Study Site Trials

 The SICS selected for trialling in the Study Site are described below:

Country General Treatment Category Study Site Trials
Greece Cover crops, tillage, crop change

1. Soil erosion rate assessment - No till in organic olive orchards; Conventional till (15-20 cm) in organic olive orchards; Conversion from orange orchard to avocado; Conventional orange orchard; Cover crop (vetch) in organic vineyards; Bare soil in organic vineyards


Study Site poster 2018 (download)

 Conversion from orange orchards to avocado      

 OrangeGrove

    Greece experiment factsheet Avocado Final front coverRead this fact sheet in Greek here  

 Avacado

   
       

 

 Key findings

  • The biological health and condition of the avocado plot were inferior to the orange tree plots according to the earthworm density experiment.
  • Water and solute movement, as well as soil aeration, were positive for both cultivations, as identified by the top and bottom soil bulk density experiments.
  • High content of soil organic carbon concentration was measured at both plots. Orange orchards presented reduced soil organic carbon compared to avocado trees, during the 3-year monitoring, probably due to higher inputs.
  • The level of weed infestation was 10% less in the avocados field compared to the orange trees field.
  • Electric conductivity values indicate high salinity levels in both plots. Even higher values were observed for avocado trees.

 

 No-till and conventional till in organic olive orchards      
 Olives1     Greece experiment factsheet olives FINAL front coverRead this fact sheet in Greek here  
 Olives tilled    
       

 

 Key findings

  • Intensified tillage contributed significantly to increased soil erosion and affected the rooting system of the crop, causing exposed tree roots.
  • The biological health and condition of the no-till plots were clearly better compared to the tilled plots.
  • Apart from tillage, irrigation also increases soil erosion since irrigated trees are less resilient to water stress due to shallow roots.
  • High content of soil organic carbon concentration was measured at both plots.
  • Water and solute movement, as well as soil aeration, are appropriate even in the case of no-till.

 

Bare soil and cover crop in organic vineyard      
Vineyard  

 Greece experiment factsheet Vineyard Final front cover

Read this fact sheet in Greek here

 
Vineyard covercrops    
       

 

 Key findings

  • Cover crops led to significantly less soil erosion.
  • Soil aggregate stability test resulted in good soil stability and resistance to erosion for both plots, however, for the vetch applied plot, slaking effect was slightly less observed, indicating better structure maintenance.
  • The biological health and condition of the vetch cover plots were clearly better compared to the no vetch.
  • High content of soil organic carbon concentration was measured at both plots.
  • Water and solute movement as well as soil aeration was slightly improved where cover crops were grown.

 

Geographical description

Crete is the largest of the Greek islands, and the 5th largest in the Mediterranean, with a total area of 8,265 km2. While retaining its own local cultural traits, the island shapes a significant part of the cultural heritage of Greece, but also contributes 5% of the national Gross Domestic Product (GDP), with agriculture and tourism as its main industries.

Map
Spatial distribution of soil erosion on the Island of Crete.

Pedo-climatic zone
Crete’s climate is classified as dry sub-humid (Csa according to Köppen and Geiger, Mediterranean South). About 53% of the annual precipitation occurs in the winter, 23% during autumn, 20% during spring while there is negligible rainfall during summer (Koutroulis and Tsanis, 2010). Annual rainfall ranges from 300 to 700 mm from east to west in the low areas along the coast, and from 700 to 1000 mm in the plains of the mainland, while in the mountainous areas it reaches up to 2000 mm. The annual water balance breaks down to 68-76% evapotranspiration, 14-17% infiltration and 10-15% runoff. Soils are mainly Calcisol.

Cropping systems

Cropping intensity
Almost 40% of the island is cultivated at various intensities depending on desired end product quality and intended market: e.g. olive trees can be non-irrigated (traditional/household use) or irrigated (modern/intense), vineyards may be conventional or organic, etc.

Types of crop
Agriculture is an important source of income, contributing to Crete’s GDP by 13%. Olive is the most important crop, cultivated on all soils and terrain slopes up to altitudes of about 900 m. Specifically for Chania, agricultural land is divided in 5 main crop categories: grapes 3%, trees 90% (olive trees 70%, other trees 20%), vegetables 2%, and other crops 5%.

Management of soil, water, nutrients and pests
Irrigation types on the island vary depending on crops and local water availability (e.g. olive trees are either regularly irrigated or not irrigated at all, orange groves are often waterlogged and vineyards are often drip irrigated). Fertilisation also varies (chemicals vs animal manure). Due to high ownership fragmentation and rough topography, management is seldom large scale, and crop picking is almost always traditional and labour intensive using minimal mechanical equipment.