Response of Sugarcane in a Red Ultisol to Phosphorus Rates, Phosphorus Sources, and Filter Cake

Table 1

Soil phosphorus determined by the resin method (P-res) and by the remainder method (P-rem) at depths of 0.0–0.2 m and 0.2–0.4 m, leaf phosphorus at four months (P-4) and at eight months (P-8) after sprouting, and acid phosphatase activity (APase) and juice phosphorus (P-juice) of sugarcane grown in Eutrophic Red Ultisol, as a function of phosphate fertilization with source, application rate, and filter cake.

	P-res 0.0–0.2	P-res 0.2–0.4	P-rem 0.0–0.2	P-rem 0.2–0.4	P-4	P-8	APase	P-juice
	mg dm^−3				g kg^−1		nmol min^−1 mg^−1	mg L^−1
P sources
Araxa	47	20^ab	30	19	1.4^b	1.7	2340.9	47.8
Bayovar	45	18^b	29	19	1.5^b	1.7	2309.5	47.9
Triple superphosphate	57	25^a	30	18	1.6^a	1.7	2284.0	49.3
P2O5 rates
0	15	8	27	19	1.4	1.6	2346.7	37.0
90	35	18	30	19	1.5	1.7	2402.7	48.9
180	53	24	30	18	1.6	1.7	2324.4	53.2
360	99	33	32	19	1.7	1.8	2172.6	53.7
Filter cake
Presence	63	24	31	19	1.7	1.8	2079.5	49.5
Absence	37	18	29	19	1.4	1.6	2543.4	47.2
	test
Source	3.0^ns	4.2	0.1^ns	0.2^ns	9.8	0.2^ns	0.4^ns	0.4^ns
Rate	101.3	26.3	10.0	0.6^ns	14.6	4.7	3.3	22.5
Filter cake	54.6	8.3	3.9^ns	2.0^ns	81.0	62.3	73.2	2.1^ns
Source × rate	2.1^ns	1.4^ns	0.1^ns	0.9^ns	2.2^ns	1.2^ns	1.5^ns	0.4^ns
Source × cake	4.7	0.2^ns	0.1^ns	0.1^ns	1.3^ns	0.6^ns	7.1	0.2^ns
Rate × cake	4.5	1.0^ns	0.2^ns	0.4^ns	2.7^ns	0.9^ns	16.6	0.4^ns
Source × rate × cake	1.0^ns	0.7^ns	0.1^ns	1.1^ns	2.2^ns	0.9^ns	2.3^ns	0.1^ns
CV, %	29.9	40.4	10.6	6.5	8.9	4.7	10.0	13.7

Averages followed by single letters are significantly different from other averages in the same column (Tukey test, ). , and ns: significant (, ) and insignificant ( test).