140 



THE IKRI-GATION AGE. 



The Art of Irrigation 



CHAPTER TEN 



By T. S. VAN DYKB 



Before these small streams were used, large streams 

 in deeper furrows were in use and are probably as old 

 as irrigation. But they were not intended to wet the 

 whole ground except in a very few cases. There are 

 some soils in. which water can be made to rise by a long 

 run of water in ditches so that roots from the surface 

 can reach it. Sometimes it can be brought so near the 

 surface that a great variety of garden stuff can be 

 raised by it with no water ever applied to the top. A 

 common sight in river bottoms in California is im- 

 mense corn growing on rich alluvium with the water 

 table several feet below the surface and held there by 

 the water flowing above ground all summer, or by the 

 flow beneath the sand, which is common to all the rivers 

 that run dry. Potatoes, pumpkins, melons, celery, 

 beans, peas and many things besides corn often grow 

 with the water only two feet below the surface. Many 

 trees, like the orange and lemon, will not endure this, 

 but others, like the pear, do well enough provided the 

 water is moving and is not stagnant. I have seen 

 luscious grapes grow on the same ground but they would 

 not do to ship, or for wine, and probably would make 

 a poor raisin if they did not sour in drying. Alfalfa 

 will often grow on such ground, but not well and will 

 not make the huge crops it will on well drained upland 

 where its roots cannot touch water but plenty is ap- 

 plied on the surface. 



On such ground nothing is necessary but to start 

 the seed and if it is not too hot or the air not too dry, 

 quick seeds can most always be started by the moisture 

 which cultivation will draw up from below, though there 

 are some soils of such even texture that no amount of 

 cultivation will do this. The seed, once started, no 

 water is needed on the surface. 



But where lands are moist from supply from a 

 natural stream the water is generally moving. If you 

 attempt to imitate" this with a ditch on upland, where 

 there may be no sand or gravel beds to carry off water 

 enough to prevent stagnation, the result may be quite 

 different. Especially if there is much iron or alkali in 

 the soil. Iron in stagnant water is apt to injure any- 

 thing whose roots get into it. Many trees endure it and 

 look well enough but the quality of the fruit is low and 

 often under market size. In other things like black- 

 berries the size of the plant may be the only thing 

 affected, while the fruit is still fairly abundant and good 

 enough for home use. In trying to moisten land by 

 raising this water sheet below, you never can tell what 

 the outlet is for surplus water and, consequently, when 

 this stagnation will happen. In lands along a natural 

 stream this point is well established and if you find no 

 stagnant water there at the outset you are likely to 

 have none in the future. Hence you had better not at- 

 tempt this kind of subirrigation even on a small scale. 

 I have seen it tried several times where the land lay 

 on a heavy slope upon rock of the same slope, from 

 which the top soil was formed. Parties had small 

 streams insufficient for surface irrigation, with no places 

 to make natural reservoirs and where artificial ones 



would be too expensive. They attempt to slide water 

 down the rock face below the soil by a ditch running 

 all the time along the upper edge. The sliding part 

 was successful enough and the land well moistened, 

 but with the exception of a few vegetables it was not a 

 success, although the soil was two feet and a half deep 

 and rich and loose, with vegetable mould, the whole 

 having been covered for ages with a dense growth of 

 heavy brush. No water could be found running out of 

 the lever edge of the slope and it seemed a plain case of 

 stagnation. Trees were runty with sour fruit, alfalfa 

 yielding about one-fourth of a crop, etc. While the 

 principle is bad for most things, there still may be 

 many things that could be raised to advantage on such 

 soil where one can do no better, though you had better 

 confine your efforts to stuff for home use. 



The use of large furrows or very small ditches has 

 nearly always been to wet the soil in the immediate 

 vicinity of the trees or plant without any regard to its 

 condition a few feet away. This is common today in 

 heavy market gardening by the Chinese, Italians and 

 others. Corn, potatoes cabbage and many other vege- 

 tables are grown on the ridge between two furows made 

 with a small plow or a shovel plow, throwing earth 

 both ways. Down these a stream of about a quarter of 

 a second foot is run. This generally runs fast and 

 muddy but the volume is so great that it soon wets the 

 ridge well to the top. The waste is collected in a ditch 

 below and passed on to another tract. As soon as it is 

 dried down to the right point the plow, generally a 

 shovel plow, is run again in the furrow, breaking up the 

 baking earth and throwing some fine material to the 

 top of the ridge. It is then left in that condition until 

 the next irrigation. 



This method works quite well, the main objection 

 being that on ground thoroughly graded, pulverized 

 furrows one-quarter of the depth and carrying one- 

 twentieth of the water long enough to wet the whole 

 ground, as in fine orchard work, will, in most cases, 

 produce better stuff a-nd more of it without irrigating 

 one-half as often. Mud puddles and baked ground will 

 not be seen and the cultivation will be much deeper and 

 finer with its effects more lasting. But unless one owns 

 the land, the grading and the regulators at the head of 

 the streams may cost too much. These large streams 

 can generally be handled without regulators because the 

 irrigator is on hand during the whole run and if some 

 do carry too much it is of little moment because there 

 is still enough left to go through. Much rougher 

 ground can be handled in this way because the furrows 

 are so deep that the water cannot escape sideways, as it 

 easily can from small furrows, and where one can get 

 only a short lease on land, like most of the Chinese it 

 may be the best thing to do, though a poor model for 

 anything but economy. 



Another use of large furows, generally by the owner 

 of the land himself, is much less excusable. Planting 

 trees, vines and vegetables along the flat shores of a little 

 brook or on the low banks above is a trick almost as 

 old as the human race. The modern man improves on 

 this in many places by making an artificial brook more 

 or less straight. In this he sometimes keeps water run- 

 ning all the time. A little corn, potatoes, beans and 

 other stuff may be raised in this way if the water is 

 not too cold. But fruit is quite sure to be insipid or 

 sour, with no keeping qualities. To avoid this he ran 

 water in it only once in a while, keeping it dry most of 



