Effectiveness of Extractants for Bioavailable Phosphorus in Tropical Soils Amended with Sewage Sludge

Table 1

Phosphorus concentrations in diagnostic leaves of maize plants grown in a Typic Eutrorthox amended annually with sewage sludge for 13 consecutive years and in diagnostic leaves of sugarcane plants grown in a Typic Hapludalf amended once with sewage sludge and sludge compost ().

Rates	(diagnostic leaves)
	g kg^−1
Maize
0	2.78^a
5	3.02^a
10	3.11^a
20	3.07^a
RL	ns
RQ	ns
Sugarcane
0	2.30^a
50	2.40^a
100	2.35^a
200	2.57^a
RL	ns
RQ	ns

: linear regression; RQ: quadratic regression; ns: not significant at 5%.
^**Values with the same letter within a column are not different (Tukey, ).