CONTRIBUTIONS OF ALFALFA

TO WILDLIFE AND THE ENVIRONMENT

Dan Putnam

Extension Agronomist,

Department of Agronomy and Range Science,

University of California, Davis 95616

(This article first appeared in the Proceedings of the 28th National Alfalfa Symposium, Bowling Green, KY, February 26-27, 1998)

ABSTRACT

Alfalfa growers throughout the world appreciate the high-yielding, high quality characteristics of their crop, and its value to the farm enterprise. However, this appreciation typically ends at the farm gate. There are few individuals in the general public who are aware of the economic importance of alfalfa (the third largest US crop, worth 7 billion) much less the other benefits that alfalfa provides to the landscape. The unique characteristics of alfalfa contribute significantly to broader societal goals, such as preservation of wildlife habitat and protection from erosion. Alfalfa has a significant role as a nitrogen fixer, for improvement of soil tilth and soil organic matter, for reducing fuel requirements of agriculture, as an insectary for beneficial insects, and as a habitat for many species of wildlife. These important contributions are in addition to its significant economic value in its own right, and the critical role alfalfa plays in dairy and other livestock industries. Although steps can be taken by growers to improve interactions between forage production and wildlife (such as protection of nesting waterfowl), alfalfa should be more broadly recognized by the general public for its diverse benefits, and for its fundamental contribution to the long-term sustainability of agricultural systems and to improved wildlife habitat.

INTRODUCTION

The economic importance of alfalfa to farms and ranches throughout the US is well known in the agricultural sector. The direct economic value of alfalfa, the nations 3rd largest crop, is about 7.1 billion dollars each year. In addition to this, alfalfa plays a vital role in the dairy and livestock industries. Many nutritionists value the highly-digestible fiber and high protein of alfalfa in dairy, sheep, horse and other livestock rations. Because it is the beginning of a food chain involving many steps, the economic value of alfalfa is complex and much larger than this $7.1 billion. Alfalfa is intertwined with many different enterprises which are partially or wholly dependent upon the crop as a critical feed component. In particular, dairy farming is the most important enterprise in many states, and largely dependent upon alfalfa.

However, alfalfa does not easily translate into something of widely-recognized value to the consumer. There are few ice cream lovers who would make the connection between a lush green alfalfa field and the ice cream cone they are enjoying. How many buyers of wool sweaters know the important role that alfalfa may have played in the "growing" of their purchase. It's hard to make the connection for most people. Partly as a result of this disconnection, forages in general, and alfalfa in particular, are not widely appreciated or understood by society as a whole.

I am reminded of a story which illustrates this point. A colleague at the University of California was discussing the issue of water-use and alfalfa with an individual from Los Angeles representing urban water-users. Their discussion lasted over two hours as they discussed the intricacies of water-use-efficiency, comparisons between crops, etc. At the end of the conversation, the lawyer casually asked: "let's see, alfalfa.... hmmm. Does that have anything to do with hay?"

In situations such as these, the gulf of understanding about agriculture and forages in particular becomes clear. Is it any wonder, then, that the many benefits of alfalfa are rarely understood by the general public, and the crop is even targeted in some quarters for its use of pesticides, excessive water use, and other crimes? Even among growers, forages are often considered the "Rodney Dangerfield" of crops, getting less respect than row crops.

American Bald Eagles grace sprinklers waiting to irrigate an alfalfa field.

AGRICULTURE vs. THE ENVIRONMENT: A FALSE DICHOTOMY

Most frequently in news accounts, one finds 'environmental interests' pitted against 'agricultural interests' in public discussions about pesticides, water quality, endangered species and wildlife. There is a widespread assumption among those who are most vocal about environmental issues that if land is allocated for agriculture, it is lost for wildlife habitat or environmental preservation. To them, it appears that agriculture is always a 'negative' environmentally. Such dichotomies of thinking are sometimes useful for political causes, for selling books, or for raising money, but they rarely represent the true picture.

