Impacts of Sewage Sludge in Tropical Soil: A Case Study in Brazil

Table 3

Chemical characteristics of the soil after five application of Barueri (B) and Franca (F) sewage sludge.

Characteristic	Unit	Barueri sewage sludge						Franca sewage sludge
		C	NPK	B1N	B2N	B4N	B8N	C	NPK	F1N	F2N	F4N	F8N
pH (water)		5.6	5.8	5.6	5.9	5.8	5.2	5.8	5.5	5.9	5.5	5.7	5.3
P	mg dm^−3	5.6	16.5	45.5	58.2	132.3	320.6	6.2	13.4	55.3	62.0	56.6	105.4
K	mg dm^−3	32.3	67.3	40.0	35.3	30.3	48.0	35.0	50.7	41.7	40.3	31.7	29.3
Ca	mmolc dm^−3	27	34	38	46	50	47	31	33	39	35	45	48
Mg	mmolc dm^−3	16	21	14	16	15	18	17	12	18	19	19	14
H+Al	mmolc dm^−3	49	41	48	40	48	61	54	52	41	52	49	59
SB	mmolc dm^−3	45	57	52	63	66	66	49	46	58	56	65	63
CTC	mmolc dm^−3	93	99	101	103	114	127	103	98	99	107	113	121
V	%	47.2	57.3	52.0	60.9	57.3	52.3	47.4	47.2	58.8	51.5	57.1	51.6
B	mg dm^−3	0.4	0.7	0.4	0.5	0.5	1.0	0.4	0.3	0.6	0.5	0.5	0.5
Cu	mg dm^−3	1.9	1.6	6.5	10.4	18.8	43.5	1.5	1.4	5.1	3.4	4.0	5.7
Fe	mg dm^−3	47.8	35.8	57.7	76.8	103.3	236.9	44.2	46.5	86.4	120.2	114.6	190.8
Mn	mg dm^−3	10.2	9.2	11.2	11.3	12.5	13.1	10.2	11.5	19.2	19.5	15.2	16.7
Zn	Mg dm^−3	1.7	1.6	20.5	39.8	72.3	109.7	0.7	1.5	15.2	11.1	14.5	49.2

FS: sewage sludge from the Franca Wastewater Treatment Plant. BS: sewage sludge from Barueri Wastewater Treatment Plant. C: control; NPK: mineral fertilization recommended for the crop; F1N, F2N, F4N, and F8N: SS from Franca based on the nitrogen concentration that provides the same amount of N as in the mineral fertilization, one, two, four, and eight times the N recommended sewage sludge dosage, respectively; B1N, B2N, B4N, and B8N: sewage sludge from Barueri based on the nitrogen concentration that provides the same amount of N as in the mineral fertilization, one, two, four, and eight times the N recommended sewage sludge, respectively.