University of California

Vegetation Management

Melvin R. George and Josh Davy

Introduction

Management of vegetation with fire, heavy equipment, herbicides, improved forage plants and fertilizer played an important role in range improvement following WWII until the late 1970s.  Increased fuel and fertilizer costs following the energy crisis of the mid 1970s, low prices for livestock in the 1980s and 90s, increased liability associated with prescribed burning, EPA’s ban on the use of 2,4,5-T for brush control, requirements for environmental impact statements, and other economic and policy changes all conspired to reduce the economic return from many range improvement practices.  In addition, low grazingland rental rates often made it more cost effective to rent another acre than to improve an acre. While these forces may have reduced the application of range improvement practices on California’s rangelands for the past 30 years, vegetation management remains the only practical way to increase carrying capacity or to improve wildlife habitat.  Current trends of higher lease rates and limited availability of rental property due to conversion to other uses may rejuvenate interest in these practices.

Vegetation management (brush and weed control, seeding, and fertilization) has been a continuing theme of research at University of California since the late 1880s.  Prior to the 1970s the focus was primarily to increase carrying capacity by growing more forage and improving animal performance by increasing forage quality.  Following federal and state environmental legislation in the 1970s management for water quality, air quality and threatened and endangered species became important management objectives on California’s and the nation’s rangelands.  While increasing carrying capacity by producing more forage remains an important objective, ranchers and public agencies also manage for fire hazard reduction, improved water quality, air quality, and biodiversity.  Suppressing introduced species and restoring native species has become a major theme among conservation organizations and some government agencies.

This chapter focuses primarily on vegetation management practices that improve forage production and quality, namely brush and weed control, rangeland seeding and rangeland fertilization.

Brush and Weed Control 

Woody Plant Management

Historically oak and shrub removal has been recommended to increase forage production in the oak-woodlands.  From the 1940s to the 1980s mechanical and chemical tree and shrub control and prescribed burning were often used to selectively thin the oak-woodlands.  In some cases all trees and shrubs in chaparral and the oak-woodlands were controlled resulting in a type-conversion from woodland to annual grassland. Seeding and fertilization often accompanied tree and shrub control. 

On sites where oak trees are dense and canopy cover is high, forage productivity can be increased by oak tree thinning (Kay 1986b, Kay and Leonard 1979).  On sites where tree density is sparse, such as the oak savannahs of the central and southern Sierra Nevada foothills, forage productivity and quality is greater under the trees and oak removal may decrease forage production (Holland 1979).  In most cases removal of blue oaks (deciduous) to less than 25% canopy cover  resulted in increased forage production. In general, live oak (evergreen) stands with  greater than 25% canopy cover will have less forage growth than cleared areas (Kay 1986b, Kay and Leonard 1979).

Fire

Control of woody plants in the oak-woodlands and chaparral ecosystems has been a major theme of ranchers and fire control agencies.  Fire was the earliest form of brush and weed control in California’s annual rangelands.  Native Americans used fire as a management tool to enhance habitat and to manage food and fiber plants.  McClaren (1986) and McClaren and Bartolome (1989) estimated fire return intervals of about 25 years in the oak woodlands prior to European settlement.   After settlement the return interval was around 7 years, due to more frequent burning by settlers.   In the 1940s Sampson (1940) estimated that oak-woodland burning by ranchers resulted in return intervals of 8-15 years.  Beginning in the 1940s County Range Improvement Associations, in collaboration with University of California and California Department of Forestry, conducted prescribed burns to increase forage production and decrease fire hazard.    From 1945 to 1975 more than 9000 burning permits were used to burn more than 2.5 million acres of California rangeland.  While prescribed burning continues today, urbanization and air quality concerns have reduced the use of fire as a management tool.  Today fire frequency is more likely to be on the order of 25 to 50 years or longer.  Thus, while prescribed burning, mechanical and chemical brush control were frequently used to remove or reduce the shrub and tree layers in the oak woodlands and chaparral (Murphy and Crampton 1964, Murphy and Berry 1973), since the beginning of the 21st century they are used less infrequently.

While fire was the first method of brush control, over the years mechanical and chemical methods have also been important.  Often fire, mechanical, biological and chemical methods have been used in combination.  Partnering with government agencies such as CalFire may provide avenues for mitigating liability for controlled burning through programs such as the Vegetation Management Program (VMP).  These programs usually require the landowner to prepare for the fire by constructing fuel breaks, though the burn itself is conducted by the government agency.

Herbicides

In the 1950s and 60s effective tree thinning practices were developed in oak-woodland.  These  included  basal frilling with the application of 2,4-D and/or 2,4,5-T or tree cutting (cut stump) followed by 2,4-D or 2,4,5-T application to the cut surface.  These practices were used to type convert chaparral and oak-woodlands to annual grasslands (Leonard et al. 1956, 1959).  In the 1980s, EPA banned the use of 2,4,5-T because it frequently contained dioxin as a synthesis contaminant.   Triclopyr, imazapyr and glyphosate are currently used for woody plant control.

Biological

Biological control has been defined simply as the utilization of natural enemies to reduce the damage caused by noxious organisms to tolerable levels (DeBach and Rosen, 1991). One approach to biological control has been termed “classical biological control”; it involves the discovery, importation, and establishment of exotic natural enemies with the hope that they will suppress a particular organism’s population. This approach has been most successful in situations in which an organism moves or has been transported to a new environment, usually without the natural enemies that have regulated its population and prevented major outbreaks.  There are few examples of classical biological control agents for woody plants on rangelands.  Tamarix beetles have shown some effect on saltcedar along rangeland riparian areas.  Biological control of Klamath weed (Hypericum perforatum), a non-woody plant, is discussed in a later section.

Weed scientists consider the use of grazing or browsing by domestic animals to be a cultural practice rather than a classical biological control.  Goat browsing has been used successfully  in California’s oak woodlands and chaparral (Spurlock et al. 1978).  While browsing is not an effective means of reducing well established brush stands, it is useful in managing resprouting and reestablishment following fire and other methods of control.  Targeted grazing for managing vegetation is covered in the Grazing Management chapter.

Mechanical

Mechanical methods (Roby and Green 1976) are often used in the control of woody plants.  For example, heavy equipment such as bull dozer blades with brush rakes (Adams 1976a) or heavy-duty disks (Adams 1976b) can be used to remove large shrubs, and anchor chains (Adams 1976c) pulled between two bull dozers can uproot smaller shrubs.  In past years, the ball and chain method was used to layover and uproot brush on steep slopes (Adams 1976d). 

Oak Conservation

Before it was recognized that blue oaks and other oak species were not regenerating on some sites, it was common practice to remove live oaks, and in some places blue oaks, to increase forage production.  Following oak removal, increased light, moisture, heat and soil nutrients contributed to increased forage production compared to that of natural grassland patches that occur in a mosaic pattern with the oak woodlands.   But three reports (Kay and Leonard 1979, Kay 1986b, Dahlgren et al. 1997) have shown that about 15 years after oak removal forage production where oaks had been removed was similar to forage production in the natural grassland patches.  They attribute this to gradual depletion of the nutrients that had accumulated under the oak canopy.

