stand establishment in crusting soil is one of the main concerns in the production of crops with delicate seedlings such as cotton, onions and rape seed. crust breaking, maintaining soil moisture and adding chemical and organic amendments to soil are different methods to weaken soil strength and allow the shoots to emerge. these methods are not always successful because they depend on factors s...

crust breaking of saffron is an important operation at the first stage of growth that should be accuratly operated as in this period sprouts of saffron rise up to near the soil surface. after primary irrigation, farmers soften the soil surface by means of different cultivation implements, which enables saffron flowers arise from subsurfarce. this research was conducted to compare tillage implem...

In soil mechanics, student's models are classified as simple models that teach us unexplained elements of behaviour; an example is the Cam clay constitutive models of critical state soil mechanics (CSSM). 'Engineer's models' are models that elaborate the theory to fit more behavioural trends; this is usually done by adding fitting parameters to the student's models. Can currently unexplained be...

For most of history, few things have mattered more to human communities than their relations with soil, because soil provided most of their food and nutrients. Accordingly, some of the earliest written documents were agricultural manuals intended to organize, preserve, and impart soil knowledge. Indeed, ancient civilizations often worshipped the soil as the foundry of life itself. For the past ...

Pavement breaking generates a high level of ground vibration that is potentially damaging to nearby buildings and infrastructures. In this paper, a numerical model for the estimation of the impact load due the blow of a falling-weight pavement breaker is first developed. The estimated impact load is in good agreement with the experimental result. Next, the fracturing of the concrete road is inv...

The acquisition by parasites of the capacity to infect resistant host genotypes, that is, resistance-breaking, is predicted to be hindered by across-host fitness trade-offs. All analyses of costs of resistance-breaking in plant viruses have focused on within-host multiplication without considering other fitness components, which may limit understanding of virus evolution. We have reported that ...

Long-term tillage negatively affects soil aggregation, but little is known about the short-term effects of tillage. We investigated the effects of intensive tillage (moldboard plowing) and conservation tillage (chisel plowing) on aggregate breakage during tillage in a long-term study located in the semiarid Ebro river valley (NE Spain). The type of tillage resulted in different soil aggregate d...

To study Assessing the impact of tillage practices on soil carbon losses dependents it is necessary to describe the temporal variability of soil CO2 emission after tillage. It has been argued that large amounts of CO2 emitted after tillage may serve as an indicator for longer-term changes in soil carbon stocks. Here we present a two-step function model based on soil temperature and soil moistur...