Americas and Oceania Group - International Plant Nutrition Institute

Site-Specific Nutrient Management for Optimizing Productivity of Rice-Maize Cropping in the Krishna and Godavari
Agro-Climatic Zones of Andhra Pradesh
Project Leader: P. Venkata Rao, Scientist, Acharya N G Ranga Agricultural University, Hyderabad Agronomy
Department of Agronomy, College of Agriculture and Saline Water Scheme, Bapatla, Andhra Pradesh.
E-mail: venkat.potnuru@yahoo.com
Project Cooperators: R. Veeraraghavaiah, Agricultural College, Bapatla and G. Subbaiah, Agricultural College, Bapatla
Rice-maize cropping system in Andhra Pradesh comprises about 50% of the total area under this system
(525,000 ha) in India. However, there is a lack of adequate knowledge on efficient nutrient management
practices, resulting in uncertain yields and raising doubts on the long-term sustainability of this cropping
system. This project was initiated to develop guidelines for nutrient use in the three major rice-maize growing
districts of Andhra Pradesh using the principles of site-specific nutrient management (SSNM). Fifteen
locations representing variable management zones of the region were selected for the study, and yield targets
of 6 and 12 t/ha were set for rice and maize, respectively. Ample NPK rates at 180-70-80 for rice and 255-
170-240 for maize were proposed at all locations to achieve the yield target. These rates were also compared
with the state fertilizer recommendations of 120-40-40 kg N-P 2 O 5 -K 2 O/ha, respectively, for rice and 120-60-
60 kg N-P 2 O 5 -K 2 O/ha, respectively, for maize as well as with farmer practices.
Nutrient application in maize for a yield target of 12 t/ha resulted in an average maize yield of 10.2 t/ha
(range 8.1 to 11.9 t/ha across different sites). Target yields were attained at six of the 15 experimental sites.
Inadequate plant population coupled with delayed basal fertilizer applications by 20 to 25 days could have
contributed to yield reductions at nine sites. Maize yields with state recommendation ranged from 7.5 to 10.3
t/ha with an average of 8.6 t/ha. Similarly, maize yields with farmer practice varied between 6.7 and 8.7 t/ha,
with an average of 7.9 t/ha. Thus, SSNM-based fertilizer recommendations resulted in a yield increase of 19%
over state recommendation and 28% over farmer practice. Omitting N, P, and K from the ample NPK rates
resulted in yields of 5.5, 6.9, and 7.8 t/ha of maize, respectively. Reducing P and K rates either individually
or jointly from ample NPK did result in a significant yield difference across the locations, thereby indicating
yield response to both these nutrients. The results from this study were used to develop Nutrient Expert
Decision Support tool for Andhra Pradesh, and the tool is currently being used for providing field-specific
fertilizer recommendations. The project was completed in 2011. India-011
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 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-tocost
(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 v
96 IPNI Interpretive Summaries