Abstract
When olive groves are grown on clay soils with steep slopes,
as in many Mediterranean regions, it is imperative to reduce runoff and soil
erosion costs by adopting appropriate soil control practices. Coverage of the
soil by pruning residues can also represent an opportunity for commonly adopted
mechanical tillage. This test evaluates water infiltration costs and ground
runoff volumes in a steep, clayey olive grove in southern Italy. These
hydrological variables are measured at the plot scale under 4 soil control
practices (mechanical tillage, general synthetic soil security and soil cover
with different plant residue rates). The measurements were performed using a
precipitation simulator under both dry (undisturbed) and wet (i.e. on soils
disturbed by heavy rain) situations. Mechanical tillage results in lower water
infiltration costs and better runoff production. The retention of a layer of
soil by plant residues (of the order of 3.5 to 17.5 plots/ha of dry count)
reduces the runoff load on average by 30%, in particular due to the costs of
Expanded soil infiltration (about a hundred percent, compared to mechanical
tillage). After soil disturbance from previous rainfall, the runoff generating
capacity of a soil disturbed with the help of heavy rainfall is significantly
high compared to undisturbed soils due to decreased infiltration rates in the
soil. floor. Overall, retaining plant residues on the soil may be desirable to
reduce soil runoff charges, especially for saturated soils. 1. Introduction
In many regions of the Mediterranean basin, olive growing
takes place on sloping land, regularly steep, where other crops cannot develop.
Thanks to its low water requirements, the olive tree has the potential to grow
in hilly areas, where irrigation cannot be practiced.
Although in present times olive cultivation has tended to be
practiced on flat land, within the Calabrian region of southern Italy, many
hectares of olive groves are nevertheless located in sloping regions. Here, the
semi-arid climate makes these lands susceptible to heavy runoff and soil
erosion; this has an impact on the productivity of olives due to the reduced
capacity of the soil to store water [1,2,3,4]. Additionally, when olive groves
are grown on soils with a high clay content (where the mixture of slope and
texture makes it more difficult or impossible for other plants to grow), the
low infiltration capacity of soils governed by “excess infiltration” for runoff
generating mechanisms can further increase runoff and erosion costs [5].
Therefore, the importance of an amazing infiltration capacity of the soil is
obvious. This can be accomplished by adopting appropriate soil control
strategies.The higher the infiltration, the better the water availability for
crops, which is ideal in a semi-arid environment characterized by persistent
water scarcity .
In Mediterranean olive groves, mechanical tillage still
represents the maximum common practice for soil management [6,7,8,9], as it
briefly improves rainfall infiltration and water distribution in the profile
soil, destroys weeds, reduces the risk of fire and transports fertilizers into
the soil [8,10]. However, this exercise over years can also lead to degradation
of soil structure, which can reduce the rate of water infiltration, accelerate
runoff and erosion strategies, and reduce water availability in the
rhizosphere; in addition, mechanical tillage can also overcompact the soil and
occasionally result in loss of nutrients, fertilizers and natural matter. Thus,
in Mediterranean orchards, there is a need for sustainable agronomic practices
(i.e. soil management models, which can be alternatives to mechanical tillage),
combining the contrasting necessities of conservation soil and water,
maintaining or cultivating, at the same time, making crops [11]. These
contrasting desires can be complemented by "conservation agriculture"
[12], which refers to a set of cultivation strategies based entirely on the
cultivation of the soil, integrating the security of soil, water and organic
sources with the needs cultures.
One of the most suitable methods of soil conservation for
Mediterranean orchards (therefore, for oli
