- Author: Ben Faber
Planting Avocados
It seems like the simplest thing is the hardest. Recently, I was called out to evaluate why newly planted trees were failing at two sites and they both had a common problem. In one case, the trees had been planted too deeply at the beginning. At another, a large amount of planting amendment had been incorporated, and over a year's time, the trees had settled, so that they too had their graft unions covered with soil. In the latter case, the trees' unions were 4-8 inches below grade. It seems appropriate to review basic planting practices. In the best-case scenario, trees are planted from February to May, but depending on the area, they can be planted at other times, as well. So, I just got a call about planting, so it's probably time for a refresher.
Often times the grower harkens to the old adage: “dig a $5 hole for a 50-cent plant.” And so a lot of time and money and energy are put into that hole. Nothing costs $5 anymore. Trees cost closer to $50, so there might be a greater urge to do it all right. So the first thing first is forget the planting mix and those mycorrhizal inoculums. They either don't work or they might just damage your expensive tree.
Adding organic matter to a planting hole appears to be a promising step towards achieving that five-dollar hole. It seems logical that steer manure, peat moss, compost, etc. would improve poor soils by increasing aeration, nutritional value, and water holding capacity. And it does - in the immediate vicinity of the planting hole. Eventually, amended planting holes will have negative consequences to plant health.
The initial results are positive; roots grow vigorously in this ideal environment as long as irrigation is provided. But what happens when these roots encounter the interface between the planting hole and the native soil? Native soil contains fewer available nutrients, is more finely textured and is less aerated. Roots react much in the same way as they do in containers: they circle the edge of the interface and grow back into that more hospitable environment of the planting hole. The roots do not establish in the native soil, eventually resulting in reduced growth rates.
Soil water movement is problematic as well. Amended backfill has markedly different characteristics than surrounding native soil; it is more porous and water will wick away to the finer-textured native soil. In the summer, moisture within the planting hole will be depleted by the plant but not replaced by water held more tightly in the native soil. When irrigating, water will move quickly through the amended soil only to be held back by the more slowly draining native soil. The resulting bathtub effect, where water accumulates in the planting hole, floods the roots and eventually kills the plant.
Finally, all organic material eventually decomposes. If you've incorporated organic matter, within a few years that organic matter will have become ash and the bulk has turned into carbon dioxide. The soil will have settled and if you have followed the rule of thumb of 25% by volume, the trunk stem probably will have sunk below grade and the bud union will be buried. The buried union only exacerbates the flooding problem during irrigation or wet conditions. This was the problem that I went out to see.
Basic planting steps
1) Dig a hole somewhat wider, but no deeper than the sleeve that the tree comes in. Making the hole wider (18 inches) allows room to manipulate the tree by hand and remove the sleeve once it is in the hole. Making the hole deeper than the sleeve allows for soil to accumulate around the graft union. Even if the hole is backfilled to the “appropriate” depth, because of subsidence of the loose earth, the tree can become buried. Do not put gravel in the bottom of the hole. This is commonly thought to improve drainage. It does not, it makes it worse.
2) Gently tamp loose earth around the tree. Do not back fill with a planting mix. This creates a textural discontinuity which interferes with water movement both to and anyway from the tree. The fill soil should be free of clods to avoid air gaps and poor contact between roots and soil. Do not cover the root ball with soil; the irrigation water needs to come into direct contact with the root ball.
3) The trees should be watered as soon as is practical after planting.
4) Using drip irrigation the, the emitter should be near the trunk, so that water goes directly onto the root ball. Shrinking and swelling of the polyethylene tubing can move the emitter off the ball.
5) After about 4-6 months the drip emitters can be moved from the trunk to 6-8 inches from the tree. Moving the emitters avoids keeping the trunks wet and reduces the likelihood of crown rot.
6) In most situations, newly planted trees should be irrigated every 5-10 days with 2-5 gallons of water for the first 2-4 months until the roots get out into the bulk soil. Depending on what the weather is like, they still might require frequent irrigations, because the rooted volume holding water is still small. After the first year in the ground, another dripper can be installed on the opposite side of the tree. As the tree grows the number of drippers should be increased or the system converted to fan or microsprinklers.
