Maize Yield and Physical-Chemical Fertility Mapping for the Management of the Soil

Abstract

The purposes of this study were: first, to evaluate the traffic effects on soil qualities of a work site layout composed by a forage harvester with maize attachment and a truck for unloading and transportation of the harvested maize; second, to manage the fertilisation with precision farming techniques, after the characterisation of the top soil fertility. Field tests were carried out in a farm near Rome: immediately after harvesting operations, the above mentioned effects were quantified through variation of some soil physical parameters: penetration resistance, dry bulk density and shear strength. These parameters were determined on the tracks left by the harvester machine and by the truck that flanked the harvester machine after the passage and on soil not interested by the passes (Control). The soil chemical properties, considered on a grid basis were: pH, soil particle size, total nitrogen, available phosphorous, cation exchange capability, exchangeable potassium and organic matter content. The effects of the different variables on production were analysed and interpreted with the purpose to relate them with the yield variability. Penetration resistance in the different layers (0-40 cm depth), after the single passage of the harvester machine and the truck, showed statistically significant increases respect to the control. Even shear strength revealed an elevated degree of soil compaction after the passage of the harvester machine and the truck. This trend is also due to the elevated value of the soil moisture content. The chemical fertility analysis and its mapping analysed together to the yield map has allowed to program the most suitable fertilising plan aimed at keeping the crop productivity level, the environmental protection and increase of economic benefits for the farmers. A decreasing of fertilisation costs was proved for each hectare; moreover a reduction in the environmental impact due to a low chemical fertilisers administration, occurs.