Soils with excess soluble salts, saline soils, and/or excess sodium (Na⁺) concentrations (sodic) are a natural feature of desert soils and common in arid land agriculture.  This is primarily due to an accumulation of soluble salts near the soil surface as water evaporates from the soil surface.
 
Saline soils are a problem in crop production systems because of the sensitivity to salinity of crop plants, although plants vary in their degree of sensitivity.  The period of greatest plant sensitivity to salinity is in the early stages of development, during germination and stand establishment.
 
Sodic soils are a problem in crop production systems because of the adverse effects of excess sodium on soil structure, causing a dispersion of soil particles and the breakdown of soil aggregates.  This leads to poor water infiltration and percolation in the soil profile.
 
Some basic points associated with saline and/or sodic soils and management are outlined in the following sections.
 

1. Saline soils have an electrical conductivity of the soil solution (extract, EC_e) of EC_c > 4 dS/m.  Functionally, saline soils have sufficient soluble salts to interfere with and diminish plant growth and development.
   1. Soil salinity is a relative term or condition based on the critical salt sensitivity levels of the crop plant in question.
   2. Plants vary tremendously in their degree of salt tolerance.
   3. Reclamation and management of soil salinity requires an understanding of the specific level of sensitivity of the target plant to salinity.
   4. Saline soils commonly have good soil aggregation and structure.
   5. Reclamation of saline soils requires sufficient water to accomplish leaching and the removal of soluble salts.  Thus, good internal soil drainage is important.

 

1. Sodic soils have a high level of exchangeable sodium (Na⁺) on the soil cation exchange complex (CEC).  Sodic soils have an Exchangeable Sodium Percentage, ESP > 15 of the soil CEC or a sodium adsorption ratio, SAR > 13 from the soil extract.
   1. Sodic soils commonly have poor soil structure and aggregation due to the dispersed condition of soil particles caused by high concentrations of Na on the CEC.
   2. In practice, finer textured soils, e.g. clay, clay loam, silty clay loam, etc. with high clay content can develop sufficient dispersion and poor soil structure at ESP or SAR levels ~ 6-10.  So, the ESP and SAR designations are general and not absolute.

https://www.nrcs.usda.gov/wps/PA_NRCSConsumption/download/?cid=nrcseprd589210&ext=pdf
Sodic soil reclamation does require an amendment that will facilitate the chemical exchange of Na⁺, usually from a calcium (Ca²⁺) source, such as gypsum (CaSO₄).
 

1. Reclamation for saline soils requires additional irrigation water for leaching.  Chemical amendments are not necessary for soluble salt removal.

An effective and straightforward method of calculating a leaching requirement (LR) can be calculated with the following equation that was presented by the USDA Salinity Laboratory (Ayers and Westcot, 1989).
Leaching Requirement (LR) Calculation:

Where: 
ECw = salinity of the irrigation water, electrical conductivity (dS/m)
ECe = critical plant salinity tolerance, electrical conductivity (dS/m)

1. Saline soils do NOT need amendments for reclamation or management.  Only leaching is needed.

 

1. Sodic soil reclamation involves a two-step process:

1. Exchange of Na with Ca and 2) leaching of soluble Na⁺ from the crop root zone.

 

1. Adequate soil leaching is required in both cases of saline and sodic soils.
   1. In the case of sodic soil reclamation, the leaching needs to occur after appropriate amendment applications for Na⁺ exchange with a suitable cation such as Ca²⁺.

 

1. Adequate drainage is necessary to accomplish sufficient leaching of solutes through the soil profile and below the root zone in the reclamation of both saline and sodic soils.

 

1. Irrigation systems capable of delivering sufficient water for leaching are necessary.
   1. Level basin flood irrigation best serves salinity leaching requirements.
   2. Sufficient salinity leaching can be accomplished with furrow flood or overhead sprinkler irrigation.
   3. Drip irrigation systems much be designed to provide sufficient volumes of water to accomplish adequate soil leaching.

i.Drip irrigation systems are commonly very limited in this respect.
 

1. Crop rotation systems are important in leaching and salinity management.
   1. For example: Crops planted on the flat and irrigated by level basin irrigation serve to facilitate good salinity leaching in a field.

i.Examples: wheat, alfalfa, sudangrass, etc.
 

1. Good field observations of crop growth and development in conjunction with regular soil and water sample analysis are key elements to the management of salinity and sodicity in agricultural fields.  

