The Owner Built Homestead - Chapter 4: Water Management

Soil and water are intimately related, and modern methods of using them treat both very poorly. In this chapter of his book, Ken Kern discusses a less destructive and wasteful approach to water management.


| March/April 1972



water management - water application to field crops

The conventional (i.e. USDA) method of irrigation and water management is wasteful.


ILLUSTRATION: USDA


A brief presentation of the Hydrologic Cycle was included in the preceding chapter. My intention was to impress the reader with an important concept: water is a function of the land. Like the land, and things which grow on the land, water too has been badly misused. We may settle in arid regions where streams flow only during cold, non-growing seasons. So we have to divert water from stream channels or impound it behind dams. Then we over-irrigate, causing nitrate leaching and the establishment of pathogenic fungi. Commercial fertilizers and poisonous sprays are then used to counteract these evils. Or we may farm the rich bottom land—but must first drain the meadows and valleys of stored water. The tile drainage systems employed lower the water table and contribute to down-stream flooding. We may cut or burn forests and native grass to graze cattle or plow the land. Then soil-depleting cultivated plants replace native vegetation: tillage practices leave the land stirred up and exposed to the ravages of wind and rain. Agriculture then becomes, for the most part, an occupation dealing with floods and drought, erosion and infertility, insects and diseased plants.

Consequently, as a function of the land, water and water management become very closely interrelated to soil and the way in which soil is used. Organisms and plant roots living in the soil remove oxygen and respire carbon dioxide. This free movement of carbon dioxide out, and oxygen into the soil is a first criterion of healthy plant growth. Standing surface water, for instance, may contribute to crop damage by impeding this action. Flooded soil encourages undesirable bacterial transformations: when soil aeration is poor, plant roots have difficulty in excreting carbon dioxide, and beneficial aerobic (airborne) microorganisms cannot function. Anerobic (waterborne) micro-organisms then take over and reduce valuable nitrates to toxic nitrite and gaseous nitrogen.

A leaching action—caused from excessive rainfall or irrigation—also contributes to an impoverished soil-condition by washing essential nitrates through the soil profile. The effect of percolating water on a soil's nutrient reserve depends a lot on the structure and texture of the soil. Heavy (clay type) soils will hold more water without nutrient leaching. The structural aggregates of heavy soils retain nutrients as they allow water, to drain around them.

Tillage operations also impede plant growth—mostly through compaction of the soil. Heavy equipment compaction reduces oxygen diffusion as well as obstructing root growth. Contrary to popular opinion, even light tillage wastes more soil moisture than it saves. As particles of soil are stirred up by tillage equipment, all sides are exposed to the air—which permits that much more moisture to evaporate. No more moisture is available to a crop which is cultivated than is available to a comparable crop uncultivated. One despairs at the wasted effort in "dust mulching": once a dry layer is formed on the surface of the soil, no amount of hoeing or cultivating can appreciably reduce the evaporation rate. And the common practice of lightly cultivating immediately after irrigation can be even more detrimental to a crop. Cultivated soils tend to cake and crust on wetting and drying: few empty pores remain where oxygen can diffuse, and water is held against drainage. Cultivation destroys surface "feeder" roots. And for other reasons, too, (which will be detailed in the following chapter) the Roto Tiller is seen as the most undesirable piece of equipment employed on most "organic" homesteads.

A proper water management program can be established once one understands the basic principles of water usage in relation to the growing plant and in relation to the soil. When it rains—or when one irrigates—old air is forced out and new air is pulled into the soil by the downward water movement. In its passage through the atmosphere, water absorbs traces of carbon dioxide which make it slightly acid. Certain minerals are thereby partially dissolved by this acidity: water acts as a solvent for the carbon dioxide and oxygen that the plant obtains from the atmosphere. Water is also the medium through which the plant obtains nitrogen and mineral nutrients from the soil to the plant and combines with nutrients entering plant leaves directly from the air.





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