Abstract
Conventional agricultural practices that rely heavily on blanket fertilizer recommendation, eventually leading to deteriorated partial factor productivity and N use efficiency. We investigated the effect of SPAD-based N-management on productivity and N use efficiency of rice and wheat in eastern India. Here, in the experiment three SPAD thresholds (34, 36 and 38 in rice and 38, 40 and 42 in wheat) using three N levels (15, 25 and 35 kg N ha−1) in split were incorporated as real-time N management (RTNM), one fixed-time N management (FTNM), farmers’ fertilizer practice (FFP) and control (No fertilizer) were introduced in wet and dry seasons for rice and wheat, respectively, during the years 2010 to 2012. Topdressing with 25 kg N ha−1 at medium SPAD (S36 in rice and S40 in wheat) increased soil N availability, leaf N content and grain yield of rice (5215 kg ha−1) and wheat (4483 kg ha−1) over the grain yield recorded under a low rate of N topdressing at low SPAD. While saving 33.3% N in rice and 18.8% N in wheat, the agronomic N use efficiency (58.5% in both rice and wheat) and nitrogen recovery efficiency (32.2% in rice and 15.1% in wheat) can be increased when compared with conventional FTNM. The SPAD-based management strategy showed great promise in efficient management of N fertilizer, and we estimated the optimal SPAD threshold for rice and wheat as 37.5 and 41.8, respectively.
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Claims 9
Claim · model-written summary
SPAD-guided topdressing raised rice soil nitrogen availability, leaf nitrogen and grain yield to 5215 kg ha−1.
- Taxon
- rice
Oryza sativae0 - Treatment
- 25 kg N ha−1 at medium SPAD (S36 in rice and S40 in wheat)e0
- Outcome
- soil N availability, leaf N content and grain yielde0
- Direction
- increasede0
- Value
- 5215 kg ha−1e0
- Comparator
- a low rate of N topdressing at low SPADe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Topdressing with 25 kg N ha−1 at medium SPAD (S36 in rice and S40 in wheat) increased soil N availability, leaf N content and grain yield of rice (5215 kg ha−1) and wheat (4483 kg ha−1) over the grain yield recorded under a low rate of N topdressing at low SPAD.”
Claim · model-written summary
SPAD-guided topdressing raised wheat soil nitrogen availability, leaf nitrogen and grain yield to 4483 kg ha−1.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- 25 kg N ha−1 at medium SPAD (S36 in rice and S40 in wheat)e0
- Outcome
- soil N availability, leaf N content and grain yielde0
- Direction
- increasede0
- Value
- 4483 kg ha−1e0
- Comparator
- a low rate of N topdressing at low SPADe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Topdressing with 25 kg N ha−1 at medium SPAD (S36 in rice and S40 in wheat) increased soil N availability, leaf N content and grain yield of rice (5215 kg ha−1) and wheat (4483 kg ha−1) over the grain yield recorded under a low rate of N topdressing at low SPAD.”
Claim · model-written summary
SPAD management saved 33.3% nitrogen in rice relative to conventional fixed-time management.
- Taxon
- riceOryza sativae0
- Treatment
- SPAD-based management strategye1
- Outcome
- Ne0
- Direction
- savinge0
- Value
- 33.3% Ne0
- Comparator
- conventional FTNMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While saving 33.3% N in rice and 18.8% N in wheat, the agronomic N use efficiency (58.5% in both rice and wheat) and nitrogen recovery efficiency (32.2% in rice and 15.1% in wheat) can be increased when compared with conventional FTNM.”
e1“The SPAD-based management strategy showed great promise in efficient management of N fertilizer”
Claim · model-written summary
SPAD management saved 18.8% nitrogen in wheat relative to conventional fixed-time management.
- Taxon
- wheatTriticum aestivume0
- Treatment
- SPAD-based management strategye1
- Outcome
- Ne0
- Direction
- savinge0
- Value
- 18.8% Ne0
- Comparator
- conventional FTNMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While saving 33.3% N in rice and 18.8% N in wheat, the agronomic N use efficiency (58.5% in both rice and wheat) and nitrogen recovery efficiency (32.2% in rice and 15.1% in wheat) can be increased when compared with conventional FTNM.”
e1“The SPAD-based management strategy showed great promise in efficient management of N fertilizer”
Claim · model-written summary
Agronomic nitrogen use efficiency increased to 58.5% in rice and wheat.
- Taxon
- rice and wheatOryza sativaTriticum aestivume0
- Treatment
- SPAD-based management strategye1
- Outcome
- agronomic N use efficiencye0
- Direction
- increasede0
- Value
- 58.5%e0
- Comparator
- conventional FTNMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the agronomic N use efficiency (58.5% in both rice and wheat) and nitrogen recovery efficiency (32.2% in rice and 15.1% in wheat) can be increased when compared with conventional FTNM.”
e1“The SPAD-based management strategy showed great promise in efficient management of N fertilizer”
Claim · model-written summary
Nitrogen recovery efficiency increased to 32.2% in rice.
- Taxon
- riceOryza sativae0
- Treatment
- SPAD-based management strategye1
- Outcome
- nitrogen recovery efficiencye0
- Direction
- increasede0
- Value
- 32.2%e0
- Comparator
- conventional FTNMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrogen recovery efficiency (32.2% in rice and 15.1% in wheat) can be increased when compared with conventional FTNM.”
e1“The SPAD-based management strategy showed great promise in efficient management of N fertilizer”
Claim · model-written summary
Nitrogen recovery efficiency increased to 15.1% in wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- SPAD-based management strategye1
- Outcome
- nitrogen recovery efficiencye0
- Direction
- increasede0
- Value
- 15.1%e0
- Comparator
- conventional FTNMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrogen recovery efficiency (32.2% in rice and 15.1% in wheat) can be increased when compared with conventional FTNM.”
e1“The SPAD-based management strategy showed great promise in efficient management of N fertilizer”
Claim · model-written summary
The estimated optimal rice SPAD threshold was 37.5.
- Taxon
- riceOryza sativae0
- Outcome
- optimal SPAD thresholde0
- Value
- 37.5e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we estimated the optimal SPAD threshold for rice and wheat as 37.5 and 41.8, respectively.”
Claim · model-written summary
The estimated optimal wheat SPAD threshold was 41.8.
- Taxon
- wheatTriticum aestivume0
- Outcome
- optimal SPAD thresholde0
- Value
- 41.8e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we estimated the optimal SPAD threshold for rice and wheat as 37.5 and 41.8, respectively.”
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