On blue oak sites where regeneration was poor fire wood cutting and removal of oaks have decreased.  Raguse et al. (1986) developed guidelines for oak-woodland range improvement.  They recommended leaving woody vegetation along riparian zones and other drainage ways to reduce erosion and on rocky outcrops and shallow soils where opportunities for increased forage production are low.  They recommended not removing trees on slopes exceeding 30 to 40 %.  They also recommended leaving scattered groups or corridors of trees of different age classes for wildlife habitat and to maintain an aesthetic viewscape.  They recommended seeding of improved forage species only in cleared areas and only to fill gaps in the ranch’s forage sources.  In the 1980s a major effort to protect oak ecosystems and improve regeneration was implemented  by the university and state agencies and control of oaks on public and private lands decreased.

Natural regeneration of blue oaks may be limited because they are weak resprouters on some dry sites and because of a number of factors that limit seed germination, seedling establishment and survival to the tree stage.  In the past 30 years researchers have developed successful restoration methods of planting acorns and transplanting seedlings and protecting naturally produced seedlings and saplings (McCreary et al. 2011).   McCreary (2001) provides an extensive review of oak regeneration problems and practices on California’s oak-woodlands.

Weed Management

Annual rangeland grazing or carrying capacity is severely reduced by weed infestations.  While the annual rangelands are largely populated by introduced annual plants, some are the target of weed control efforts to improve forage quantity and quality and to improve native grass and forb restoration.  Yellow starthistle (Centaurea solstitialis), medusahead (Taeniatherum caput-medusae) and barb goatgrass (Aegilops truncialis) are the focus of most rangeland weed control programs, but control of various other thistles, perennial  pepperweed(Lepidium latifolium), and certain poisonous plants remain locally important.  DiTomaso (2000) reviewed the impact and management of invasive weeds on rangelands and called for integrated approaches to rangeland weed management.  He concluded that successful management of noxious weeds on rangelands will require the development of a long-term strategic plan incorporating prevention programs, education materials and activities, and economical and sustainable multi-year integrated approaches that improve degraded rangeland communities, enhance the utility of the ecosystem, and prevent reinvasion or encroachment by other noxious weed species.  Guidelines for controlling many of these weeds are available on the UC Weed Research and Information Center’s website (http://wric.ucdavis.edu/).

Yellow Starthistle

DiTomaso et al. (2006) published a management guide for yellow starthistle that addresses the introduction and spread of yellow starthistle as well as its biology, ecology and control methods, including strategic planning of control programs.  Tillage, mowing and hand removal are among the mechanical methods reviewed in this guide.   Prescribed burning and targeted grazing can be valuable tools in an integrated management program.  Herbicides both pre-emergent and post-emergent can also successfully control yellow starthistle.  In particular, clopyralid, aminopyralid, and aminocyclopyrachlor provide excellent control at low rates.  All three of these compounds have both pre- and post-emergence activity. A combination of a spring burn followed by a pre-emergent herbicide application in the following growing season has been found to be one of the most successful strategies for yellow starthistle control.  The burn suppresses current plants and acts to stimulate germination of much of the remaining seed bank the next fall, which the herbicide then controls.  Biological control has primarily focused on insects that attack the flower heads. Only  two insects have proven somewhat effective, including the hairy weevil (Eustenopus villosus) and the false peacock fly (Chaetorellia succinea), have been reported to reduce seed production.  Revegetation  with native or introduced grasses, legumes or other forbs is an important component of long-term yellow starthistle management.

Medusahead

Methods for controlling medusahead have been studied and implemented since the 1950s.  Control approaches have often targeted windows for burning when medusahead is still growing, but when most associated species are mature and dry (Kyser et al. 2008, Murphy and Lusk 1961, McKell et al. 1962).  Grazing management approaches have successfully reduced flowering by targeting a narrow period just before the flower emerges in April or May (DiTomaso et al. 2008). Glyphosate can be an effective control method when applied in early spring to young medusahead plants. However, it is non-selective and can damage desirable broadleaf or grass vegetation, including native perennial grasses at moderate to high rates.  In the correct ecosystem, proper timing and low rates of glyphosate can control medusahead without damaging desirable perennial plants (Kyser et al. 2012a).  Fall applications of aminopyralid at high rates have been shown to prevent medusahead germination throughout the season (Kyser et al. 2012b).

Barb goatgrass

Barb goatgrass was first identified in California in the early 1900s, but it has spread rapidly in recent years.  Barb goatgrass grows in dense stands supported by deep and rapidly establishing root systems that make it extremely competitive in annual rangelands.  Davy et al. (2008) reviewed the biology and ecology of barb goatgrass as well as control methods.    Fire can be an effective method of control if repeated for two consecutive years (DiTomaso et al. 2001). While no grass-selective herbicides are registered for rangelands in California, glyphosate is a practical and effective method for controlling selected patches.  Mowing and grazing can be effective if heavy defoliation is applied just prior to seed head emergence.

Invasive plants cause serious ecological damage to California’s wildlands, and successfully addressing this widespread problem requires an integrated approach.  Effective control will require long-term management using combinations of biological, mechanical, cultural and chemical methods (DiTomaso 2000).   Integrated management may incorporate specific sequences of practices and approaches including targeted grazing and permanent changes in grazing practices.  Successful control will also require cooperation of private landowners and public agencies working within organized weed control areas.

Klamath Weed

Klamath weed is not considered a large rangeland weed problem because its control in the 1940s was so successful.  The importation in 1944 of Chrysolina quadrigemina and its close relative, C. hyperici, was the first North American attempt at controlling weeds with insects. The insects are natural enemies of Klamath weed also known as St. John's wort. This native European plant is a pest on rangelands throughout the temperate regions of the world because it displaces forage plants and is toxic to cattle and sheep. In 1943 it was estimated that 400,000 acres of California rangeland were infested with Klamath weed.

The beetles Chrysolina hyperici and C. quadrigemina were first released in 1945 and 1946 and both species became established but , respectively C. quadrigemina proved especially effective for Klamath weed control. Populations of the beetles quickly grew and spread. After 5 years, millions were collected from original release sites for redistribution throughout the Pacific Northwest. Ten years after the first releases, Klamath weed populations in California were reduced to less than 1% of their original size  (Huffaker and Kennett, 1959) and the weed no longer threatened the livestock industry. From 1953 to 1959 alone, California saved an estimated $3,500,000 per year due to this biological control program (DeBach and Rosen, 1991).

Rangeland Seeding

Seeding of improved forage species has been the primary means of improving productivity of annual grasslands and cleared or thinned oak-woodlands and chaparral.  Introduction of annual legumes and perennial grasses from the Mediterranean Region, often by way of Australian forage improvement programs, has been an integral part of range improvement programs. Subterranean clover (Trifolium subterraneum) was introduced from Australia in the 1930s. Rose clover (T. hirtum) was introduced in the 1940s by Professor R. Merton Love of the Agronomy and Range Science Department (a legacy department of the current Plant Sciences Department).  Smilograss (Oryzopsis milliacea), an Asian native grass, was introduced from New Zealand by Drs. E.W. Hilgard and E.J. Wickson in 1878.   Hardinggrass (Phalaris tuberosa) was introduced from Australia by Dr. P.B. Kennedy shortly after his arrival at UC Berkeley in 1912.  Later, summer dormant orchard grasses and summer dormant tall fescue were introduced for rangeland seeding.  Bur clover (Medicago polymorpha) is an annual medic that was introduced during European colonization of California.  In the 1950s and 60s it was joined by other annual medics (Medicago spp.) from Australian breeding programs.  Lana vetch (Vicia villosa) was introduced for rangeland seeding in the 1950s by USDA Soil Conservation Service (now USDA Natural Resources Conservation Service).

