Table 3. Regression equation and coefficient of
determination (R2) for percentage of soybean grain
yield (Y) obtained during several years from five
soils. Soils initially received five P rates.
Soil P (X) extracted by Mehlich-1 (MIP), Mehlich-3
(M3P), Bray-i (BIP), and an anion-cation exchange
resin (Resin-P).
Regression equation R2**
Y = 48.3 + 1.95 (MIP) 0.0123 (M1P)2 0.38
Y = 42.8 + 2.23 (M3P) 0.0160 (M3P)2 0.47
Y = 41.36 + 2.21 (BIP) 0.0152 (B1P)2 0.49
Y = 32.48 + 2.76 (Resin-P) 0.0225 (Resin-P)2 0.60
** Intercept, Bl, and B2 coefficients are significant at the
1% level of probability.
Table 4. Regression equation and coefficient of
determination (R2) for percentage of P in leaves (Y)
and extractable soil P (X) determined by Mehlich-1
(M1P), Mehlich-3 (M3P), Bray-i (BIP), and an anioncation exchange resin (Resin-P) after the second and third consecutive plantings from three soils
with 63, 27, and 12% clay.
Regression equation R2**
%P = 0.2 + 0.0047 (MIP) 0.000036 (M1P)2 0.44
%P= 0.2 + 0.0048 (M3P) 0.000036 (M3P)2 0.48
%P= 0.2 + 0.0052 (BIP) 0.000040 (BIP)2 0.50
%P = 0.2 + 0.0067 (Resin-P) 0.000067 (Resin-P)2 0.50
** Intercept, BI, and B2 coefficients are significant at the
1% level of probability.
300