Agriculture Reference
In-Depth Information
ORCHARD FLOOR MANAGEMENT
The physical and chemical properties of the orchard's soil need to be
maintained in a good condition to ensure that root growth occurs without
dii culty. However, weeds need to be controlled, people and machinery need
to move around in the orchard, and irrigation needs to reach all of the trees.
No single system can be used for all soil types as all have their advantages
and shortcomings. Rainfall, soil characteristics, irrigation system, water
availability, type of weeds, and the species and age of the trees should be taken
into account when deciding upon orchard management, without forgetting
costs and returns. The main orchard fl oor management systems used are
mechanical cultivation, cover crops, mulching and keeping the soil bare with
herbicides, as used on the coralline sandy soils of Florida.
Cultivation with machinery is very ef ective with annual weeds and it helps
break the crust that sometimes forms and allows incorporation of fertilizers
and organic matter. Its shortcomings are that, after the orchard is 3-4 years
old, disturbing the soil between tree rows is normally not recommended due to
the danger of damaging the root system and the entrance of some pathogen
through the wounded roots. The destruction of irrigation ditches or furrows
can be another problem with mechanical cultivation. The presence of pipes
and hoses limits the use of cultivation, and the multiplication of weeds with
underground structures (nutgrass) can be another problem. Shallow and
careful cultivation avoiding under the tree canopy should be done with of set
discs or equipment that scratches the soil. As the trees grow, the soil should be
worked at increasing distances from the tree canopy line (Razeto, 1993).
Temporary or permanent cover crops are an alternative, especially if there
is good moisture in the soil throughout the year (Table 3.4). These crops help
maintain good soil structure, increase water penetration, prevent erosion from
wind and rain, and keep soil temperature lower. In the humid tropics, a legume
such as kudzu or other suited legume species can be used, with the additional
benefi ts that they fi x nitrogen. Kudzu can be an invasive weed because of its
rapid growth and habit of climbing up and over trees. Extra management is
necessary to periodically cut the climbing shoots with a machete and change
the vines' growth direction with the hands or a long stick.
Growing sod as a cover crop requires ample water and nitrogen in order
not to af ect tree production (Fig. 3.7a). Mowing or grazing is needed with sod,
with the extra advantage of allowing machinery to get into the fi eld sooner
after rain and irrigation. On steep land, the presence of a cover will prevent soil
erosion during heavy rains. Aesthetically, sod is a good approach, but there is
strong competition for water and nutrients with the crop. In areas with a dry
season, the transpiration from the sod can be very high and it will also need
fertilizer, so care must be taken to irrigate and fertilize taking this additional
need into account. In the absence of irrigation, competition for water can be a