While it may be true that agriculture puts its share of pressure on the environment, there are many aspects of farming which should clearly be placed on the positive side of an environmental balance sheet. Alfalfa in particular provides a number of important contributions which should be considered of value to the goals of cleaner air and water, better habitat for wildlife, and more judicious use of resources. As the United States (and the world) face ever rising urban populations, the value of agriculture, and alfalfa in particular, in maintaining open spaces for wildlife and other important functions should be increasingly recognized.

It is incumbent upon the practitioners of agriculture to communicate this broader value to the general public. In the late 20th century, it is no longer sufficient to produce excellent quality food products, but to communicate to a skeptical public that farmers are good stewards of the land and will take steps to further protect the land, water, and wildlife. Several of these important functions pertaining to alfalfa's contributions to environmental health and wildlife habitat are discussed below.

ALFALFA-THE BEGINNING OF AN IMPORTANT FOOD CHAIN

Alfalfa forms the basis for a complex food and utilization chain which touches many forms of life. It is of course economically important to many human enterprises, primarily dairy farming, and supports many other industries from cheesemaking to horse racing. However, the inclusion of alfalfa in the landscape makes many contributions far beyond its narrow economic value, or its value to the livestock industries. It is the beginning of a food chain for a host of other wild species which live nearby, within, underneath, feed upon, and temporarily nest in alfalfa fields. Clearly, the tradeoff between alfalfa production and environmental goals is not a "zero sum game" with the environment being the automatic looser when land is allocated to alfalfa.

ALFALFA - AN "INCREDIBLE" INSECTARY

A fieldside view of an alfalfa field may show little apparent activity - simply a mass of green. However, each successive regrowth of alfalfa creates an environment which teems with insect life. The numbers and kind of insects that inhabit alfalfa have been described as "incredible" (Manglitz and Ratcliffe, 1988). A count of 591 species was recorded in a field near Ithaca, NY (Pimental and Wheeler, 1973). Insects are so abundant in alfalfa fields that university entomology classes can often be found sweeping in alfalfa fields to study the diversity of insects to be found there.

Important host for beneficial insects. Some of these insects, of course feed on alfalfa as a primary source of food, but there are many beneficial insects as well. These 'beneficials' prey on herbivorous or sucking insect pests of alfalfa. Dozens of predacious and parasitic insects occur in alfalfa, and several "work horses" of biological control are especially abundant (Leigh, 1991). Bigeyed bugs (Geocoris pallens and G. puncitipes), damsel bugs (Nabis americoferus), and minute pirate bugs (Orius tristicolor), are some of the major predators. Lady beetles (Hippodamia spp.) have long been recognized to control many types of aphids, and are often abundant in alfalfa fields. A parasitic wasp (Lysiphlebus testaceipes) is of importance in aphid control in alfalfa, and several other wasps help control beet armyworms, and other lepidopterous pests of alfalfa and other field crops.

The role of beneficial insect pests in helping to reduce crop damage in an alfalfa integrated pest management (IPM) program has been understood for some time. However, several of the species present in alfalfa also effect a number of other neighboring crops where they may greatly reduce the threat of pest damage. Due to its reservoir of insects, planting alfalfa in strips with other crops has been proposed to help distribute and nurture beneficial insects (Leigh, 1991).

Alfalfa is also the primary honey crop in the US. It accounts for about one-third of the annual honey production in the US (Barnes and Sheaffer, 1988), which is produced during alfalfa seed production. This is a "spin-off" industry of seed production in some areas, particularly in Western States, which benefits both alfalfa and the consumer.

The contribution of alfalfa to biological diversity and for the nurturing of beneficial insects for other species often goes unrecognized. This should be considered an important environmental benefit of incorporating alfalfa into a cropping system.

ALFALFA ATTRACTS WILDLIFE

While it is true that alfalfa production fields often represents a significant change from the naturally occurring flora and fauna of a region, it is not true that wildlife are automatically losers in this tradeoff. Agricultural activities interact significantly with wildlife on several different levels, and many forms of wildlife adapt, adjust, or even thrive within and alongside agriculture.

