Spatio-temporal response of maize yield to edaphic and meteorological conditions in a saline farmland
E. Scudiero, N. Dal Ferro, G. Simonetti, F. Morari
Dept. Environmental Agronomy, University of Padova, Legnaro, Italy
P. Teatini
Dept. Civil, Environmental and Architectural Engineering,
University of Padova, Padova, Italy
D. L. Corwin
USDA-ARS, United States Salinity Laboratory, Riverside, CA, USA
ABSTRACT
Spatio-temporal variability of crop production strongly depends on soil heterogeneity,
meteorological conditions, and their interaction. Canopy reflectance can be used to
describe crop status and yield spatial variability. The objectives of this work were
to understand the spatio-temporal variability of maize (Zea mays L.) yield using
ground-based reflectance acquisitions in a salinity- and water-stress-affected 21-ha
field beside the Venice Lagoon, Italy. Intra- and inter-annual reflectance variations
were analyzed, across the entire field and at each map-cell over time, to understand
how the different soil-related stress types (i.e., salinity and water) arise under
different meteorological conditions. The results show that normalized difference
vegetation index (NDVI), acquired during the maize flowering and kernel maturation
stages (over the three growing seasons of 2010, 2011, and 2012), effectively describes
yield spatio-temporal variability. In particular, stressed areas exhibited the smallest
changes in NDVI over a single growing season. Soil salinity and water stress are
responsible for ca. 44% of the intra-annual NDVI change. When multi-year NDVI data
are compared, areas affected by soil salinity show the smallest temporal variability.
Nevertheless, areas that are slightly saline and constantly affected by water stress
could not be distinguished from highly saline areas. Multi-year reflectance data can
be a useful tool to characterize areas where soil salinity is the main factor limiting
crop production. In areas where several stress types occur simultaneously and
consistently over time, this analysis could benefit precision irrigation techniques
able to consider within the same field both leaching requirement and/or irrigation needs.
