creased growth of grasses. Treated plots were 
established on a uniform site. The treatments 
were ammonium sulfate, ammonium nitrate, 
and gypsum. The first season, 1965, was favor- 
able for plant growth. On both nitrogen- 
treated plots, the total yields were high, but 
the percentage of clover was much lower than 
on gypsum-treated or control plots. Ammonium 
sulfate-treated plots (134 pounds of nitrogen 
per acre) yielded 7,478 pounds per acre of air- 
dry herbage (2.7 percent clover). Ammonium 
nitrate-treated plots (98 pounds of nitrogen 
per acre) produced 6,307 pounds (1.2 percent 
clover). Gypsum-treated plots (60 pounds of 
sulfur per acre) produced 5,549 pounds (26.0 
percent clover), and control plots averaged 
3,437 pounds (7.3 percent clover). 
We concluded that: (1) sulfur increased the 
clover yield and thereby improved the forage 
quality, and (2) that the adverse effect of ni- 
trogen fertilization on clover growth was the 
result of competition between species with dif- 
ferent growth requirements and with different 
growth habits. Early-maturing species (mostly 
grasses) on the nitrogen-treated plots made 
rapid growth and exhausted soil moisture be- 
fore the temperature was favorable for clover 
to grow rapidly. Thus, the adverse effect of ni- 
trogen on the legumes was indirect. Clovers on 
the sulfur-treated plots remained green for 2 
to 3 weeks after all vegetation on the nitro- 
gven-treated plots had dried. 
The second season, 1966, was a carryover 
year for the fertilizer. It proved to be dry and 
unfavorable for plant growth. Both the total 
herbage yield and the percentage clover were 
much lower than those in 1965. The two nitro- 
gven-treated plots yielded slightly more than 
2,000 pounds per acre (0.5 percent clover). 
Gypsum-treated plots produced about 2,000 
pounds of air-dry herbage (6 percent clover). 
Control plots yielded about 1,200 pounds (1.3 
percent clover). The results from the 2 years 
demonstrate how climate can affect the botani- 
cal responses from fertilization on annual-type 
ranges in California. 
In another test, Westfall (1966) reported 
unusually favorable results from sulfur fertil- 
ization. For the first 2 years after fertilization, 
legumes on sulfur-fertilized plots made up 88 
percent of the vegetation complex, compared to 
17 percent on control plots and 5 percent on 
ammonium sulfate-treated plots. Although 
there were no tests of animal responses or 
chemical analyses of the forage, the sulfur fer- 
tilization most likely improved the quality of 
the forage. 
The influence of sulfur in improving the 
quality of range forage is demonstrated by the 
unpublished results of a long-term grazing 
study at the San Joaquin Experimental Range. 
Sulfur fertilization combined with yearlong 
60 
grazing have consistently produced more clo- 
ver than unfertilized yearlong and seasonally 
grazed ranges. Because the grazing rate is 
moderate, animal responses are due more to 
forage quality than to forage quantity. In 1967, 
a very wet year, vegetation on upland sites was 
more than 30 percent clover, by weight, on the 
sulfur-fertilized units. This was more than 
twice the percentage yield of clover on any of 
the nonfertilized units. Consequently, the cows 
from sulfur-fertilized yearlong-grazing units 
were from 100 to more than 200 pounds heavier 
at weaning time than cows from other range 
units. Their calves, when weaned, were also the 
heaviest calves in the study. 
Sulfur fertilization, by increasing legume 
leafage and legume seeds on some annual-plant 
ranges, also provides more preferred food for 
California quail. Glading et al. (1940) listed 
both seeds and leafage of several legumes as 
“preferred foods”. Subsequent work by Dun- 
can and Shields (1966), Shields and Duncan 
(1966), and Duncan (1968) shows that legume 
seeds and leafage are ‘ice cream” for Califor- 
nia quail. Thus, changing vegetative composi- 
tion by fertilization influences the diet of some 
wildlife as well as domestic livestock. 
SUMMARY AND CONCLUSIONS 
The literature reveals conflicting evidence on 
the effects of fertilizers on the quality of range 
forage. This conflict may be attributed to the 
wide variety of: (1) Climate and soils, (2) 
growth habits of plants, (3) rates and type of 
fertilizers, (4) stages of maturity in which the 
plants are harvested for analysis, (5) methods 
of sampling and the plant parts sampled, and 
(6) the descriptive units in which the results 
are reported. There is a definite need for more 
standardization of the objectives, the methods 
used, and the reporting of results so that com- 
parisons can be made. Also, many of the experi- 
mental designs should provide for economic 
analysis. 
Nitrogen has been used more extensively as 
a fertilizer than any other nutrient for range 
crops. Thus, nitrogen fertilization has proba- 
bly improved the quality of range forage in 
more areas than any other type of fertilization. 
This improved quality has generally meant in- 
creased crude protein, increased succulence, 
and increased leaf-to-stem ratios .Even in sem- 
iarid areas, nitrogen fertilization has improved 
forage quality; however, forage yields may not 
have been increased. 
Phosphorus, potassium, and sulfur fertil- 
izers have improved the quality of range leg- 
umes and other forbs—especially in areas of 
high rainfall. These fertilizers have also im- 
proved the quality of range grasses in high- 