Since alfalfa is a productive and palatable plant and a productive insectary, it provides an important food source for many types of creatures which inhabit nearby areas. Songbirds in particular are attracted to the insect population. There is also considerable below-ground biological activity in alfalfa fields. Since it is a perennial, gophers, ground squirrels, mice, voles and other rodents often abound in alfalfa, and in some areas are important pests, along with rabbits and other herbivores. This biological activity, sometimes the bane of growers, has its positive side - providing an important habitat for wildlife. Hawks, raptors, foxes, and other hunters frequent alfalfa fields looking for prey.

Wildlife aggregates in alfalfa. In extensive surveys conducted in the Sacramento Valley, California and in subsequent analysis by wildlife biologists, many species of wildlife were found to be present in alfalfa fields. Of the 643 regularly-occurring resident and migratory terrestrial wildlife (amphibians birds, mammals, and reptiles), 162 species or 25% were considered regular users of alfalfa fields to varying degrees (Kuhn et al.). Ten percent use alfalfa extensively for breeding and reproduction. A partial listing is provided in Table 1. Furthermore, many of these wildlife species show a strong preference for alfalfa, including several endangered or threatened species. Alfalfa has been found to be visited by 18 times the number of species than would be expected by chance (Smallwood and Geng, 1993). Predators of small mammals and ground-dwelling invertebrates were most selective for alfalfa. Several migratory Hawks, Falcons, the Great Blue Heron, White-faced Ibis, Killdeer, Northern Harrier, Brewer's Blackbirds, American Crows, Yellow-billed Magpies, and European Starlings. In the western US, the fact that all the western states, from California through Washington have large acreage of irrigated alfalfa is significant for the Pacific flyway for both waterfowl and raptors. The same is likely true throughout Midwestern states.

Alfalfa - Important for threatened species. Several species which have been classified as "threatened" or "special concern" show strong preference for alfalfa habitats. Of all the species that use alfalfa, six are on the federal endangered or threatened species lists. Two of these, the peregrine falcon and San Joaquin kit fox, use alfalfa peripherally or for finding prey. Three of these, the giant garter snake, loggerhead shrike, and Aleutian Canada goose, use alfalfa and association ditches to a greater extent. The Swainson's Hawk is a CA-listed threatened species and a candidate for federal threatened species list. It travels 11,000-17,000 miles yearly from S. America (Kemper, 1995), and visits alfalfa fields 10 times the number of times expected by chance (Smallwood, 1993). Alfalfa is also strongly selected by the Norther Harrier and White-faced Ibis, which are state-listed species of special concern.

Food for large vertebrates. The characteristics which make alfalfa the premier dairy forage also are quite attractive to wild species. In many parts of the US, deer, elk, and antelope are a significant factor in alfalfa production. It is difficult to maintain fences around alfalfa fields, and deer are a major "pest" in many eastern states. In certain areas of the northwestern US, elk are the primary yield-reducing "pests", and large herds are often supported by remote alfalfa fields when naturally-occurring vegetation is limiting and herd numbers are high. This should in many respects be viewed as a positive contribution of alfalfa to wildlife habitat.

