Simulated soil erosion and crop productivity

Non-Peer ReviewedSeveral different soil types were employed to study the effects of simulated soil erosion on wheat and canola productivity. Varying amounts of topsoil were scraped from the surface of experimental fields and crops were grown using three levels of fertilizer applications. Topsoil removal treatments included 0 cm removed, (a basis for comparison) , 5, 10, and 20 cm of topsoil removed. Fertilizer application treatments consisted of no fertilizer applied, recommended rate of fertilizer applied and approximately double the recommended rate. Crops utilized for this study were Columbus wheat and Westar canola. It was found that yields generally decreased as the amount of topsoil removed increased. Data indicated yields to be severely depressed on all topsoil removal treatments where no fertilizer was applied. Soil texture played a role in determining the outcome of yields in that on the coarse textured soils, even twice the recommended rate of fertilizer was not able to bring the yields back to that of the control. The recommended rate of fertilizer application was able, on the other hand, to mitigate topsoil losses on the fine textured soils and in some cases yields exceeded the control at twice the recommended rate of fertilizer

The concept of matric flux potential applied to simulation of evaporation from soil.

Two simulation models of evaporation were based respectively on (a) soil matric flux potential and (b) soil hydraulic conductivity and water potential. Mathematical analysis showed that the former method gave a lower and more accurate estimate of soil water movement in unsaturated soil, and therefore of evaporation from the soil. The difference between the accuracy of the two methods tended to be greatest in soils of coarse texture. The matric flux potential method required less computer time than the other method did. (Abstract retrieved from CAB Abstracts by CABI’s permission

Avaliação da embebição e do desenvolvimento inicial das estruturas embrionárias de sementes de milho submetidas a diferentes potenciais hídricos

Substrates with water potentials between O and -12atm, were used to evaluate the behavior of corn seeds during the germination process. Water deficiency treatments were compared with the control (adequate available water) using seeds with and without fungicide treatment. The analysis and the interpretation of the results permitted to conclude that the absorption of water, the emergency and the initial development of the embryonic structures are interdependent and vary with the water deficit. For these cases the reduction of water potential promotes difficulties in the evolution of the processes. The presence of fungicide treatment may not influence quantitatively the processes occurring in the beginning of the germination.Empregando substratos com potenciais hídricos variáveis entre 0 e -12atm, o presente trabalho objetivou avaliar o comportamento das sementes de milho postas a germinar. As situações de deficiência hídrica foram diretamente comparadas à testemunha (plena disponibilidade de água), usando sementes com e sem tratamento fungicida. A análise e a interpretação dos resultados permitiram concluir que a absorção de água, a emergência e o desenvolvimento inicial das estruturas embrionárias são interdependentes e reagem no mesmo sentido ao déficit hídrico; para esses casos, a redução do potencial hídrico promove dificuldades na evolução dos processos. Paralelamente, a presença de tratamento fungicida pode não influenciar, quantitativamente, os fenômenos envolvidos no início da germinação