Annual Legumes

Seeding of rose clover and subterranean clover to improve productivity on Mediterranean-type rangelands began in the 1950s. The primary effect of annual legumes on annual rangeland productivity is to increase winter and spring forage production and to improve the nutritional quality of the available forage.  Gains of 150 to 300 pounds of beef per acre can be consistently produced on annual legume improved ranges. In "good clover years" this type of production is possible on clover alone. However, since good clover years do not occur every year, the introduction of annual legumes, including subterranean clover, rose clover, and annual medics is recommended. Maximum profit per acre results from careful attention to adequate soil fertility, seeding adapted varieties, ensuring proper inoculation at planting, and good grazing management.

Adaptation

Subterranean clover, rose clover, lana vetch and the annual medics are adapted to annual rangelands where elevations are below 915 m (3000 ft) and rainfall exceeds 38 cm (15 in).  Rose and subterranean clover are most commonly used and grow well together on neutral to acid soils. The annual medics tend to be best adapted to neutral to basic soils. Several varieties of annual clovers and annual medics mature over a wide range of dates from very early to very late spring (Table 1). Some subclovers are adapted to wet or poorly drained soils. Most fields to be seeded contain a variety of soils so that the seeding mixture should contain several varieties and types of clover. It should include both early and late maturing varieties that are adapted to a variety of sites to ensure good forage growth during very dry winters or springs, as well as under "normal" conditions. Following is an example seeding recommendation from Tehama County in 2013: 

 

Seeding Rate

(lb/a)

Hykon Rose Clover

3-4

Losa Subterranean Clover

3-4

Campeda Subterranean Clover

3-4

Antas Subterranean Clover

3-4

TOTAL

12-16

 

Seeding and Fertilization

Murphy et al. (1973) published guidelines for planting and managing annual legume seedings.  Most lands planted to annual legumes are deficient in either sulfur or phosphorus, or both, so that adequate amounts are required to produce a good initial stand and to maintain maximum forage and seed production.  While there may be a carryover effect the year after fertilization, especially from phosphorus applications, maintenance fertilization is necessary to maintain clover stands and productivity.

Clovers need to grow in association with certain soil bacteria (Rhizobium) to provide the nitrogen they need for growth (Holland et al. 1969). In most areas these required strains of bacteria are not present in the soil and must be furnished by inoculating the seed with the right bacteria at seeding time. Well-inoculated clovers supply extra nitrogen to make the associated grasses more productive. The pellet method of inoculation is recommended.

Some seedbed preparation is often necessary to reduce competition, ensure the survival of rhizobium bacteria, and provide for seed coverage; however, direct seeding in low residue has been successful in many locations. A light disking is preferred so that small legume seeds will not be buried too deep. Seed can be drilled using a rangeland or grassland drill or broadcast from the air or ground.  A broadcast seeding should be lightly covered by ring rolling or harrowing. Broadcast seedings that are not covered are highly susceptible to failure in marginal rainfall areas.  Range drills are sometimes available from area seed companies. Seeding should be done as close to the first fall rain as possible and before cold weather. Fall seedings in October and early November are much more successful than December seedings. If germinating rains do not come before cold weather, delay seeding until the following year.

Grazing Management

Legumes stimulate the earIy growth of grasses and filaree. In the winter and early spring, seeded ranges should be grazed to use the grass and prevent non-Iegumes from crowding the clovers. Reduce grazing while clover is blooming will allow an adequate seed set. Stands should be heavily grazed during the summer and fall to make use of the dry feed and to trample the seed into the ground. More stands of clovers have been lost by grazing too light than by overgrazing.

Annual Grasses

Annual ryegrass is the main improved annual forage grass used on annual rangelands.  With proper fertilization it can provide high quality forage during the growing season and remains an important species for improving forage quantity and quality.  Annual ryegrass germinates rapidly and is able to quickly stabilize soils following burns and other disturbances. Unfortunately, this characteristic also makes annual ryegrass a strong competitor to native species.  Consequently, it has been listed as an invasive non-native plant that threatens wildlands by the California Invasive Species Council.  If your goal is to maintain and increase native grasses and forbs, excluding annual ryegrass is a legitiment management practice.  However, if you need to stabilize soil quickly or you are seeking improved forage, seeding annual ryegrass remains an important agricultural practice.

Blando brome (Soft chess brome, Bromus hordeaceus) and Zorro fescue (annual fescue, Vulpia myuros) are also available for seeding for erosion control.  Soft chess brome is a desirable forage species that is naturalized and widespread on annual rangelands.   Annual fescue is widespread but not desirable for improving forage.  Both of these grasses were selected from wild populations and developed into commercial varieties by the USDA NRCS Plant Materials Center.

Perennial Grasses

The primary reasons that ranchers have seeded perennial grasses on annual rangelands is to provide a higher amount of winter feed and green feed several weeks later in the season than the naturalized annual grasses and forbs. Hardinggrass and some other perennial grasses have the ability to break summer dormancy and begin growth before the first fall rains and remain green until after seed has matured in early summer. This can add several weeks to the green forage season.  However perennial grasses are hard to establish, sometimes taking 3 to 5 years to become completely established and able to compete with annual grasses.  Consequently perennial grass seedings have not been wide spread on annual rangelands.

From 1937 to 1951 the University of California Extension Service and Agricultural Experiment Station planted thousands of test plots to determine what grasses were adapted to seeding following brush burns and other woody plant control.  Planting methods and seeding recommendations were developed for the annual rangelands and intermountain areas where rainfall exceeded 10 inches (Love and Jones 1952).  Hardinggrass was seeded in many counties and remnants of those plantings can still be found.  However, McKell et al. (1966) found that grazing during active growth reduced yields and increased mortality.  Likewise ranch managers have reported low persistence of grazed stands in all but the very best soils.   Kay (1960) found that hardinggrass tolerates fire making it a good candidate for erosion control.  However, the California Invasive Plant Council has listed hardinggrass as an invasive non-native plant that threatens wildlands.  In the 1960s summer dormant orchardgrass did well in many test plots around the state and became part of perennial grass seeding recommendations.  Several other grasses, including smilograss, tall wheatgrass (Agropyron elongatum) and mission veldtgrass (Ehrharta calycina)  were also recommended.  Recent releases of summer dormant tall fescue varieties are currently showing promise as a companion with summer dormant orchardgrass.

