Precision nitrogen management practices in wheat influences nutrient uptake and their use efficiencies and fertility status of soil under conservation agriculture

Abstract

A field experiment was conducted at New Delhi during Rabi season of 2012-13 to study the precision
nitrogen management in wheat grown under conservation agriculture. The experiment was laid
out in a factorial randomized block design with twenty treatment combinations four nutrient
management in preceding maize [absolute control, recommended dose of fertilizers (RDF), 50%
RDF and site-specific nutrient management (SSNM)] and five precision N management practices in
wheat [control, RDF, green seeker, SPAD and soil-test crop response (STCR)} in sandy loam soil.
Amongst tested N management strategies; a saving of N by 9.5 and 30 kg with green seeker and
SPAD, respectively while enhancement of 18.4 kg N/ha by STCR was found compared to
recommended dose of fertilizers (RDF). N, P and K content and their uptake in grain, straw in
wheat was significantly higher with STCR based nutrient management applied in wheat as well as
with nutrient expert based SSNM applied in maize as residual effect. The same trend was also
followed in case of protein content in wheat grain. However, the nutrient harvest index (NHI) of N,
P and K was significantly higher under nutrient expert based SSNM applied in maize as residual
effect. Whereas, NHI of N and P was significantly higher with absolute control but NHI of K was
not influenced by different precision N management practices. Soil ammonical and nitrate
concentration was significantly higher by STCR based nutrient management as well as with nutrient
expert based SSNM applied in maize as residual effect, however soil phosphate concentration was
significantly higher with SPAD in wheat and 100% RDF as residual effect of nutrient management
in maize, respectively. Among different precision N management practices significantly higher Zn
concentration was recorded with STCR, however Cu and Fe concentration was significantly higher
with 100% RDF and STCR, respectively.