Americas and Oceania Group - International Plant Nutrition Institute

of rice. The dry matter yield range in the K0 and K100 pots were 10.1 to 33.3 g/pot and 14.8 to 39.2 g/pot,
respectively. Analysis of the plant sample for K and other nutrient are in progress. After harvesting the first
crop, soil in each pot was mixed and 15 days aged seedlings of rice were transplanted on December 4, 2011,
in each pot as second crop. In a separate experiment, maize seeds were sown on November 10, 2011, which
is now in V6 stage. Maize will be harvested at V8 stage and yield parameters as well as nutrient uptake will
be analyzed. Both rice and maize will be grown for 6 to 8 crop cycles in the same pot to estimate K supplying
capacity of the soils. The results from the pot experiment will be validated in two field experiments with five
different rates of K in the upcoming rabi maize and boro rice. Bangladesh-006
Importance of Soil Test-Based Nutrient Application through Farmers’ Participatory Approach in Red and Lateritic Soils
of West Bengal
Project Leader: G.N. Chattopadhyay, Visva Bharati University Soil Testing Laboratory Institute of Agriculture,
Sriniketan, West Bengal. E-mail: gunin_c@yahoo.com
The current study was initiated in 2011 to assess the use of Geographic Information System (GIS)-based
soil fertility maps for field specific fertilizer decision-making in smallholder systems. On-farm studies done
in this project have established that GIS map-based fertilizer recommendation in rice-potato-sesame cropping
system produced equivalent yield and economic benefit as actual soil test. Economic analysis also showed
that a 100 m grid-based sampling as opposed to plot by plot sampling can reduce the cost of soil analysis
substantially (one-seventh), while still producing comparable net returns.
Another set of experiments were set up to check whether a higher grid size of sampling could be adopted to
further decrease soil sampling cost. Three different fertility maps of the study area were prepared using 50 m,
100 m, and 250 m grid of soil sampling. Fertilizer recommendation from these grid-size maps were evaluated
against the actual soil-test based fertilizer recommendation in the rice-potato-sesame cropping system.
Generalized recommendation practiced in the study area was included in the experiment as a control. Results
from rice suggested that plant height (cm), leaf area index, dry matter accumulation (g/m 2 ), crop growth rate
(g/m 2 /day), number of panicles/m 2 , grains/panicle, yield, and economic return were similar in 50 and 100 m
map-based recommendation and actual soil samples. However, the parameters evaluated were significantly
lower in 250 m map-based fertilizer recommendation. Similar results were obtained in potato and sesame. An
assessment of system net return in rice-potato-sesame under the four evaluated fertilization strategies showed
that average net return in the 50 and 100 m map-based recommendation and actual soil test were significantly
higher (INR 14,567/ha) than the 250 m grid-based fertilizer recommendation. Average system net return in
the 50 and 100 m map-based recommendation and actual soil test were higher by INR 28,830/ha as compared
to the generalized fertilizer recommendation.
The results from the study suggest that 250 m grid-based fertility maps were unable to capture fertility
variations at the village scale (area < 100 ha) and sampling density of one sample/ha is the suitable option.
However, such sampling density may not be practical at higher scale (district or state) and the sampling
density at such scales should be based on an overall balance between application cost and return from field
specific nutrient management practices. EZ-India-43
GIS-based Spatial Variability Mapping of Agricultural Holdings for Precision Nutrient Management in the Red and
Lateritic Soil Zone
Project Leader: G.N. Chattopadhyay, Visva Bharati University Soil Testing Laboratory, Sriniketan, West Bengal.
E-mail: gunin_c@yahoo.com
Project Cooperator: T. Ravishankar, National Remote Sensing Centre, Department of Space, Govt. of India
This project aims to assess the correlations between soil parameters, yield, and actual crop response to
applied nutrients in an intensively cultivated village in the red and lateritic soil zone of West Bengal to
develop a Geographic Information System (GIS)-based model for nutrient decision support in rice-wheat
cropping system. Based on the nutrient variability map of the study area, five on-farm trials were set up in
wheat with seven treatments including: Control, Farmer practice, State recommendation (100% NPK), 100%
NPK+S+B+Zn, 100% PK+S+B+Zn, 100% NK+S+B+Zn, 100% NP+S+B+Zn. Wheat yield was generally
poor in the season due to shorter winter and low winter temperature. Mean wheat yield was highest (2.5 t/
ha) in the 100% NPK+S+B+Zn treatment and average reduction in yield due to omission of N, P, and K were
0.95, 0.81, and 0.7 t/ha, respectively.
In the following rice season, yield and nutrient variability data assessed from the village were used in a
GIS platform to identify 8 management zones within the village. The management zone map was merged
88 IPNI Interpretive Summaries