Xtremehorticulture

Xtremehorticulture of the Desert

Soil Testing for Home Gardens and Landscapes

2 Comments / agriculture, home garden, raised beds, residential, soil test /

 Testing the soil for home landscapes doesn’t need to be done every year. They are expensive. Start with a baseline soil test (beginning) and test the soil every three to five years or when you think it is necessary. Many of these retail home soil tests can also be marketing tools for selling amendment products. Home soil testing come in kits like La Motte’s or a soil sample you can send in for analysis like the one below. Testing raised beds for gardening is no different than a small garden area without sidewalls. Make sure ALL the important plant nutrients have been tested in desert soils. There has been a lot of negative endorsements in general info about home soil tests. But in my opinion they aren’t too bad if you are looking for general numbers.  This is an example of a home soil test result from Las Vegas, Nevada. It was not too bad. Not as precise as a commercial agricultural soil testing lab but not too bad. Agricultural Labs For more precision I would recommend a commercial agricultural soil testing laboratory that can invest  hundreds of thousands of dollars in important equipment. For research we use A and L Soil Testing Laboratory in Modesto, California, or do it ourselves but a good soil testing labs are considerably less expensive than doing it yourself for research. The major advantage of a lab doing it for a fee and home testing is usually the numbers of tests you can run. Home testing usually involves several tests for the same price while a commercial lab you only can submit one soil sample for a fee. Use a Local Lab It is important to submit samples to a lab that represents your type of soil. Some of the big labs need to know a bit about your soil sample before you begin. Soil testing can be different in different parts of the country. If you live in an arid/desert part of the country, submit it to an arid/desert soil testing laboratory. This is an example of a commercial agricultural soil testing laboratory report.  Commercial agricultural soil testing laboratories invest a considerable amount of money in testing equipment. They are expensive but when accuracy is needed they do a very good job.  Examples of commercial agricultural soil testing laboratories in desert areas to consider include A and L in Modesto, and  IAS in Phoenix, In some states an agricultural soil test is available from the University. These are a good bargain and give you valuable and accurate information. What to Test? Most soil testing includes nitrogen, phosphorus and potassium and a few other nutrients. Besides these, in desert soils make sure your soil is tested for iron, manganese and zinc as well. Don’t forget the pH (alkalinity) and EC (salts) to include the salts of sodium, chlorides and boron. Boron is important for soil testing in desert soils. Remember…”garbage in, garbage out.” Always submit a good soil sample.

Soil Testing for Home Gardens and Landscapes Read More »

Do Liners at the Bottom of Raised Beds Help or Hinder?

1 Comment / desert, Las Vegas, Mohave Desert, Mojave Desert, nevada, raised beds, vegetable garden /

Q. I’m setting up some raised beds for planting this spring and wondered about water evaporation from the soil. Since water retention in the soils here in Vegas is an issue due to the heat would it make sense to put a liner in the beds to help keep the moisture from draining out so quickly? A. No, I would not do that. Water will drain to the liner and begin to puddle or “perch”. You need continuous movement of water through the soil to prevent your raised bed from staying too wet above the liner. Raised bed under construction with cement side walls against a block wall.             In the Las Vegas Valley, water originating from the Colorado River carries significant amounts of salt. Our soils also contain large amounts of salts. Some are good salts and some are not but regardless we must keep these salts moving through our soils.             The best way to do this is to “overwater” our soils to flush salts through the soil. The overwatering does not have to be much, maybe 15 to 20%. But this 15 to 20% has to go somewhere.             To keep these salts moving or eliminated from our soils we have to make sure water leaves raised beds and goes somewhere. A liner at the bottom of the bed slows down this “flushing” action.             If you are going to put some sort of barrier at the bottom make it porous so water can move through it.

Do Liners at the Bottom of Raised Beds Help or Hinder? Read More »

How Much Compost to Add to Garden Depends on Soil

Leave a Comment / how much compost to add to desert soil, raised beds, vegetable bed /

Q. I am starting a new garden spot. How much compost should I add to the soil? A. If this is a new spot of raw desert soil or fill, the first year incorporate about 12 cubic yards of compost into 1000 square feet of growing area to a depth of 12 inches. The second year of growing incorporate half of that; the third year, half of what you applied the second year. If desert soil has never had compost added to it or it was never in any kind of agricultural production then the first application will be very heavy. The second year not as much is needed and the third year the amount added is even less.             Each year afterwards add 2 yards per 1000 square feet to maintain soil organic matter and production levels. Why so much? You can visit my blog and learn why.             I would recommend growing in beds clearly identified for your garden. The areas between the beds are designated for foot traffic. When compost is added at the rate of 12 cubic yards for every 1000 square feet it doesn’t seem like much when it is incorporated to a depth of 12 inches.             Raised beds do not require hard construction sidewalls. Constructing hard sidewalls gives you about six inches of extra growing space around the edge of the beds. Constructed beds should be 12 to 18 inches tall and three to four feet wide. Foot access should be provided on all sides of the bed.             Raised beds will stay in place without hard sidewalls if constructed properly. You can see beds like these on the UNCE Orchard in North Las Vegas.               The second year about half of the compost is added to the raised beds that was added the first year to build soil organic matter. Raised beds do not need constructed hard sidewalls. Mulch is put down the center aisle for walking.             Drip irrigation is best. Drip emitters should be about 12 inches apart for most crops. Crops that require closer spacing (onions, garlic, beets, and carrots) may require emitters closer than this. All emitters should release water at the same rate and pressure.             Space tubing one foot apart lengthwise down the beds. A 3 – 4 foot wide bed would have three in each bed. The four foot wide would accommodate three as well but spaced further apart.             Mulching vegetables during the summer heat helps. Use straw or a light topdressing (3/8 inch minus) of screened compost. After amending the soil and building the raised beds, the drip irrigation is installed. This is drip tubing with emitters spaced every 12 inches along the tubing.             If rabbits are a problem, fence the area with 2 ft. wide chicken wire, one inch hex, buried on the bottom edge one inch deep. Fertilize vegetables lightly once a month. Use a high phosphorus fertilizer at planting time. Irrigate daily during the summer months. Remove weeds daily when they are small.

How Much Compost to Add to Garden Depends on Soil Read More »

Constructing Raised Beds With and Without Side Walls

Leave a Comment / construction, desert soils, instructions, raised beds /

Q. Hello Professor Morris, I’m trying to figure out how to just post questions in the blog,  so you won’t have to reply separately (if the answer is in the newsletter I’ll just see it there).  I wonder if there is a best size or height for a raised bed.  I want to put in enough good soil, but don’t want to make it higher if I can make it larger, to grow more plants using the same amount of soil.  Trenching desert soil for creating rasied bed A. The height is up to you  and what your back can handle. For root crops and asparagus they should be a minimum of 18 inches deep. Most desert soils can grow excellent vegetables and flowers if they are amended properly at the very beginning. You can use existing desert soils at the location of the bed or you can import manufactured soils from sand and gravel companies or nurseries. If you import a manufactured soil, do not use reject sand. If you are importing a soil to use in place of your soil at the site, select a manufactured soil that resembles the soil at the site as closely as possible. Take a sample of the soil at your site when you are selecting the imported soil so you can compare the two. Check it to match the texture (how sandy or clayey it is) so the garden bed will drain water into the existing soil. Problems with drainage can occur if the two soils, the soil at the site and your imported soil, are dramatically different from each other. Adding compost before tilling and forming the raised bed Raised garden beds should be oriented north to south if at all possible. Their dimensions should be 3 to 4 feet wide if you can access the bed from either side. If the bed is accessible from only one side then perhaps 3 feet would be the maximum width. Keep garden beds at least 3 feet from foundations and block walls if at all possible. Once established, you should avoid walking on the raised garden beds other than for possibly planting or harvesting. Use kneeling boards. Never walk on them wet. I would recommend drip irrigation and using tubing with built in in-line drip emitters. I would use the larger drip tubing such as half-inch and not the smaller laser tubing. Visit with Timmy who runs irrigation department at the Plant World Nursery on Charleston. He will set you up with a drip irrigation system and components that you can run off of a hose bib or garden hose if you want to. These steps will create multiple raised beds at the site without constructing sidewalls by using and amending the existing soil. 1.         Rip the soil to a depth of 12 to 18 inches with multiple trenches over the entire site. I usually use a trencher. 2.         Remove large rocks. 3.         Flood the trenches with water as best as you can. 4.         Fill trenches with compost. 5.         Collapse the sides of the trenches Finished, planted and labeled raised vegetable bed made from raw desert soil and compost. 6.         Apply 3 to 4 inches of compost to the entire site and rototill as deep as possible. 7.         Remove rocks larger than a golf ball. 8.         Create pathways that are 18 to 24 inches wide between the raised beds by shoveling the amended soil onto the raised beds. 9.         Shape the beds using a landscape rake and garden rakes so that it is a level and the sides of the beds are at a 45° angle. The cross section of the width of the bed should resemble a long trapezoid. 10.       Firm the bed using a roller so that your footprints sink no more than 1/2 inch into the soil when you walk on it. 11.       Install irrigation. 12.       Your bed is ready for planting. 13.       Every time you plant, incorporate a 2 to 3 inch layer of compost subsequently for the next two years. After two years you can reduce the amount of incorporated compost to 1 inch. These steps will create a raised bed using constructed sidewalls. 1.         Rip or at least disturb the soil to a minimum of 6 inches beneath the raised bed. 2.         Construct the sidewalls with your choice of building materials and to your desired height. For root vegetables and asparagus the depth should be a minimum of 18 inches. 3.         Line the inside of the constructed sidewalls, not the bottom, with heavy gauge pond liner. 4.         If you’re using a manufactured soil that has not been amended with compost: •        Mix good quality compost with your desired soil outside of the raised bed in a volume ratio of three parts compost to one part soil (3:1). •        Remove any rocks larger than a golf ball. If you are planning on a lot of root crops then screen the soil so that any remaining rocks are less than 1/2 inch. 5.         If you’re using a manufactured soil already amended with compost: •        Mix good quality compost with your desired soil outside of the raised bed in a volume ratio of one to two parts compost to one part soil (1 or 2:1) depending on the manufactured soil color. If the manufactured soil color is predominantly gray or tan, then use 2:1. If the manufactured soil color is light brown, then use 1:1. •        Remove or screen any rocks in the soil. 6.         Fill the raised bed with the amended soil and settle the soil with water as you are filling it. Fill the raised bed so that the soil is 2 inches below the top of the raised bed. 7.         Make sure the raised bed is firm and not fluffy. 8.         Install your irrigation system.

Constructing Raised Beds With and Without Side Walls Read More »