And in the case of mycorrhizae, they are wonderful. They are nature's gift to all of us. They aid plants in their uptake of nutrients, improve plant health and may actively transmit information from one plant to another. They are a diverse range of fungi associated with plant roots and are everywhere – even Antarctica. And that's the point, introducing them to the planting is not going to help. They are there already, a sea of them. Putting a few nursery-grown spores into a planting hole when there are already highly adapted fungi present just does not happen easily. So not using a planting mix and not adding mycorrhizal inoculum is going to make that hole a little bit cheaper.
In root rot conditions
Planting in ground that has had root rot can add some new steps to the planting process. On relatively flat ground (<15 degree slope) trees will benefit from being planted on a berm or mound. This creates better aeration and drainage for the roots. It also means that the trees tend to dry out faster, so more frequent irrigation may be necessary. Where machinery can be employed, creating berms is usually less expensive. Surrounding soil should scraped to the planting site, and little incorporated with the soil surface where the berm or mound is to be built. In bringing surrounding native soil to the planting site, it is important that an interface between the imported soil and the soil surface is not created. Just mounding a different soil on top of a surface alters water flow through the mound into the bulk soil. The berms can be built 1.5 to 2 feet high with a 4:1 slope. The raised planting position should be irrigated to settle the soil. The soil should then be allowed to dry out prior to planting to avoid mucky soil. Only clonal rootstocks should be replanted into root rot soil. Applying gypsum (15 pounds per tree), a thick layer of mulch around the base of the tree (3-6 inches deep, but not immediately on the stem of the tree) and finally application of fungicides will help. Application on the berm or mound also protects the soil from eroding away with rains.
The key to root rot has always been dependent on irrigation management. There is nothing more important than getting the right amount on at the right time. If you are doing interplanting into an existing orchard where trees have died, it is imperative that the new trees be put on their separate irrigation line so that they can be irrigated according to their needs. Simply putting a smaller emitter on the young trees compared to the older trees means that they will still be irrigated on a cycle that is not optimum for their survival. It doesn't matter if you are using clonals; they will die just as easily with poor water management as a seedling.
The following is a pictorial guide to proper tree planting ( click on "ATTACHED FILES" planting holes.
planting holes
- Author: Hung Kim Doan
Please join us for a weekly lunchtime seminar series. Each week we'll be joined by a guest speaker for a 30-minute presentation followed by questions from the listeners and more general discussion.
The Zoom link will be the same each week. No pre-registration required.
Meeting link:https://ucanr.zoom.us/j/95260378391?pwd=TXNTNmtNalo5TzY0bjdISEszeXRXUT09
*The presentation (not the Q and A discussion) will be recorded and made available.
Habrá traducción al Español
Date |
Topic |
Tuesday, January 24 |
Nitrogen Mineralization from Organic Fertilizers and Composts Joji Muramoto, Organic Production Specialist, UC Santa Cruz |
Tuesday, January 31 |
Tools and Approaches for Assessing and Improving Irrigation Efficiency on the Farm Michael Cahn, Irrigation and Water Resource Farm Advisor, UCCE |
Tuesday, February 7 |
Organic Management of Nematodes Philip Waisen, Vegetable Crops Advisor, UCCE |
Tuesday, February 14 |
How to Identify and Scout for Insect Pests Alejandro del Poso, Assistant Professor of Entomology, Applied Insect Ecology - Turfgrass and Ornamentals, Virginia Tech University |
Tuesday, February 21 |
Why, How and When to Choose Between Open-pollinated, Hybrid, and Land-race seeds? Charlie Brummer, Director and Professor, Center for Plant Breeding, UC Davis |
Tuesday, February 28 |
Management of Soilborne Plant Pathogens with Organic Amendments Amisha Poret-Peterson, USDA-ARS, Davis |
Tuesday, March 7 |
Biology and Management of Thrips and the Diseases They Spread Daniel Hasegawa, USDA-ARS, Salinas |
Tuesday, March 14 |
Weed Management on Small farms and in Organic Production Systems Darryl Wong, Executive Director, Center for Agroecology & Sustainable Food Systems, UC Santa Cruz |
Tuesday, March 21 |
Recruiting Owls and Raptors for Pest Management Breanna Martinico, Human-Wildlife Interactions Farm Advisor, UCCE |
Questions? Contact Margaret Lloyd mglloyd@ucanr.edu, Aparna Gazula agazula@ucanr.edu or Lucy Diekmann lodiekmann@ucanr.edu, Hung Kim Doan hkdoan@ucanr.edu
- Author: Ben Faber
A recent call came through inquiring about the cause of “water spotting” or "staining" on lemons from a coastal orchard. The orchard was sprayed for pests using a horticultural oil in October and at harvest, the spotting was noted. The guidelines for oil use are to avoid use when temperatures exceed 90 deg or so and when it gets cold or is forecast to get cold. The cold injunction is because that fruit mass causes condensation which leads to the spotting. It should never be used when frost is forecast either. The problem along the coast is the weather is about as fickle as weather can get anywhere in the state. Hot one day and cold the next. You can break the rules 9 out of 10 times and get away with it, but according to our Advisor Craig Kallsen in Kern, you get caught the one time when you break the rule.
