Pl. Defreitas et al., A METHOD FOR STUDYING THE EFFECTS OF SOIL AGGREGATE SIZE AND DENSITY, Soil Science Society of America journal, 60(1), 1996, pp. 288-290
Soil macroproperties, such as bulk density, porosity, water conductivi
ty, and aeration, have been utilized in order to evaluate soil structu
re effects on crop yields. It has been suggested that many of the limi
tations to crop growth can be explained by the physical properties of
the aggregates. To explore some aspects of this, a method to simulate
soil aggregates of different sizes and densities was developed and tes
ted. A Collamer silt loam soil (fine-silty, mixed, mesic Glossoboric H
apludalf) was dried, crushed, sieved, and compressed to different dens
ities (1.4, 1.6, and 1.8 Mg m(-3)). The resulting 25- and 50-mm-thick
cylindrical soil slices were cut to two different cubical sizes (25- a
nd 50-mm sides). Cylinders with continuous horizontal and vertical mac
ropores were assembled from these artificial aggregates to make six di
fferent treatment combinations of aggregate size and density. Corn (Ze
a mays L.) seedlings were transplanted into the cylinders and grown in
a growth chamber for 27 d. Results show that high aggregate density l
imits crop growth and that, at intermediate densities, aggregate size
assumes more significance as a limiting factor.