Soil aggregate stability and carbon fractions in soils containing
organic matter additions in intensive greenhouse vegetable fields
Abstract
Soil degradation in intensive greenhouse vegetable fields is a major
agricultural concern since these soils are widely used for food
production. Organic materials play essential roles in soil aggregate
stability and carbon sequestration. We conducted a 5-year fertilization
study in intensively farmed greenhouse vegetable fields to examine the
effects of added organic matter on soil aggregate stability, organic
carbon fractions and their interrelationships. Four experimental
treatments were included: 1) mineral fertilizer only (CK); 2) mineral
fertilizer combined with chicken manure (CM); 3) rice husks (RH); and 4)
chicken manure plus rice husks (MH). These organic materials
applications significantly improved the proportion of >
0.25 mm aggregates while decreasing the ratio of soil < 0.25
mm aggregates. The mean weight diameters of water-stable soil aggregates
was increased with organic fertilizer addition and were ranked RH ≈ MH
> CM > CK. The organic materials applications
treatments had a greater soil organic matter, humic acid and humus than
the CK. RH addition significantly increased the proportion of
>2 mm aggregates, possibly due to higher humus and
polysaccharide carbon content. CM application increased soil Fe-ox
content due to soil acidification and increased aliphatic carbon content
that in turn increased the proportion of 1-2 mm aggregates. The study
indicated a possible advantage for chicken manure and rice husk
incorporation for the generation and persistence of stable soil
aggregates.