Are we watering correctly?

The arid summer causes an increased need to water vegetable patches. The heat and wind promote fast vaporization of water. It is certain that without water vegetable seed will not germinate and begin growth. Soil moisture is indispensable for dissolution of nutrient materials in soil, as well as the transport of the minerals to different parts of the plant. Water also provides for cooling of plants during an overheating from direct sun rays in a process known as transpiration.

The lack, as well as the excess of soil moisture slows the growth of vegetable plants. Thus, leaves develop badly and abnormally as well as the other vegetative organs. The effect on the growing crop is that of a lower yield and poorer quality.

Most active zone or layer for the radicals (roots) of vegetable plants is a depth of 20-30 centimeters. Therefore anyone who is irrigating should provide moisture to this layer of soil. Infrequent and shallow irrigations during a time of dry weather do not benefit plants, and occasionally even give negative effect. When moisture is lacking in the root system’s preferred zone, the growth of the outside surface radicals is instigated. Deeper irrigations will wet the soils in the preferred root zone where minerals are more plentiful.

It is possible to determine the dampness of a patch of soil of one digs to a depth of 20 - 30 cm. At this level, simply look for any abrupt changes in soil color or texture. If the soil is dry above this level, then irrigations should be in order. Soil moisture can also be determined by the ’feel’ method. Simply form a small ball with the soil in your hands. If the ball breaks apart or refuses to form, the soil is in need of moisture immediately. A ball that shapes easily in your hand indicates a loamy content, and soil moisture is probably adequate. When a strong ball is formed, and the soil structure is somewhat puddled, this generally indicates too much soil moisture.

The appearance of the garden plants themselves can also be an indicator of soil moisture. However, in some extreme conditions of very hot weather, even plants having adequate soil moisture may show symptoms of being under-irrigated. In these cases, the plant simply can not keep up with the transpirational demand. Spraying the foliage of garden plants with water is useful in times of extremely hot weather.

Water requirements of the different types of vegetable plants vary greatly (see Table, below). Moisture loving plants include cucumber, lettuce, spinach, cabbage and radish. The root systems of these high water users are typically in the upper layers of soil, and thus, their evaporating surface is quite large. Also, weight of the root system relative to that of the above ground portion in these kinds of plants is very low, thus indicating a high rate of transpiration relative to the root surface area. Ratios of 1:25 and 1:11 for roots : above ground portion are typical for cucumber and cabbage, respectively.

The radical, or root of some vegetable plants can penetrate deeply into the soil and branch out to mine a large volume of soil for moisture. Radicals are usually quite fleshy organs, and imbibe a great deal of moisture during seed germination and at the beginning of growth. In root crops, the roots thicken as the plant matures and the radical becomes a special storage organ. Moisture extremes are damaging to a crop. These include an excess of moisture, and/or stagnation, as well as sharp changes in the soil water content. Roots can burst or cleave under excess moisture, and rough irregular and woody roots are typical of root crops that are not irrigated sufficiently. Optimal soil moisture for root crops would be around 80%

The onion has a specific period of growth when water demand is high. Due to the compactness of the root system of onion, steady irrigation is required for the first three weeks of development. Later, when the bulb is filling out, the demand is again high. Irrigation during the maturation of the bulb can cause problems with disease and can reduce bulb quality, especially during storage.

Both cabbage and cucumber are very particular to both soil moisture and ambient humidity. It is practically impossible to raise cucumber without good irrigations. The fragile root systems of cucumber perish very quickly without water. Cucumber leaves are also very large and transpire large quantities of water vapor. With inconsistent soil moisture, cucumber plants will produce ugly and bitter fruit. Water cucumbers 1 - 2 times per week, and apply 20 - 30 l per M². On excessively hot days, the plants should have their leaves sprinkled to conserve plant moisture.

After the emergence of young cabbage seedlings, 20 - 25 l water per M² are needed on a regular basis until the young plants are acclimated to the garden environment. Early varieties are more often in need of regular irrigations. The average and late varieties require heaviest irrigations during the time of head formation as well as 2-3 weeks prior to harvest.

Consumption of water by miscellaneous garden plants

Pumpkin, watermelon, string bean, corn, tomato and carrots are all very capable of obtaining water from deep layers of soil and to utilize it economically. At the early stages of growth of the plant - when the root system pattern is reshaped, frequent and deep irrigations are harmful to the plant, since the priority of plant is the creation of the root system near a surface of the soil.

The greatest requirement of vegetable cultures for water is during the intensive growth phase occurring from the end of spring up to the middle of July. During this period, plant water status will be a major factor in defining value of a crop and its quality. The lack of water in this period causes low quality in turnip, radish, onion and beet. Even a short-lived drought for a root crop, for example radish, can cause the root to become flabby and bitter. At the same time excess of moisture in the second half of summer degrades a crop of watermelons, onions and carrots.

It is necessary to examine the quality of soil on miscellaneous sites of a kitchen garden and irrigate appropriately. A patch arranged near walls or along fences will dry faster. Therefore, it is necessary to water them more frequently. The clay soils hold moisture well, and sand, on the other hand, requires lighter and more frequent irrigations. Saturated soil, in any case, decreases the availability of oxygen, and that decreases the process of decomposition of organic matter. With an optimum mixture of soil moisture and oxygen, the organic matter is decomposed faster, and both nitrogen and carbon dioxide are made available to plants.

