Root growth, nutrition and crop yield can be affected by soil chemical modifications caused by superficial limestone and phosphogypsum application in a no-till system. Using this approach, this study was conducted in southeastern Brazil, continuing an experiment that has been ongoing since 2002 with the objective of evaluating the residual effects of the surface application of lime and phosphogypsum on the soil chemical characteristics and the root growth, nutrition and yield of soybean, black oat and sorghum in a dry winter region cultivated in 2008/2009 and 2009/2010. The experimental design was a randomized block with 4 replications. The treatments were applied in November 2004 and were as follows: original conditions, limestone application (2000 kg ha −1), phosphogypsum application (2100 kg ha −1), and limestone (2000 kg ha −1) + phosphogypsum (2100 kg ha −1) application. Superficial liming with or without phosphogypsum reduced the surface and subsurface soil acidity 5 years after application in the no-till system. The movement of Ca 2+ and Mg 2+ from the surface layer into the subsoil over time was evident. The phosphogypsum application associated with liming increased the Ca 2+ levels throughout the soil profile. Liming maintained high levels of Mg 2+ throughout the soil profile with or without phosphogypsum application. The organic matter content increased with liming with or without phosphogypsum, indicating that in the long term, these practices can increase the C accumulation. Phosphogypsum application had a residual effect on the SO 4-S levels, and high sulphate concentrations were observed in the subsoil after 5 years. Superficial liming improved crop nutrition and, when associated with phosphogypsum, increased Ca absorption by soybean and sorghum, as reflected in the increased yields of these crops.

Core Ideas Urochloa brizantha as cover crop produced more biomass and nutrient cycling than U. ruziziensis. Nitrogen fertilizer on Urochloa cover crops increased biomass production but limited maize yield. The highest maize yields were obtained when N was applied on day before seeding or under conventional method (N applied at seeding plus sidedressing). All N applied on Urochloa residue prior to maize can be an option, but is risky in regions of high rainfall. Crop residue decomposition is slower in no‐till (NT) systems, especially in high‐biomass systems. Adopting optimum nN management can provide increased soil coverage and synchronize the supply of nutrients with the period of highest crop demand in agroecosystems. A three‐year experiment was conducted to assess the feasibility of applying N on forage grass cover crops before termination {Urochloa brizantha (Hochst. Ex A. Rich.) R.D. Webster [syn. Brachiaria brizantha (Hochst. Ex A. Rich) Stapf] and Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins [syn. B. ruziziensis (R. Germ. and C.M. Evrard)]}, or on forage grass cover crop residues immediately before maize (Zea mays L.) seeding, aiming to supply N to the following maize crop. Urochloa brizantha had 25% higher biomass production and a higher amount of nutrient content than U. ruziziensis. The N application before termination increased biomass production and nutrient content in cover crop residues compared with the conventional fertilization method (30 kg N ha−1 in the maize seeeding plus 170 kg N ha−1 sidedressed in V6 growth stage). Nitrogen applied one day before seeding (DBS) of maize or using conventional method resulted in a higher number of ears per plant and more kernels per ear as well as a higher grain yields of maize (13.8 and 14.1 Mg ha−1, respectively) compared to N applied on cover crops. Our results suggest that, while both forage grass cover crops produced greater amounts of dry matter (DM) and released similar amounts of nutrients, applying all N to cover crops before maize is not a feasible alternative. Nitrogen application 1 DBS could be an alternative management option to supply N to maize because this method resulted in similar nitrogen use efficiency (NUE) as conventional fertilization method.

SUMMARYSilicon (Si) is beneficial to plants in several aspects, but there are doubts about the effectiveness of leaf application. The purpose of this work was to evaluate the effects of Si, applied in a newly developed stabilized silicic acid form to the leaf, on nutrition and yield of irrigated white oat and wheat. Two experiments were performed (one per crop) in winter 2008, in Botucatu-SP, Brazil. A completely randomized block design with 14 replications was used. Treatments consisted of a control (without Si application) and Si leaf spraying, at a rate of 2.0 L ha -1 of the commercial product containing 0.8 % soluble Si. Silicon rate was divided in three parts, i.e. applications at tillering, floral differentiation and booting stages. Silicon leaf application increased N, P, K, and Si concentrations in white oat flag leaf, resulting in higher shoot dry matter, number of panicles per m 2 , number of grains per panicle and grain yield increase of 34 %. In wheat, Si leaf application increased K and Si concentrations, shoot dry matter and number of spikes per m 2 , resulting in a grain yield increase of 26.9 %. Index terms: Avena sativa, Triticum aestivum, silicon, mineral nutrition, yield components.(1) Received for publication in August 8, 2011 and approved in July 11, 2012.

In tropical integrated crop-livestock under no-till (NT) systems, the surface application/reapplication of lime and/or gypsum can reduce re-acidification rate of the soil and improve plant nutrition, crop yields, and profitability. This study was conducted in the Brazilian Cerrado, which has dry winters, and aimed to evaluate the effects of surface application/ reapplication of lime and/or gypsum on soil improvement, plant nutrition and crop yield improvement, as well as the forage dry matter (DM) yield, estimated meat production, and economic results. The crop rotation used between November 2004 and August 2008 was as follows: peanut (Arachis hypogaea) and white oat (Avena sativa) cultivated alone (on the first and second spring/summer and autumn/winter, respectively) and corn (Zea mays) intercropped with palisade grass [Urochloa brizantha cv. 'Marandu'] and pasture (on the third and fourth spring/summer and autumn/winter, respectively). The experimental design was a randomized block with four replications. The treatments consisted of natural conditions of a sandy clay loam kaolinitic and thermic Typic Haplorthox (control) and the surface application of lime and/or gypsum in October 2002 and reapplication in November 2004. Surface liming was an efficient practice for increasing pH and reducing the exchangeable acidity (H ? Al) and concentration of Al extending to a depth of 0.60 m. Gypsum application increased Ca 2? levels through the soil profile. Liming (with or without gypsum) had a positive effect on the nutrient acquisition by peanut, white oat, and corn crops, producing on average 48%, 52%, and 61% more pod and grain yield, respectively, than that obtained in the absence of soil amendments and with gypsum