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20211
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Subject: Soil Sciences × Author: Blestar Singh × Start date: 2012 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Assessing reactive nitrogen fluxes from soil in baby corn based cropping system
    (Punjab Agricultural University, Ludhiana, 2021) Blestar Singh; Varinderpal Singh
    Spatial variability in soil N supply restricts efficient N use especially when blanket fertilizer N applications are made at fixed growth stages. Need-based fertilizer N use practices provide a potential solution to achieve high N use efficiencies while sustaining potential yield. Field experiment was conducted at FieldFresh Food Pvt. Ltd., Ladhowal, Ludhiana with baby corn cultivar Syngenta 5414 in spring season (March-June, 2019) to study spectral properties of baby corn for scheduling optimum fertilizer nitrogen use and to measure reactive nitrogen fluxes from soil in baby corn based cropping system. The spectral properties were measured using leaf colour chart developed by Punjab Agricultural University (PAU-LCC) and chlorophyll meter (SPAD meter) and GreenSeeker optical sensor. A close linear relationship (R2= 0.99) between SPAD meter readings and PAU-LCC score indicated that PAU-LCC can be used as an inexpensive and reliable substitute of SPAD for drawing need-based N topdressing decisions in baby corn. Spectral reflectance data recorded at different growth stages revealed that NDVI readings at V9 growth stage could precisely predict the in-season N requirements in baby corn. Fertilizer N topdressings based on threshold leaf greenness of PAU-LCC 5 and SPAD 50 produced significantly higher average cob yield (18.7%) with improved recovery (84.5%) and agronomic (24.8 kg cob kg-1 N) efficiencies of applied fertilizer N in comparison to conventional N practice. The improved congruence of fertilizer N supply and crop N demand in PAU-LCC and SPAD based N management treatments reduced ammonical and nitrate N leaching losses by 59 and 78%, respectively, while mitigating 48% global warming potential. Insignificant differences in N indices of different soil layers between no-N and fertilizer N treatments expressed that higher fertilizer N applications neither improved baby corn yield nor soil N status. The N balance in soilplant systems provides a quantitative framework of N inputs and outputs. Out of the total fertilizer N applied, 54.4% is taken up by the plants, 2.56% accounts for the residual soil N, and 24.7% remains unaccounted while remaining is lost to atmosphere in the form of leaching or gaseous emissions.