Soil mechanical resistance, aeration, and water availability directly affect plant root growth. The objective of this work was to identify the contribution of mechanical and hydric stresses on maize root elongation, by modeling root growth while taking the dynamics of these stresses in an Oxisol into consideration. The maize crop was cultivated under four compaction levels (soil chiseling, no-tillage system, areas trafficked by a tractor, and trafficked by a harvester), and we present a new model, which allows to distinguish between mechanical and hydric stresses. Root length density profiles, soil bulk density, and soil water retention curves were determined for four compaction levels up to 50 cm in depth. Furthermore, grain yield and shoot biomass of maize were quantified. The new model described the mechanical and hydric stresses during maize growth with field data for the first time in maize crop. Simulations of root length density in 1D and 2D showed adequate agreement with the values measured under field conditions. Simulation makes it possible to identify the interaction between the soil physical conditions and maize root growth. Compared to the no-tillage system, grain yield was reduced due to compaction caused by harvester traffic and by soil chiseling. The root growth was reduced by the occurrence of mechanical and hydric stresses during the crop cycle, the principal stresses were mechanical in origin for areas with agricultural traffic, and water based in areas with soil chiseling. Including mechanical and hydric stresses in root growth models can help to predict future scenarios, and coupling soil biophysical models with weather, soil, and crop responses will help to improve agricultural management. The maize crop was cultivated under four compaction levels (soil chiseling, no-tillage system, areas trafficked by a tractor, and trafficked by a harvester), and we present a new model, which allows to distinguish between mechanical and hydric stresses. Root length density profiles, soil bulk density, and soil water retention curves were determined for four compaction levels up to 50 cm in depth. Furthermore, grain yield and shoot biomass of maize were quantified. The new model described the mechanical and hydric stresses during maize growth with field data for the first time in maize crop. However, soil compaction alone is not always the problem, and therefore a quantification how it affects crop yield and root growth is of high relevance. The effect of soil compaction has led to many debates, especially regarding the establishment of critical limits to plant growth ( Moraes et al., 2014 ; De Jong van Lier and Gubiani, 2015 ). If there is no chemical or biological limitation, plant growth is mainly directly affected by four physical factors in soils, which are temperature, aeration, resistance, and water content ( Letey, 1985 ). Moreover, it is indirectly affected by several soil characteristics, for example, texture, aggregate structure, and pore size and distribution ( Letey, 1985 ). Mathematical modeling has become an important tool for describing the functionality of biophysical processes including soil–root interactions, such as water absorption and root growth ( Dupuy et al., 2010 ). The physical conditions of the soil that influence plant growth are dynamic in time and space, and an improvement in the techniques used for the understanding of these conditions is necessary. (2010b) . The results of the model are variables of the soil (water balance, infiltration, runoff and deep drainage, real evaporation, water content, matric The modeling of the stresses of root elongation and root growth during the maize development cycle indicated that there were changes in the soil physical conditions during the crop cycle under the compaction levels ( Figure 10 ). The transpiration rate of maize, during the initial period of development, was lower in the areas with chiseled soil than in the other treatments ( Figure 11 ). The depth of the root system and the root elongation rate were altered due to the water and mechanical stress in the soil profile over a growth season. In addition, there are other factors ( e.g. , hydraulic root resistance, root radial and axial conductivity, root mucilage and rhizosphere hydraulic properties) that were not included in this model, as well as biological ( e.g. , rhizosphere microorganisms) and chemical factors ( e.g. , chemical signals, redox potential, and nutrient available) ( Vereecken et al., 2016 ) that could affect the root growth. Models of root growth, because of soil hydric and mechanical stress on the elongation of roots, are dynamic in time and space and are, therefore, useful for the interpretation of the soil alterations that can affect plant growth. Because the physical properties that limit root elongation (soil resistance to penetration, aeration, and water content) are heterogeneous and dynamic in time, the only way to infer their effect on overall root development and root water uptake was through modeling ( Figure 10 ). In line with results of, e.g. , Nosalewicz and Lipiec (2014) , actual transpiration ( i.e. , root water uptake) ( Figure 10 ) was reduced with increasing soil compaction. Biopores decrease the axial pressure on the root tip, while still exerting radial pressures on the root in narrow pores ( Bengough, 2012a ) decreasing the root diameter ( Jin et al., 2013 ). Conclusions Maize root growth modeling, including soil physical limitations (mechanical and hydric stress), can be used for the analysis of architecture development associated with soil water flow models, increasing the fundamental understanding of stress that acts on the growing roots. Experimental data showed that the no-tillage system provided the best soil physical conditions for maximum maize yields. In the other scenarios, yield was reduced due to soil chiseling and/or through the excessive level of compaction caused by harvester traffic.

Abstract Soil compaction is a serious problem globally with 20% of arable land at risk from compaction in regions for food production. Compaction can affect intensive grasslands. Damaging the structure of the soil of grassland through compaction can reduce dry matter yield by 14% from tractor compaction after 3 years. One method of reducing soil compaction in grassland production is with controlled traffic (CT), which involves restricting the movement of agricultural machinery to set areas of a field. Global Navigation Satellite System (GNSS) was used to track all traffic across two grass silage fields in south-west Scotland over 3 years: one with CT and the other with normal traffic (NT). The fields were sown with 50/50 perennial ryegrass/red clover and monitored for dry matter (DM) yield. Yields were compared within each field as strips with Nil nitrogen (N), Moderate N and High N. CT gave greater dry matter yield for all the N treatments and years than NT. Increases were 7.0% for Nil N treatment, 8.2% for Moderate N treatment and 9.3% for High N over 3 years. The soil structure was better across the CT field than the NT field with more earthworms; however, soil organic matter (SOM) was not affected. Information © The Author 2025