One Thousand Questions in California Agriculture Answered Part 57

That could only be determined by a.n.a.lysis, and the a.n.a.lysis must be made when the water is rather low, because during the rainy season, or soon after it, the water may have less mineral impurity than later in the season when it may be more concentrated.

Shall He Irrigate or Cultivate?

Our soil is of an excellent quality, and I feel if the moisture were properly conserved by suitable methods it could be made to produce fruits or some other very much more profitable than from hay and grain crops.

Whether you can grow deciduous fruits successfully without irrigation depends not only upon how well you conserve the moisture by cultivation, but also whether the total rainfall conveys water enough, even if as much as possible of it is conserved. Again, you might find that thorough cultivation will give you satisfactory young trees, but would not conserve moisture enough for the same trees when they come into bearing.

This proposition should be studied locally. If you can find trees in the vicinity which do give satisfactory fruit under the rainfall, you would have a practical demonstration which would be more trustworthy than any forecast which could be prepared upon theoretical grounds.

Condensation for Irrigation.

If a circular funnel of waterproofed building paper, or some better cheap device, were fastened about the base of the tree in such a manner as to catch and concentrate most of the drippings from the leaves, and that water made to run down through a tube leading a suitable depth into the earth, it seems to me that the number of foggy nights that occur in many localities during the season might thus supply ample water for a tree's needs.

The probability is that water would not be secured in sufficient quant.i.ties to serve any notable irrigation purposes, or if the fogs were so thick as to yield water enough, the suns.h.i.+ne would be too scant for the success of the plant. Put your idea to the test and see how much water you could get from a tree of definite leaf area, which could be readily estimated.

Winter Irrigation.

Last May I irrigated my prune trees for the first time, again during the first two weeks of last December. If no rain should come within the next two weeks, would you advise me to irrigate then? Should I plow before irrigating, or should irrigation be done before the buds swell?

Unless your ground is deeply wet down by the rains which are now coming, irrigate it once, and do not plow before irrigating. The point is to get as much water into the ground and as much gra.s.s growth on top as you can before the spring plowing. Never mind about the swelling of the buds.

The trees will not be affected injuriously by getting a good supply of winter water into the soil. There might be some danger with trees which bloom late in the spring, like citrus trees or olives, because by that time the ground has become warm and the roots very active. At the blooming time of deciduous trees less danger would threaten, because there is less difference between the temperature of the ground and the water which you were then applying from a running stream. If you irrigated in furrows and, therefore, did not collect the water in ma.s.s, its temperature would rise by contact with air, which would be another reason for not apprehending trouble from it.

How Much Water for Oranges?

How much water would you consider absolutely necessary to carry to full-bearing citrus trees an clay loam-that is, how many acres to a miner's inch, figuring nine gallons per minute to the inch?

It would, of course, depend upon the age of the trees, as old bearing trees may require twice as much as young trees. We would estimate for bearing trees, on such retentive soil, 30-acre inches per year applied in the way best for the soil.

Damping-off.

My orange seed-bed stack has "damp-off." Same say "too much water;" "not enough water;" "put on lime;" etc. I use a medium amount of water and more of my stack is affected than that of any other grower. One man has kept his well soaked since planting, and only about six plants were affected. Another has used but little water, keeping them very dry; he has lost none.

Damping-off is due to a fungus which attacks the tender growth when there is too much surface moisture. It may be produced by rather a small amount of water, providing the soil is heavy and the water is not rapidly absorbed and distributed. On the other hand, a lighter soil taking water more easily may grow plants without damping-off, even though a great deal more water has been used than on the heavier soil.

Too much shade, which prevents the sun from drying the surface soil, is also likely to produce damping-off, therefore, one has to provide just the right amount of shade and the right amount of ventilation through circulation of the air, etc. The use of sand on the surface of a heavier soil may save plants from damping-off, because the sand pa.s.ses the water quickly and dries, while a heavier surface soil would remain soggy. Lime may be of advantage if not used in too great quant.i.ties because it disintegrates the surface of the soil and helps to produce a dryness which is desirable. Keeping the surface dry enough and yet providing the seedlings with moisture for a free and satisfactory growth is a matter which must be determined by experience and good judgment.

Irrigated or Non-Irrigated Trees.

Is there any difference between the same kind of fruit trees grown without irrigation and with it?

It does not make a particle of difference, if the trees are grown well and matured well. Overirrigated trees or trees growing on land naturally moist may be equally bad. Excessively large trees and stunted trees are both bad; with irrigation you may be more likely to get the first kind; without it you are more likely to get the latter. There is, however, a difference between a stunted tree and a wellgrown small tree, and as a rule medium-sized trees are most desirable than overgrown trees. The mere fact of irrigation does not make either good trees or bad trees: it is the man at the ditch.

Too Little Rather Than Too Much Water.

Looking through an orchard of 18-year-old prune trees on riverbottom land, I found a number of the trees had died. A well bored in the orchard strikes water at about 15 feet. I find no apparent reason far the death of these trees unless it is that the tap roots reach this body of water and are injuriously affected thereby.

We do not believe that water at 15 feet depth could possibly kill a prune tree. It is more likely that owing to spotted condition of the soil, gravel should occur in different places, and with gravel three or four feet below the surface a tree might actually die although there was plenty of water at a depth of 15 feet. There is more danger that the trees died from lack of water than from an oversupply of it, and it is quite likely also that you could pump and irrigate to advantage large trees which did not seem to be up to the standard of the whole place, as manifested by lack of bearing, smallness of leaves, which would be apt to turn yellow too early in the season.

Possibly Too Much Water.

My trees are four years old and are as follows: Peach, fig, loquat, apple, apricot and plum. Last year they had plenty of blossoms, but I got no fruit. I always watered them twice a week in summer.

You are watering your trees too much; stimulating their growth too much, and this, while a tree is young, is apt to postpone its fruit bearing.

Give the soil a good soaking about once a mouth, unless you are situated in a sandy or gravelly soil, in which more frequent applications may be necessary.

Too Little Water After Dynamiting.

In planting almonds on a dry hard soil I dynamited the holes and ran about 200 gallons of water into each hole before planting. About 95 per cent of the trees started growth, but seem now to be in a somewhat dormant state, the leaves of some being slightly wilted. All the trees were watered since planting. I have been told I made a mistake by throwing water in the dynamited holes. When the holes were watered the ground was very dry and the water disappeared in a few minutes.

You have used too little water rather than too much. Dry soil of fine texture can suck up an awful lot of moisture, which can be drawn off so far, or so widely distributed, that there will not be enough for the immediate vicinity of the roots. The dynamiting tended to deep drying and necessitated much more irrigation.

Irrigating Young Trees.