Except for poor rainfall years, weed management prior to sowing perennial grasses is the greatest factor for successful establishment.  Annual grass competition during establishment of perennial grasses can cause complete failures of perennial grass seedings.  Following is an example timeline for seeding perennial grasses and managing established stands on soils that are not highly compacted and do not require deep tillage:

  1. Apply a non-selective herbicide such as glyphosate in early spring the year before planting to control all weeds.
  2. Wait for the first fall germination and again spray a non-selective herbicide such as glyphosate
  3. Drill seed immediately after spraying in the fall at less than ¼ inch in depth.
  4. Using a broadleaf selective herbicide such as 2,4-D control broadleaf weeds in early spring after planting
  5. Defer grazing until the new seeding is fully established and cannot be pulled from the ground, which is usually the second or third year after planting depending on rainfall during establishment.
  6. Planting annual legumes in the same manner as described above once the perennial grasses are established can be used as a long term method of providing nitrogen.
  7. To maintain the established stand grazing is best deferred in the fall, grazed from winter to mid spring, deferred from grazing in late spring, and grazed again in the summer.  As with perennial grasses in irrigated pastures, plants should not be grazed to a height low enough to damage the crown as this will limit future production and stand life.

Native grasses, especially California needlegrass (Nasella pulchra) were tested along with the introduced perennial grasses and are included in the recommendations by Love and Jones (1952).  Restoration of native grasses has been a recurring objective of range managers on California’s annual rangelands (Kay et al. 1981, George et al. 1992) since the 1940s.  The goal of restoring grasslands and woodland understories to some pre-settlement condition has proven to be unrealistic because not only is there uncertainty about the historical composition and extent of California native grasslands but restoration failure is common. Rangeland and restoration scientists have tried to restore native grasses but have not  found  dependable native grass restoration practices for use on land that is steep, rocky or highly eroded.  Competition from naturalized annual grasses and forbs remains a major barrier to native grass restoration.  Season-long heavy grazing has also resulted in poor stand survival.  On arable land native grasses can be grown for seed and pasture following standard crop production practices.  Scientists continue to seek practices to control the annuals and promote native perennials.

Fertilization of Non-Seeded Annual Rangeland

Why Fertilize

Annual rangeland soils without legumes are nitrogen (N) deficient (Jones 1974, Jones and Woodmansee 1979).  To increase winter forage and total production, N must be added by a legume or N fertilization. Phosphorus (P) and sulfur (S) deficiencies are also widespread. In some areas, molybdenum deficiencies are quite common. Deficiencies of potassium, boron, and lime occur on acid soils, but are not widespread. Usually these latter deficiencies become evident only after adequate amounts of P and S have been applied on legume pastures.  In the 1950s and 60s the effects of N, P, and S on forage production were estimated on several annual rangeland soil series using greenhouse pot studies (Table 2) as well as field plots (Tables 3 and 4).  These studies showed that most soil series responded to P and /or S as well as N.

For about 15 years in the 1950s and 60s University of California at Davis researchers studied the effect of N fertilization on range forage production and animal productivity on 28 ranches in 20 counties (Martin and Berry 1970).  When analyzed together fertilizer effects the first year increased carrying capacity from 38 head days per acre to 92 head days per acre and livestock gains from 66 kg/ha to 190 kg/ha ( 60 lbs/a to 170 lbs/a).  Greater first year benefits were observed where N plus S or N plus P were required than where only N was needed.  Second year carryover effects measured at 13 locations were much greater where N was applied with either S or P than from N alone  (Martin and Berry 1970, Jones 1974). Table 5 is a comparison of the 1957 costs and returns, reported by Martin and Berry in 1970, to projected costs and returns in 2012.  In 2012 fertilizer costs for N, depending on the formulation, were 2 to 5 times higher than in 1957 and stocker cattle prices were 5 to 6 times higher.

In the mid-1980s N was again shown to be beneficial in a large scale study of the effects on fertilization and legumes on beef production at the UC Sierra Foothill Research and Extension Center northeast of Marysville, California (Raguse et al.1988).  In this study N was applied at 45 and 90 kg/ha (40 and 80 lbs/a) with and without P and S.  Phosphorus and S were applied at two rates with and without N, P at 33 kg/ha to 66 kg/ha (30 and 60 lbs/a) and S at 37 and 74 kg/ha (33 and 66 lbs/a).  This study showed that animal weight gains were greater with N than without and that the greatest gains resulted from application of N, P and S.  This study also showed that dry matter digestibility was increased.

One of the most important benefits of N fertilization is that it can substantially increase production during the winter and early spring. This early feed is extremely valuable because it replaces expensive hay or other energy supplements for livestock. For ranchers dependent on annual rangeland for winter and spring feed the onset of the green season is awaited with great urgency each year. N fertilizer can increase winter forage production before the spring flush of growth, and effectively replace two to six weeks of supplemental feeding during the winter. N fertilization will also increase spring feed, but this is usually not a forage short season for the range livestock producer in California.

The decision to apply nitrogen (N) fertilizer to rangeland is based on:

  1. The need to extend the adequate green forage season by increasing winter forage production. 
  2. The need to increase total production and an ability to fully utilize increased feed.
  3. The absence of native or seeded legumes in significant amounts.
  4. Average annual rainfall of 30 to76 cm (12 to 30 in).
  5. Expectation that the site will respond adequately to generate a return on the fertilizer investment.
  6. The desire to invest capital in a short-term improvement, or have the flexibility of a year-to-year decision.

If precipitation exceeds 76 cm (30 in) the risk of nitrogen loss by leaching is great. An annual legume seeding should be considered instead of N fertilization on high rainfall sites. An annual legume seeding has a higher initial cost, but is frequently less costly than N fertilization if costs are amortized over the life of the stand.  Annual legumes also improve forage quality substantially.

Weather and Site Productivity

Knowledge of range sites and their forage productivity and response to fertilization is critical in making the decision to fertilize annual rangeland. Range forage response to fertilization varies with prevailing weather patterns (Figure 1a). During a favorable weather year above average forage productivity is further increased by application of N (Figure lb). Likewise low productivity during an unfavorable year can be increased by fertilization but not to the levels expected under favorable weather conditions (Figure lc). However, the percentage increase may be greater than in a wet year. To properly assess the response to fertilization on a given range site, the site's forage productivity and fertilizer response during a favorable, average, and unfavorable weather year should be estimated to allow the decision maker to better assess fertilization benefits and risks over the range of weather patterns characteristic of California's Mediterranean climate.

Fig1

Figure 1. Seasonal productivity of fertilized and unfertilized annual range forage during A. average, B. favorable and C. unfavorable years.  NOTE: These are simulated curves representing an "average range site" and are not the product of a specific study.

A favorable year in terms of forage production can result from fall rains coinciding with warm fall temperatures or from extended warm, wet spring weather. An unfavorable year results when the fall rainy season is delayed  or when cold fall temperatures occur earlier than normal.  Most years are intermediate to these favorable and unfavorable extremes (see  Chapter 1).

Table 6 and Figure 1 illustrates the estimated annual forage production for a favorable, average, and unfavorable year on a range site of average productivity in the California annual rangeland. Included are expected and possible productivity improvements based on numerous fertilizer trials. Tables 7 and 8 show the combined results of 54 grazing trials designed to evaluate the effects of N fertilization over a 15-year period in 20 counties (Martin and Barry 1970).

