Sugarbeet Production and the Environment
Stephen Kaffka
Extension Agronomist,
Department of Agronomy and Range Science
University of California, Davis
Apart from building cities, shopping malls, suburbs and highways, farming is the way in which people alter their environment most significantly. Whenever a change is made in the environment to accommodate farming, a new set of conditions is created and nature adjusts. In adjusting, some species are favored while others are not, resulting in altered arrangements among the affected species. In recent years, some environmentalists, looking at these changes, have criticized modern farming and farmers. Since producing food requires a large area and a substantial allocation of resources, it is reasonable to reflect upon the relationship between food production and the environment. We can use sugarbeet production as a subject for this reflection.
Most (not all) environmentalists acknowledge the right of people to feed themselves. The human population has increased to unprecedented numbers. The current estimate is 5.7 billion and most demographers agree that by the end of our childrens’ lifetimes, there will be one and one-half to two times the current human population, or 8 to 12 billion people. Even with dietary changes, food and fiber production will have to increase at about the rate of the human population. If preferences for a better diet for the world’s poor are also taken into account, then the need for food will increase even further. In a featured article on environmental sustainability in the Annual Review of Ecology and Systematics, (1995) an environmentalist named John Clark called food production a crucial issue for the future of humankind and for humankind's relationship to the natural environment. How can needed increases in food best be achieved?
Robert Goodland (1995) of the World Bank has suggested that to sustain the environment in the future it will be more important to improve the efficiency of all technological processes (including farming), than simply to increase the total amount of natural resources used. The Dutch agronomist, C. T. de Wit (1987) put it most directly when he said that the only way to avoid a rape of the earth in trying to feed the growing human population is to use current farm land up to the limit that it can be most efficiently cultivated. The more efficient food production can be, the more wild lands and wild life that can be saved for future generations to enjoy. Where does sugarbeet production in California fit into this larger concern for global sustainability?
Sugar as food. To answer this question it is helpful to think about the use of sugar in human nutrition and the characteristics of the sugarbeet plant. The answers might be surprising to some. Sugar has an important role in human nutrition worldwide, providing, according to a recent estimate (Hawker, 1985), 11% of human calories worldwide. Sugar is completely digestible, and converted efficiently into metabolic energy in our bodies. In some poor countries, it provides an even higher percentage of essential, daily caloric intake. For those of us in parts of the world where calories are not limiting, sugar provides some of the life's most pleasurable moments in foods such as ice cream, cakes, cookies and related foods. Both as an energy source for the world’s poor and as a source of pleasure in the human diet, sugar will remain an important component of food production worldwide.
Water use. When sugarbeets are compared to other many other crops, they turn out to be one of the most efficient food plants in the human arsenal against hunger. Table 1 compares estimates of the amount of digestible food derived from a sugarbeet crop and lettuce crop, in comparison to the amount of water used. A range of estimates is provided because yields and water use can vary and the digestibility of fiber (from lettuce) in the human digestive tract is variable. Table 2 compares sugarbeets with other field crops. When evaluated in this way, sugarbeets turn out to be a very efficient user of water (and other resources) compared to many other crops. The argument advanced by some that field crops in general (including sugarbeets) are inefficient users of water confuses food value with economic value. Sugarbeets are 3 to 5 times more efficient than lettuce at producing digestible food energy (Table 1) and among the most efficient of the field crops (Table 2) in terms of digestible calories produced. Lettuce can be a valuable crop (economically), but it is an expensive use of water and other resources in terms of its nutritional value.
The amount of water needed to produce sugarbeets is highly variable. Crop evapotranspiration can range from 24 inches of water in a year to as high as 50 inches, depending on where and when the crop is grown. When planted in the fall in the Central Valley, for example, and harvested in July, the crop requires between 24 and 32 inches of water for a root yield of 30 to 40 tons and a sugar yield of 8,000 to 12,000 pounds or more. Because no irrigation system is completely efficient, more water may have to be applied, depending on winter rainfall and soil water holding capacity. But fall planting, together with the yield levels that can be achieved and the digestibility of the final product, makes sugarbeet among the most efficient food crops that can be produced in California from the perspective of water use. Fall planting has other potential advantages as well including reduction in losses to rhizomania, reduced mildew occurrence, and fewer problems with armyworms. It is my view that a larger proportion of the state’s sugarbeet crop should be planted during this time period to take advantage of both the environmental and economic savings possible. Doing so is consistent with the need to improve efficiency without sacrificing yield in our crop production systems.
