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

Soil acidity and low natural fertility are the main limiting factors for grain production in tropical regions such as the Brazilian Cerrado. The application of lime to the surface of no-till soil can improve plant nutrition, dry matter production, crop yields and revenue. The present study, conducted at the Lageado Experimental Farm in Botucatu, State of São Paulo, Brazil, is part of an ongoing research project initiated in 2002 to evaluate the long-term effects of the surface application of lime on the soil's chemical attributes, nutrition and kernel/grain yield of peanut (Arachis hypogaea), white oat (Avena sativa L.) and maize (Zea mays L.) intercropped with palisade grass (Urochloa brizantha cv. Marandu), as well as the forage dry matter yield of palisade grass in winter/spring, its crude protein concentration, estimated meat production, and revenue in a tropical region with a dry winter during four growing seasons. The experiment was designed in randomized blocks with four replications. The treatments consisted of four rates of lime application (0, 1000, 2000 and 4000 kg ha −1), performed in November 2004. The surface application of limestone to the studied tropical no-till soil was efficient in reducing soil acidity from the surface down to a depth of 0.60 m and resulted in greater availability of P and K at the soil surface. Ca and Mg availability in the soil also increased with the lime application rate, up to a depth of 0.60 m. Nutrient absorption was enhanced with liming, especially regarding the nutrient uptake of K, Ca and Mg by plants. Significant increases in the yield components and kernel/grain yields of peanut, white oat and maize were obtained through the surface application of limestone. The lime rates estimated to achieve the maximum grain yield, especially in white oat and maize, were very close to the rates necessary to increase the base saturation of a soil sample collected at a depth of 0-0.20 m to 70%, indicating that the surface liming of 2000 kg ha −1 is effective for the studied tropical no-till soil. This lime rate also increases the forage dry matter yield, crude protein concentration and estimated meat production during winter/spring in the maize-palisade grass intercropping, provides the highest total and mean net profit during the four growing seasons, and can improve the long-term sustainability of tropical agriculture in the Brazilian Cerrado.

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entressafra (08/05/00) e o outro em época convencional, na safra de verão (27/11/00); em ambos se avaliaou o comportamento das variedades de soja: Conquista (MG/BR 46) e Liderança (MG/BRS 66), submetidas a 4 doses de potássio (0, 40, 80 e 160 kg ha -1 de K 2 O). Utilizou-se delineamento experimental em blocos casualizados com quatro repetições, cujos tratamentos se dispunham em um esquema fatorial 2 x 4 (variedades e doses), em cada época de semeadura. Nas duas épocas de semeadura as variedades diferiram significativamente em todas as características agronômicas avaliadas, destacando-se a variedade Conquista com os maiores valores, com exceção para número de vagens por planta na semeadura em época convencional. Não se observou interação significativa entre as variedades e doses de potássio (K). Com relação às doses constatou-se apenas uma resposta significativa para altura de planta, na semeadura em época de entressafra. As concentrações de K observadas nos grãos não variaram proporcionalmente em função das doses utilizadas. Palavras-chave: Glycine max, cloreto de potássio, variedadesPotassium fertilization in soybean in two times of sowing AB S TR ACTIn a typical Oxisol of Mato Grosso do Sul State, Brazil cerrado área, two experiments were carried out, being one with sowing in off-season time (08/05/00) and the other in conventional time (27/11/ 00). In both experiments, the behavior of two soybean varieties was evaluated: Conquista (MG/BR 46) and Liderança (MG/BRS 66), submitted to 4 potassium doses (0, 40, 80 and 160 kg ha -1 of K 2 O). The experimental design was in randomized blocks with four repetitions, and the treatments disposed in a factorial outline 2 x 4, (varieties and doses), in each sowing time. In both sowings, the varieties differed significantly in all the agronomic characteristics appraised, standing out the variety Conquista with the largest values, with exception for number of green beans for plant in the sowing in conventional time. Significant interaction was not observed between the varieties and potassium (K) doses. Regarding the doses, just a significant answer was observed for plant height in the off season sowing time. The amounts of K observed in the grains didn't vary proportionally in function of the used doses; therefore extra absorption of the nutrient was not verified.

SUMMARYLime and gypsum influence nutrient availability and uptake, as well as the content of organic acids in the aerial plant parts. These changes, quantified by plant analysis of soluble nutrients, may potentiate the effect of soil amendment, ensuring the sustainability of the no-tillage system. In this sense the effect of lime and gypsum surface application on the content of water-soluble nutrients in peanut and oat residues was evaluated. The experiment was conducted on an Oxisol in Botucatu (