Factors other than prevailing weather contribute to the inherent productivity of the range site. Those sites that have inherently low productivities may respond to range improvement but the response may not be great enough to pay for the cost of improvement. Range fertilization frequently produces a 1 ½- to 2-fold increase in dry matter production. A site normally averaging 1500 pounds of dry matter per acre will yield an additional 1500 pounds from N fertilization and there is a reasonable chance that this improvement is economically feasible. If the average productivity is only 500 pounds per acre then the economic feasibility of a two-fold increase or 500 additional pounds of forage per acre is less likely. Range economists often advise ranchers to improve those range sites with the highest potential first. This is good advice except where the lower potential site improvement has strategic value or an exception is known through past research or experiences.

Additional benefit from N fertilization may be achieved by using N application as a method of manipulating livestock utilization of the range.  Although it is not widely practiced, it has been shown that use of underutilized range forage can be increased by applying N and other fertilizers to that forage. Once the livestock find this area of application they seek it out and use it to a greater extent than before it was fertilized. Similarly it has been shown that the application of N to weed infestations can increase their utilization. If the utilization of medusahead and immature summer annuals such as yellow starthistle and tarweed is increased and grazing is properly timed it can reduce flowering and seed set of these weeds.

What to Apply

Ammonium sulfate (21-0-0-24S), ammonium phosphate sulfate (16-20-0-13S) and urea (40-0-0) are most frequently applied on annual rangeland. Ammonium sulfate is frequently used because S deficiencies are widespread on annual rangeland and it is less expensive than 16-20-0 containing both S and P. Where S and/or P are deficient, application of these nutrients should be considered. When the soil contains adequate levels of P and S, urea may be used. Nitrate N tends to leach too rapidly, and is often lost early in the first year before it can be utilized by the forage plants.   Although urea is an inexpensive N source, volatility losses can reduce its effectiveness if soil pH is greater than 7 and if applied too early in the fall when soil temperatures are still high. To avoid volatilization, rainfall in excess of ¼ inch is necessary for urea soil incorporation and greater than ½ inch is desired.  A worst case scenario is an early fall rain of less than ¼ inch that breaks down the prills but does not carry the urea into the soil.  Chicken manure and other manures can be satisfactory sources of N where transportation and spreading costs do not prohibit their use. Manures are longer lasting N sources because the N is released slowly as the organic matter decomposes.  Soil and tissue testing can help to answer the question of what nutrients to apply in addition to N.  Commercial agricultural testing laboratories can conduct needed soil and plant tissue tests at very low costs.

When to Apply

In the 12 to 30-inch rainfall zone, N is generally applied in the fall to lengthen the green feed period by increasing winter growth. The amount and distribution of rainfall, as well as temperature, are principle factors governing the timing of application. N is not profitable in central and southern California, where annual rainfall is less than 12 inches annually, because reduced soil moisture restricts plant growth and response to fertilizers.

Research at the Hopland Field Station, where N was applied monthly from September through January in a 36-lnch rainfall zone, showed that the earlier N was applied in the fall the greater the winter forage growth (Jones 1960). Total forage as measured at the end of the growing season was not affected by the time of application unless the application was made after February. N is generally not recommended where rainfall is greater than 30 inches since leaching losses are high. Denitrification can contribute to N losses, especially on poorly drained soils that are saturated for extended periods.

Winter temperatures averaging much below 10o C (50o F) severely limit responses to N fertilization. Daily mean temperatures below this limit are common in northern California and Oregon during the months of December, January, and February. Therefore, N should be applied before the first autumn rains when mean temperatures are 10o C (50o F) or more. Lack of response in cold weather is mainly a simple restriction of plant growth, but N fertilized grass often is less damaged by frost and appears to recover faster than N deficient grass. Nitrogen should not be applied to ground covered in snow as much of the snow may be lost to evaporation along with the applied fertilizer.

How Much to Apply

Generally, a good forage response is gained from applying between 45 kg/ha and 90 kg/ha (40 and 80 Ibis/a) of N. The variation in recommendations between counties is a reflection of year and range site differences, especially annual variation in amount and distribution of precipitation. How much N to apply has been a continuing question and the subject of numerous fertilizer trials. Rates of N up to 200 Ib./A have been applied and forage or animal yield measured.

Production functions for N fertilization follow the law of diminishing returns. Therefore, beyond a certain level, each additional increment of fertilizer will give less production than the previous increment. The point of diminishing returns is where the return equals the cost of the added increment. On California annual rangelands, this point is commonly in the range of 45 kg/ha and 90 kg/ha (40 and 80 Ibis/a), and it will vary within this range due to seasonal and yearly variations in weather. Lower rates seldom yield adequate forage production to justify the expense.

How Often to Apply

Traditionally, N applications have been made in the fall near the time of the first rains. in regions of high rainfall and where heavy winter grazing has occurred, the forage may become extremely N deficient in the spring even though N was applied the previous fail. Under these circumstances spring applications of N fertilizer may be beneficial, but this practice has not been adequately evaluated on annual rangelands.

Where rainfall is not great enough to leach all of the fertilizer N out of the soil, and plant N uptake is insufficient to use all of the fertilizer N, there may be a carry-over response to N fertilization during the next growing season. In the 1950s many grazing trials were conducted to demonstrate the response of range livestock gains to range N fertilization. Carry-over effects were assessed in 13 of the tests. In all but one test there was an appreciable carry-over effect from fertilization, the additional gain being equivalent to about 50 percent of the first year effects on the average. Part of the gains in these studies should be credited to the P and S also applied, but the amount of credit to be given cannot be determined with the available data. Without applied N or a good stand of legumes, there is usually no response to P or S on annual rangelands of California.  

How to Apply

Fertilizer can be applied from the ground or by aircraft. Large, inaccessible, rough and rocky ranges are usually fertilized by aircraft. Fertilizer application equipment and tractors are usually restricted to use on rangeland where slopes are less than 20 to 30 percent and the surface is relatively free of rocks or other obstructions to the equipment. The analysis of range sites on a given ranch during a range management planning process will help to identify those areas that can be treated from the ground and those that must be treated from the air.

Forage Quality

Fall N fertilization generality increases the protein content in annual grasses and broad leaved forbs early in the growing season. However, an increase in protein in winter is not beneficial since there is typically adequate protein for animal needs in unfertilized pasture at that time of year. The primary benefit from N in the early part of the season is an increase in dry matter production. As the season advances, the protein levels may decrease more rapidly in plants fertilized at moderate N levels than in those not fertilized. As a result, at the end of the growing season fertilized plants are often lower in protein then are unfertilized plants. Exceptions may occur in very dry spring seasons when moisture becomes limiting and plants are unable to grow to their full potential, thus drying up before growth dilutes the N (protein) to a low level.

Yearly application of N generally increases the percentage of grasses and forbs. The particular grasses or forbs which increase will depend upon the grazing or clipping management of the pasture in question. For example, slender wild oats (Avena barbata) or ripgut brome (Bromus diandrus) often become dominant where N fertilizer is applied to ungrazed plots. In similarly treated plots that are heavily grazed, soft chess may become dominant. This is due to the greater tillering ability of soft chess when grazed as compared to wild oats or ripgut which tiller poorly.  Moderate to heavy grazing pressure tends to reduce the impact of fertilizer on botanical composition.