A rotation crop. Diverse crop rotations are important. They help control insect pests and diseases without the use of pesticides, and can contribute to improved soil structure and fertility, depending on the crops and management practices used. For those of us who do agricultural research, finding ways to keep crop rotations diverse, thereby helping farmers to resist the pressure to over-specialize on fewer crops, may be our most important service.
Farmers and researchers traditionally have thought about crops singly, without reference to their overall effects on the complete cropping system or on the environment. If we think of sugarbeet as part of a cropping system, however, it appears to provide several advantages. For example, it is among the most salt tolerant crops available. This is an advantage in the Imperial and San Joaquin Valleys where salinity management is an increasingly difficult issue. Besides tolerance of higher soil salinity levels than most crops, the reuse of tail water and perhaps of drainage water for irrigation appears possible with sugarbeets, reducing in both instances drainage water volume and overall water requirements on a farm basis. Sugarbeets also are known to be efficient scavengers of nitrogen (Table 2). They are a very deep-rooted crop. This role could be especially important when sugarbeets are rotated with inefficient crops such as cool season vegetables or when they are gown in the winter, when rainfall leaches nitrate from fallow fields into ground water.
Biodiversity. Sugarbeet crops support a surprising amount of wildlife, but especially bird life. They are thought to be very important for raptors such as hawks and owls because they provide good shelter for small rodents around field edges . The same is also true of other predators of rodents such as snakes. Some raptors and snakes considered threatened are among those species benefiting from sugarbeet fields. Anyone with overwintered sugarbeet fields also knows that they provide excellent cover and food sources (insects) for nesting pheasants.
No crop is completely beneficial, nor is any crop completely harmful. Rather, they are a mixture of both, depending on the manner, timing and frequency of production and the way in which benefit and harm are determined. It is important to evaluate crops against several standards when thinking about the relationship of a crop to the environment. Since we must produce food, we will do so better if we have diverse crop rotations that are planned with thought for both economic and environmental issues. Sugarbeets can have several benefits for California crop rotations. Because of these benefits, I hope that farmers in California will continue to use sugarbeets to diversify their crop rotations.
REFERENCES
Clark, J. (1995). Economic development versus sustainable society. Ann. Rev. Ecol. Sys. (26)225-248.
DeWit, C. T. , Huisman, H. and Rabbinge, R. R. (1987). Agriculture and its environment: Are there other ways? Agric. Sys. 23:211-236.
Goodland, R. (1995). The concept of environmental sustainablity. 26:1-24. Annu. Rev. Ecol. Sys.
Hawker, J.S. (1985). Sucrose. In: P. M. Dey and R.A. Dixon (eds). Biochemistry of Storage Carbohydrates in Plants. Academic Press. New York. pp1-51.
Kaffka S. R. And Hills F. J. (1994). Sugarbeet. In: Encyclopedia of Agricultural Sciences, Vol. 4, Academic Press, New York pp 215-223.
Sammis, T. W. (1980). Comparison of sprinkler, subsurface, and furrow irrigation methods for row crops. Agron. J. 72:701-704.
Wrick, K.L.F. (1979). The influence of dietary fibers on intestinal passage, laxation and stool characteristics in humans. Phd Thesis, Cornell Univ., Ithaca, New York. 331p.
Table 1. Comparison of sugarbeet and lettuce crops
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** Values for lettuce are based on average yields and
the assumption that the majority of dry matter in lettuce is cellulose(fiber).
Fiber is indigestible in the stomach but is variably fermentable in the
human lower intestine(Wrick, 1979). As with sugarbeet, protein yields are
not used in the comparison. Water use and DM estimates are from Sammis
(1980).
Table 2. Approximate water use efficiency (WUE) and
nitrogen use efficiency (NUE) of various crops grown at Davis, California,
compared on a biomass, harvested yield, and human-digestible energy basis.
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