APLICACIÓN DEL TRÁFICO CONTROLADO EN LA COSECHA DE MAÍZ (Zea mays L.): EFECTO SOBRE RENDIMIENTOS DEL CULTIVO Y LAS PROPIEDADES FÍSICAS DEL SUELO CONTROLLED TRAFFIC APPLICATION IN CORN (Zea mays L.) HARVEST: EFFECT ON YIELDS AND SOIL PHYSICAL PROPERTIES

Previous Argentine studies have led to a recommendation to limit the load and traffic intensities on agricultural soils in order to avoid permanent topsoil and subsoil compaction, especially, in harvest operations. Compaction is caused by the high traffic intensity of tractors used for crop protection treatments and harvest operations, rather than for actual seeding, in special, when these operations are carried out on wet soil or with high-pressure tyres. Direct drilling systems usually have lower traffic intensities than the conventional tillage systems. Controlled traffic is other possibility to reduce soil compaction been done, however, about the compaction of non-tillage soils in harvest operations. The main objectives of this work were a) to quantify the changes in the physical properties of a clayey soil, due to traffic in harvest operations. b) To assess corn yield as a response variable related to different traffic alternatives: 1) controlled traffic in harvest operations, 2) conventional traffic intensities in harvest operations. c) To enhance present knowledge on the effects of traffic alternatives in harvest operations on the soil after nine years of direct drilling system cultivation. In the study area, an increase in the yield of corn estimated at 33,7 % on average was observed during three consecutive years of controlled traffic was applied in harvest operations. In spite of the high level of initial soil compaction one can see that all the compared traffic alternatives produced increases in the topsoil cone index and bulk density generating, also, reduction in the total soil porosity. From the economic point of view and after the controlled traffic (15,2 Mg km ha) application, the first year corn yield increases represented US$ 161,5 ha. Second year increases represented US$ 195,5 ha and third year increases represented US$ 331 ha. (Corn costs about US$ 85 Tn). The saving of fuel was about US$ 1,35 ha