Economics of Range Improvement

In California the cost of improving an acre of rangeland has always had to compete with the cost of renting an acre of grazing land.  Often it has been cheaper to increase carrying capacity by renting another acre rather than paying the per acre cost of range improvement.  However, as it becomes harder to find grazing land to lease range improvement may become more important.  Brush control is one of the oldest and quickest ways to increase carrying capacity for livestock production but the economics of this and other range improvement practices have changed.  Before the energy crisis of the 1970s it was less costly to use  fossil fuels and fertilizers that are fossil fuel based in range improvement.  Following the increase in fuel costs brush control practices, especially mechanical methods, became more costly as did the cost of planting seed and applying fertilizer.  Beginning in the 1950s ranchers in collaboration with the university and several government agencies planned and conducted burns to control brush.  By the 1970s subdivisions and single family homes had moved into the states range and forestlands creating huge liability for burning.  Prescribed burning is still economical in many instances but the liability risk and cost has resulted in a decrease in burning.

The decision to improve rangelands depends on several factors including: 1) financial returns from the improvement, 2) risk of failure, 3) government subsidies, 4) financial returns from alternative practices, 5) effects on vegetation including recovery following treatment and 6) current and projected livestock prices and ranch costs.

Unlike range improvement to increase ranch profit, restoration of native plants to rangelands is not constrained by profit goals.  Consequently restoration projects often operate under a different set of economical rules than those that guide ranchers.  Restoration of native plants to public and private lands is often subsidized by government programs or by funds from conservation organizations.  Creating a profit is seldom an objective.  Unfortunately, in California the risk of restoration failure is great and these investments in restoration are often lost. 

Literature Cited

Adams Jr.,  T.E. 1976a.  Brush Management-Straight Dozer Blade And Brush Rake Clearing.  Berkeley, CA, USA: California Division of Agricultural Sciences Leaflet  2923.  7 pgs.

Adams Jr.,  T.E. 1976b. Brush Management-The Ball And Chain.  Berkeley, CA, USA: California Division of Agricultural Sciences Leaflet  2920.  7 pgs.

Adams Jr.,  T.E. 1976c. Brush Management-The Brushland Disk.  Berkeley, CA, USA: California Division of Agricultural Sciences Leaflet  2921.  7 pgs.

Adams Jr., T.E. T.E. 1976d.  Brush Management-Modified And Smooth Chains.  Berkeley, CA, USA: California Division of Agricultural Sciences Leaflet  2922.  7 pgs.

Dahlgren, R, M.J. Singer and X. Huang.  1997. Oak tree and grazing impacts on soil properties and nutrients in a California oak woodland.  Biogeochemistry 39:45-64.

Davy, J.S., J.M. DiTomaso, and E.A. Laca.  2008.  Barb Goatgrass.  Berkeley, CA:  University of California Division of Agriculture and Natural Resources Publication 8315.  5 pgs.

DeBach, P. and D. Rosen. 1991. Biological control by natural enemies, 2nd edition. Cambridge University Press.

DiTomaso, J.M. 2000. Invasive weeds in rangelands: Species, impacts, and management.  Weed Science, 48:255-265.

DiTomaso, J.M, G. B. Kyser, and M. J. Pitcairn. 2006. Yellow starthistle management guide. Cal-IPC Publication 2006-03. California Invasive Plant Council: Berkeley, CA. 78 pp. Available: www.cal-ipc.org.

DiTomaso, J.M. G. B. Kyser, M. R. George, M. P. Doran, and E. A. Laca.  2008. Control of medusahead (Taeniatherum caput-medusae) using timely sheep grazing.  Invasive Plant Science and Management 1:241–247.

George, M. R., J. R. Brown, and W. J. Clawson.  1992.  Application of nonequilibrium ecology to management of Mediterranean grasslands.  J. Range Manage. 45(5),436-438.

Holland, A.H., W.A. Williams and J.E. Street.  1969.  Range-legume inoculation and nitrogen fixation by root-nodule bacteria.  Berkeley, CA: California Agricultural Experiment Station Bulletin 842.  19 pgs.

Holland, V.L. 1979.  Effect of blue oak on rangeland forage production in central California.  In: Proceedings Symposium Ecology, Management and Utilization of California Oaks.  Berkeley, CA:  USDA Forest Service General Technical Report PSW-44.  pp. 314-318.

Huffaker, C. B. and C.E. Kennet. 1959. A ten-year study of vegetational changes associated with biological control of Klamath Weed. J. Range Management 12: 69-82.

Jones. M. B. 1960. Responses of annual range to urea applied at various dates. Journal of Range Management 13: 188-192.

Jones, M.B. 1974.  Fertilization of annual grasslands of California and Oregon.  In: Mays, D. (ed.) 1974.  Forage Fertilization.  Madison, WI:  American Society of Agronomy.

Jones M.B. and R.G. Woodmansee. 1979. Biogeochemical cycling in annual grassland ecosystems, Botanical Review 45. 111-144.

Kay, B.L. 1960.  Effect of fire on seeded forage species.  Journal of Range Management13:31-33.

Kay, B.L. and O.A. Leonard.  1979.  Effects of blue oak removal on herbaceous forage production in the northern Sierra foothills.  In: Proceedings Symposium Ecology, Management and Utilization of California Oaks.  Berkeley, CA:  USDA Forest Service General Technical Report PSW-44.  pp. 323-328.

Kay, B.L. 1986.  Long-term effects of blue oak removal on forage production, forage quality, soil and oak regeneration. In: Proceedings Symposium Multiple-Use Management of California’s Hardwood Resources.  Berkeley, CA:  USDA Forest Service General Technical Report PSW-100.  Pp. 351-357.

Kay, B.L., R.M. Love, and R.D. Slayback. 1981.  Discussion: Revegetation with Native Grasses I. A Disappointing History.  Fremontia 9: 11-15.

Kyser, G. B., J.E. Creech, J. Zhang, and J.M. DiTomaso. 2011. Selective Control of Medusahead (Taeniatherum caput-medusae) in California Sagebrush Scrub using Low Rates

of Glyphosate. ipsm-05-01-03.3d

G. B. Kyser, V. F. Peterson, J. S. Davy, and J.  M. DiTomaso. 2012. Preemergent control of medusahead on California annual rangelands with aminopyralid. Rangeland Ecology & Management: July 2012, Vol. 65, No. 4, pp. 418-425.

Leonard, O.A., C.E. Carlson, and D.E. Bayer.  1956.  Studies on the cut-surface method.  II. Control of blue oak and madrone.  Weeds 13:352-356.

Leonard, O.A. 1959.  Effect of blue oak (Quercus douglasii) of 2,4-D and 2,4,5-T concentrates applied to cuts in trunks. Journal of Range Management 9:15-19.

Love, R. M. and B. J. Jones and V.P. Osterli.  1952.  Improving  California  Brush Ranges.  Berkeley, CA, USA: California Agricultural Experiment Station Circular 371. 38 pgs.

Martin WE and Berry LJ (1970) Effect of Nous fertilizers on California range as measured by weight gains of grazing cattle. California Agricultural Experiment  Station Bulletin 846. 23 p.

McClaran, M.P.  1986.  Age structure of Quercus douglasii in relation to livestock grazing and fire.  Ph.D. Dissertation.  Univ. of Calif., Berkeley.  119 pp.

