can result in a crude protein yield comparable 
to that of a mixture of grasses and legumes. 
Wagner (1954) reported that the application 
of 240 pounds of nitrogen per acre on or- 
chardgrass yielded a forage that contained 
18.51 percent crude protein, dry basis. More 
than 160 pounds of nitrogen per acre applied 
annually to orchardgrass or tall fescue was 
needed to equal the season’s protein production 
from the grass-legume mixtures. Similar re- 
sults have been reported by Ramage et al. 
(1958). They found that during a 3-year pe- 
riod, orchardgrass fertilized with 400 pounds 
of nitrogen per acre had an average crude pro- 
tein content of 19.84 percent, dry basis. Stroeh- 
lein et al. (1968) concluded that on desert 
grasslands of southern Arizona, forage produc- 
tion can be increased and forage quality im- 
proved by properly timing fertilizer applica- 
tions with adequate soil moisture conditions. 
They reported an extension of the green feed 
period, increased protein, and increased prod- 
uction when fertilization was delayed until 
after the start of summer rains. 
Adding sulfur to nitrogen increased the 
crude protein contents of annual-type vegeta- 
tion in California. Walker and Williams 
(1963) reported that adding 132 pounds of ni- 
trogen and 150 pounds of sulfur as ammonium 
sulfate increased total crude protein by 753 
percent. However, Hylton et al. (1968) found 
that protein synthesis in shoots of Spanish clo- 
ver was affected very little by sulfur deficiency. 
According to Teel (1962), potassium is nec- 
essary for protein synthesis, and a deficiency 
of potassium limits the normal metabolic 
events in plant biosynthesis to the extent that 
certain substrates accumulate or engage in al- 
ternative reactions. Yet, Duell (1965) reported 
that forage plants fertilized with ammonium 
nitrate and lime, but without potassium, had 
consistently higher crude protein percentages 
than plants fertilized with phosphorus, potas- 
sium, nitrogen, and lime. Also, Vincent-Chan- 
dler et al. (1962) found that in grasses grown 
under humid tropical conditions, the percent- 
age of crude protein dropped consistently as 
potassium—up to 1,600 pounds of it per acre 
—was added. These three studies suggest that 
under humid conditions, potassium added to ni- 
trogen can increase the yield of forage and the 
total yield of crude protein, but the percentage 
of crude protein may decrease because in- 
creased plant growth has a ‘‘dilution’”’ effect. 
Fertilizers other than nitrogen have not gen- 
erally affected the quality of grass herbage in 
the plains and mountains of the United States 
(Cook, 1965; Hull, 1963; Lavin, 1967; Leven 
and Dregne 1963). 
The effects of nitrogen fertilization on the 
quality, and on the morphological characteris- 
tics that influence quality, of bermudagrass 
were measured by Prine and Burton (1956). 
58 
Besides increasing the percent of protein, pro- 
tein yield, and free nitrogen content, nitrogen 
fertilization increased plant height, stem 
length, length of longest leaf blade per stem, 
and number of internodes per stem. But the 
treatments also decreased the percent of leaves 
and percent of stems with seed heads. 
Work reported by Honnas et al. (1959) 
showed some contrasts among blue grama, 
hairy grama, and sideoats grama in response 
to ammonium phosphate fertilizer. Blue grama 
and hairy grama responded favorably in leaf 
length, number of stems, and forage produc- 
tion, while in general, sideoats grama_ re- 
sponded negatively. However, sideoats grama 
seed yield did increase. 
Burton et al. (1956) found that the palata- 
bility of coastal bermudagrass was improved 
substantially by nitrogen fertilization. They 
noted that protein and moisture content of her- 
bage generally increased as nitrogen—up to 
1,500 pounds of it per acre—was added. De- 
spite improved palatability, the nitrogen treat- 
ments may have toxic effects to animals be- 
cause of increased nitrate concentrations in 
forage (Kay 1966). Any condition which slows 
the growth rate of forage plants but does not 
prevent nitrate uptake may lead to nitrate ac- 
cumulation. Hence, forages high in nitrate are 
often found when plant growth is retarded be- 
cause other nutrients are limiting growth after 
high nitrogen fertilization. Nitrate accumula- 
tion may also occur after drought, cool periods, 
or cloudy periods. 
Alexander et al. (1961) found that the pro- 
tein content and the digestibility of protein of 
coastal bermudagrass herbage was directly re- 
lated to nitrogen fertilization. The protein con- 
tent of the herbage was increased up to 30 per- 
cent by increasing the rate of fertilization 
from 50 to 100 pounds of nitrogen per acre. 
The total digestible nutrients increased only 
slightly as the nitrogen level was increased 
from 50 to 100 pounds per acre. But animal 
gains were markedly higher at the high nitro- 
gen rate, apparently due to differences in dry 
matter intake, protein content, and digestibil- 
ity. 
Digestible protein of well-managed forages 
may be higher than needed for maximum ani- 
mal output. But herbage from forage plants 
does not generally supply enough energy to 
maximize animal output (Blaser 1964). Nitro- 
gen fertilization of grasses usually increases 
carrying capacity and animal production per 
acre but seldom increases outputs per animal. 
It also improves the protein content and the 
protein digestibility, but cellulose, or crude 
fiber content, and lignification are not gener- 
ally altered. The soluble carbohydrates (sugars 
and starch or fructosan) in forage may de- 
crease with added nitrogen. Thus, the digesti- 
ble energy of grass forage may not be appreci- 
