
2. Improve Irrigation Scheduling
3. Deficit Irrigation
4. Reduce Irrigated Area
a. Irrigation System.
- Fix leaks. Unfortunately, there are almost always leaks for all kinds of reasons. Pickers step on sprinklers, squirrels eat through polytube, branches drop on valves, coyote puppies like to chew….the system should be checked during every irrigation
- Drain the lines. At the beginning of each year every lateral line should be opened in order to drain the fine silt that builds up.
- Maintain or increase the uniformity of irrigation so that each tree or each area gets about the same amount of water. Common problems include different sized sprinklers on the same line or pressure differences in the lines. Where there are elevation changes, every line should have a pressure regulator, they come pre-set to 30 psi. Having all of your lines set up with pressure regulators is the only way you can get an even distribution of water to all of the trees, and it solves the problem of too much pressure at the bottom of the grove and not enough at the top.
- Clean the filters often. You don't have a filter because you think that the district water has already been filtered? Hah! What happens if there is a break in the line in the street and the line fills with dirt during the repairs? All of your sprinklers will soon be filled with dirt.
- Is water flow being reduced at the end of the lateral line? It could be because scaffold roots are growing old enough to pinch off the buried line. The only cure is to replace the line.
b. Cultural Management.
- Control the weeds because weeds can use a lot of water.
- Mulch? Mulching is good for increasing biological activity in the soil and reducing stress on the trees, but the mulch will not save a lot of water if you are irrigating often….the large evaporative surface in mulches causes a lot of water to evaporate if the mulch surface is kept wet through frequent irrigation. Mulches are more helpful in reducing water use if the trees are young and a lot of soil is exposed to direct sunlight.
2. Improve the Irrigation Scheduling.
- CIMIS will calculate the amount of water to apply in your grove based on last week's water evapotranspiration (ET). You can get to CIMIS by using several methods; for avocado growers the best method is to use the irrigation calculator on the www.avocado.org website. If you need further instruction on this, you can call our office and ask for the Avocado Irrigation Calculator Step by Step paper. You need to know the application rater of your mini-sprinklers and the distribution uniformity of your grove's irrigation system.
- CIMIS tells you how much water to apply, but you need tensiometers, soil probes or shovels to tell you when to water.
- “Smart Controllers” have been used successfully in landscape and we have used one very successfully in an avocado irrigation trial The one we used allowed us to enter the crop coefficient for avocado into the device, and daily ET information would come in via a cell phone connection. When the required ET (multiplied automatically by the crop coefficient) reached the critical level, the irrigation system would come on, and then shut down when the required amount had been applied. Increased precision can be obtained by fine tuning these devices with the irrigation system precipitation (application) rate.
3. Deficit Irrigation.
- Deficit irrigation is the practice of applying less water than the ET of the crop or plant materials. Deficit irrigation is useful for conserving water in woody landscape ornamentals and drought tolerant plants where crop yield is not an issue. Water conserved in these areas may be re-allocated to other areas on the farm or landscape.
- There hasn't been enough research on deficit irrigation of avocado for us to comment. We suspect, however, that deficit irrigation will simply lead to dropped fruit and reduced yield.
- Stumping the avocado tree could be considered a form of deficit irrigation. In this case, the tree should be stumped in the spring, painted with white water-based paint to reflect heat, and the sprinkler can be capped for at least 2 months. As the tree starts to re-grow, some water should be added back, probably about 10-20% of the normal water use of a mature tree.
- Regulated Deficit Irrigation for Citrus is an important method for saving water, and in some cases will reduce puff and crease of the peel. In one orange trial done by Dr. David Goldhammer in the San Joaquin Valley, an application of 25% of ETc from mid-May to Mid July saved about 25% of applied water for the year and reduced crease by 67%, without appreciably reducing yield.
- 3. Reduce Irrigated Area.
- Taking trees out of production. Trees that are chronically diseased and do not produce fruit (or the fruit is poor quality) should be taken out of production during this period. Also consider: trees in frosty areas, trees in wind-blown areas, trees near eucalyptus and other large trees that steal the water from the fruit trees.
- Changing crops. You may want to take out those Valencias during this period and replant to something that brings in more money, like seedless, easy-peeling mandarins. The young trees will be using a lot less water.
- Fallow Opportunities. You may decide to do some soil preparation, tillage or cultivation, or even soil solarization of non-irrigated areas.
We have found that this four step process is a logical way to achieve water cutbacks with least impact. It is possible to achieve a ten percent reduction in water by only improving irrigation system uniformity and scheduling procedures. Often, these two measures also result in better crop performance and reduced runoff. Reducing irrigated area or taking areas out of production should be a last resort and a well thought out decision. Plan for the future, hopefully water will be more available in future years.