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Interpretive Summaries:
2008 - Spatial Variability in Soil Physio-chemical Properties and Nutrient Status in an Intensively Cultivated Village of West Bengal
2007 - Spatial Variability in Soil Physico-Chemical Properties and Nutrient Status in an Intensively Cultivated Village of West Bengal
2006 - Spatial Variability in Soil Physio-Chemical Properties and Nutrient Status in an Intensively Cultivated Village of West Bengal
Spatial Variability in Soil Physio-Chemical Properties and Nutrient Status in an Intensively Cultivated Village of West Bengal, 2008
This study was initiated to map nutrient variability in agricultural soils and to examine the possibility of using village-level nutrient variability maps for fertilizer application decision support. Geographic Information System (GIS) maps of spatial variability were created in 2006 and utilized to predict the nutrient status of unsampled farmer plots. Two-plot trials were set up in five farmer fields in the winter rice season and the subsequent summer rice season to compare existing farmer practice and fertilizer recommendations generated from the GIS maps of the village. Nutrient application rates for the GIS plots were based on an average yield goal for that particular season, standard nutrient uptake values of rice, and use efficiencies for each nutrient, and followed the framework of state recommended rates for N, P, and K in high, medium, and low fertility soils.
Results for the winter rice season showed consistently higher yields in GIS-SSNM plots versus those receiving common farmer practice, but the yield differences were low due to drought. However, in the summer rice season an average yield increase of 1,290 kg/ha was observed over farmer practice as both nutrient and water management were better controlled. Fertility maps were re-developed 2 years after the initiation of the study to assess the changes in soil fertility due to cropping. Average soil P and K contents decreased by 60 kg P2O5/ha and 88 kg K2O/ha between 2006 and 2008. The frequency distribution for soil samples shifted towards the low fertility category with a substantial increase in sample numbers in the lowest category. The scarcity of P and K fertilizer sources in the region and high cropping intensity of the village probably worked in tandem for this rapid decline in soil fertility.
The GIS-based fertility mapping procedure clearly showed the potential of using maps for site-specific nutrient recommendations. Besides delineating the fertility management zones within the study area, the nutrient recommendations coming from the maps significantly improved rice yield as compared to the existing practices. Lastly, the technique gave a clear visual indication of changing fertility levels in the village with time, which is important knowledge for the nutrient management planning process. EZ India-45
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