Surface liming, phosphogypsum and single superphosphate for grain production in a no-till wheat-soybean cropping system

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Tropical and subtropical soils are acidic and have low nutrient reserves. To know how soil properties affect plant nutrition and crop yield, a field trial examined the effects of surface liming combined with single superphosphate (SSP) by broadcast and in the sowing furrow or phosphogypsum (PG) to the soil surface on the soil chemical properties and nutrition and yield of a wheat-soybean rotation under no-till in Southern Brazil. Surface-applied lime was effective in alleviating soil acidity from the soil surface to a 1.00 m depth. Combining liming with SSP or PG did not provide greater alleviation in acidity across the soil profile than lime alone. Liming increased Ca-leaf and Mg-leaf contents and reduced K-leaf content of wheat, as well as increased leaf contents of N, Ca, and Mg of soybean. Applying SSP, both broadcast or in the sowing furrow, and PG increased P and S leaf contents of wheat and soybean. The cumulative yield of five wheat harvests was increased by 40 % with surface lime, 54 % with surface lime + SSP in the sowing furrow, and 70 % with surface lime + SSP by broadcasting or PG to the soil surface. The cumulative yield of five soybean harvests was increased by 36 % with surface lime, regardless of the addition of SSP and PG. The combined use of surface liming either with broadcast SSP or with PG to the soil surface should be encouraged in a wheat-soybean cropping system under no-till because of the achievement of important increases in wheat yield.