McClaren, M.P. and J. W. Bartolome.   1989.  Fire related recruitment in stagnant Quercus douglasii populations.  Canadian Journal

McCreary,D.R. 2001.  Regenerating Rangeland Oaks in California.  Berkeley, CA:  University of California Division of Agriculture and Natural Resources Publication 21601.  62 pgs.

McCreary D, Tietje W, Davy J, Larsen R, Doran M, Flavell D, Garcia S. 2011. Tree shelters and weed control enhance growth and survival of natural blue oak seedlings. Cal Ag 65(4):192-196. DOI: 10.3733/ca.v065n04p192

McKell, C.M., A. M. Wilson and B. L. Kay.  1962. Effective Burning of Rangelands Infested with Medusahead.  Weeds 10:125-131.

McKell, C.M., R.D. Whalley, and V. Brown. 1966. Yield, survival and carbohydrate reserve of hardinggrass in relation to herbage removal.  Journal of Range Management 19:86-89.

Murphy, A. H. and W. C. Lusk. 1961. Timing of medusahead burns. Calif. Agric. 15:6–7.

Murphy, A.H. and B. Crampton. 1964.  Quality and yield of forage as affected by chemical removal of blue oak (Quercus douglasii).  J. Range Manage.  17:142-144.

Murphy, A.H. and L.J. Berry. 1973.  Range pasture benefits through tree removal.  Calif. Agric. 27:8-10.

Murphy, A.H, M.B. Jones, J.W. Clawson, and J.E. Street.  1973.  Management of Clovers on California Annual Grasslands.  Berkeley, CA:  California Agricultural Experiment Station Circular 564.  20 pgs.

Raguse, C.A., T.K. Albin-Smith, J.L. Hull, and M.R. George.  1986.  Beef production on converted foothill oak woodland range in the western Sierra Nevada.  In: Proceedings Symposium Multiple-Use Management of California’s Hardwood Resources.  Berkeley, CA:  USDA Forest Service General Technical Report PSW-100.  Pp. 361-366.

Raguse, C. A., J. L. Hull,  M. R. George, J. G. Morris, K. L. Taggard. 1988. Foothill range management and fertilization improve - beef cattle gains.  California Agriculture 42:4-8.

Raguse, C.A.,  K. L. Taggard, J. L. Hull, J. G. Morris, M. R. George, and L. C. Larsen. 1988. Conversion of fertilized annual range forage to beef cattle liveweight gain. Agronomy Journal 80:591-598.

Roby, G.A. and L. R. Green. 1976. Mechanical Methods of Chaparral Modification.  Washington D.C.: U.S. Department of Agriculture Handbook NO. 487.  46 pgs.

Sampson, A.W.  1940.  Plant succession on burned chaparral lands in northern California. California Agricultural Experiment Station Bulletin No. 685.

Spurlock, G.M., R.E. Plaister, W.L. Graves, T.E. Adams, and R.B. Bushnell.  1978.  Goats for California Brushland.  Berkeley, CA:  University of California, Division of Agricultural Sciences Leaflet 21044.  30 pgs.

Willoughby, I.  1999. The control of coppice regrowth in roadside woodlands. Forestry 72:305-312.

 

 

List of Tables.

Table 1.  Annual legumes recommended for seeding annual rangelands in the 1980s.

Table 2.  Yields (g) from Soil Vegetation Project fertilizer pot studies in the 1950s and 1960s.

Table 3.  Yields (lb/a) from Soil Vegetation Project fertilizer plot studies in the 1950s and 1960s.

Table 4.  Yields (lb/a) from Soil Vegetation Project fertilizer plot studies in the 1950s and 1960s.

Table 5.  Comparison of fertilizer costs and returns between 1957 and 2012.

Table 6.  Total forage production and estimated response to N fertilization on California annual rangeland for a precipitation range of 15 to 30 inches.

Table 7.  Beef production (lb/a) response to N fertilization during wet and dry years compared to the average of 15 years for 54 trials in 20 counties.

Table 8.  Rates of beef production to N fertilizer applied (lbs. beef/lb N) during a wet and dry year compared to the average for 15 years for 54 trials in 20 counties.

 

 

 

List of Figures

Figure 1. Seasonal productivity of fertilized and unfertilized annual range forage during A. average, B. favorable and C. unfavorable years.  NOTE: These are simulated curves representing an "average range site" and are not the product of a specific study.

 

Table 1.  Annual legumes recommended for seeding annual rangelands in the 1980s.

 

Minimum rainfall (in)

Flower Date

Estrogen Level

Hard seed content

Number of seeds per lb (1,000)

SUBTERRANEAN CLOVERS

Early Season

Nungarin

10

Late Feb.

Low

Very high

65

Northam

10

Early Mar.

Low

High

70

Geraldton

10

Early Mar.

High

Medium

85

Early Mid Season Varieties

Daliak

12

Mid Mar.

Low

Medium

80

Yarloop

18

Mid Mar.

Very high

Medium

60

Seaton Park

18

Mid Mar.

Low

Medium

65

Trikkala

18

Mid Mar.

Low

Low

50

Mid Season Varieties

Dinniup

18

Late Mar.

Very high

High

85

Esperance

20

Early Apr.

Low

Medium

70

Woogenellup

20

Early Apr.

Low

Low

 

Howard

20

Early Apr.

High

Low

60 80

Clare

20

Early Apr.

Low

Very low

70

Late Season Varieties

Mt Barker

25

Late Apr.

Low

Very low

70

Larissa

25

Late Apr.

Low

Low

60

Nangella

30

Late Apr.

Low

Very low

70

Tallarook

35

Early May

High

Very low

60

ANNUAL MEDICS

Bur

10

February

N. A.

High

145

Harbinger

10

January

N. A.

High

190

Hannaford

10

February

N. A.

High

110

Jemalong

10

February

N. A.

High

110

ROSE CLOVERS

Olympus

10

February

Low

Very high

155

Hykon

12

February

Low

Very high

135

Kondinin

12

March

Low

Very high

165

Wilton

15

April

Low

Very high

160

CRIMSON CLOVER

Crimson Clover

15

March

N. A.

High

140

 

Table 2.  Yields (g) from Soil-Vegetation Project fertilizer pot studies in the 1950s and 1960s.

