Soil properties after 10 years of organic versus conventional management in two greenhouses in Almeria (SE Spain)

Abstract

Field experiments were conducted to evaluate the effect of a long-term (10 years) organic management on a greenhouse soil compared with the same soil under intensive conventional management. Soils of each greenhouse have an artificial sequence of layers: 0–10 cm depth of sand mulch with a dominant particle size of 0.5 mm–2.0 mm, and between 10 and 40 cm depth of loamy sandy soil layer with moderate infiltration as crop substrate. During the last 10 years, organic greenhouse received manure equivalent up to 170 kg N ha−1 year−1 (over 5600 kg ha−1 year−1 of manure of 3% N) mixed with crop substrate at 10 cm depth, while conventionally managed greenhouse received no organic amendments during this time. Water and nutrients were supplied to both greenhouses by drip irrigation, as required for crops. Crop rotation was similar in both greenhouses. An experimental plot (90 m2) was established in each greenhouse and nine soil samples were taken near the drippers. Organic management diminished pH and bulk density and, as a consequence, improved infiltration, but reduced the water retention capacity. Total organic carbon, total nitrogen and cation exchange capacity were augmented by comparison with conventional management.