Oil sprays are an important component in citrus IPM programs for the control of armored and soft scales, aphids, leafminers, and certain species of mites. When used alone, they may be applied using outside coverage (OC) for aphids, leafminers or mites, intermediate coverage (IC) if used for soft scales, and thorough coverage (TC) if used for armored scales at rates of 1 to 6% depending on the crop, time of year and the target pest. Oils are frequently used at rates of 0.25 to 1% in combination with other insecticides. Because petroleum oils can cause phytotoxicity, the following precautions are important:
- Soil moisture should be maximum before application; spray as soon after an irrigation as the ground will permit operation of the equipment. Be sure to maintain adequate soil moisture from spring throughout the entire irrigation season.
- Do not spray oils when temperatures exceed 95°F or relative humidity falls to 20% or below (in coastal regions, do not spray if the temperature will exceed 85° to 90°F or the relative humidity goes below 30%); also do not use oil sprays immediately before, during, or following an unusually cold weather period.
- Problems of leaf drop and fruit drop can be minimized, in general, by adding 2,4-D to the oil spray mixture. Be careful not to apply 2,4-D within 2 miles of sensitive crops such as tomatoes, cotton, olives, and grapes and do not use 2,4-D during spring to avoid phytotoxicity problems.
- If navel orange orchards are sprayed with oil when oranges are approaching maturity, generally from November until harvest, protection against water spot may be obtained by using gibberellic acid. (Caution: fall oil sprays may increase the risk of damage caused by frost).
- Complete coverage of the tree with an oil spray provides more effective control than increased dosage. If spraying is done by ground, equip the rig with a tower capable of elevating a sprayer 4 feet above the tallest trees.
- Generally, narrow range oils with a 50% distillation range of 415 to 455 are recommended for use in citrus.
- The heavier the oil is (e.g., NR 440 is heavier than NR 415), the better its insecticidal properties will be, but also the greater the potential for phytotoxicity to the tree.
Precautions for Using Petroleum Oil Sprays from UC Integrated Pest Management website
- Author: Ben Faber
Soils vary across a landscape according to soil-forming factors present in a particular location. To help those involved in land management and planning, the U.S. Department of Agriculture launched the National Soil Survey in 1899 to systematically map changes in soils across the country. Results were originally organized by county, and the mapping results published in county soil surveys.While the paper surveys were useful, one had to use several maps at different scales to locate the soil-map units for a site-specific location, then cross-reference the mapping unit to tables provided in the survey to obtain information on soil properties. Today, county soil survey information has been converted to a digital format known as the Web Soil Survey (WSS), which is accessible to the public via the Internet. The WSS provides the USDA's official soil survey data and information in a digital format. The tool was developed and is maintained by the USDA's Natural Resources Conservation Service (NRCS). Information in WSS is generated from the National Cooperative Soil Survey conducted by NRCS. The WSS can provide user-defined, site-specific information on soil properties that can be useful for agricultural producers, conservation professionals, scientists and others.
