Agriculture Reference
In-Depth Information
Table 6.5
Average yearly amounts of N, P, K recommended for citrus according to tree age.
(Legaz and Primo-Millo
1988
)
Tree age (years)
Nitrogen
Phosphorus (P
2
O
5
)
Potassium (K
2
O)
g/tree
Kg/ha
g/tree
Kg/ha
g/tree
Kg/ha
1-2
40-80
16-32
0-20
0-8
0-30
0-12
3-4
120-160
48-64
30-40
12-16
40-80
16-32
5-6
240-320
96-128
50-60
20-24
100-120
40-48
7-8
410-500
164-200
80-100
32-40
160-200
64-80
9-10
550-600
220-240
120-150
48-60
250-300
100-120
> 10
600-800
240-320
150-200
60-80
300-400
120-160
Table 6.6
Monthly distribution of a macronutrients fertigation programme for Spanish Mediterra-
nean citrus growing area. Values expressed as percent of annual amount. (Legaz and Primo-Millo
1988
)
Fertilizer
March
April
May
June
July
Aug
Sep
Oct
Young trees
Ammonium
nitrate
N
5
10
10
15
20
20
15
5
Phosphoric
acid
P
2
O
5
10
15
15
15
15
10
10
10
Potassium
nitrate
K
2
O
5
8
10
10
20
25
15
7
Magnesium
nitrate
MgO
5
10
12
15
20
20
10
8
Mature trees
Ammonium
nitrate
N
5
12
15
18
25
15
10
Phosphoric
acid
P
2
O
5
10
20
15
15
15
15
10
Potassium
nitrate
K
2
O
7
10
13
15
25
20
10
Magnesium
nitrate
MgO
10
12
15
18
20
15
10
fertilization, in order to not unbalance the plant. Special caution is required in using
disease-free vegetative material that can be transmitted by budding.
Pruning is a very important practice that usually is performed by hand, although
mechanical pruning is increasingly used. Young plants are shaped with two to three
arms during the initial years. Mature mandarin trees are usually pruned once a year. Or-
anges, grapefruit and lemons are often pruned every 2 or 3 years because of high cost.
Fertilization is done either by conventional procedures or by fertigation (see
Table
6.6
), providing elements according to particular soils and climatic conditions.
In most citrus producing areas, conventional nitrogen fertilization is done by using
ammonia sulphate, ammonia nitro sulphate, ammonia nitrate, or urea, at annual rates
of 0.6-0.8 kg N per adult tree, with distribution two or three times a year depending
on the soil's characteristics and type. Phosphorus and potassium fertilization is basi-
cally made in the spring, using calcium superphosphate and potassium phosphate
