Tree and Shrub Watering Guidelines

EMERGENCY: Aug 2, 2011. Since writing this article in mid July, the drought (heat/wind/dryness) has become much worse. And it promises to go on for an extended time. I have discussed this topic with many, and one thing seems clear. Gardeners are NOT checking their soil to actually feel the moisture. I strongly recommend: Dig down at least 8 inches into the soil (for garden, shrubs and trees). At that depth, a handful of that soil should be wet enough to not fall apart when squeezed and dropped. Tree tops are turning brown in our native forests --a sure sign of severe stress.

Here in Northwest AR, the hot/dry/windy weather that we are currently experiencing, is ow taking its toll on our shrubs and trees. The low humidity and wind has depleted the soil water to an extent that I have not seen in the past decade. If you have not watered your trees and shrubs, do it now. You could lose them.

How Much Water to Apply? First, here are some facts. A one-inch rain supplies 62 gallons for each 100 square feet. A tree can easily use one to two (or more) inches of rain per week. Consider the watering area for a tree to be at least as large as the the area under the crown. (Just get the average distance in feet across the whole crown and square it). A small tree (5-inch diameter stem) can easily have a crown area of 200 square feet and a mature tree can easily have a crown area of over 600 square feet.

For each 100 square feet, add roughly 90 gallons of water per week. For most small trees (200 hundred square feet of area under the crown), I simply turn on the faucet so that I am getting 1 gallon of water per minute, and let it run for 5 hours. A soaker hose is ideal for getting good distribution. For a large, mature tree (600 square feet of area under the crown), I let the water run for about 15 hours. If you have not watered in the past 8 weeks (with essentially no rain), you should start by doubling these amounts. The soil is gun-powder dry and this amount of water is needed.

I know this may sound excessive, and I understand if you have concerns. However, consider the costs associated with tree removal, replacement, energy savings from shade on a house, and/or losses from fruit or nut production. It will quickly add up, so don’t wait and don’t skimp on the water. Use this as a guide and adjust on the methods that fit your situation. Water at night if possible.

Water Costs will vary by where you live. At Washington Water, without city sewage costs, I pay about $12.00 per each 1,000 gallons. I have 15 trees, averaging about 300 square feet of crown area per tree. At the rate of adding 90 gallons per 100 square feet, that means I need about 4,050 gallons of water per week, at a cost of about $50.00. Even if I have to do that for 6 weeks, i.e. $300.00, that is a real bargain compared with loss of shade, future pecan production, and tree removal and replacement.

Water Conservation. Anything you can do to help the soil hold more water is beneficial. I use a 6-inch layer of mulch of wood chips and leaves around my trees. As the trees grow I make the mulch circle larger each year, up to 8 feet in diameter. As the mulch decomposes, it gets incorporated into the soil, which increases the soil water holding capacity. Through transpiration, trees use a lot of water and there is not much you can do to change that water consumption.

Priorities. You may feel that you cannot water all your trees. If so, select those for watering on the basis of value. Water those Of the trees you plan to save, water those in the driest places (shallow soils) first.

Humates (Humic Acid) -- Good for all Soils

                          Humates

On a world-wide basis, roughly two thirds of the planet’s organic carbon has been lost during the last 50 years of extractive agriculture. In Arkansas, the average soil organic matter has decreased to 1.25 percent. Five percent organic matter is a reasonable goal for garden soils.

Whether you use organic or conventional methods, adding humates to the soil is a good choice. Almost all humates are extracted from Leonardite or lignite, often referred to as brown coal. Humates not new, and fifty years of research has quantified the multiple benefits. Though often labeled simply as “humid acid,” there may be many organic acids (like those that are found in humus) in the product. Humic acid is available locally.

The benefits of humates directly parallel the benefits of humus -- pH buffering, moisture retention, microbe stimulation, soil structure enhancement, improved nutrient uptake, and even removal of toxins (like Roundup). These and other benefits result in reduced need for fertilizers. Humid acid has an extremely high Cation Exchange Capacity (450), so serves a tremendous benefit in reducing leaching of other minerals. We all needed that in April and May. Reduced leaching saves money.

The product comes in liquid or the dry form. Several on-line sources mix the product with other helpful soil amendments like kelp (for potassium) or beneficial microbes. Whether you use the liquid or the dry, a little goes a long way. One quart of the locally available humic acid (12%) covers 5,000 square feet.

This is not just a garden product. It is used on lawns, orchards, pastures, and grain crops.

Spring and Summer Crops are turning out very well, despite the cool spring, rain and now the HOT June. The photos below show onions, beets, carrots, cabbage, peppers, and potatoes harvested on June 17. Tomatoes, beans, okra, and sweet potatoes look very good. Of course, they love this hot weather. These are some of the easiest vegetables to grow. Learn the details. See below.

Fall Gardening is just six weeks away, and I have already been talking with folks about some of the specific things that are needed to be successful. It seems, just when the gardening enthusiasm begins to wane (in hot August), that is the time to re-charge for the fall. Paying attention to the garden in the fall is critical to winter weed control and having a healthy soil in the spring.

Waterlogged Soils and Soil-less Growing Mix

Waterlogged Soils. After a very dry early spring we hit the jackpot in late April with 12-16 inches of rain in a week. That has caused many problems. The most noticeable effects were the erosion and soil compaction. On even a slight slope, that pounding rain may have taken away an inch or more of top soil. You may have also noticed some plants turning yellow and some of them even wilting. The Reason -- those waterlogged soils contain almost no air and the plants can not take up nutrients and grow.

If you had serious soil issues, plan now for making some changes. Wet soil problems are usually fixable. It may be that drainage ditches are needed, or maybe you even have to change the garden location.

The value of raised beds was never more self evident than with these recent rains. Except for one bed of newly emerging carrots, all my raised beds were covered with spring vegetable crops and/or mulched with straw. They suffered very little with the rain. A couple days after the rains stopped, I “fixed” the carrot bed by adding a little compost and covering the area with finely chopped, old straw. Production for the spring crops looks great.

Soil-Less Growing Mix. One gardening book, and other “experts” advocate growing gardens in a soil-less mix composed of several different kinds of organic material. I am opposed to this practice. It is not surprising that I have had several calls this year from soil-less mix

users who describe past results as “poor” to “miserable.”

These soil-less mixes are generally not sustainable and far from what I call good organic gardening practices. Produce from those gardens are invariably poor in nutrient content. As a rule, if the plants can even get

started in such a mix, they end up having lush vegetation, with little to no fruit production, and a preponderance of insect issues. It is no wonder. As a rule compost does not have the correct ratios of minerals needed by plants for good fruit production. I have heard gardeners say, “you can’t use too much compost.” That is not true. I caution gardeners routinely, to use compost wisely, i.e. sparingly.

There is no simple solution for those garden beds filled with a soil-less mix. Several gardeners I know are digging out their expensive soil-less mix and starting over with some top soil at about ten percent the cost. A small amount of the mix may be useful as a soil amendment. It will depend on the nutrients in the mix, but I would start with no more than 10 parts soil to 1 part soil-less mix for any vegetable garden. See photo below for results comparing a soil mix(left )from a soil-less mix(right).