Soil

Series

County

Fertilizer Treatments

Ck

S

P

PS

N

NS

NP

NPS

Auburn

Shasta

5.4

7.2

8.8

8.6

9.2

11

24

29.8

Auburn

Shasta

7.5

8.8

11.8

12

14.8

18.2

34.5

38.8

Kinman

Humboldt

18.5

25.2

24.8

27

28.5

36.5

37.8

43.8

Kneeland 1

Humboldt

12.7

18.7

25.2

25

45

51.5

Kneeland 2

Humboldt

23.5

33.7

24

24

71.2

75

Kneeland 3

Humboldt

16.2

18.7

36.5

40

37

47.7

Laughlin

Mendocino

68.8

37

105.5

115.5

54.8

38.8

236.8

259.8

Lodo

Tehema

10.6

10.8

12

11.6

32.6

39.2

45.6

48.8

Lodo

Tehema

10.5

11.2

28.8

36.8

29

38

Lodo

Tehema

7.5

8

27

32.2

26.5

37.5

Lodo

Tehema

4.8

4.8

17.5

21

22.8

33.2

Los Gatos

Shasta

14

13.8

21.5

40.3

51.5

Mattole 1

Humboldt

9.8

9.5

32.8

30.5

59.8

56.5

Mattole 2

Humboldt

13

16

25.8

20.2

58.8

58

Mattole 3

Humboldt

19.2

18.5

33.2

33

52.2

56.2

McMahon

Humboldt

14

16

44.5

46.2

77

79

McMahon

Humboldt

19.2

34.8

26

52

53

57

McMahon

Humboldt

18.4

15.6

17

20.6

34.2

34.8

55.6

70.2

Millsap

Glenn

13.5

14.5

59.2

62.2

65.2

73.2

Millsap

Glenn

23.5

24.2

52.2

64.2

59

59

Millsap

Glenn

7.5

7.5

16

19.5

19

32

Millsholm

Glenn

9.7

13.5

70

78.2

89.8

81.2

Millsholm

Glenn

27.5

25.7

26.2

19.2

66.5

63.5

75.8

69.8

Nacimiento

Tehema

15.2

14.2

38.8

25.5

51.8

64.2

Sehorn A

Glenn

13.5

14.5

11.8

12.5

35

34.2

40.8

30.8

Sehorn B

Glenn

14.8

11.8

12.8

22

31

34.8

42

36.5

Sierra

Shasta

6.8

6.2

8.8

10.6

1.6

8.4

36

42

Toomes

Tehema

33.2

35.2

33

36.8

64.8

64.2

71.2

56.8

Toomes

Tehema

3.8

5.4

13.2

11.6

1.2

2.6

18.4

8.2

Tyson

Humboldt

20.2

27

27

26

34.2

45.2

29.2

57.5

N = 160 lb/A of nitrogen in urea

P = 88 lb/A of phosphorus in triple super phosphate

S = 100 lb/A of sulfur in gypsum

 

Table 3.  Yields (lb/a) from Soil-Vegetation Project fertilizer plot studies in the 1950s and 1960s.

 

 

Soil

Series

County

Fertilizer Treatments

 

N0P0S0

N0P0S100

N0P200S0

N0P200S100

N150P0S0

N150P200S0

N150P0S100

N150P200S100

 

Argonaut

Amador

5568

5484

6432

5964

7026

7728

6732

6246

 

Auburn

Butte

2682

2562

3192

2832

3942

4818

4212

5220

 

Kneeland

Humboldt

1536

1344

1632

1752

1560

1800

936

1752

 

Laughlin

Humboldt

910

914

1346

1008

2995

2988

2954

3338

 

Millsap

Glenn

709

894

916

980

2951

4693

5368

5380

 

Millsholm

Glenn

1264

2058

1974

2704

3386

4938

5158

5878

 

Newville

Glenn

366

365

337

296

848

1050

1148

864

 

Sehorn

Glenn

2540

3040

3010

3200

5040

5610

5400

5900

 

Sehorn

Glenn

2168

2992

3536

4704

4150

5786

5386

6342

 

Sierra

Yuba

1290

1338

1770

1506

2412

3384

2772

3492

 

Yorkville

Humboldt

159.2

152.6

177.8

154

193.6

267

236.6

231

 

Yorkville

Humboldt

1090

578

893

1358

2280

2035

2515

2654

 

N = 150 lb/A of nitrogen in urea

 

P = 200 lb/A of phosphorus in triple super phosphate

 

S = 100 lb/A of elemental sulfur

 

 

Table 4.  Yields (lb/a) from Soil-Vegetation Project fertilizer plot studies in the 1950s and 1960s.

Soil

Series

County

Fertilizer Treatment

Ck

S

P

PS

N

NS

NP

NPS

Gaviota

Shasta

3568

3224

2664

3624

3336

3752

3008

4256

Guenoc

Shasta

622

509

1315

1154

1142

1185

3379

3708

McMahon

Humboldt

2907

2290

3708

3265

2583

4177

5684

4640

Millsholm

Glenn

1686

1498

1018

2214

1792

1904

2125

2214

Sehorn

Glenn

1572

1404

1652

1614

3750

6438

5634

6222

Sehorn

1597

2246

1814

2637

1709

2160

1709

2272

Sehorn

1572

1404

1652

1614

3750

6438

5634

6222

Sehorn

Tehema

2540

3040

3010

3200

5040

5400

5610

5900

Toomes

Shasta

462

696

828

426

1068

978

1386

1518

N = 160 lb/A of nitrogen in urea

P = 88 lb/A of phosphorus in triple super phosphate

S = 100 lb/A of sulfur in gypsum

 

Table 5.  Comparison of fertilizer costs and returns between 1957 and 2012.

 

1957

2012

No Fertilizer

N Fertilizer

No Fertilizer

N Fertilizer

In Weight (lb.)

367

370

367

370

Stocking Rates:

In Weight (lb./a)

147

370

147

370

Stocking Rate (a/hd)

2.5

1

2.5

1

Stocking Rate (hd/a)

0.4

1

0.4

1

 Gain (lb./a)

60

170

60

170

Out Weight (lb./a)

207

540

207

540

Gross Income from Grazing ($/a)

 $   46

 $  120

 $   257

 $   670

(Out wt@22.20 cwt.)

In Weight Cost ($/lb.)

       $   36

$    90

 $   210

 $   529

(in wt.@ 24.25 cwt.

Fertilizer Cost ($)

 $    13.92

 $    46.00

Interest for 124 Days @ 4 %

 $       0.73

 $       2.11

 $       2.86

 $      7.82

Net Income ($/a)

 $       9.58

 $     14.12

 $     43.61

 $    86.68

Ave Profit from Fertilizer ($/a)

 

 $       4.54

 

 $    43.07

 

Table 6.  Total forage production and estimated response to N fertilization on California annual rangeland for a precipitation range of 15 to 30 inches.

 

Dry Matter 

Improvement due to N fertilization

 

(lb/a)

Reasonable

Possible

Unfavorable year

1000

1 - 1 1/2 X

1 1/2  - 2 X

Average year

2000

2X

3 - 4 X

Favorable year

3000

1 - 1 1/2 X

3 - 5 X

 

Table 7.  Beef production (lb/a) response to N fertilization during wet and dry years compared to the average of 15 years for 54 trials in 20 counties.

 

Precipitation

Beef Production (lb/a)

Weather Year

(inches)

0

N

NP

NS

Unfavorable year (dry)

12.66

47

117

172

 

Average (1954 - 1968)

21.4

60

140

195

157

Favorable year (long rainy season)

26.12

66

160

144

 

 

Table 8.  Rates of beef production to N fertilizer applied (lbs. beef/lb N) during a wet and dry year compared to the average for 15 years for 54 trials in 20 counties.

 

 

Precipitation

Lbs. of Beef/Lb N

 

 

(inches)

N

NP

NS

Unfavorable year (dry)

year

12.66

1.1

1.7

Average (1954 - 1968)

1954-1968)

21.4

1.2

2

1.5

Favorable year (long rainy season)

year

26.12

1.15

1.22

 

 

 

 


 

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