Sulfur doses, organic compost and gypsum in macronutrients contents of collard greens leaves

Due to the lack of information related to fertilization of collard greens, the objective of the research was to evaluate the influence of sulfur doses in macronutrients contents in collard greens cultivated with organic compost and gypsum. Twelve treatments were evaluated in a split-plot: three types of soil preparation in plots and four sulfur doses top dressing in subplots. The three types of soil preparation were the incorporation of organic compost (30 t ha-1); gypsum (1.2 t ha-1); organic compost (30 t ha-1) plus gypsum (1.2 t ha-1). The total sulfur doses in top dressing were zero; 53.32; 106.68 and 160.00 kg ha-1 of S, equivalent to 0; 266; 532 and 800.0 kg ha-1of ammonium sulfate. For standardization of the nitrogen dose (280 kg∙ha-1), applied in top dressing it was used urea. From the dry matter of commercial leaves, it was evaluated the N, P, K, Ca, Mg and S contents. The types of soil preparation do not affect all macronutrients content. The sulfur top dressing applied does not alter the contents of leaf macronutrients N, P, K and Ca on collard greens cultivated with organic compost and gypsum. The sulfur content presents a linear increase, while for the magnesium content there is decrease the higher the sulfur doses. The decreasing order of macronutrient content of commercial collard greens leaves was K> N> Ca> Mg> S> P, with averages 37.92, 36.50, 21.69, 4.50, 4.23, 3.80 g kg-1, respectively.