Analysis for Planning Suitable Maize Husbandry in New Production Areas of Argentina: A Simple Model Based on Eco-Physiology and Climatic Variables.

During several decades maize (Zea mays, L.) production in Argentine was concentrated within the most productive sub-region of the Pampas (33°56′ S, 60°33′ W), where maize crops were conducted predominantly under dryland conditions. During the last decades, favorable international prices of commodities and changes in climate (e.g. important increases in precipitation) promoted an expansion of maize production area. Hence, some maize crops are cultivated out of the traditional production area without a profound analysis for planning the most suitable cultural practices. Crop simulation models (e.g. Ceres-maize model) are a valuable tool to explore the impact of agricultural practices on crop production. These models, however, demand several inputs (e.g. genetic, weather, soil inputs) not usually available for farmers and agronomists. Eco-physiology studies of maize crops have quoted several simple relationships which describe maize responses to environmental conditions and the impact of some climatic constrains, such as frost damage and heat stress, on maize growth. A simple model based on: (i) functional relationships (ontogeny and air temperature, photosynthetic active radiation interception and thermal time after sowing, biomass production and photosynthetic active radiation interception, grain yield and biomass production), (ii) long term series (ca. 30 years) of daily climatic records (maximum and minimum air temperature, solar radiation, precipitations), and (iii) soil properties (effective soil depth, available soil water capacity), was used to analyze different scenarios (combination of sowing dates and locations) within current maize production area. For each scenario the model predicts inter-annual variability of maize developmental stages, cumulative probabilities of potential grain yields (i.e. without biotic and abiotic stresses), and the risk of frost damage and heat stress. Cumulative probability of total rainfalls during the fallow periods and maize growing seasons of each scenario were also computed, as the occurrence of precipitations greater than 10mm around sowing to allow seed germination.