Effects liming surface application, on soybean grain quality, under non-tillage systems, based on the oil, protein and nutrient contents, are not well defined yet. A field trial was carried out on a dystrophic Red Latosol (Hapludox) at Ponta Grossa, State of Paraná, Brazil, to evaluate liming surface application effects, under a non-tillage scheme, on soybean yield, oil and protein contents, and grain mineral composition. A randomized complete block design was used, with three replications, in a split-plot experiment. In the main plots, four doses (0, 2, 4 and 6 t.ha-1) of dolomitic limestone were surface applied in July of 1993, and in the subplots two doses (0 and 3 t.ha-1) were reapplied in June of 2000. Soybean yield was evaluated in 2001/02. Liming had no effect on the efficiency of symbiotic N2 fixation, evaluated by total leaf-N, and on soybean grain, oil and protein yields, despite the high acidity (pH in CaCl2 4.3 and 25% of soil base saturation) in the soil surface layer (0-5 cm). Surface application of lime under a non-tillage system increased soybean oil and had no effect in protein contents. Surface liming application increased P and Ca, and decreased Zn contents in soybean grain. The increase of P and the reduction of Zn in grains were related (P < 0.01) to an increase of soil pH. Also Ca in grains increased in the same pattern as the increase of exchangeable Ca, in the soil surface layer (0-5 cm).
Glycine max (L.) Merrill; soil acidity; dolomitic limestone; oil; protein; nutrient
