Influence of Stabilized Biosolids Application on Availability of Phosphorus, Copper, and Zinc

Table 4

Effect of SS and stabilized SS on Olsen-P in relation to soil type, sewage source, mixing rate, and incubation period.

Treatments	Fluvial soil				Calcareous soil
	SS1		SS2		SS1		SS2
	30 day	60 day	30 day	60 day	30 day	60 day	30 day	60 day
Mixing rate, 10%
C	7.7^f	7.7^d	7.7^e	7.6^c	8.8^e	8.8^e	8.8^e	8.8^f
SS	19.4^c	20.7^b	20.7^b	21.0^a	25.2^b	25.7^b	24.1^abc	24.9^c
SS + CFA	17.0^d	17.8^c	18.6^c	19.9^a	20.4^d	18.1^d	24.5^ab	27.2^b
SS + B	21.8^a	18.0^c	23.6^a	22.1^a	22.1^c	25.2^b	26.1^a	25.9^c
SS + SBFL	21.2^ab	19.3^bc	21.2^b	20.8^a	31.3^a	28.3^a	21.9^bcd	29.2^a
SS + CaCO3	20.0^bc	18.7^bc	17.3^cd	15.3^b	26.1^b	27.3^ab	22.8^abcd	21.3^d
SS + WH	18.8^c	23.4^a	16.9^cd	15.5^b	20.7^d	22.5^c	20.7^cd	21.6^d
SS + RS	15.2^e	17.6^c	15.6^d	20.7^a	21.0^cd	20.0^cd	21.0^bcd	19.3^e
SS + CS	16.9^d	18.7^bc	16.1^d	19.1^ab	19.9^d	20.2^cd	19.8^d	22.3^d
Mixing rate, 25%
C	7.7^c	7.6^f	7.7^f	7.6^d	8.8^h	8.8^e	8.8^f	8.8^f
SS	19.4^a	20.7^ab	20.7^b	21.0^a	25.2^b	25.7^a	24.1^b	24.9^c
SS + CFA	16.6^b	16.3^de	19.8^bc	21.8^a	19.9^ef	20.9^bc	22.5^bc	25.4^bc
SS + B	21.2^a	18.6^abcd	23.3^a	21.2^a	21.8^de	22.6^b	24.5^b	29.7^a
SS + SBFL	19.7^a	21.0^a	18.2^cd	20.7^a	27.9^a	26.6^a	28.0^a	27.6^ab
SS + CaCO3	16.9^b	18.1^bcd	17.0^de	16.9^c	24.3^bc	25.8^a	21.8^cd	21.6^d
SS + WH	19.4^a	17.8^cde	16.3^e	16.5^c	18.5^fg	20.4^c	19.8^de	21.9^d
SS + RS	14.8^b	15.3^e	16.2^e	16.9^c	18.1^g	17.4^d	18.8^e	19.1^e
SS + CS	19.5^a	19.3^abc	19.5^bc	19.1^b	22.7^cd	21.3^bc	22.6^bc	21.9^d

Values accompanied by different letters are significantly different within column (𝑃<0.05).
C: control (un amended soil), SS: sewage sludge, CFA: coal fly ash, B: bentonite, SBFL: sugar beet factory lime, RS: rice straw, WH: water hyacinth, CS: cotton stalks, nd: not detected, —: not measured.