Abstract
Technologies of precision agriculture, digital soil maps and meteorological stations provide a minimum data set to guide precision farming operations. However, determining optimal nutrient requirements for potato (Solanum tuberosum L.) crops at subfield scale remains a challenge given specific climatic, edaphic and managerial conditions. Multilevel modeling can generalize yield response to fertilizer additions using data easily accessible to growers. Our objective was to elaborate a multilevel N fertilizer response model for potato crops using the Mitscherlich equation and a core data set of 93 N fertilizer trials conducted in Quebec, Canada. Daily climatic data were collected at 10 km □□ 10 km resolution. Soils were characterized by organic matter content, pH and texture in the arable layer, and by texture and tools of pedometrics across a gleization-podzolization continuum in subsoil layers. There were five categories of preceding crops and five cultivar maturity orders. The three Mitscherlich parameters (Asymptote, Rate and Environment) were most often site-specific. Sensitivity analysis showed that optimum N dosage increased with non-leguminous high-residue preceding crops, coarser soils, podzolization, drier climatic condition and late cultivar maturity. The inferential model could guide site-specific N fertilization using an accessible minimum data set to support fertilization decisions. As decision-support system, the model could also provide a range of optimum N doses across a large spectrum of site-specific conditions including climate change.
Highlights
The main forcing variables for potato (Solanum tuberosum L.) growth and development are air temperature, photoperiod, intercepted radiation, precipitation, soils, and nutrient management (Hanks and Ritchie, 1991; White et al, 2007; Fortin et al, 2008)
The N fertilization limits the productivity of potato agroecosystems (Dueri et al, 2007; Hirel et al, 2007) but fertilizer N recovery varies from 10 to 70% in potato crops (Tran and Giroux, 1991)
The Mitscherlich equation fitted to the experimental data returned a R2 value of 0.70 for the random effects of blocks and trials, 0.66 for the random effects of trials only, and 0.47 without random effect
Summary
The main forcing variables for potato (Solanum tuberosum L.) growth and development are air temperature, photoperiod, intercepted radiation, precipitation, soils, and nutrient management (Hanks and Ritchie, 1991; White et al, 2007; Fortin et al, 2008). The potential yield of potato is the theoretical yield that can be achieved with a well-adapted cultivar grown from the best possible seeds under optimal conditions, including weather, soil, and agronomic practices (Haverkort and Struik, 2015). Because response curves show that economic loss is much larger with under- than over-fertilization, growers tend to apply more N than suggested by extension services (Joern and Vitosh, 1995; Prunty and Greenland, 1997). Nitrogen fertilizer trials can support decisions fitted to specific soil management zones (Cambouris et al, 2006)
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