Yield Estimation under Maize -Wheat Cropping System
Anil Kumar Sanjeev Panwar Rajinder Kaur and Sanjeev Pawar
Design of Experiments
IASRI, Library Avenue, Pusa, New Delhi-12
Under All India Co-ordinated Research Project on Cropping Systems an experiment "Long range effect of
continuous cropping and manuring on soil fertility and yield stability" was initiated during 1977 with the
objective to study the long range effect of a crop sequence with high yielding varieties at graded fertilizer
levels on yield stability and soil fertility. Being a compulsory experiment this was conducted at all the
cropping systems research centres with the major prevailing cereal based cropping systems like rice-rice,
rice-wheat, maize-wheat, sorghum-wheat and pearlmillet - wheat.
Maize-wheat sequence at Ludhiana centre was selected for the study. Eighteen fertility combinations,
comprising three levels of N (40, 80 and120 kg/ ha) and P (0, 40 and 80 kg P2O5 / ha) and two levels of K
(0 and 40 kg K2O/ ha) were evaluated in a 32 x 2 partially confounded factorial design in three replications
with one control (N0P0K0) in each replication.
Grain yield for Maize and wheat crops for a period from 1979 to 2000 has been estimated using
curve expert package. Different linear/non-linear models viz. 3rd degree polynomial fit, MMF, logistic,
linear fit, quadratic fit, rational function, exponential fit, etc. have been fitted to all the 19 treatments.
Since data for the year 1980 for both kharif (maize) and rabi (wheat) seasons were missing, best-fitted
models for each treatment were used to interpolate the missing yield. Grain yield for further three years i.e.
2001, 2002 and 2003 to all the nineteen treatments were also obtained by using best-fitted models.
Under Kharif season (Maize) for treatment T18 (NPK: 120: 80: 40) ,missing yield by sinusoidal fit, 3 rd
degree polynomial fit and quadratic fit models were interpolated as 39.28 Q/ha, 39.68 Q/ha and 37.98 Q/ha
respectively for year 1980, whereas yield for years 2001, 2002 and 2003 were predicted by sinusoidal fit
model predicted as 37.44 Q/ha, 35.94 Q/ha and 34.37 Q/ha respectively. Whereas 3 rd degree polynomial fit
model predicted as 39.45 Q/ha, 38.75 Q/ha and 37.64 Q/ha and quadratic fit model predicted as 44.56 Q/ha,
46.54 Q/ha and 48.67 Q/ha for years 2001, 2002 and 2003 respectively.
Under rabi season (Wheat) for treatment T18 (NPK: 120: 80: 40), missing yield by 3 rd degree polynomial
fit, quadratic fit and reciprocal models were interpolated as 49.63 Q/ha, 48.64 Q/ha and 44.46 Q/ha
respectively for year 1980, whereas yield for years 2001, 2002 and 2003 were predicted by 3 rd degree
polynomial fit model as 55.59 Q/ha, 56.01 Q/ha and 56.24 Q/ha respectively. Whereas quadratic fit
predicted as 58.56 Q/ha, 60.53 Q/ha and 62.64 Q/ha and reciprocal model predicted as 53.29 Q/ha, 53.81
Q/ha and 54.32 Q/ha for years 2001, 2002 and 2003 respectively.