SUMMARY Soluble ammonium nitrate (AN) and urea were compared with slow-release oxamide and sulphur-coated urea (SCU) as N sources for clipped annual ryegrass (Lolium multiflorum) or common bermuda grass (Cynodon dactylon) in four greenhouse experiments. Mixed and surface applications of a wide range of N rates were evaluated for 9 to 14 cuttings of grass forage. Both granular oxamide and SCU exhibited slow-release N properties, especially when surface-applied. Uptake distribution of N with high application rates of AN and urea tended to resemble that with the slow-release sources. Slow-release properties of oxamide and SCU were accentuated at high application rates. Lower N recovery from surface-applied urea than from AN indicated volatilization loss of urea N. Volatilization loss also occurred with oxamide, but low N recovery from oxamide and SCU resulted largely from incomplete dissolution of the granules during the 18- to 34-week experimental periods. Very low N recovery was obtained from urea formaldehyde having an activity index of 42.
[1]
C. M. Hunt,et al.
Nitrogen Release from Sulfur‐Coated Urea, as Affected by Coating Weight, Placement and Temperature1
,
1971
.
[2]
D. Mays,et al.
Sulfur‐Coated Urea and Uncoated Soluble Nitrogen Fertilizers for Fescue Forage1
,
1969
.
[3]
G. Blouin,et al.
Sulfur coating on nitrogen fertilizer to reduce dissolution rate
,
1968
.
[4]
C. M. Hunt,et al.
Response of Corn to Nitrogen in Oxamide and Ammonium Nitrate in Greenhouse Experiments1
,
1964
.
[5]
C. M. Hunt,et al.
Nitrogen Fertilizers, Hydrolysis, Nitrification, and Nitrogen Availability of Oxamide, as Influenced by Granule Size
,
1961
.
[6]
D. Mays.
Sulphur-coated urea: a slow-release nitrogen source for grass.
,
1970
.