Nitrogen Use Efficiency on Xaraés
Palisadegrass According to
Fertilization Strategy
Carlos Augusto Gomide; Vinicius Pacheco; Mirton Morenz;
Domingos Paciullo.
Embrapa Dairy Cattle
Introduction
Brazilian herd
200 mi cattle
Beef cattle
Largest meat exporter
Dairy cattle
5th Largest milk producer
Brazil
115 millions ha of cultivated pastures
80% Brachiaria spp
≈ 60 millions ha of B. brizantha
North
Northeast
Midwest
Southeast
South
Current Scenario of Brazilian Milk Livestock
• Increased demand for animal products + Environmental
preservation + Crop competition (soybean and sugar cane)
• Intensification of livestock production under grazing
• Increase of fertilizers utilization
“New” management practices
Higher intensity
of defoliation
+
shorter
defoliation
interval
Reduction of
residual height
Increased plant
stress
Lower residual
leaf area
Decrease in
nutrient
absorption after
defoliation (N)?
Literature Background
Bredemeier & Mundstock (2000) – Root carbohydrates supply is
one of the most important factors to affect the Nitrogen
absorption;
Richards (1993) – both root elongation and respiration are
strongly reduced after (24 h) a defoliation of 40-50% of aerial
part;
Vessey et al. (1990) - the nitrogen absorption rate is
synchronized with emergence of new leaves.
Objective
 Evaluate the effect of stubble height and time of
fertilization after cut over the structural and productive
traits and the nitrogen use efficiency (NUE) of Xaraés
palisadegrass (Brachiaria brizantha cv Xaraés)
Material and Methods
Location: Minas Gerais State at Embrapa’s Experimental Station
The geographic coordinates:
21º33' S latitude
43º16' W longitude
410 m altitude
Treatments
2 residual heights (15 e 25cm)
Brachiaria brizantha
cv. Xaraés
2 fertilization time:
after cutting X after the complete expansion of the first leaf
Plots were fertilized with 50 kg/ha.cycle
with N,P and K (20-05-20)
9 m2
Block 1
15 cm
AFL
15 cm
AC
25 cm
AFL
25 cm
AC
Block 2
25 cm
AFL
15 cm
AFL
25 cm
AC
15 cm
AC
Block 3
15 cm
AC
15 cm
AFL
25 cm
AFL
25 cm
AC
Block 4
25 cm
AC
15 cm
AFL
15 cm
AC
25 cm
AFL
AC – After cut
AFL – After first
leaf appearance
25 cm
15 cm
Material and Methods
Defoliation interval : 95% of PAR intercepted.
 Ceptometer - AccuPAR Model LP-80
 Readings at 3 points/plot (weekly)
Response Variables
 Canopy height;
 Leaf, stem, dead material mass and total forage mass;
 Nitrogen Use Efficiency (NUE)
Statistical Analysis
 Mixed Procedure of SAS®;
 "LSMEANS" command;
 “F” test with 5% of significance level.
Results
Canopy Height (cm)
Effect of stubble height
Effect of fertilization scheme
75
75
72.7 a
71.6 a
70
65
60
70
67.4 b
15 cm
25 cm
65
60
55
55
50
50
66.3 b
AC
AFL
Results
Table 1 - Values ​(kg.ha-1) of leaf, stem, dead material and total
forage mass in response to stubble height and fertilization
scheme
Stubble Height
Fertilization
15 cm
25 cm
After Cut
After 1st
Leaf Ap.
Standard
error
1,310 a
1,282 a
1,299 a
1,292 a
40.0
692 b
832 a
727 a
797 a
33.2
635 b
1,011 a
932 a
713 b
58.9
2,637 b
3,125 a
2,959 a
2,803 a
63.4
Variable
Leaf
Stem
Dead Mat.
Total
Means followed by the same letter do not differ by the “F” test at 5% probability
Results
Table 2 - Nitrogen efficiency use (Kg DM/Kg N) of Xaraés
palisadegrass according to fertilization strategies
Stubble Height
Fertilization
15 cm
25 cm
After Cut
54.2 Ab
64.2 Aa
After 1st Leaf Appear.
51.3 Ab
60.8 Ba
Average
52.7 b
62.5 a
Means followed by the same letter, lowercase in rows and uppercase in
columns, do not differ by the “F” test at 5% probability
Conclusions
Thanks for your attention!
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Acknowledgments: