Modelling structural changes in tilled topsoil over time as a function of cropping systems

Abstract

The optimization of tillage practices requires the evaluation of the long-term effects of cropping on changes in soil structure. A model is presented that simulates changes in soil structure in the tilled horizons of cultivated ®elds. The indicator of soil structure that we have modelled is based on a morphological description of the structure and the assessment of the percentage of severely compacted zones and clods showing no visible porosity in the tilled layer of a soil pro®le. The model takes into account the spatial variation of the structure induced by traf®c and tillage. Severely compacted zones are created under wheel tracks, they are cut and transferred during ploughing, and they are fragmented into ®ne soil during secondary tillage. The model was evaluated over 7 years in a ®eld trial on loamy soil in three experimental plots, where the crop sequences and ®eld operations induced contrasted changes in the percentage of severely compacted zones and clods. The model satisfactorily reproduced the changes with time of the indicator, and the correspondence between simulated and observed values was fairly good (r = 0.82, model ef®ciency = 0.61). However, some variations from one year to the next were poorly predicted. The sensitivity analysis did not suggest modi®cation to the parameter values but showed that the performance of the model could be improved if the fragmentation (due to weather and tillage) were more precisely described in the model. Nevertheless the present version of the model and the corresponding simulation program (SISOL) can be used to compare the effects of different technical choices on the evolution of soil structure.Correspondence: J. Roger-Estrade.

Soil compaction modifies morphological characteristics of seminal maize roots

“…During most agricultural practices, mechanized cultivation disturbs the soil, causing fragmentation, compaction and displacement (Roger-Estrade et al 2000). Consequently, two types of earth may appear within the soil profile: fine and compacted zones (most often defined as clods).…”

Modeling water and isoproturon dynamics in a heterogeneous soil profile under different urban waste compost applications

“…Although the soil was tilled every year, the material distribution in the tilled layer was kept constant. This choice was supported by the fact that the overall structure of the tilled layer reaches a steady state within a few years under constant agricultural practices (Roger-Estrade et al, 2000) which was the case in the current experiment. The BT and BT/IC horizons were divided into two layers in order to correspond with the field measurements (TDR, tensiometers) installed at two different depths within these horizons.…”

“…This method is used to describe the soil structure of the tilled layer of agricultural fields. It is based on the visual observation of soil macroscopic features on the vertical face of a large soil pit oriented perpendicular to the tillage direction (Coutadeur et al, 2002;Roger-Estrade et al, 2000). The soil profile was divided into vertical and horizontal compartments according to the effects of the tillage implements and the internal structure of each of these compartments.…”

Physical Properties of Soil Structures Identified by the Profil Cultural under Two Soil Management Systems

“…It enables researchers to establish links between soil structure and other factors, such as root development (Roger-Estrade et al, 2000a;Mentges et al, 2016), the availability and distribution of minerals (Vizier et al, 1995), and hydrodynamic characteristics (Mentges et al, 2016).…”