Americas and Oceania Group - International Plant Nutrition Institute

Studies on the effect of rate and time of N application on maize-wheat system yield showed that application
of N in maize at 240 kg/ha produced maximum grain yield (7.5 t/ha) that was at par with yield obtained (7.1 t/
ha) with N application at 160 kg/ha in 3 splits on the basis of a leaf color chart (LCC). Nitrogen applied at 150
kg/ha in 2 splits in wheat resulted in highest grain yield (5.1 t/ha). Percent increase in yield of the maize-wheat
system, over no application of N, was highest (254%) with the application of 240 and 150 kg N/ha in maize
and wheat, respectively.
In the omission plot experiment, wheat yield was highest (4.8 t/ha) in the ample NPK (150:110:100) plot.
Omission of N and P from the ample NPK treatment reduced yield by about 4 and 2.1 t/ha, respectively,
with no reduction in yield due to K omission. In the following maize season, both ample NPK and omission
plots were divided into two equal plots and residues of the previous wheat crop were retained in one plot and
were completely removed from the other plot. Maize yield in the ample NPK (250:120:120) plots, with and
without residues, were 8.36 and 8.28 t/ha, respectively. The lowest yield of maize (0.8 t/ha) was obtained in
the N omission plot where wheat residues were retained while the yield was slightly higher (1.1 t/ha) in the
N omission plot with no residues retained. Reduction in maize equivalent yield of the system due to nutrient
omission, as compared to ample NPK plot, followed the order N (84.8%) > K (42.4%) > P (32.1%). IPNI-22
Global Maize Project in India: Maize-Wheat Cropping System in Northern Karnataka
Project Leader: D.P. Biradar, Department of Agronomy, University of Agricultural Sciences Dharward, Dharwad,
Karnataka. E-mail: dpbiradar@yahoo.com
Project Cooperator: Y.R. Aladakatti, Associate Professor (Agronomy), Dharward
Evaluation of the maize-wheat cropping systems using ecological intensification (EI) with application
of 180-90-100 kg N-P 2 O 5 -K 2 O/ha and FP (farmer’s practice) with application of 115-52-45 kg/ha resulted
in maize grain yields of 3.9 t/ha and 2.8 t/ha, respectively. A 23% higher net return of INR 24,003/ha with
benefit-to-cost (B:C) ratio of 2.67 was realized with EI than with FP. Grain yield of wheat using EI with
application of 130-70-60 kg N-P 2 O 5 -K 2 O and FP with application of 115-52-45 kg/ha was 4.1 t/ha and 3.2 t/
ha, respectively.
Rate and application studies found that 240 kg N/ha application could generate 7.2 t/ha maize, which was
higher than the 6.2 t/ha produced with 160 kg N/ha. Net returns and B:C ratios with 240 and 160 kg N/ha were
INR 48,067 (3.76) and INR 41,206 (3.59), respectively. Application of N in three splits with and without the
use of leaf color charts (LCC) resulted in equivalent maize yields of 4.9 and 4.7 t/ha, but these results were
superior to N provided in two splits. Grain yields in the succeeding wheat crop were 4.2 and 3.6 t/ha using 150
and 100 kg N/ha, respectively. Application of N in three splits with and without the use of leaf color charts
(LCC) resulted in equivalent wheat yields of 3.1 t/ha. However, the results were superior to N provided in two
splits, which recorded a grain yield of 2.7 t/ha, respectively.
Studies on indigenous soil nutrient supply indicated ample NPK (250-120-120) and NPK rates derived
through site-specific nutrient management (SSNM) (200-90-100) resulted in maize yields of 7.7 and 6.9 t/
ha, respectively. Omitting N, P, and K from ample NPK resulted in a maize yield of 2.7, 6.1, and 6.6 t/ha,
respectively. In wheat, ample NPK (150-110-100) and SSNM rates (120-60-50) produced 4.2 and 4.1 t/ha.
Nitrogen, P, and K omission recorded a wheat yield of 1.8, 3.8, and 3.9 t/ha, respectively.
Considering the results obtained from experiments in the previous year, N rate for wheat in the EI treatment
was slightly improved from 130 to 150 kg/ha. Soil and plant analysis have been carried out and the data on
nutrient uptake is currently being compiled at the time of this report. IPNI-23
Global Maize Project in the United States: Ames, Iowa
Project Leader: Roger Elmore, Iowa State University Agronomy Department Ames, IA. E-mail: relmore@iastate.edu
Project Cooperator: John Sawyer
The objective of this study is to determine whether or not an ecological intensification approach can
increase yields more quickly over time than current farmer practice. The study design is a split plot. The
main plot is management system: 1) farmer practice (FP), and 2) ecological intensification (EI). The split plot
is: 1) N application according to the management system, and 2) no N. The treatments are in a randomized
complete block, with four replications.
In 2011, there were no soybean grain yield differences between the systems (58.8 and 60.8 bu/A for FP and
EI, respectively). For corn grain yield, the N application was significant between without and with N (138 and
221 bu/A for without and with N, respectively). There was no effect of management system nor was there an
interaction between management system and N application. Therefore, the site was highly N responsive in
both systems, but systems or differences in N source and application rate had no effect on corn yield (FP with
N was 220 bu/A and EI with N was 222 bu/A). IPNI-26
10 IPNI Interpretive Summaries