The kitchen gardener might wonder, “Just how much water can my garden soil hold?” The answer to this question is a term ’field moisture capacity.’ Field moisture capacity is defined as the moisture content of soil after drainage of excess moisture due to gravity. At ’field capacity,’ a soil holds its moisture under capillary tension in the small pores that surround the small particles of sand, silt and clay. Moisture is also held on organic matter in the soil. Larger pores in the soil profile contain air even at field moisture capacity. Different garden soils hold different amounts of moisture. As a general rule, soils with a high clay content have a larger field moisture capacity than sandy soils.

The water used for irrigation is best taken from stagnant pools where the water plants grow. The water plants consume carbon dioxide with the aid of light through a process known as photosynthesis. Oxygen is then liberated into the water. By evening this water highly oxygenated. If this type of water is not available at your garden site and you have the capacity for water storage, you can help oxygenate the stored water just by simple churning.

There are some different methods of irrigation. Most simple is with the help of a baler. Sown seeds and emerged plants can be irrigated through nozzles having a mesh at the opening. Watering from a plain hose pipe can be a hazard to very young plants. The heavy stream of water from the hose pipe can wash the soil away and expose the roots. If it is necessary to irrigate from a hose pipe, it should be held so that the applied water comes out in a spray. One can easily use the thumb to cover part of the opening of the hose pipe. Sprayers of various sizes can also be used to break up the stream of water so that no high-gravity drips will drop on soil and impart sealing of the surface layer.

In May workers in the kitchen garden usually apply water from balers although other methods are also employed. A ’bottle dripper’ can be fashioned from empty 0.5 l bottles. First plunge the spout of the bottle into the ground to a depth of 10 centimeters. Then take out the bottle and fill it with water. Quickly turn the filled bottle over into the prepared slot and seal it into the garden soil. After that the bottle uplifts, shakes up, and the earthen fuse allows for a slow dripping of the bottled water into the garden soil. The water from a bottle slowly percolates in soil for an entire week. In a 5 M² area, 15 bottles of this nature might be typical.

It is possible at times to use natural recesses on a site to arrange elementary pools. They not only are decorative, but also maintain a microclimate by providing humidity to the air. The same water is oxygen-rich, heated sun, and can be used for irrigation purposes.

On hot sunny days, it is better to water in the evening, although sometimes irrigation is still required at mid-day. Thus it is necessary to aim the water stream so as to not wet the leaves, as the drips, generated on them develop into peculiar lenticles, and promote small solar combustions. If one needs to flush away dust, in hot weather it is best conducted only in the evening or until 11 in the morning. Morning irrigations are much less effective, as the sun fast evaporates the moisture and the plant will again be in a deficit situation as contrasted by having watered in the evening. It is desirable that temperature of water and soil be approximately identical.

Although it is most labor-consuming and expensive, a drip irrigation system is the most effective. A specialized tube or hose is placed throughout the garden, and holes are placed in the tube to which drip emitters or small sprinklers can be placed. A big advantage of this system is that the emitters or sprinklers can be placed at the optimum location nearby each plant. The irrigations can be timed manually, or with an electrical system and valves. This allows a soaking of the necessary areas in the garden, but will also prevent waterlogging when the system is shut off at the appropriate time. Thus, oxygen will be plentiful when a drip system is used properly and roots will be properly nourished with both water and air.

In some cases, kitchen gardens have no adequate supply of water on site. Here, a system of mulching can help considerably to conserve water. Many different types of material are available for mulching the garden. Manure, peat, straw, small twigs, or fallen leaves can all be used in a loose layer 3 - 5 cm deep to help prevent moisture loss form the garden soil. Similarly, building materials such as polyethylene film (clear or black), kraft paper and roofing felt can be used for mulching as well. Spread these materials over the garden patch and cut holes where there are, or will be plants. These materials may also help to warm up the soil, thereby encouraging root growth and healthy plants. Weeds can also be prevented, especially with black polyethylene film. When organic materials are used for mulching, there is the added benefit of incorporation of these materials into the soil after the crop is harvested. These organic materials will help the next garden by increasing soil fertility. It is said that by mulching, productivity can be increased by as much as 50 % or more.

If digging a well for ground water is an option, one should choose a site where the water is as close to the surface as possible. Dig the well in the dry summertime to ensure that water will be available in the summers to come. A stack of boxes, perhaps the size of a typical computer box should be used to consolidate the walls of the well. When the new well is stacked to the opening with boxes, soil can be added to the corners and then the ground can be stamped firmly. As water comes into the well, it fills the spaces within the boxes and the arrangement will withstand the treatment for a long period of time. A barrel can be placed near the opening of the well where water can be stored and warmed in the sun. Place a cover over the opening in order to reduce evaporation. To remove water from a deep level in the well, use a jack with a counterbalance. If large quantities of water can be obtained from the well, perhaps a motorized pump would be the best option.

When our climate is more arid than normal, there are usually problems with water availability. In arid years, the ground-water level drops sharply. Therefore, clever and successful gardeners have several tricks to saving moisture at the garden site. What is one of these tricks? A clever gardener can dig grooves parallel and perpendicular across the garden in a 1 X 1 M pattern. This should be done before snowfall begins. The grooves will fill with snow and remain there until the spring thaw. An extra amount of snow is collected in this manner, and the excess will help reduce the fall in the ground-water in those arid years.

In the summer the savings of moisture will help maintain the soil in a friable status. Weeds should be destroyed whenever noted, as well as any diseased plants. These problems can exhaust the soil, and make it unproductive after only a short time. Rotation of crops can also help retain the friability of the soil. Always use high quality oxygenated water. Rain water is perfect for this purpose. It can be gathered by placing barrels under the gutters of houses, and placed in the sun for solar heating. To enrich the water with iron, put old tacks and nails into the barrels and let them rust. The liquefied iron is a rich plant nutrient.