It is important to note that the accuracy of WSS is determined by the scale of the soil map. Most soil surveys are conducted at a scale of 1:20,000; reading soil data and maps should be performed at the same scale to ensure accuracy. A major advantage of WSS over the original paper surveys is that data can be extracted in digital formats, which can be imported directly into a geographic information system (GIS). The information can thenbe spatially aligned with other digital information, such as maps, satellite imagery, photo- graphs, and user-specified geographic coordinates obtained from global positioning systems, or GPS. This allows land-resource managers to efficiently aggregate information tailored to a specific purpose or location. For example, agricultural producers can overlay crop yield maps created with yield monitors with WSS information to determine how different soils may affect crop production
https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm
Web Soil Survey (WSS) provides soil data and information produced by the National Cooperative Soil Survey. It is operated by the USDA Natural Resources Conservation Service (NRCS) and provides access to the largest natural resource information system in the world. NRCS has soil maps and data available online for more than 95 percent of the nation's counties and anticipates having 100 percent in the near future. The site is updated and maintained online as the single authoritative source of soil survey information.
Soil surveys can be used for general farm, local, and wider area planning. Onsite investigation is needed in some cases, such as soil quality assessments and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center at the following link: USDA Service Center or your NRCS State Soil Scientist at the following link: NRCS State Soil Scientist.
- Author: Ben Faber
|
Keys to Soil Taxonomy, Thirteenth Edition (5.14 MB) Online version
The Keys to Soil Taxonomy provides the taxonomic keys necessary for the classification of soils in a form that can be used easily in the field. It also acquaints users of soil taxonomy with recent changes in the classification system.
Recommended Citation
Soil Survey Staff. 2022. Keys to Soil Taxonomy, 13th ed. USDA-Natural Resources Conservation Service.
Illustrated Guide to Soil Taxonomy
Illustrated Guide to Soil Taxonomy, version 2.0 (21.62 MB)
The Illustrated Guide to Soil Taxonomy was produced for use by multiple audiences and is not intended to replace the full version of the Keys to Soil Taxonomy for the professional soil classifier. Some of the more technical and complicated criteria have been omitted or referenced in notes to make the user aware that there are exceptions. More complete criteria and definitions are available in the full version of the Keys to Soil Taxonomy.
This edition of the illustrated guide (version 2.0) is based upon the twelfth edition of the Keys to Soil Taxonomy.
When using the illustrated guide, open the bookmarks tab on the left side of the screen in Adobe Acrobat to navigate the document.
Recommended Citation
Soil Survey Staff. 2015. Illustrated guide to soil taxonomy. U.S. Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, Lincoln, Nebraska.
Keys to Soil Taxonomy, Spanish Version
Claves para la Taxonomía de Suelos, Décima segunda Edición, 2014 (5.41 MB) online
For decades, NRCS has worked with soil scientists from around the world to increase awareness and expand knowledge of the importance of soil and its impact on all aspects of life. The translation expands the horizons of the Keys to Soil Taxonomy by allowing professionals around the world to apply and interpret the system in a more uniform and consistent way. While soils differ globally, the ability to apply a system that is universally understood and accepted is a goal shared by many soil scientists.
As the world struggles with global warming and other environmental challenges, having a universally accepted method that can be applied when soil problems are addressed will contribute to successful outcomes. Soil scientists and other professionals from Latin America, the United States, and other countries will benefit from this translation effort for years to come.
The translation of the “Keys” into Spanish was performed by Carlos Alberto Ortiz-Solorio, Ma del Carmen Gutiérrez-Castorena, and Edgar V. Gutiérrez-Castorena of Área de Génesis, Morfología y Clasificación de Suelos, Programa de Edafología, Campus Montecillo, Colegio de Postgraduados en Ciencias Agrícolas.
Recommended Citation
Soil Survey Staff. 2014. Claves para la Taxonomía de Suelos, 12th ed. USDA-Natural Resources Conservation Service, Washington, DC.
Ordering Keys to Soil Taxonomy
A printed copy is available from:
NRCS Distribution Center
Enter keywords: keys to soil taxonomy
Phone: 888-526-3227
E-mail: NRCSDistributionCenter@ia.usda.gov
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