Demanda energética e balanço de energia das culturas de milho e soja semeadas diretamente em campo natural degradado.

Abstract

Aiming to evaluate power requirements and energy balance when introducing grain on physically degraded pasture fields, an experiment was established, comparing different winter crops (CN/P - Natural camp/ fallow; A-Oats; A+E - Oats plus vetch). With a planter coupled to the three point linkage of the tractor, maize and soybeans, (three and five rows, respectively), were planted, placing the fertilizer shank to work to 6 and 12 cm depths. The soil was fairly compacted averaging 1,7 Mg m-3 density. Completely randomized split plots were used working with four repetitions. Main treatments were the winter cover crops and summer grain crops (maize and soybeans), and secondary treatments were the working depth of fertilizer shanks. Fertilizer composed more than 65% of the total energy cost for maize growing; for soybeans it meant only 55% when following A + E and 42% following CN/P. Taking into account results from two years, the highest demand of energy was from those treatments using winter cover crops.