Nutrition and grain yield of black oatas affected by surface application of lime and phosphogypsum at the establishment of no-tillage system

Nutrition and crop yield can be affected by chemical modifications of the soil owing to lime and phosphogypsum surface application. The purpose of this study was to evaluate the effects of surface application of lime and phosphogypsum, at the establishment of a no-tillage system, on nutrition and grain yield of black oat, in a dry-winter region, in area previously used with conventional tillage. The experiment was carried out in 2003 and 2004, on a Haplorthox in Botucatu County, Sao Paulo State, Brazil. A randomized complete block design was used in a split-plot scheme with four replications. The plots(18.0x5.4m) were composed by four dolomitic limestone levels (0; 1,100; 2,700, and 4,300 kg ha(-1)), with Neutralization Power = 84.3 % and Reactivity = 84.5 %, and the subplots (9.0 x 5.4 m) were composed by without and with phosphogypsum application (2,100 kg ha(-1)). The increase in soil Ca as a result of lime and phosphogypsum application, reduced the Mg content in the black oat flag leaf in a year with water deficiency. Surface liming increased K and reduced Cu and Fe concentration in the black oat flag leaf. Surface application of phosphogypsum increased the S content in the black oat flag leaf Surface liming increased the black oat grain yield in the year with water deficiency, with higher effects being observed when phosphogypsum was applied.