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

Figure 4

Acid phosphatase activity (APase), as a function of P sources and filter cake (a), P application rates and filter cake (b and c), and sugarcane juice P as a function of P application rates (d). Averages followed by single letters are significantly different (Tukey test, ). Capital letters compare P sources with the effect of filter cake. Lowercase letters compare the effect of filter cake on each source. and ns: significant () and insignificant, respectively.

(a)

(b)

(c)

(d)