For example, young plants in the germination and seedling stages of development are most susceptible to salinity and water stress.  Abnormal amounts of seedling damage and/or difficulties in germination can often be early signs of increasing soil salinity.
Also, early signs of increasing salinity are often observed with plants demonstrating water stress with plant-available water levels in the soil that should seemingly be adequate for maintaining non-stressed plants.  Thus, fields that are requiring an irrigation in shorter intervals than usual can possibly be an early sign of increasing salinity and it is good to follow-up with a good set of soil samples and a sample of the irrigation water to check.
Early identification of problems in the field with increasing Na concentrations are commonly noticed with increasing tendencies of the soils in the field to form surface crusts very easily, which reduces water infiltration into the soil surface.  This is often recognized at the time planting and stand establishment with germination problems resulting from increasing degrees of soil crusting.

Frost and freeze damage affect countless fruit and vegetable growers leading to yield losses and occasionally the loss of the entire crop. Frost damage occurs when the temperature briefly dips below freezing (32°F).With a frost, the water within plant tissue may or may not actually freeze, depending on other conditions. A frost becomes a freeze event when ice forms within and between the cell walls of plant tissue. When this occurs, water expands and can burst cell walls. Symptoms of frost damage on vegetables include brown or blackening of plant tissues, dropping of leaves and flowers, translucent limp leaves, and cracking of the fruit. Symptoms are usually vegetable specific and vary depending on the hardiness of the crop and lowest temperature reached. A lot of times frost injury is followed by secondary infection by bacteria or opportunist fungi confusing with plant disease.

Most susceptible to frost and freezing injury: Asparagus, snap beans, Cucumbers, eggplant, lemons, lettuce, limes, okra, peppers, sweet potato

Moderately susceptible to frost and freezing injury: Broccoli, Carrots, Cauliflower, Celery, Grapefruit, Grapes, Oranges, Parsley, Radish, Spinach, Squash

Least susceptible to frost and freezing injury: Brussels sprouts, Cabbage, Dates, Kale, Kohlrabi, Parsnips, Turnips, Beets

More information:

https://www.extension.iastate.edu

https://www.farmprogress.com

Given the positive feedback from last week’s article, I thought I’d share with you another video that showcases the cutting-edge advancements in AI technologies. This time, the topic is Digital AI Twins. Reid Hoffman, a renowned expert in AI technologies, has created a digital twin of himself named “Reid AI” using a custom Generative Pretrained Transformer (GPT). Reid AI was trained using content from over two decades worth of Hoffman’s public speeches, podcasts and published books. The result is a digital entity that mirrors Hoffman’s knowledge, insights, and even his conversational style. In the segment, Hoffman interviews his AI counterpart. The conversation is not only entertaining but also very realistic, blurring the lines between human and machine. I was pretty impressed and think you will be too. Given the rapid advancements in these technologies, one can’t help but wonder what’s next in the evolution of AI and how this technology will change the world.

Check it out here or by clicking image below.

Fig. 1. Reid Hoffman meets his AI twin. (Credit: Reid Hoffman).

The Southwest Agricultural Summit that recently took place in Yuma included a breakout session on Thursday, 21 February 2024 titled “New Developments in Weed Control”.
In this session Jose Antonio Cabrera representing BASF technical services for Coastal CA and Arizona provided a review of the new technologies being developed by his company in the Weed Control area. This includes new active ingredients as well as novel encapsulation technologies. The breakout session also included the lecture “Registration Support for Pest Management Tools in Specialty Crops, The IR-4 Project: Purpose and Process” by Roger B. Batts. “The IR-4 Project was established in 1963 by the U.S. Department of Agriculture to ensure that specialty crop farmers have legal access to safe and effective crop protection products. Helps growers address pest management concerns, develops data necessary for the registration of safe and effective pest management solutions with the U.S. Environmental Protection Agency¹.
Roger is the Weed Science biologist from the NC State University IR-4 headquarters. If you have questions such as: What is the IR-4 Mission? Why is IR-4 Needed? What are the programs within the IR-4 project? you will find some answers in the IR-4 Presentation Slides here.
We are currently conducting trials in Yuma in coordination with this project that could result in the addition of new labels and weed control tools for our Arizona vegetable growers.
Thank you for attending the SW Ag Summit Weed Science breakout session.
 
 
Reference:

1. https://www.ir4project.org/

 

Get your free copy of the Weed Seedling Identification Pocket Guide at the Yuma
Agricultural Center.

 

Results of pheromone and sticky trap catches can be viewed here.

 

Corn earworm: CEW moth counts remain at low levels in all areas, well below average for this time of year.

Beet armyworm: Trap increased areawide; above average compared to previous years.

Cabbage looper:  Cabbage looper counts decreased in all areas; below average for this time of season.

Diamondback moth: DBM moth counts decreased in most areas. About average for this time of the year.

Whitefly: Adult movement beginning at low levels, average for early spring.

Thrips: Thrips adult counts reached their peak for the season. Above average compared with previous years.

Aphids:  Aphid movement decreased in all areas; below average for late-March.

Leafminers: Adults remain low in most locations, below average for March.