Table 1. Partial listing of types of wildlife observed in alfalfa fields. Of 643 forms of wildlife, 25% are found in alfalfa fields. Asterisks indicate species which have a preference (*) or a strong preference (**) for alfalfa based upon transect studies, Kuhn et al., and personal observations. Lack of asterisks indicates no preference or unknown. Species Food Species Food Species Food Killdeer** I Ring-necked Pheasant* G Ash Throated Flycatcher* I Dunlin** I Great Blue Heron* V Scrub Jay I,P Red-Tailed Hawk* V Great Egret* V,I Common Raven* G Swainson's Hawk** V,I Snowy Egret* I,V American Robin I Ferruginous Hawk** V Black-Crowned Heron* I,V Cliff Swallow I Rough-legged Hawk* V White-faced Ibis** I,V Valley Quail I,P Northern Harrier** V,I Cattle Egret* I,V Coyote V White-tailed Kite** V,I American Avocet I Desert Cottontail** P,D Prairie Falcon* I,V Brewer's Blackbird** I Blacktailed Jackrabbit* P,D American Kestral* I,V Redwinged Blackbird G Grey Fox* V,I Turkey Vulture S Rock Dove P Striped Skunk I,V Yellow-billed Magpie* G Mourning Dove P Raccoon I,V American Crow* G Golden Eagle* V CA Ground Squirrel* P,D Loggerhead Shrike* I Western Meadowlark I Pocket Gopher** P,D Western Kingbird* I Merlin* I,V CA Vole** P,D European Starling* I Long-billed Curlew** I W. Fence Lizard I California Gull* G Mallard Duck* G Gopher and Racer Snakes* V,I * Indicates species has preference for alfalfa (population is 1.3 to 3 x the population to be expected by chance), ** indicates species has strong preference for alfalfa (greater than 3 x the population expected by chance). Designations are a mixture of transect study designations in the Sacramento Valley, CA, and subjective evaluation (Smallwood, 1997, pers. comm.). Data collected and reported by Smallwood and Geng, 1993, Erichsen et al., 1996). Food Source: V = vertebrate animals, I = invertebrate animals and insects, S = scavengers of dead animals, P = plant matter, G = general, D = causes some damage to alfalfa.

ENHANCING WILDLIFE IN ALFALFA FIELDS

Although this summary shows that alfalfa is a significant habitat for many species of wildlife, there is more that growers can do to produce alfalfa in a way that is beneficial to both wildlife and the environment. Pest management can be practiced in a fashion that protects and utilizes the beneficial insects in alfalfa, which benefit other crops as well as wildlife (Integrated Pest Management). Several growers have taken steps to provide nesting sites for owls and bats to encourage their rodent and insect-eating habits. Other growers have installed perch poles in an otherwise horizontal landscape to encourage raptor activity. A grower in the Sacramento Valley each year retrieves waterfowl eggs from fields prior to first cutting, and incubates them and releases a significant quantity of ducks each year. This is done in several CA counties, in cooperation with many volunteer groups, and they release thousands of waterfowl per year.

Other growers have tried to develop devices to be mounted on swathers (flushing bars) to help protect nesting birds in alfalfa fields. Unfortunately, few major equipment manufacturers have taken an interest in these devices. Sound-warning devices mounted on swathers may not be effective, since the birds and nesting fawns may become sensitized, but further research on these methods may be necessary. Leaving nesting areas near ponds for waterfowl is a good method of attracting nesting waterfowl away from the swathers in the spring.

Grazed alfalfa fields can provide important wildlife habitat. However, continuously grazed alfalfa likely does not provide sufficient cover or food for wildlife habitat. Adjustment of grazing practices to rotational grazing to allow better nesting habitat has been studied in the upper Midwest, and grazed pastures can be better managed to provide superior wildlife habitat, as well more efficient grazing results (Undersander & Westmoreland, 1997).

Raising community awareness is an important way to increase the public's knowledge of wildlife on you farm. Farm Bureau or other farm organizations can help with this. Many growers have been quite innovative in enhancing the wildlife on their farms, but need to be better at publicizing their efforts. Arranging field tours with local nature groups, waterfowl groups are important. Participation in county and state regulatory processes are also important. A group of farmers in Merced Co., CA became active with the EPA's efforts to protect the threatened Aleutian Canada goose. Their awareness and data collected about the importance of alfalfa as habitat for this goose resulted in much-reduced regulatory measures (Kuhn et al., 1996). This is an example of the ability of growers to become proactive on wildlife and regulatory issues.

These, and many other steps would enable an enhancement of the benefits to wildlife of the alfalfa production system.

IMPORTANCE OF ALFALFA TO CROPPING SYSTEMS, SOIL CONSERVATION

One of the most important characteristics of alfalfa is its role in maintaining and improving soil health, preventing soil erosion, and boosting the yields of subsequent crops. These characteristics are considered common knowledge among growers and agricultural scientists, but not appreciated more widely. The historical use of alfalfa as a "soil amending" crop, is a complex effect of several important characteristics:

Dinitrogen fixation. One of the most important characteristics of alfalfa is its ability to "fix" atmospheric nitrogen so that it is available for plant growth. This is accomplished by symbiotic association with Rhizobium meliloti, N2-fixing bacteria which infect the roots. Biological fixation contributes an estimated 140 million metric tonnes of N annually to the earth, about 80% of which comes from symbiotic relationships such as alfalfa/R. meliloti (Vance et al., 1988). It is estimated that over 6 million metric tons of N is fixed each year by leguminous crops in the USA, approximately 1/3 of which comes from alfalfa (Phillips and DeJong, 1984).

