Julio Cesar Salton

Perdas por erosão e rendimentos de soja e de trigo em diferentes sistemas de preparo de um latossolo roxo de Dourados (MS)

Soil and water losses were evaluated from 1987 to 1995, on a very clayey red dusky latosol, with 0.03 m m-1 slope, of Embrapa-Centro de Pesquisa Agropecuaria do Oeste, at Dourados, Mato Grosso do Sul State, Brazil. Soil tillage systems used for growing wheat and soybean in succession were: chisel plow + tandem disk (ES), offset disk + tandem disk (GP), no tillage (PD) and conventional tillage, with no vegetable cover (DE). All tillage operations and seeding were in the up and down hill. PD was the most efficient tillage system to control soil and water losses and was the most productive. GP was the least efficient. Means of soil and water losses for PD, ES, GP and DE were, respectively: 0.8; 2.8; 5.3 and 7.3 t ha-1 year-1, and 27, 80, 112, and 149 mm year-1. Compared to DE, the PD controlled 89% of soil and 82% of water erosion losses, and yielded 17% more soybean and wheat grain than GP. As for wheat, ES was 12% more productive than GP. Rainfall-runoff erosivity factor (R) was 6.411 MJ mm ha-1 h-1 year-1, and the erodibility fator (K) was 0.0045 t h MJ-1 mm-1, reflecting characteristics of high infiltration and high internal drainage of this soil. During the 1994/95 growing season, the highest soil loss period per time unit was from seedbed preparation to seeding soybean, and the period of highest absolute soil erosion losses was from 30 to 60 days after seeding soybean. This shows the great importance of soil cover, specially during the inicial cropping phase, and support the recommendation of the no tillage system for this region.

Teor e dinâmica do carbono no solo em sistemas de integração lavoura-pecuária

The objective of this work was to evaluate the ability of soil management systems to change the contents and dynamics of soil carbon. Natural vegetation and systems composed of perennial tropical pastures, annual crops under conventional tillage and no-tillage systems, and pasture rotation with annual crops were evaluated in long-term experiments carried out in Dourados, Maracaju and Campo Grande, Mato Grosso do Sul state, Brazil. The experiments were set in a completely randomized block design, in Dourados and Maracaju, and in a randomized complete block design in Campo Grande. Contents and stocks of total C in soil and in soil organic matter (SOM) fractions were measured. The quality of SOM was estimated by the ratio of C in labile and nonlabile fractions, and expressed in the form of lability. Permanent pasture or pasture in rotation with crops increased C in the particulate fraction and the SOM lability. Lower rates of accumulation and of stocks of soil C were observed in systems explored only with annual crops, while higher values were recorded in systems with pasture.

Variáveis relacionadas à estabilidade de complexos organo-minerais em solos tropicais e subtropicais brasileiros

A estabilidade de complexos organo-minerais e uma caracteristica importante quanto a quimica e fisica de solos tropicais e subtropicais. O objetivo deste estudo foi identificar variaveis relacionadas a estabilidade de complexos organo-minerais, avaliada pela energia de ultra-som necessaria para a dispersao total do solo em particulas primarias, em seis solos das regioes Sul e Centro-Oeste do Brasil com textura e mineralogia distintas. A energia de ultra-som necessaria para dispersao total dos solos variou de 239 a 2.389J mL-1, sendo diretamente relacionada aos teores de carbono orgânico (R2=0,799, P<0,05). A mineralogia da fracao argila teve um papel determinante na estabilidade dos complexos organo-minerais, a qual foi relacionada aos teores de oxidos de ferro de baixa cristalinidade (R2=0,586, P<0,10), mas nao teve relacao com os teores totais de oxido de ferro pedogenicos. A analise qualitativa da fracao argila, realizada por difratometria de raios-X, demonstrou que a estabilidade dos complexos organo-minerais variou positivamente em funcao das proporcoes de gibbsita e de goethita na fracao argila, o que reforca o papel desses minerais na protecao fisica e estabilidade coloidal da materia orgânica em solos tropicais e subtropicais.

Fauna invertebrada e atributos físicos e químicos do solo em sistemas de integração lavoura-pecuária

The objective of this work was to evaluate the effect of integrated crop-livestock (ICL) systems on the main groups of soil invertebrate macrofauna and the relationship of these organisms with soil physical and chemical attributes. The conventional system, integrated crop-livestock system, no-tillage system, continuously cultivated pasture, and natural fragments of Cerrado and of semi-deciduous forest were compared. The experiment was carried out in Dourados, MS, Brazil, on a Typic Hapludox soil, divided into strips. The highest density, richness, and diversity of families were found in the ICL system, under no-tillage, and in the continuously cultivated pasture. The conventional system caused greater reduction of the soil invertebrate community. The ICL system favors the maintenance of the invertebrate fauna diversity, the formation of stable aggregates, and soil fertility. The Sthaphylinidae family is a potential soil quality bioindicator, especially in the semi-deciduous forest and in the ICL system.

Índice de manejo de carbono e atributos químicos de Latossolo Vermelho sob diferentes sistemas de manejo

The objective of this work was to evaluate changes in the soil chemical attributes, carbon stock and in the C management index of a clayed Oxisol under different management systems. The soil under management systems with different historical usage was evaluated under the following covers: Zea mays, Urochloa decumbens, Panicum maximum cv. Tanzania. A cerrado area was used as check. Four composite samples were collected at 0-5, 5-10 and 10-20 cm soil depths. The phosphorus contents decreased with depth, and the higher values were observed in the area with P. maximum. In the area with Z. mays, higher values for K+, Ca++, Mg++, CEC, and base sum and saturation were observed. The total organic C content (TOC) was higher under cerrado vegetation cover, and smaller under P. maximum at 5-10 cm soil depth. The higher stocks of TOC, and of carbon in particulate fractions (C-POM) and in fractions associate to the soil mineral phase occurred in the area with U. decumbens, which promoted higher values for lability and C management indexes, similar to those for cerrado vegetation. In all coverings, the organic soil matter lability decreased with depth. The C-POM fraction had higher sensibility to variation in management practices, and is related to TOC.