Agriculture Reference
In-Depth Information
perennial crops in arid zones (Table 3.1). The data will enable a decision to be
made on usage, as species and varieties vary in their salt tolerance, with some
crops being very susceptible to salt injury (Table 3.2).
Previous land usage
A replant problem can exist with some fruit crops. Peach trees are probably
one of the best examples in a deciduous fruit crop; replanting into old peach
orchard areas often leads to failure due to chemical substances left by the
initial crop that can af ect the growth of the replanted crop (allelopathy) (Rice,
1974). This is sometimes referred to as soil fatigue. Another cause of replant
problems can be due to fungi, bacteria or nematodes that were hosted by the
former crop. Plants of the
Solanaceae
family are very prone to being infected by
root fungal diseases, bacteria and nematodes, and therefore it is recommended
not to plant a species of this family right after another. Citrus are also known
to show this problem. In many cases, the only solution to this soil fatigue is
crop rotation, which can last as much as 10 years using dif erent species,
including grasses, before planting the same crop again. The alternative is to
plant a crop that will not be af ected by the above factors.
Planning
The collection of all the above data before land preparation allows you to plan
and cost out the project before starting. Potential problems can be avoided by
in-depth planning and making decisions on species and variety, rootstock,
soil management practices, irrigation system and fertilization practices. The
analysis could also lead to the possibility of rejecting a particular fi eld or farm
because the soil or water is not suitable for the fruit species to be grown. If the
grower lacks the proper background knowledge about these matters, a soil
specialist should be consulted to assist in making the right decisions to avoid
unnecessary expenses and future problems. Most tropical fruit crops have a
Table 3.1.
Irrigation water quality for tropical fruit trees.
Conductivity
(dS/m)
TDS (total dissolved
salts) ppm
Water quality
No detrimental effects
0.25
175
Sensitive crops could be affected
0.25-0.75
175-525
May have adverse effects
0.75-2.0
525-1400
Salt-tolerant plants only
2.0-3.0
1400-2100
Unsuitable
>3.0
>2100