This partnership completely negates the need for N fertilizers in alfalfa, and reduces the need for fertilizer N in rotated crops. Some growers of specialty crops would likely continue to grow short-rotation alfalfa with little direct economic return due to its ability to aid in the success of subsequent crops. Alfalfa consistently produces a higher nitrogen yield from N2 fixation and a higher percentage of N derived from fixation than other legumes on a seasonal basis (Vance et al., 1988). Estimates of N2 fixation in alfalfa vary from 114 to 536 lb of N per acre per year (Evans and Barber, 1977), and averages about 200 lbs/Nacre fixed per year in the US.

There are at least two environmental benefits of the N2-fixing ability of alfalfa in a cropping system:

1. The substitution of alfalfa for high N-demanding crop, and
2. The benefits of N2 fixation which accrue to the following crop in a rotation with alfalfa
   

Alfalfa replaces high N-requiring crops. If alfalfa were not grown as the primary forage in a region, what would the environmental costs be? The substitution of crops such as corn, sorghum, wheat, barley, cottonseed, or grass forages for alfalfa would require substantially higher use of N fertilizers and energy than currently used. An example from California illustrates this point. Approximately 7 million tons of alfalfa hay was produced in California in 1997. This resulted in a harvest of more than 224,000 tons of N (average of 20% Crude Protein in the Hay). If 60% is considered to come from N2 fixation (a conservative estimate), 134,000 tons of N was added to the cropping system from the atmosphere by the alfalfa crop that year.

At a minimum, this amount (134,000 tons) of N as fertilizer would have to be added back to the system as fertilizer to provide this amount of protein N from other crops. However, this is a minimum estimate. This amount does not allow for inefficiencies of fertilizer uptake, leaching, and differences in plant incorporation, which would further increase this amount. If the 1.4 million tons of protein produced in California that year were produce by corn silage (at 8.5% CP), an additional 650,000 acres of corn would be required, removing over 220,000 tons of N from the soil, a requirement which would primarily need to be met through N fertilizers. Since the Haber/Bosch process for N fertilizer manufacture is very energy intensive, substantial additional quantities of fossil fuel would be consumed each year to meet this need. Alfalfa has an important role in reducing the fossil fuel requirements of cropping systems, by saving the substantial N fertilizer inputs required for non-legumes.

Alfalfa provides N to a subsequent crop. Legumes such as alfalfa have long been know to improve the yields of subsequent crops (Pieters, A.J. 1927, Baldock et al., 1981). There is typically an N credit of 50-170 lb/acre N given to corn when grown after alfalfa or other legumes (Kurtz et al. 1984). Nitrogen fixation is a significant factor in this yield benefit, but other factors, such as improved soil tilth, are also important. Nitrogen stored in roots and above-ground plant matter can be made available to a subsequent crop through degradation after plowdown. Considerable N is removed at each cutting, but much of this is "renewable" through N fixation of subsequent regrowth. The amount of N provided to a crop following alfalfa is quite variable, and will depend upon a number of factors, primarily the stand, yield and stage of growth when the alfalfa is plowed down, and uptake of N by that crop. Nitrogen application to corn can be reduced by 100-150 lb/acre if it is preceded by alfalfa or red clover (Miller and Heichel, 1995). This, in addition to substitution of high N-requiring crops, substantially reduces the environmental pressure of cropping systems.

