Über die künstliche Veränderung physikalischer Bodenfaktoren

Birmensdorf

1957

S. 1-31

14 Abb., 9 Tab., 7 Lit. Ang.

Bandaufführung

1265

157672

Imperfectly drained clayey or silly soils with high density very often have unfavourable physical conditions for plant growth. This may be the casein forest nurseries, afforestation watersheds and for erosion control. In Switzerland bad soil structure is particularly bound to certain forms of parent materials geologically coming from Flysch-deposits, Rissmoraine oder Würmmraine. The structure improving ability of Krilium (Monsanto) in soils of high density, with too little non capillary pore space and with unstable aggregates is studied. The change in pore-size distribution has been determined with the sorption curve. Conditioned with 0,1% Krilium a neutral clayey soil like (Zugerberg) obtains a significant decrease of water content at any tension between 0,020 and 15 atm. The noncapillary pore space increases. An extreme conditioning of 1,0% is able to increase noncapillary pore space in clayey soils like "Zugerberg" and in sillyy soils like "Fort 1", but it also increases water content in the range of field capacity to permenent wilting point. If a certain concentration is reached, Krilium disperses soil aggregates and increases increases water content in the range of low tension such as 0,040 atm up to the permanent wilting point at 15 atm. The increase of waterstable aggregates having diameters between 0,25 and 6,0 mm as influenced by different Krilium concentrations has been studied. In neutral clayey soils the increase compared with the corresponding standard was about 4 to 10 times, this improvement was statistically significant at the 0,05 and 0,01 level. The improvement was also satisfactory in neutral silty soils of the type "Fort 1", whereas is acid silty and acid sandy-loam soils of the types "Kühstelli" and "Fopp" respectively, the effect was practically zero. It ha been shown that the ability of Krilium to form bigger and more waterstable aggregates is not anly a function of clay content but also a function of the pH of the soil. The aggregate formin ability of Krilium increases with increasing pH. The increase of the k-value (saturared permeability, Drcy) due to Krilium conditioning was very high in the impervious clay soil "Zugerber". With a 0,1 and 1,0% conditioning it was possible to increase the k-value 72 and 959 times respectively. In neutral and acid silty soils like "fort 1" and "Kühstelle", we were able to increase the k-value compard with the standard 6 and 29 times respectively. The improvemenr of the k-value was such, that e. g. the clay soil "Zugerberg" with a 0,1% conditioning could percolate a heavy rainfall of more than 30 mm/h, whereas the unconditioned standard could nor percolate more than 0,9 mm/h of rainfall. The structure improving influence of Krilium with respect to plant growth has been shown to be very dependable on soil and on clay content.