the soil will hold moisture enough to carry the tree to its proper period of dormancy.  This may be determined by the aspect of the trees and by digging down two or three feet to see whether the soil carries moisture which is likely to be sufficient until the coming of the rains.  Whether late irrigation will be necessary is also determinable by the character of the soil; on close retentive soil it may not be necessary, while on loose, sandy or gravelly soil it may be essential to the life of the tree.  One has to settle all these matters by judgment and not by recipe.

Fertilizers in Irrigation Water.

Do you recommend putting fertilizers in irrigating water?  I am about to water the orchard and am thinking of putting some nitrate in the water.

You can distribute any soluble fertilizer by dissolving it in irrigation water, but few have ever done it because of the difficulties of getting equal strength in running water.  It is much easier to distribute on land before irrigation.

Irrigating Alfalfa on Heavy Soils.

How does alfalfa succeed on adobe and soils slightly modified from it? 
Does irrigation work well an adobe planted to alfalfa?

If you get the irrigation adjusted so that the soil shall not be water-logged and so that the water does not stand on the surface when the sun is hot, you can get plenty of good alfalfa on a heavy soil.  Irrigation on adobe soils must be done more frequently and a less amount at each application to guard against the dangers named above.

How Much Water for Crops?

Same of my land is heavy but the most of it is light soil.  I want alfalfa mostly, same potatoes and grain, and later oranges, olives and other fruit.  How much water in inches or acre feet is required per acre per year far the irrigation of it?

The amount of water required to grow different crops depends upon the crop itself, upon the time of the year in which it grows, the character of the soil, etc.  There is no such thing as stating how much water would be used for all crops on all soils, and at all times of the year.  The range would be from, say, ten acre inches for irrigation of deciduous fruits, which need moisture supplementary to rainfall; twice or thrice as much for citrus fruit trees; four or five times as much for alfalfa where a full number of cuttings are required.  These are, of course, only rough estimates which would have to be modified according to local rainfall and soil character.  Water should be applied frequently enough to keep the lower soil amply moist.  A color of moisture is not enough and a muddy condition results from too much water.  One has to learn to judge when there is moisture enough, and a good test of this to take up a handful of soil, squeeze it and open the hand.  If the ball retains its shape it is probably moist enough.  If it has a tendency to crack upon opening the hand, it is too dry.  This test, of course, is somewhat affected by the character of the soil, but one has to form the best judgment possible how far allowance has to be made for that.