Aggregate size distribution and geometric mean diameter affected by polymers (PVA&PAM) and humic acid applications under wetting-drying processes
Künye
Aksakal, E. L., Öztaş, T., & Turgut, B. (2010). Aggregate size distribution and geometric mean diameter affected by polymers (PVA&PAM) and humic acid applications under wetting-drying processes. Kızılkaya, R., Gülser, C., Dengiz, O. (Ed.). International soil science congress on "management of natural resources to sustain soil health and quality" Bildiri Tam Metin Kitabı (29 - 30 Mayıs 2020) içinde (657-665. ss.). Samsun: On Dokuz ÜniversitesiÖzet
Wetting/drying (WD) processes affect on soil structural and hydraulic properties. The objective of this study was to determine effects of organic polymers (polyvinylalcohol-PVA and polyacrylamide-PAM) and humic acid (HA) on aggregate size distribution (ASD) and geometric mean diameter (GMD) of soils under wetting/drying (W/D) processes. Soil samples were collected from four commonly distributed soil great groups; Typic Ustert, Fluvaquent, Argiustoll and Calciorthid in Erzurum. Soil samples passed through 4.76 mm sieve were treated with 0,05% PVA, 0,01% HA and 0,001% PAM on weight to weight basis and left to WD processes (3, 6 and 9 times) at different moisture levels (field capacity and 90% of saturation). Significant differences were obtained in ASD of treated and non-treated soil samples. in the control sample, the highest proportion (37.3%) of soil aggregate size group had a size of smaller than 0.42 mm, and the lowest proportion (12.9%) had the size of 0.42-0.84 mm. The GMD of soil aggregates in the control changed between 1.46 mm and 1.68 mm. On the average, the proportions of the aggregate size groups of <0.42, 0.42-0,84 and 0,84-2 mm decreased with the rates of 73.0, 32.3 and 2.0%, respectively in the samples treated with PVA, PAM and HA, but , the proportions of the aggregate size group of 2-6,4 mm increased with a rate of 24.3%. Significant amounts of new aggregates greater than 6.4 mm alsa formed with PVA, PAM and HA applications. Humic acid application was the most effective treatment in increasing of the GMD. The WD cycles decreased the proportions of the aggregate size groups of <0,42, 0,42-0,84, 0,84-2 and 2-6,4 mm, but increased 6,4-12,7 and >12,7 mm aggregate proportions in ali the moisture levels. The GMD significantly increased after WD processes. Changes in the proportions of aggregate size groups following WD cycles was the lowest in PVA treated samples as compared to the PAM and HA applied samples. This result suggests that PVA is more effective in stabilizing soil aggregates and on reducing negative effects of WD processes on the stability of small size soil aggregates