A. Huisz,, T. Tóth, T. Németh. 2009.
Water-Stable Aggregation in Relation to the Normalized Stability Index.
Communications in Soil Science and Plant Analysis. 40: 800 – 814.

Abstract: In spite of the good quality of soils in Hungary, soil structure is
deteriorated by intensive tillage. Because of general dissimilarities between field
and laboratory circumstances and therefore lack of comparability, the former
results are questionable. An optimized method initiated by Six, Elliott, and
Paustian (2000) was adapted to investigate changes in soil structure and quality
caused by different kinds of added organic matters. Our samples originated from
the long-term fertilization experiments in Keszthely, western Hungary. The
experiments were set up in 1960. The texture of the investigated soil is sandy loam;
the type of soil is Eutric Cambisol (soil type FAO) or Alfisol (soil type USDA).
Tillage and its depth was fall plowing to 25 cm. Crop rotation was maize–maize–
potato–winter wheat–winter wheat. Samples were taken from depths of 0–20 and
20–30 cm, from the fallow, which had the same treatment as the potato field.
Changes in soil structure were quantified by wet sieving. Soil structural stability
was characterized by comparing aggregate size distribution after the use of a
lower and a higher disruptive force, which was simulated by two different
pretreatments. Determinations were done in triplicates. Soil structure may be
improved by adding readily decomposable organic matter. The extent of
amelioration depends on the chemical buildup and decomposability of the crop
residues. Three different kinds of organic matters were investigated: (1) maize
stem (M), (2) wheat straw (W), and (3) maize stem and wheat straw (MW). By
comparing the aggregate stabilizing effects of the differently decomposable
organic matters to each other and predicting the lower decomposability but
persisting effect of M, the expected MW . M . W order was proven. These are
parallel with those results of Harris, Chesters, and Allen (1966) and John et al