Alfalfa is Deep-Rooted and Improves Soil Tilth. The "rotation effect" is the benefit in growth and yield of a crop which is grown after alfalfa. This is not simply the result of the transfer of elemental N. This rotation effect is a result of complex causes of improved water-holding capacity, better soil tilth (improved structure), increased soil organic matter, and reduction of soil pathogens, and possibly other factors (such as shifts in micorrhizal populations) in addition to the N residues supplied (Barnes and Sheaffer, 1995). The "rotation effect" is especially apparent with alfalfa.

Alfalfa roots have been measured at a 39 meter depth and 5 meters depth is common (Sheaffer et al., 1988). Alfalfa roots penetrate much more deeply than most grass species or annual field crops. Therefore, alfalfa roots create many channels in the soil which (if undisturbed) are used by subsequent crops to more fully explore the soil. In addition, there is a tremendous amount of biological activity in the alfalfa rhizosphere, and a number of organic acids are secreted by alfalfa roots which contributes to soil "tilth" - the crumbly soil structure which is so beneficial for plant growth.

In a recent study at the UC Davis campus, we plowed up an experimental plot which contained strips of 4-year old alfalfa, and 4-year old fallow strips. The difference in the soil structure was dramatic and obvious: blocky, tight clods which were very difficult to cultivate were present in the fallow strips, and crumbly, loose, well aerated soil in those areas occupied by alfalfa. This "mellowing" of the soil following alfalfa is known to most growers, who have observed the differences in soil tilth and subsequent crop performance.

Erosion protection. Although much of current concern about the environmental effects of agriculture focuses on the possible contamination and harmful effects of pesticides, soil erosion has always been a significant environmental hazard of agriculture. The development of the Soil Conservation Service received its impetus from the dust bowl days of the 1930s; and the primary cause of wind and water erosion being excessive tillage with row crops. One of the major thrusts of these efforts was to encourage the incorporation of leguminous cover crops and perennial forage crops which are far superior at preventing erosion than highly cultivated field or horticultural crops. Most agronomists in the corn belt feel that incorporation of alfalfa into corn/soybean rotations would be desirable for protection from erosion.

Perennial legumes protect the soil in several ways: by reducing the amount of cultivation per year, by hold the soil in place through extensive rooting, and by providing a vigorous above-ground canopy which prevents rain droplets from loosening soil. These are very real and tangible effects, especially on highly erodible soils. Any cost-benefit analysis of alfalfa's role in the environment should incorporate these considerations.

Protection of groundwater, help with waste problems. The deep rooted characteristics of alfalfa have led soil scientists to look at alfalfa as an important crop in helping to "mop up" subsurface nitrate in the soil (Russelle, 1994). Nitrate contamination of groundwater (sometimes from N fertilizers) is a problem on some sensitive, sandy soil types. Alfalfa, due to its vigorous roots, is recognized as being important in mitigating groundwater pollution with nitrate. Additionally, scientists are looking at alfalfa to help with "bioremediation" of contaminated sites, and for helping in the disposal of municipal wastes, or for the disposal of dairy wastes. The robust biological characteristics of alfalfa have not escaped notice for these applications.

Alfalfa as a renewable fuel. As the world faces a highly urbanized future, with its associated environmental pressures, development of renewable sources of energy should be an important broader societal goal. A project in Minnesota, initiated by the Northern States Power Company, has analyzed the potential of using alfalfa as a renewable source of energy (Martin and DeLong, 1995). This concept, which would benefit the environment, the consumer, and the dairy industry, is to use the high-lignin alfalfa stem for energy, and use the leaves, which are higher in feed value, as a high quality dairy feed. The major reason that alfalfa was examined (rather than the more ubiquitous corn) was the lack of energy requirement for fertilizers in alfalfa, and alfalfa's many benefits to the sustainability of cropping systems in the corn belt, as described above. While it remains to be seen whether all aspects of this program will be feasible, other regions may find it important to examine this option as a method of producing renewable energy in the future, a strategy which may benefit both urban and agricultural interests.

