A simple equation to determine the breakdown of individual aggregate size fractions in the usual wet-sieving method (using nested sieves)
1997
Christopher, T. B. S. | A. M. Mokhtaruddin | M. H. A. Husni | M. Y. Abdullah
An equation was developed to estimate the breakdown of individual aggregate size fractions in the usual wet-sieving method using nested sieves. The key was to assume that aggregate breakdown happens sequentially and consistently, and that the aggregate breakdown between any two aggregates in the same aggregate size fractions is equal in percentage. Applying these two assumptions, this equation was developed: Xi = (Wai X D) I Wai +Di_1), where Xi is the weight of aggregate breakdown in aggregate size fraction i before wetsieving, and Di and Di_1 is the weight of aggregates that have passed through sieve i and (i-I), respectively. The equation was tested with five soil series. The soils were separated into six aggregate size fractions : 4.76 -8.0, 2.83 -4.76, 2.0 2.83, 1.0 -2.0, 0.5 -1.0 and 0.3 -0.5 mm. For every soil, each of their aggregate size fraction was separately wet-sieved to determine the actual aggregate breakdown. The separate wet sievings results were then combined in such a way to simulate the usual wet-sieving method. The equation was then calibrated by simple linear regression where the calibrated equation was : y = 100sin2oc j; where y, is the calibrated breakdown estimate for aggregate size fraction i, and OC i is (0.0166xi+ 0.1) in unit radians. This calibrated equation was highly significant at 1%, and the R2 = 0.961. The calibrated equation was validated with three additional soils. Paired sample t-test showed there was significant differences between the actual and calibrated breakdown estimate values.
اظهر المزيد [+] اقل [-]الكلمات المفتاحية الخاصة بالمكنز الزراعي (أجروفوك)
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