Sustainable Soil Management Is More than What and How Crops Are Grown - Principles of Sustainable Soil Management in Agroecosystems - page 380

Despite these alarming erosion rates that have been reported in olive groves on
sloping and mountainous land, there are authors questioning the severity and extent
of water erosion in olive orchards in southern Spain (Fleskens and Stroosnijder
2007). Other authors, however, insist on soil erosion being a widespread threat to the
sustainable land use through olive production (Gomez et al. 2008; Vanwalleghem
et al. 2010, 2011). Moreover, land use change and the abandonment of the terraced
slopes, functioning as anthropic hydrological infrastructures, which protected the
soil and preserved the natural vegetation in the recent past, have been progressively
collapsing, mainly due to the rapid removal of the soil, causing important land deg-
radation problems (Dunjó et al. 2003).
Despite the gradual introduction of no-till as the soil management system in olive
groves, a first agrienvironmental measure scheme was introduced in Andalucía in
the late 1990s, aiming to fight soil erosion in olive orchards mainly by vegetation
cover between trees and natural vegetation on the land borders. Other soil erosion
control practices were also promoted such as soil tillage along contour lines and
the maintenance of pruning residues in the interrow space (Franco and Calatrava
2006). The adoption especially of no-till increased tremendously from 1995 onward
and covers today, depending on the study region, between 50% and 95% of the area
under olive production (Franco and Calatrava 2006; Leyva et al. 2007; Martinez
2009).
Despite this notable progress in terms of adoption of soil conservation measures
in the case of perennial crop production in Spain (Table 14.4), there are still regions
where the adoption of soil conservation practices is very low, and, in general, there is
much room left for the extension of policy measures to mitigate and invert soil deg-
radation (Calatrava et al. 2011). In addition, the findings of Gomez et al. (2009b) that

TABLE 14.4
Evolution of the Area Under Cover Crop Soil Management Systems in Total
Woody Crops and Olives in Spain

2011 % 2010 % 2009 % 2006 %

Total woody
crops (ha)

4.932.002 100 4.986.046 100 5.043.896 100 5.039.440 100

With cover
crops (ha)

1.178.297 23.9 1.218.726 24.4 1.066.182 21.1 836.731 16.6

With no-till
(bare soil) (ha)

453.219 92 443.309 8.9 431.472 8.6 347.449 6.9

Olives, total
area (ha)

2.580.577 100 2.572.793 100 2.568.383 100 2.476.540 100

Olives with
cover crops
(ha)

680.510 26.4 683.363 26.6 627.1668 24.4 438.828 17.7

Olives no-till
(bare soil) (ha)

341.674 13.2 328.716 12.8 299.711 11.7 225.998 9.1

Source: Encuesta sobre Superficies y Rendimientos Cultivos (ESYRCE) 2006, 2009, 2010, 2011.