ALFALFA-AN EFFICIENT USER OF WATER

Most of the alfalfa (>95%) grown in the western United States is irrigated. Many do not know that alfalfa was first successful in the West in the 1850s after the advent of large-scale irrigation. It was immediately well adapted to the Mediterranean climate of California after the Gold Rush, and the deserts of the Southwest, and the more temperate mountainous valleys of the Northwest and the high mountainous deserts of Nevada and Utah. From there it spread eastward to become successful throughout the Midwest and eastern states in later years, after cold-hardiness characteristics were incorporated into improved varieties.

Alfalfa is commonly criticized for its water-use in western states. This is somewhat ironic, since alfalfa and other perennial forages have been promoted in the Corn Belt and elsewhere by both agronomists and environmentalists as a way to lessen the environmental impact of agriculture. However, there is a critique of irrigated alfalfa production in the West which goes something like this: "Alfalfa uses a large amount of water per unit of dollar return. Therefore, water should be shifted from alfalfa and allocated to higher value crops, or allocated to environmental or urban uses which have broader societal value." Here are a few quotations:

"I've singled out the four largest water users in California for special condemnation. The No. 1 water user in this state is irrigated alfalfa, No. 2 is irrigated pasture, No. 3 is irrigated cotton, No. 4 is irrigated rice."

-Marc Reisner, (Author of Cadillac Desert, as quoted in Beard, 1994).

"The main objective of this scenario is to eliminate the estimated annual overdraft in the year 2020 by reducing alfalfa and irrigated pasture acreage"

- California Water 2020, Gleick et al., 1995.

This recommendation for solving the West's water problem by eliminating "low value" crops such as alfalfa is commonly heard. This usually means that the crop is of low value to the one making the recommendation, and that their priorities (presumably of higher "value") would receive preference. There is little doubt that there are crops which yield higher economic return per unit area than alfalfa (alfalfa shares this characteristic with other agronomic species: wheat, rice, sugarbeets, and corn). It is also true that a substantial amount of water is used to produce alfalfa. The consumptive water use of alfalfa varies considerably throughout the West, and likely ranges from about 30 inches to 80 inches/year, depending upon location.

However, alfalfa is quite efficient with its use of water. Water allocation to crops should be compared with the yield, growth characteristics, acreage, and food value obtained, not just total water used. Alfalfa is harvested throughout the year (in Imperial Valley, CA, they harvest 9-10 times, from February through December). Alfalfa is also grown on large acreage thereby increasing water-use compared with other crops of lower acreage. It is a very high-yielding crop, and the entire above-ground plant is harvested and used, unlike most field and horticultural crops. This season-long productivity means that yearly water-use is high, but also that the efficiency of conversion to useful plant material is very high. A comparison of the water-use efficiency (which factors the component of the crop harvested) of several species showed alfalfa to be the highest in water-use efficiency compared with several species, including corn for grain, sugarbeet, barley, and dry edible beans (Loomis and Wallinga, 1991).

CONCLUSIONS

Farmers generally have a deep and abiding appreciation for the wildlife on their farms. In fact, that is probably one of the primary incentives for many who pursue this profession: the love of the outdoors, and of nature. However, alfalfa growers need to be more articulate about the importance of their crop to wildlife. In the 1990s, agriculture must increasingly convince a skeptical public that it provides other benefits as well, by providing open spaces, and nurturing of many wildlife species which enhance the aesthetic value of the landscape.

Often, in arguments between "environmental interests" and "agricultural interests", the complexities of crop landscape ecological interactions are lost. A too narrow view of agricultural land-use, which only ascribes benefits to agriculture, confuses the public about the value of a productive agriculture to the overall societal well-being, including protection of the soil, biological diversity, and wildlife. Alfalfa makes many important contributions to broader societal goals relating to a sustainable agriculture and the environment. Removal or severe reduction in alfalfa acreage would not only have large economic consequences, but also reduce these benefits. While there is considerable room for further enhancement of the benefits of alfalfa to cropping systems and wildlife, it should be recognized that perennial legumes, particularly alfalfa, are vitally important to the future of our environment.

ACKNOWLEDGMENTS

I am grateful for the assistance of Lee Fitzhugh, Jim Kuhn, Shawn Smallwood, Donald Phillips, and Steve Orloff for comments and information provided in the preparation of this manuscript.

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