PREDICTION OF POST-HARVEST SOIL TEST VALUES ANDFERTILISER CALIBRATIONS FOR MAIZE UNDER INTEGRATEDPLANT NUTRITION SYSTEM ON ALFISOL

Abstract

A field experiment was conducted during 2010-11 to develop PHSTVs prediction equations
adopting Inductive cum Targeted yield model (Ramamoorthy et al., 1967), on a Typic Rhodustalf
of Tamil Nadu, with hybrid maize (NK 6240) under IPNS. The experiment was laid out in a
fractional factorial design comprising twenty four treatments and the test crop experiment with
hybrid maize was conducted with four levels each of N (0, 100, 200 and 300 kg ha-1
), P2O5 (0, 40,
80 and 120 kg ha-1
) and K2O (0, 40, 80 and 120 kg ha-1
) and three levels of FYM (0, 6.25 and 12.5 t
ha-1
). The IPNS treatments were superimposed across the strips. There were 21 fertiliser treatments
along with three controls which were randomized in each strip in such a way that all the treatments
occurred in both the directions. Using the plot wise pre-sowing soil test values, fertiliser doses and
grain yield and/or the uptake of NPK by the crop as dependent variables and post-harvest soil
test values as independent variable, PHSTVs prediction equations were developed. The predicted
soil test values revealed that the soil fertility was found to decline markedly under unfertilized
control and increased based on the fertiliser doses imposed. Significant R2 values (>0.65) were
recorded for these regression equations which could be used with confidence for the prediction
of post-harvest KMnO4-N, Olsen-P and NH4OAc-K. Using the predicted PHSTVs of hybrid maize,
soil test based fertiliser recommendation for desired yield targets of any succeeding crop could be
prescribed.